Patent Publication Number: US-6911734-B2

Title: Semiconductor device and electronic device

Description:
This application is a divisional application of U.S. application Ser. No. 10/372,898 tiled on Feb. 26, 2003. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a semiconductor device and an electronic device, and particularly to a technology effective for application to transmission of a high-frequency signal. 
   There has heretofore been known a structure having adopted a coaxial cable as high-speed signal transmission means. A semiconductor package (semiconductor device) of a PGA (Pin Grid Array) type makes use of a coaxial cable as a signal transmission path extending in its thickness direction between a part packaging surface of a multilayered wiring board and its back surface (see the following patent document 1, for example). 
   There has been also known one wherein a coaxial cable is used in an optical communication apparatus (see the following non-patent document 1, for example). 
   Patent document 1: 
   Unexamined Patent Publication No. Hei 5(1993)-167258 ( FIG. 1 ) 
   Non-patent document 1: 
   “Various Characteristics of 565 Mb/s Optical Transmitter Using DFB-LD” by Shoichi Hanaya, Katsuyoshi Karasawa, Kichi Yamashita, and Minoru Maeda, National Meeting of Communication, Optical and Radio Departments, Published in Sep. 3, 1986 (Showa 61) (pp 2-170,  FIG. 2 ) 
   SUMMARY OF THE INVENTION 
   The input/output of a signal to a semiconductor package has heretofore been performed via “wirings”. However, a problem arises in that with the operation of a semiconductor chip mounted on the semiconductor package in a high-frequency region, the efficiency of propagation of the signal is degraded if no suitable wiring structure design is carried out, thus causing degradation in high-frequency characteristics. 
   In the PGA type semiconductor package having adopted the coaxial cable, a core line of the coaxial cable and its corresponding surface wiring of the multilayered wiring board are bonded to each other in a state of being struck at right angles. The difference in sectional area as viewed in a direction normal to a core-line extending direction between the core line and the surface wiring is large. Therefore, the signal is reflected by a spot where the area of a bonding portion of the core line and the surface wiring changes. 
   As a result, a problem arises in that the high-frequency characteristics are degraded. 
   The present inventors have discussed, as a structure for realizing a high-frequency semiconductor device connected to a coaxial cable, a structure wherein inner leads are connected to a package substrate with a high-frequency semiconductor chip mounted thereon, as external connecting terminals thereof, and outer leads respectively coupled to the inner leads protrude from the package substrate to the outside thereof along a plane direction thereof. 
   However, the structure wherein the outer leads protrude outwardly of the package substrate along the plane direction thereof, is accompanied by a problem that its size reduction cannot be achieved. 
   An object of the present invention is to provide a semiconductor device and an electronic device which improve the quality of high-frequency characteristics. 
   Another object of the present invention is to provide a semiconductor device and an electronic device both of which can be downsized. 
   A further object of the present invention is to provide a semiconductor device and an electronic device both of which can be thinned. 
   A still further object of the present invention is to provide a semiconductor device and an electronic device both of which can be reduced in cost. 
   The above, other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings. 
   A summary of a typical one of the inventions disclosed in the present application will be described in brief as follows: 
   The present invention provides a semiconductor device comprising a wiring board formed with a surface layer wiring, a semiconductor chip electrically connected to and mounted on the wiring board, a plurality of external connecting terminals provided within either a main surface of the wiring board or a back surface thereof opposite to the main surface, and a transmission line section electrically connected to the surface layer wiring of the wiring board, wherein at least either input or output of a signal to the semiconductor chip is performed through the transmission line section. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view showing one example of a structure of a semiconductor device (high-frequency package) according to a first embodiment of the present invention; 
       FIG. 2  is an external perspective view illustrating one example of a structure of an optical module with the high-frequency package shown in  FIG. 1  built therein; 
       FIG. 3  is a cross-sectional view depicting the structure of the optical module shown in  FIG. 2 ; 
       FIG. 4  is a plan view showing one example of a layout of parts built in the optical module shown in  FIG. 2 ; 
       FIG. 5  is a cross-sectional view illustrating one example of the layout of the parts built in the optical module shown in  FIG. 2 ; 
       FIG. 6  is a cross-sectional view showing a structure of a semiconductor device (high-frequency package) according to a modification of the first embodiment of the present invention; 
       FIG. 7  is a partly plan view illustrating one example of a structure of a microstrip line of a wiring board employed in the high-frequency package shown in  FIG. 1 ; 
       FIG. 8  is a partly cross-sectional view showing the structure of the microstrip line shown in  FIG. 7 ; 
       FIG. 9  is a partly plan view depicting a structure of a microstrip line illustrative of a modification of the microstrip line of the wiring board employed in the high-frequency package shown in  FIG. 1 ; 
       FIG. 10  is a partly cross-sectional view showing the structure of the microstrip line illustrative of the modification shown in  FIG. 9 ; 
       FIG. 11  is a perspective view and a cross-sectional view showing a structure of a semiconductor device (high-frequency package) illustrative of another modification of the first embodiment of the present invention; 
       FIG. 12  is a cross-sectional view depicting one example of a cap-mounted structure of the high-frequency package shown in  FIG. 1 ; 
       FIG. 13  is a plan view of the cap-mounted structure shown in  FIG. 12 ; 
       FIG. 14  is a cross-sectional view showing a structure of a cross-section cut along line A—A of  FIG. 13 ; 
       FIG. 15  is a bottom view of the cap-mounted structure shown in  FIG. 13 ; 
       FIG. 16  is a plan view showing one example of the relationship of position between surface layer wirings and a cap employed in the cap-mounted structure shown in  FIG. 12 ; 
       FIG. 17  is a bottom view illustrating a structure of the cap as seen in the direction indicated by an arrow C of  FIG. 14 ; 
       FIG. 18  is a side view showing the structure of the cap shown in  FIG. 17 ; 
       FIG. 19  is a cross-sectional view illustrating the structure of the cap shown in FIG.  17  and an enlarged partly cross-sectional view of its corner; 
       FIG. 20  is an enlarged partly cross-sectional view showing a detailed structure of the cross-section cut along line A—A of  FIG. 13 ; 
       FIG. 21  is an enlarged partly cross-sectional view illustrating a detailed structure of a cross-section cut along line B—B of  FIG. 13 ; 
       FIG. 22  is an enlarged partly plan view showing one example of the relationship of position between the surface layer wirings employed in the cap-mounted structure shown in FIG.  12  and an opening of the cap employed therein; 
       FIG. 23  is a cross-sectional view illustrating a structure of a semiconductor device (high-frequency package) illustrative of a further modification of the first embodiment of the present invention; 
       FIG. 24  is an enlarged partly cross-sectional view showing one example of a structure wherein a radiating member is mounted to the cap shown in  FIG. 12 ; 
       FIG. 25  is a cross-sectional view depicting a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 26  is a cross-sectional view showing a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 27  is a cross-sectional view depicting a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 28  is a plan view showing a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 29  is a cross-sectional view illustrating the structure of the high-frequency package shown in  FIG. 28 ; 
       FIG. 30  is a plan view showing a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 31  is a plan view depicting a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 32  is a plan view showing a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 33  is a plan view depicting a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 34  is a cross-sectional view showing the structure of the high-frequency package illustrated in  FIG. 33 ; 
       FIG. 35  is a plan view depicting a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 36  is a cross-sectional view showing the structure of the high-frequency package depicted in  FIG. 35 ; 
       FIG. 37  is a plan view depicting a structure of a semiconductor device (high-frequency package) illustrative of a still further modification of the first embodiment of the present invention; 
       FIG. 38  is a cross-sectional view showing the structure of the high-frequency package illustrated in  FIG. 37 ; 
       FIG. 39  is a cross-sectional view showing a structure of a semiconductor device (high-frequency package) according to a second embodiment of the present invention; 
       FIG. 40  is a cross-sectional view showing a structure of a semiconductor device (high-frequency package) illustrative of a modification of the second embodiment of the present invention; 
       FIG. 41  is a cross-sectional view depicting a structure of a semiconductor device (high-frequency package) illustrative of another modification of the second embodiment of the present invention; 
       FIG. 42  is a cross-sectional view showing one example of a state in which a cap is mounted upon assembly of the high-frequency package shown in  FIG. 41 ; 
       FIG. 43  is a partly cross-sectional view depicting one example of a state in which an auxiliary substrate and a coaxial cable are connected to each other upon assembly of the high-frequency package shown in  FIG. 41 ; 
       FIG. 44  is a partly cross-sectional view showing one example of a testing state at the assembly of the high-frequency package shown in  FIG. 41 ; 
       FIG. 45  is a partly cross-sectional view depicting one example of a structure subsequent to the completion of assembly of the high-frequency package shown in  FIG. 41 ; 
       FIG. 46  is a plan view showing one example of a layout of parts built in an optical module according to a third embodiment of the present invention; 
       FIG. 47  is a cross-sectional view illustrating one example of the layout of the parts built in the optical module shown in  FIG. 46 ; 
       FIG. 48  is a cross-sectional view showing a modification of a connecting method of a transmission line section employed in the optical module shown in  FIG. 46 ; 
       FIG. 49  is a plan view depicting a layout of parts built in an optical module illustrative of a modification of the third embodiment of the present invention; 
       FIG. 50  is a cross-sectional view showing one example of the layout of the parts built in the optical module shown in  FIG. 49 ; 
       FIG. 51  is a plan view illustrating a structure of a tape-shaped transmission line section showing one example of the transmission line section employed in the third embodiment of the present invention; 
       FIG. 52  is a cross-sectional view showing a structure of a cross-section cut along line A—A shown in  FIG. 51 ; 
       FIG. 53  is a cross-sectional view illustrating a structure of a cross-section cut along line B—B shown in  FIG. 51 ; 
       FIG. 54  is a back view showing a structure of a back surface of the tape-shaped transmission line section shown in  FIG. 51 ; 
       FIG. 55  is a cross-sectional view illustrating a structure of a cross-section cut along line C—C shown in  FIG. 51 ; 
       FIG. 56  is a plan view showing a structure of a tape-shaped transmission line section illustrative of a modification of the third embodiment of the present invention; 
       FIG. 57  is a cross-sectional view illustrating a structure of a cross-section cut along line A—A shown in  FIG. 56 ; 
       FIG. 58  is a cross-sectional view showing a structure of a cross-section cut along line B—B shown in  FIG. 56 ; 
       FIG. 59  is a back view depicting a structure of a back surface of the tape-shaped transmission line section shown in  FIG. 56 ; 
       FIG. 60  is a cross-sectional view illustrating a structure of a cross-section cut along line C—C shown in  FIG. 56 ; 
       FIG. 61  is a plan view showing a structure of a tape-shaped transmission line section illustrative of another modification of the third embodiment of the present invention; 
       FIG. 62  is a cross-sectional view depicting a structure of a cross-section cut along line A—A shown in  FIG. 61 ; 
       FIG. 63  is a cross-sectional view showing a structure of a cross-section cut along line B—B shown in  FIG. 61 ; 
       FIG. 64  is a back view showing a structure of a back surface of the tape-shaped transmission line section shown in  FIG. 61 ; 
       FIG. 65  is a cross-sectional view illustrating a structure of a cross-section cut along line C—C shown in  FIG. 61 ; 
       FIG. 66  is a cross-sectional view showing one example of a mounting structure of a high-frequency package provided with the tape-shaped transmission line section according to the third embodiment of the present invention; 
       FIG. 67  is an enlarged partly cross-sectional view showing, in a developed form, a structure of a portion D shown in  FIG. 66 ; 
       FIG. 68  is a cross-sectional view illustrating a structure of a cross-section cut along line E—E shown in  FIG. 67 ; 
       FIG. 69  is a cross-sectional view showing a modification of the structure shown in  FIG. 68 ; 
       FIG. 70  is a cross-sectional view illustrating a modification of the structure shown in  FIG. 66 ; 
       FIG. 71  is a cross-sectional view showing another modification of the structure shown in  FIG. 66 ; 
       FIG. 72  is a plan view showing a structure of a tape-shaped transmission line section illustrative of a further modification of the third embodiment of the present invention; 
       FIG. 73  is a plan view showing a connected state of the tape-shaped transmission line section illustrative of the modification shown in  FIG. 72 ; 
       FIG. 74  is a cross-sectional view showing a mounting structure of a still further modification of the tape-shaped transmission line section according to the third embodiment of the present invention; 
       FIG. 75  is a cross-sectional view illustrating a mounting structure of a still further modification of the tape-shaped transmission line section according to the third embodiment of the present invention; 
       FIG. 76  is a perspective view showing one example of a structure of a high-frequency package according to a fourth embodiment of the present invention; 
       FIG. 77  is a plan view illustrating the structure of the high-frequency package shown in  FIG. 76 ; 
       FIG. 78  is a perspective view showing a structure of a back side of a frame-shaped transmission line section mounted to the high-frequency package shown in  FIG. 76 ; 
       FIG. 79  is a cross-sectional view depicting one example of a mounting structure of the high-frequency package shown in  FIG. 76 ; 
       FIG. 80  is a plan view showing a structure of a high-frequency package illustrative of a modification of the fourth embodiment of the present invention; 
       FIG. 81  is s perspective view illustrating the structure of the high-frequency package shown in  FIG. 80 ; 
       FIG. 82  is a perspective view showing a structure of a back side of a transmission line section mounted to the high-frequency package shown in  FIG. 81 ; 
       FIG. 83  is a plan view depicting a structure of a high-frequency package illustrative of another modification of the fourth embodiment of the present invention; 
       FIG. 84  is a perspective view showing the structure of the high-frequency package shown in  FIG. 83 ; 
       FIG. 85  is a perspective view illustrating a structure of a back side of a transmission line section mounted to the high-frequency package shown in  FIG. 84 ; 
       FIG. 86  is a cross-sectional view showing the structure of the high-frequency package shown in  FIG. 83 ; 
       FIG. 87  is a plan view illustrating a structure of a tape-shaped transmission line section according to a fifth embodiment of the present invention; 
       FIG. 88  is a plan view showing a structure of a base metal layer of the tape-shaped transmission line section shown in  FIG. 87 ; 
       FIG. 89  is a plan view depicting a structure of an insulating layer of the tape-shaped transmission line section shown in  FIG. 87 ; 
       FIG. 90  is a plan view illustrating a structure of a surface-layer metal layer of the tape-shaped transmission line section shown in  FIG. 87 ; 
       FIG. 91  is a plan view showing a structure of a cover coat layer of the tape-shaped transmission line section shown in  FIG. 87 ; 
       FIG. 92  is a cross-sectional view illustrating a structure of a cross-section cut along line A—A shown in  FIG. 87 ; 
       FIG. 93  is a cross-sectional view depicting a structure of a cross-section cut along line B—B shown in  FIG. 87 ; 
       FIG. 94  is a partly cross-sectional view showing a connecting structure of the base metal layer of the tape-shaped transmission line section shown in  FIG. 87 ; 
       FIG. 95  is a partly cross-sectional view illustrating a connecting structure of the surface-layer metal layer of the tape-shaped transmission line section shown in  FIG. 87 ; 
       FIG. 96  is a plan view depicting a structure of a tape-shaped transmission line section illustrative of a modification of the fifth embodiment of the present invention; 
       FIG. 97  is a plan view showing a structure of a base metal layer of the tape-shaped transmission line section shown in  FIG. 96 ; 
       FIG. 98  is a plan view illustrating a structure of an insulating layer of the tape-shaped transmission line section shown in  FIG. 96 ; 
       FIG. 99  is a plan view depicting a structure of a surface-layer metal layer of the tape-shaped transmission line section shown in  FIG. 96 ; 
       FIG. 100  is a plan view showing a structure of a cover coat layer of the tape-shaped transmission line section shown in  FIG. 96 ; 
       FIG. 101  is a cross-sectional view illustrating a structure of a cross-section cut along line A—A shown in  FIG. 96 ; 
       FIG. 102  is a cross-sectional view depicting a structure of a cross-section cut along line B—B shown in  FIG. 96 ; 
       FIG. 103  is a partly cross-sectional view showing a connecting structure of a surface-layer metal layer (GND) of the tape-shaped transmission line section shown in  FIG. 96 ; 
       FIG. 104  is a partly cross-sectional view illustrating a connecting structure of a surface-layer metal layer (signal) of the tape-shaped transmission line section shown in  FIG. 96 ; 
       FIG. 105  is a cross-sectional view showing a structure of a tape-shaped transmission line section illustrative of another modification of the fifth embodiment of the present invention; 
       FIG. 106  is a plan view depicting a structure of a tape-shaped transmission line section illustrative of a further modification of the fifth embodiment of the present invention; 
       FIG. 107  is a plan view showing a structure of a tape-shaped transmission line section illustrative of a still further modification of the fifth embodiment of the present invention; 
       FIG. 108  is a plan view showing one example of a connecting structure of the tape-shaped transmission line section according to the fifth embodiment of the present invention; 
       FIG. 109  is a plan view showing one example illustrative of how a return current flows in the connecting structure shown in  FIG. 108 ; and 
       FIG. 110  is a plan view showing how a return current flows in a connecting structure of a comparative example with respect to the connecting structure shown in FIG.  108 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
   Whenever circumstances require it for convenience in the following embodiments, they will be described while being divided into a plurality of sections or embodiments. However, unless otherwise specified in particular, they are not irrelevant to one another. One thereof has to do with modifications, details and supplementary explanations of some or all of the other. 
   When reference is made to the number of elements or the like (including the number of pieces, numerical values, quantity, range, etc.) in the following embodiments, the number thereof is not limited to a specific number and may be greater than or less than or equal to the specific number unless otherwise specified in particular and definitely limited to the specific number in principle. 
   It is also needless to say that components (including element or factor steps, etc.) employed in the following embodiments are not always essential unless otherwise specified in particular and considered to be definitely essential in principle. 
   Similarly, when reference is made to the shapes, positional relations and the like of the components or the like in the following embodiments, they will include ones substantially analogous or similar to their shapes or the like unless otherwise specified in particular and considered not to be definitely so in principle, etc. This is similarly applied even to the above-described numerical values and range. 
   Members each having the same function in all the drawings for describing the embodiments are respectively identified by the same reference numerals and their repetitive description will therefore be omitted. 
   (First Embodiment) 
     FIG. 1  is a cross-sectional view showing one example of a structure of a high-frequency package according to a first embodiment of the present invention,  FIG. 2  is an external perspective view illustrating one example of a structure of an optical module with the high-frequency package shown in  FIG. 1  built therein,  FIG. 3  is a cross-sectional view depicting the structure of the optical module shown in  FIG. 2 ,  FIG. 4  is a plan view showing one example of a layout of parts built in the optical module shown in  FIG. 2 ,  FIG. 5  is a cross-sectional view illustrating one example of the layout of the parts built in the optical module shown in  FIG. 2 ,  FIG. 6  is a cross-sectional view showing a structure of a high-frequency package according to a modification of the first embodiment,  FIG. 7  is a partly plan view illustrating one example of a structure of a microstrip line of a wiring board employed in the high-frequency package shown in  FIG. 1 ,  FIG. 8  is a partly cross-sectional view showing the structure of the microstrip line shown in  FIG. 7 ,  FIG. 9  is a partly plan view depicting a structure of a microstrip line illustrative of a modification of the microstrip line of the wiring board employed in the high-frequency package shown in  FIG. 1 ,  FIG. 10  is a partly cross-sectional view showing the structure of the microstrip line illustrative of the modification shown in  FIG. 9 ,  FIG. 11  is a perspective view and a cross-sectional view showing a structure of a high-frequency package illustrative of another modification of the first embodiment,  FIG. 12  is a cross-sectional view depicting one example of a cap-mounted structure shown in  FIG. 1 ,  FIG. 13  is a plan view of the cap-mounted structure shown in  FIG. 12 ,  FIG. 14  is a cross-sectional view cut along line A—A of  FIG. 13 ,  FIG. 15  is a bottom view of the cap-mounted structure shown in  FIG. 13 ,  FIG. 16  is a plan view showing one example of the relationship of position between surface layer wirings and a cap employed in the cap-mounted structure shown in  FIG. 12 ,  FIG. 17  is a bottom view illustrating a structure of the cap as seen in the direction indicated by an arrow C of  FIG. 14 ,  FIG. 18  is a side view showing the structure of the cap shown in  FIG. 17 ,  FIG. 19  is a cross-sectional view illustrating the structure of the cap shown in FIG.  17  and an enlarged partly cross-sectional view of its corner,  FIG. 20  is an enlarged partly cross-sectional view cut along line A—A of  FIG. 13 ,  FIG. 21  is an enlarged partly cross-sectional view cut along line B—B of  FIG. 13 ,  FIG. 22  is an enlarged partly plan view showing one example of the relationship of position between the surface layer wirings employed in the cap-mounted structure shown in FIG.  12  and an opening of the cap employed therein,  FIG. 23  is a cross-sectional view illustrating a structure of a high-frequency package illustrative of a further modification of the first embodiment,  FIG. 24  is an enlarged partly cross-sectional view showing one example of a structure wherein a radiating member is mounted to the cap shown in  FIG. 12 ,  FIGS. 25 ,  26  and  27  are respectively cross-sectional views depicting structures of high-frequency packages illustrative of still further modifications of the first embodiment,  FIG. 28  is a plan view showing a structure of a high-frequency package illustrative of a still further modification of the first embodiment,  FIG. 29  is a cross-sectional view of the high-frequency package shown in  FIG. 28 ,  FIGS. 30 ,  31  and  32  are respectively plan views showing structures of high-frequency packages illustrative of still further modifications of the first embodiment,  FIG. 33  is a plan view depicting a structure of a high-frequency package illustrative of a still further modification of the first embodiment,  FIG. 34  is a cross-sectional view of the high-frequency package illustrated in  FIG. 33 ,  FIG. 35  is a plan view depicting a structure of a high-frequency package illustrative of a still further modification of the first embodiment, FIG.  36  is a cross-sectional view of the high-frequency package depicted in  FIG. 35 ,  FIG. 37  is a plan view depicting a structure of a high-frequency package illustrative of a still further modification of the first embodiment, and  FIG. 38  is a cross-sectional view of the high-frequency package illustrated in  FIG. 37 , respectively. 
   The semiconductor device according to the first embodiment shown in  FIG. 1  is a semiconductor package equipped with an optical communication IC (Integrated Circuit), e.g., a high-frequency package  1  capable of performing high-speed transmission at 40 Gbps. Incidentally, the high-frequency package  1  is mounted to an optical module (an electronic device such as a semiconductor module device)  14  shown in  FIGS. 2 and 3  and has a coaxial cable  7  used as one for signal transmission on the high-frequency side. 
   Now, the coaxial cable  7  employed in the first embodiment is one example of a transmission line. Incidentally, the transmission line is a wiring path for transmitting high frequency power, such as a microstrip line, a feeder cable or the like. A general wiring is a line for transmitting power regardless of high and low frequencies. While an input portion thereof and an output portion thereof are electrically connected to each other, characteristics at the transmission of the power are not necessarily taken into consideration. Accordingly, there may be a case in which high frequency power is not transmitted (the output is zero) even though low frequency power is transmitted. 
   On the other hand, the transmission line is of a line wherein wiring shapes or configurations and configurations and layouts of peripheral conductors including wirings, the quality of a material for an insulating layer, and the thickness and structure of the insulating layer are designed in such a manner that power is propagated with efficiency without a substantial reduction in output due to attenuation and reflection of the power in the course of its propagation. 
   The high-frequency package  1  according to the first embodiment comprises a package substrate (wiring board)  4  used as a chip carrier having a microstrip line  4   g  made up of a signal surface layer wiring (surface layer wiring)  4   c  and GND layers (ground conductor layers)  4   f  formed inside through the signal surface layer wiring  4   c  and an insulating layer  4   e , a high-frequency semiconductor chip  2  electrically connected to and mounted onto a main surface  4   a  of the package substrate  4  by flip-chip connection with a plurality of solder bump electrodes  5  interposed therebetween, a coaxial cable  7  whose core line  7   a  is electrically connected to the signal surface layer wiring  4   c , an underfill resin  6  poured between a main surface  2   a  of the semiconductor chip  2  and the main surface  4   a  of the package substrate  4  to protect the flip-chip connected portion, and ball electrodes  3  used as a plurality of external connecting terminals disposed within a back surface  4   b  located on the side opposite to the main surface  4   a  of the package substrate  4 . 
   Namely, the high-frequency package  1  is one wherein a signal of a high frequency (e.g., 40 Gbps) inputted from the coaxial cable  7  is directly inputted to the semiconductor chip  2  so as to propagate through the solder bump electrodes  5  via the signal surface layer wiring  4   c  of the package substrate  4 . The high-frequency package  1  has a structure wherein the high-frequency signal can be transmitted by only the microstrip line at the whole surface layer of the package substrate  4 . 
   Owing to the transmission of the high-frequency signal by only the microstrip line at the surface layer of the package substrate  4  without through via-based wirings or the like, the high-frequency signal can be thus transmitted without a loss in frequency characteristic. 
   Namely, vias (also including through holes) are not transmission lines but wirings. In order to realize the efficient propagation of power through the transmission line, wiring widths, the thickness of each interlayer insulating film, spaces between adjacent patterns, material physical values, etc. are designed as parameters so that its characteristic impedance becomes a desired value. However, since it is difficult to make the pattern of each via and each interlayer conductor vertical and constitute them as a coaxial structure, the design for obtaining the desired characteristic impedance is difficult. Accordingly, a loss in power at each via portion is apt to occur. 
   From this point of view, the technology described in Unexamined Patent Publication No. Hei 5(1993)-167258, for connecting the neighborhood of a portion where a core line of a coaxial cable and its corresponding each bump pad are connected, as the via configuration will cause a characteristic impedance mismatch at the connecting portion. Further, the technology is considered to need, when an attempt is made to embed the coaxial cable into a substrate in its thickness direction, such a manufacturing process that a hole is defined in the substrate by a drill or the like, the coaxial cable is inserted into the hole and then positioned therein, and each bump pad and its corresponding core line are connected to each other, after which the hole is buried. This structure increases the number of processes as compared with a general process of manufacturing a wiring board. This structure will lead to cost up with a difficult technology of cable connection and embedding. 
   On the other hand, since the wiring board can be manufactured by the known technology in the first embodiment, no cost up takes place. 
   Incidentally, the surface layer wirings such as the signal surface layer wiring  4   c , the GND surface layer wirings  4   h  employed in the first embodiment are of wirings which are formed of, for example, copper or the like and disposed on the uppermost layer on the main surface  4   a  side of the package substrate  4 . They may be exposed onto the main surface  4   a  or coated with a non-conductive thin film or the like. 
   It is desirable that when high-speed transmission such as 40 Gbps or the like is performed, the signal surface layer wiring  4   c  of the microstrip line  4   g  is of the shortest. Thus, the solder bump electrodes  5 , of the plurality of solder bump electrodes  5  connected to the semiconductor chip  2  of the package substrate  4 , which are disposed toward the coaxial cable  7  (coaxial connector  11 ) from the center of the semiconductor chip  2 , are connected to the signal surface layer wiring  4   c.    
   Preferably, any of the solder bump electrodes  5  disposed on the outermost periphery, of the plurality of solder bump electrodes  5  is connected to the signal surface layer wiring  4   c.    
   Consequently, high-speed signal transmission in which a loss in the frequency characteristic of a high frequency has been suppressed to the minimum, can be realized. Since it is possible to reduce carrying of noise on the microstrip line  4   g , a reduction in high-frequency characteristic can be also suppressed. 
   In the high-frequency package  1 , the plurality of ball electrodes (bump electrodes)  3  provided as the external connecting terminals are disposed on the back surface  4   b  of the package substrate  4  in an array form. Accordingly, the high-frequency package  1  is a semiconductor package of a ball grid array type. 
   Thus, the package can be downsized as compared with an outer-lead protrusion type high-frequency package wherein outer leads protrude outwards from the package substrate  4 . 
   Incidentally, while the microstrip line  4   g  transmits a high-frequency signal as an electromagnetic wave in the insulating layer  4   e  lying between the signal surface layer wiring  4   c  and its corresponding internal GND layer  4   f , both of GND surface layer wirings (ground surface layer wirings)  4   h  disposed on both sides of a signal surface layer wiring  4   c  with an insulating portion interposed therebetween form a microstrip line  4   g  in a surface layer of a package substrate  4  as shown in FIG.  7 . 
   A frame member  8  extending along an outer peripheral portion of the package substrate  4  is attached to the package substrate  4  in the high-frequency package  1 . Further, the frame member  8  is provided with a coaxial connector (linkup or junction member)  11  fit onto the coaxial cable  7  together with a glass bead  12 . Thus, the coaxial cable  7  is fit in the coaxial connector  11 , the core line  7   a  of the coaxial cable  7  is connected to its corresponding core line  12   a  of the glass bead  12 , and the core line  12   a  is in solder-connection  31  to the signal surface layer wiring  4   c  of the package substrate  4  (it may be connected thereto by a conductive resin or the like). 
   Incidentally, the diameter of the coaxial connector  11  is about 10 mm, for example. 
   The package substrate  4  is a substrate formed of, for example, glass-contained ceramic or the like. The package substrate  4  has a thickness of about 1 mm, for example and is formed thereinside with an internal signal wiring  4   d  used as a signal line for connecting the flip-chip connected solder bump electrode  5  and its corresponding ball electrode  3  used as the external connecting terminal, except for the GND layers  4   f.    
   The high-frequency package  1  having such a structure is built in such an optical module (semiconductor module device)  14  or the like as shown in FIG.  2  and mounted on its module substrate (junction member)  13 . 
   A structure of the optical module  14  will now be described. 
   The optical module  14  shown in  FIGS. 2 through 5  is a module for high-speed optical communications, e.g., a module product mounted to a communication system apparatus or the like of a communication network base station. 
   The optical module  14  according to the first embodiment has a size of L (ranging from 100 mm to 200 mm)×M (ranging from 60 mm to 150 mm), for example, as shown in  FIG. 2 and a  height (T) ranging from 10 mm to 25 mm as shown in FIG.  3 . However, the size and height of the optical module  14  are not limited to these numerical values. 
   The high-frequency package  1  according to the first embodiment is mounted on the module substrate  13  of the optical module  14 . The module substrate  13  is covered as a whole with a module case  15 . A plurality of fins  16  are formed side by side on the surface of the module case  15 . Placing the fins  16  under wind  18  enables an improvement in the dissipation of the optical module  14 . 
   Incidentally, an external terminal of the optical module  14  is a module connector  17  attached to the module substrate  13 . Part of the module connector  17  is exposed to the back side of the module case  15 . 
   In the optical module  14 , as shown in  FIGS. 4 and 5 , a high-frequency light signal inputted from its input is converted into an electric signal by an optoelectronic transducer  20 . Further, the electric signal passes through the microstrip line  4   g  of the package substrate  4  via an amplifier device  19  so as to enter into the high-frequency semiconductor chip  2  on the input side, followed by transformation into a low-frequency signal, which in turn is transmitted to the outside of the optical module  14  via the internal signal wiring  4   d  of the package substrate  4 , the corresponding solder bump electrode  5  and the module substrate  13  shown in FIG.  1  and the module connector  17 . 
   On the other hand, a signal inputted from the module connector  17  passes through a path opposite to the above path and is transmitted as an output. 
   Incidentally, while  FIG. 4  shows that the high-frequency semiconductor chip  2  is provided two on the input and output sides, the input and output sides may be built in one semiconductor chip  2 . 
   In  FIG. 4 , arrows indicated by solid lines, of arrows indicative of the flows of signals for input and output show the transmission of the light signals by optical fibers, whereas arrows indicated by dotted lines thereof show the transmission of the electric signals through the coaxial cables  7  or microstrip lines  4   g.    
   Next,  FIG. 6  shows a modification of the high-frequency package  1 . A core line  7   a  of a coaxial cable  7  is connected directly to a signal surface layer wiring  4   c  of a package substrate  4  by solder or the like. 
   Namely, the coaxial cable  7  is directly connected to the package substrate  4  without the use of a coaxial connector  11  by solder or the like. 
   In this case, a step  4   k  for disposing the coaxial cable  7  is provided at an end of the package substrate  4 , and a GND surface layer wiring  4   h  is provided on the surface of the step  4   k . Upon placement of the coaxial cable  7  on the step  4   k , a shield (GND)  7   b  for covering the core line  7   a  of the coaxial cable  7 , and the GND surface layer wiring  4   h  on the step  4   k  are electrically connected to each other by solder or the like. 
   Owing to the direct attachment of the coaxial cable  7  to the package substrate  4  in this way, the high-frequency package  1  can be reduced in thickness and a cost reduction can be achieved because the coaxial connector  11  expensive and relatively large in diameter is not used. 
   A preferable shape or configuration of a GND layer  4   f  corresponding to an inner layer in a package substrate  4  will next be explained using  FIGS. 7 through 10 . 
   First,  FIGS. 7 and 8  respectively show a case in which the GND layer  4   f  placed inside the substrate extends to an end of the package substrate  4  in a microstrip line structure  21  using a microstrip line  4   g , and a case in which a structure wherein a coaxial structure  22  using a coaxial cable  7  and the microstrip line structure  21  are connected to each other, is taken. 
   In this case, a high-speed signal inputted from and outputted to the package outside passes through a path of the coaxial cable  7 , a signal surface layer wiring  4   c  of the package substrate  4  and a semiconductor chip  2 . At this time, a core line  7   a  of the coaxial cable  7  is connected to the signal surface layer wiring  4   c  of the package substrate  4 , and a shield  7   b  used as GND, of the coaxial cable  7  is connected to its corresponding GND surface layer wirings  4   h  of the package substrate  4 . 
   Further, a frame member  8  for supporting the coaxial cable  7  might be fixedly secured onto the package substrate  4 . Further, the frame member  8  and the shield  7   b  of the coaxial cable  7  or the GND surface layer wirings  4   h  of the package substrate  4  might be connected to each other. Incidentally, the corresponding GND surface layer wiring  4   h  and the GND layer  4   f  used as the inner layer are connected to each other by via wirings  4   i  as shown in FIG.  8 . 
   Thus, in order to bring the signal surface layer wiring  4   c  on the package  4  to the microstrip line structure  21  over it whole area so as to reduce L (inductance) of GND, there is a need to expose the GND layer  4   f  at the end of the substrate to thereby connect it to the shield  7   b  of the coaxial cable  7  or GND of the frame member  8 , or form at the substrate end, the via wirings  4   i  for connecting the corresponding GND surface layer wiring  4   h  and the GND layer  4   f  used as the inner layer and cut and expose the via wirings  4   i  upon substrate cutting-off to thereby connect the same to the coaxial cable  7  or GND of the frame member  8 . 
   However, these technologies need high accuracy upon positioning of the surface-layer/inner-layer wirings of the package substrate  4  and has a fear that when a pasty material such as Cu is used for wiring, it leads to wiring sagging, and a difficulty arises upon manufacture thereof. 
   On the other hand, a structure shown in  FIGS. 9 and 10  is one formed with a coplanar line  23   a  wherein a signal surface layer wiring  4   c  and GND surface layer wirings  4   h  are disposed on the same plane (main surface  4   a ) in an area between the outermost peripheral via wiring  4   i  of a plurality of via wirings  4   i  and a coaxial cable  7 . The coaxial cable  7  and a microstrip line  4   g  of a package substrate  4  are connected to each other through the coplanar line  23   a.    
   Namely, an area provided outside from the outermost peripheral via wiring  4   i  close to the end of the package substrate  4  is defined as a coplanar structure  23 . A coaxial structure  22 , the coplanar structure  23  and a microstrip line structure  21  are connected to one another. 
   Thus, the inductance of GND can be reduced. 
   Further, in order to make characteristic impedance matching in an area for the coplanar structure  23 , the distance between the signal surface layer wiring  4   c  and each of the GND surface layer wirings  4   h  is decreased so that they are brought close to each other as shown in FIG.  9 . Incidentally, the accuracy of position displacement between the via wiring  4   i  and its corresponding GND layer  4   f  used as an inner layer is equivalent to the prior art (e.g., about 50 μm). Since a novel technology is not required, cost up can be prevented. 
   Thus, the interconnection of the coaxial structure  22 , coplanar structure  23  and microstrip line structure  21  makes it possible to reduce a loss in high-frequency signal and bring the characteristic impedance of a high-speed signal path close to a target value. 
   Further, the characteristic impedance can be brought closer to a target value by decreasing the distance between the signal surface layer wiring  4   c  and each GND surface layer wiring  4   h  in the surface layer of the package substrate  4 . 
   As a result, degradation of high-speed signal characteristics can be suppressed and an improvement in the electric characteristics of the high-frequency package  1  can be realized without an increase in cost. 
   A high-frequency package  1  showing a modification illustrated in  FIG. 11  will next be described. 
   The high-frequency package  1  shown in  FIG. 11  makes use of a thin-type coaxial connector  24  of a plate-shaped member as a junction member between a coaxial cable  7  and a microstrip line  4   g  of a package substrate  4 . 
   The thin-type coaxial connector  24  has a microstrip line  24   c  made up of a signal surface layer wiring (surface layer wiring)  24   a  and GND lines (ground wirings)  24   b  formed on both sides thereof with insulating portions interposed therebetween. Thus, in the high-frequency package  1 , the signal surface layer wiring  24   a  of the microstrip line  4   g  of the package substrate  4 , and a core line  7   a  of the coaxial cable  7  are electrically connected to each other through the signal surface layer wiring  24   a  of the microstrip line  24   c  of the thin-type coaxial connector  24 . 
   Namely, the signal surface layer wiring  24   a  is provided on the surface of an upper stage of a thin ceramic plate or the like with a step  24   d , and the GND lines  24   b  are provided on both sides thereof. Further, only the GND lines  24   b  are provided at a lower stage of the ceramic plate. The GND lines  24   b  provided at the upper and lower stages are connected to each other by means of surface or internal layer vias or the like. 
   The coaxial cable  7  is then mounted on the lower stage, the core line  7   a  at a leading end thereof is placed on the signal surface layer wiring  24   a  at the upper stage, and a shield  7   b  of the coaxial cable  7  and the GND lines  24   b  at the upper and lower stages of the ceramic plate are connected to one another by solder or the like. Further, the core line  7   a  of the coaxial cable  7  and the signal surface layer wiring  24   a  at the upper stage are similarly connected to each other by solder or the like. 
   Thereafter, the surface layer wirings of the ceramic plate are made opposite to their corresponding surface layer wirings of the package substrate  4 , and their mutual wirings are connected to one another by solder or a conductive resin or the like. Alternatively, they may be connected by gold (Au)-to-gold (Au) crimping, or the ceramic plate and the package substrate  4  may be adhered and fixed to each other. 
   Using the thin-type coaxial connector  24  corresponding to the plate-like member as the junction member in this way enables a reduction in the thickness of the high-frequency package  1 . 
   Further, the coaxial cable  7  is easy to handle and connector repair is enabled. The thin-type coaxial connector  24  may be attached to both ends of the coaxial cable  7 . One end thereof may be formed as the thin-type coaxial connector  24 , whereas the other end thereof may be formed as such a coaxial connector  11  as shown in  FIG. 1. A  connector different in shape from the coaxial cable  7  may be attached. Alternatively, one end may be formed as the thin-type coaxial connector  24 , and the other end may be exposed as a cable end. 
   Incidentally, only the coaxial cable  7  may be provided as an alternative to the coaxial cable  7  with the thin-type coaxial connector  24  attached thereto. Alternatively, the high-frequency package  1  may be provided as the high-frequency package  1  with such a thin-type coaxial connector  24  as shown in  FIG. 11  mounted thereto. 
   A high-frequency package  1  illustrative of a modification shown in  FIG. 12  will next be described. 
   Of a plurality of ball electrodes  3  used as external connecting terminals, support balls  3   a  are first provided at the outermost-peripheral four corners as shown in  FIG. 15  in the high-frequency package  1  shown in FIG.  12 . 
   This is done to cope with such a problem that when the high-frequency package  1  is mounted on a mounting board such as a module substrate  13  or the like, the ball electrodes  3  are crushed due to the heavy weight of a coaxial connector  11 , so that electrical shorts occur between the adjacent ball electrodes  3 . Since the support balls  3   a  are provided at the outermost-peripheral four corners, the support balls  3   a  at the corners are capable of supporting a package substrate  4  upon melting of the ball electrodes  3  to thereby prevent the occurrence of such electrical shorts due to the crushing of the ball electrodes  3 . 
   Incidentally, the support balls  3   a  are respectively formed of, for example, high melting-point solder, a resin or ceramic or the like. 
   The high-frequency package  1  shown in  FIG. 12  has a cap  9  corresponding to a radiating member mounted to a back surface  2   b  opposite to a main surface  2   a  of a semiconductor chip  2  with a thermal conductive adhesive  10  interposed therebetween. 
   Namely, since the high-frequency semiconductor chip  2  might generate high heat when driven, the radiating cap  9 , or a thermal diffusion plate or radiating fins or the like are attached to the back surface  2   b  of the semiconductor chip  2 , whereby the semiconductor chip  2  can be improved in dissipation and the high-frequency package  1  can be also enhanced in dissipation, thus making it possible to prevent degradation of electric characteristics. 
   The position of layout of the cap  9  with respect to the package substrate  4  will now be explained. As shown in  FIGS. 12 through 14 , the cap  9  is mounted onto the back surface  2   b  of the semiconductor chip  2  with the thermal conductive adhesive  10  or the like interposed therebetween so as to cover the semiconductor chip  2 . At this time, the cap  9  may preferably be disposed even on surface layers (microstrip line  4   g ) such as a signal surface layer wiring  4   c  and GND surface layer wirings  4   h  or the like as shown in  FIGS. 16 and 20 . 
   Namely, the cap  9  may preferably cover the microstrip line  4   g  from thereabove to avoid carrying of noise on the microstrip line  4   g  of the surface layer due to an external electromagnetic wave. 
   Accordingly, the cap  9  may preferably cover the semiconductor chip  2  and the surface layer wirings to some extent to block entrance of the external electromagnetic waves. However, the cap  9  and the surface layer wirings such as the signal surface layer wiring  4   c  and the GND surface layer wirings  4   h  or the like must be insulated. 
   Thus, the package substrate  4  employed in the first embodiment is formed with openings (wall escape portions)  9   a  at leg portions  9   b  on a surface layer wiring of a cap  9  as shown in FIG.  17 . Each of the openings takes such a cap shape as not to make contact between the leg portions  9   b  of the cap  9  and the surface layer wiring. 
   Incidentally,  FIGS. 20 and 22  show in detail the relationship of position between the openings  9   a  at the leg portions  9   b  of the cap  9  and the signal surface layer wiring  4   c  and GND surface layer wirings  4   h  of the package substrate  4 . Namely, the legs  9   b  of the cap  9  are opened as the openings  9   a  up to spots lying outside both sides of the GND surface layer wirings  4   h  so as not to contact the signal surface layer wiring  4   c  and the GND surface layer wirings  4   h.    
   Further, spots other than an area for connection of the signal surface layer wiring  4   c  corresponding to the surface layer wiring of the package substrate  4  to the coaxial cable  7  are covered with a solder resist  4   j  corresponding to an insulative thin film (non-conductive thin film) formed of a resin or the like as shown in  FIG. 20  (GND surface layer wirings  4   h  are also similar). The solder resist  4   j  has an insulating function and even the function of stopping the flow of solder for solder connection  31  of the coaxial cable  7 . 
   Thus, since the openings  9   a  corresponding to the wall escape portions of the cap  9 , and the solder resist  4   j  used as the insulative thin film are formed with respect to the surface layer wirings, the surface layer wirings and the cap  9  can be prevented from contacting. 
   Incidentally, the cap  9  is formed, even at the corners and side portions thereof, with cut-away portions  9   c  corresponding to such wall escape portions as not to contact the surface layer wiring as shown in  FIGS. 17 and 18 . 
   Since the cap  9  also needs a shield effect, the whole surface of a base material  9   d  made up of a copper alloy or the like is covered with a chrome conductive film  9   e  as shown in FIG.  19 . Further, only its outer surface is covered with a non-conductive film  9   f  so as to prevent electrical shorts developed in other parts. 
   Such a cap  9  is mounted to the same layer as a signal surface layer wiring  4   c  and GND surface layer wirings  4   h  formed on a main surface  4   a  of a package substrate  4  as shown in  FIGS. 21 and 22 . Incidentally, the cap  9  corresponds to the same layer as a layer for underlying electrodes of solder bump electrodes  5 . 
   At spots unformed with an opening  9   a  lying between leg portions  9   b  of the cap  9 , the leg portions  9   b  are connected to an internal power supply (or GND layer  4   f ) of the package substrate  4  via a conductive material  25  and a via wiring  4   i  to enhance the shield effect as shown in FIG.  21 . The cap  9  per se is electrically connected to internal power supply layers (or GND layer  4   f  and GND surface layer wirings  4   h ) of the package substrate  4 . 
   Thus, the periphery of each solder bump electrode  5  for a high-frequency signal is brought to a state of being surrounded by a GND potential, so that the cap  9   b -based shield effect can be enhanced. 
   The solder bump electrode  5  for the high-frequency signal, i.e., the solder bump electrode  5  connected to the signal surface layer wiring  4   c  may preferably be set as the solder bump electrode  5  disposed approximately in the center of the side of a row of the outermost-peripheral solder bump electrodes  5  as shown in  FIG. 22. A  coaxial connector  11  connected to the present solder bump electrode  5  via the signal surface layer wiring  4   c  may also be preferably disposed substantially in the center of the side. 
   Thus, a microstrip line  4   g  can be set to the shortest. High-speed signal transmission can be realized which minimizes a loss in the frequency characteristic of a high frequency. It is also possible to reduce carrying of noise on the microstrip line  4   g.    
   Next, a high-frequency package  1  illustrative of a modification shown in  FIG. 23  is one having a structure wherein a cap  9  is mounted to the high-frequency package  1  using the thin-type coaxial connector  24  shown in FIG.  11 . According to the high-frequency package  1  shown in  FIG. 23 , both thinning and dissipation of the high-frequency package  1  can be enhanced. 
   A high-frequency package  1  illustrative of a modification shown in  FIG. 24  is one wherein a radiating block (radiating member)  26  is further mounted on the surface of a cap  9  attached to a back surface  2   b  of a semiconductor chip  2  with a thermal conductive adhesive  10  interposed therebetween. The high-frequency package  1  can be further enhanced in dissipation. 
   A high-frequency package  1  illustrative of a modification shown in  FIG. 25  is one showing a structure wherein a second semiconductor chip  27  is further mounted on a package substrate  4  in addition to a semiconductor chip  2 . A cap  9  for covering both chips is mounted thereon. 
   In the present example, a signal is inputted via an internal signal wiring  4   d  of the package substrate  4  from the semiconductor chip  2  connected to a coaxial cable  7  through a microstrip line  4   g  in a surface layer to the second semiconductor chip  27 . Further, the signal is transmitted from a solder bump electrode  5  of the second semiconductor chip  27  to its corresponding ball electrode  3  used as an external connecting terminal via an internal signal wiring  4   d.    
   Both high-frequency packages  1  illustrative of modifications shown in  FIGS. 26 and 27  are ones wherein balancers  28  are attached to frame members  8 , respectively. The balancer  28  has the function of adjusting the center of gravity of the high-frequency package  1  so that the high-frequency package  1  is not inclined upon mounting of the high-frequency package  1  on a substrate. 
     FIG. 26  shows the modification wherein the balancer  28  is fixed to the frame member  8  through a screw member  29 .  FIG. 27  shows the modification having a structure wherein a groove is defined in the balancer  28  and fit onto the frame member  8  to mount the balancer  28  on the frame member  8 . 
   Thus, in the high-frequency packages  1  shown in  FIGS. 26 and 27 , the center of gravity of each high-frequency package is adjusted by the balancer  28  so that the high-frequency package  1  is not inclined upon its mounting onto the substrate. 
   The positions of placement of the package substrate  4  and the semiconductor chip  2  will next be described. 
   In the high-frequency package  1 , the semiconductor chip  2  may preferably be disposed on the package substrate, preferably, in an area close to the coaxial cable  7 . 
   Namely, when the high-frequency signal is transmitted from the coaxial cable  7  to the semiconductor chip  2  through the microstrip line  4   g  in the surface layer of the package substrate  4 , noise is carried on the microstrip line  4   g  when the microstrip line  4   g  is long, so that high-frequency characteristics are degraded. Therefore, the semiconductor chip  2  may preferably be disposed so as to lean toward the coaxial cable  7  as viewed from the central portion of the package substrate  4  in order to prevent it. The semiconductor chip  2  is disposed as close to the coaxial cable  7  as possible. 
   Thus, the length of the microstrip line  4   g  can be shortened and hence the degradation in the high-frequency characteristics due to the carrying-on of noise can be suppressed. 
   The high-frequency package  1  shown in  FIG. 13  is one wherein one semiconductor chip  2  is mounted on a package substrate  4 . The semiconductor chip  2  is disposed toward a coaxial connector  11  as viewed from a central portion of the package substrate  4 . By fitting a coaxial cable  7  in the coaxial connector  11 , the semiconductor chip  2  is disposed toward the coaxial cable  7  from the central portion. 
     FIGS. 28 and 29  respectively show a case in which a high-frequency semiconductor chip  2  and a low-frequency second semiconductor chip  27  are mounted on a package substrate  4 . The high-frequency semiconductor chip  2  is disposed toward a coaxial connector  11  as viewed from a central portion of the package substrate  4  and placed toward the coaxial connector  11  as viewed from the low-frequency second semiconductor chip  27 . Further, the two coaxial connectors  11  are attached to one semiconductor chip  2  in association with each other. 
     FIG. 30  is a modification of the structure of  FIG. 28 , wherein a combination of layouts of two coaxial connectors  11  is changed. 
     FIGS. 31 and 32  respectively show cases in which one semiconductor chips  2  are mounted on package substrates  4 .  FIG. 31  shows the case in which two coaxial connectors  11  are provided at the same side. The semiconductor chip  2  is disposed toward the coaxial connectors  11  as viewed from a central portion of the package substrate  4 . 
   Even in the case of  FIG. 32 , the semiconductor chip  2  is disposed toward coaxial connectors  11  as viewed from a central portion of the package substrate  4 . However, the semiconductor chip  2  is disposed symmetrically face to face with two sides to which the two coaxial connectors  11  are opposed. 
   In a high-frequency package  1  shown in  FIGS. 33 and 34 , one semiconductor chip  2  is disposed toward a coaxial connector  11  as viewed from a central portion, and the coaxial connector  11  is provided at the side closest to the semiconductor chip  2  in association with the semiconductor chip  2 . Further, a plurality of chip condensers  30  are mounted on the periphery of the semiconductor chip  2  on a main surface  4   a  of a package substrate  4   a.    
   Namely, since the semiconductor chip  2  is disposed toward the coaxial connector  11  as viewed from the central portion, the plurality of chip condensers  30  or the like can be mounted in vacant spaces on the opposite sides beside the semiconductor chip  2 . 
   On the other hand, a high-frequency package  1  shown in  FIGS. 35 and 36  takes a configuration wherein one semiconductor chip  2  is disposed toward a coaxial connector  11  from a central portion, and a plurality of chip condensers  30  are placed in a chip-adaptable area of a back surface  4   b  of a package substrate  4 . In a high-frequency package  1  shown in  FIGS. 37 and 38 , one semiconductor chip  2  is disposed toward a coaxial connector  11  from a central portion, and a plurality of chip condensers  30  are mounted in a concave portion  41  corresponding to a cavity defined in a chip-compatible area of a back surface  4   b  of a package substrate  4 . 
   Even in the case of any high-frequency packages  1  shown in  FIGS. 28 through 38 , their size reductions, their thinning and their cost reductions can be achieved. 
   (Second Embodiment) 
     FIG. 39  is a cross-sectional view showing a structure of a semiconductor device (high-frequency package) according to a second embodiment of the present invention,  FIGS. 40 and 41  are respectively cross-sectional views showing structures of high-frequency packages illustrative of modifications of the second embodiment of the present invention,  FIG. 42  is a cross-sectional view showing one example of a state in which a cap is mounted upon assembly of-the high-frequency package shown in  FIG. 41 ,  FIG. 43  is a partly cross-sectional view depicting one example of a state in which an auxiliary substrate and a coaxial cable are connected to each other upon assembly of the high-frequency package shown in  FIG. 41 ,  FIG. 44  is a partly cross-sectional view showing one example of a testing state at the assembly of the high-frequency package shown in  FIG. 41 , and  FIG. 45  is a partly cross-sectional view depicting one example of a structure subsequent to the completion of assembly of the high-frequency package shown in  FIG. 41 , respectively. 
   While the semiconductor device shown in  FIG. 39  according to the second embodiment is a high-frequency semiconductor package for optical communications, having a coaxial cable  7  in a manner similar to the high-frequency package  1  according to the first embodiment, such a coaxial cable  7  as described in the first embodiment is not mounted via the coaxial connector  11  or the coaxial cable  7  is not mounted to the package substrate  4  corresponding to the chip carrier by direct connection. The present semiconductor device is one having a structure wherein the coaxial cable  7  is connected to the module substrate  13  of the optical module  14  (semiconductor module device) shown in  FIG. 2 , and the module substrate  13  is connected to the package substrate  4  via protruded electrodes. 
   Thus, the module substrate  13  is used as a junction member at the transmission of a high-frequency signal from the coaxial cable  7  to the package substrate  4 . The module substrate  13  is also formed, at a surface layer of its main surface  13   a , with a microstrip line  13   g  made up of a signal surface layer wiring (surface layer wiring)  13   c  and a GND layer (ground conductor layer)  13   f  formed inside via the signal surface layer wiring  13   c  and an insulating layer  13   e.    
   Now, a signal surface layer wiring  4   c  of a microstrip line  4   g  of a package substrate  4 , and a core line  7   a  of the coaxial cable  7  are connected to each other through the signal surface layer wiring  13   c  of the microstrip line  13   g  of the module substrate  13 . 
   Namely, since thin-type ball electrodes  34  used as external connecting terminals are formed on a main surface  4   a  on the flip-chip connection side, of the package substrate  4 , the main surface  4   a  of the package substrate  4  and its corresponding main surface  13   a  of the module substrate  13  are disposed in an opposing relationship. Consequently, the signal surface layer wiring  4   c  of the package substrate  4 , and the signal surface layer wiring  13   c  of the module substrate  13  can be connected to each other via the thin-type ball electrodes  34  made up of solder or the like. Thus, the microstrip line  4   g  of the package substrate  4  and the microstrip line  13   g  of the module substrate  13  are connected to each other via the thin-type ball electrodes  34 . 
   Accordingly, the high-frequency package  1  according to the second embodiment is also capable of directly introducing a signal of a high frequency (e.g., 40 Gbps) sent from the coaxial cable  7  into the corresponding semiconductor chip  2  via the signal surface layer wiring  13   c  of the module substrate  13  and the thin-type ball electrodes  34 . The high-frequency signal can be transmitted by only the microstrip line at the whole surface layer of the package substrate  4  via the module substrate  13 . 
   Consequently, the high-frequency signal is transmitted by only the microstrip lines at the surface layers of the module substrate  13  and the package substrate  4  without through via-based wirings or the like in a manner similar to the high-frequency package  1  according to the first embodiment, thereby making it possible to transmit the high-frequency signal without causing a loss in frequency characteristic. 
   Incidentally, a signal on the low frequency side passes through an internal signal wiring  4   d  of the package substrate  4  and then passes through an internal signal wiring  13   d  of the module substrate  13  via the corresponding thin-type ball electrode  34 , followed by transmission to the outside. 
   The semiconductor chip  2  is disposed in an opening  13   h  of the module substrate  13  in a state of being flip-chip connected to the package substrate  4 . Further, a radiating block (radiating member)  26  is attached to a back surface  2   b  of the semiconductor chip  2  with a thermal conductive adhesive  10  interposed therebetween. Accordingly, the radiating block  26  is disposed on the back surface  13   b  side of the module substrate  13 . 
   Since the high-frequency package  1  according to the second embodiment has a structure wherein the module substrate  13  is interposed between the coaxial cable  7  and the package substrate  4  without directly connecting the coaxial cable  7  to the package substrate  4 , an IC maker is capable of handling as a product, a structural body wherein the semiconductor chip  2  is flip-chip connected to the package substrate  4 . 
   In this case, the coaxial cable  7  is connected to the module substrate  13  on the user side. Further, the user connects the package substrate  4  and the module substrate  13  via the thin-type ball electrodes  34  to thereby assemble the high-frequency package  1 . 
   In the high-frequency package  1  using the module substrate  13  as the junction member in this way, the package substrate  4  equipped with the semiconductor chip  2  and the module substrate  13  connected with the coaxial cable  7  are assembled in a discrete form and thereafter both are connected to each other. It is therefore possible to divide their yields. 
   Namely, an assembled body of the semiconductor chip  2  and an assembled body of the coaxial cable  7  can share yield risks respectively, and the yields of a structural body subsequent to the connection of both assembled bodies can be enhanced. 
   Since the high-frequency package  1  using the module substrate  13  does not use the expensive coaxial connector  11 , it can be reduced in cost and thinned. 
   Further, since all the external connecting terminals are provided on the main surface  4   a  on the flip-chip connection side, of the package substrate  4 , a screening test can be easily performed upon screening of semiconductor chips  2  each used for the high frequency of 40 Gbps. 
   Namely, since all the external connecting terminals for the high and low frequencies are provided on one-sided surface (main surface  4   a ) of the package substrate  4 , a probe becomes easy to contact upon the screening test. The test can be performed without using a jig having a complex shape. 
   As a result, a test time interval can be shortened. 
   Incidentally, a high-frequency package  1  illustrative of a modification shown in  FIG. 40  is one wherein a cap  9  is mounted onto a back surface  2   b  of a semiconductor chip  2  with a thermal conductive adhesive  10  interposed therebetween. Further, a radiating block  26  is mounted on the surface of the cap  9  with a thermal conductive adhesive  10  interposed therebetween. 
   In this case, the cap  9  is formed with an opening (wall escape portion)  9   a  for isolating the cap  9  and surface layer wirings such as a signal surface layer wiring  4   c , etc. from one another. 
   Further, since the radiating block  26  is provided on the cap  9  as well as the cap  9 , the high-frequency package  1  shown in  FIG. 40  is capable of further enhancing dissipation or radiation thereof and preventing degradation of high-frequency characteristics. 
   Next, a high-frequency package  1  illustrative of a modification shown in  FIG. 41  has a configuration wherein a junction member for connecting a coaxial cable  7  and a signal surface layer wiring  4   c  of a package substrate  4  is of a sub or auxiliary substrate  32  corresponding to a second package substrate. The auxiliary substrate  32  is formed, at a surface layer of its main surface  32   a , with a microstrip line  32   g  made up of a signal surface layer wiring (surface layer wiring)  32   c  and a GND layer (ground conductor layer)  32   f  formed inside via the signal surface layer wiring  32   c  and an insulating layer  32   e.    
   Now, the signal surface layer wiring  4   c  for a microstrip line  4   g  of the package substrate  4 , and a core line  7   a  of the coaxial cable  7  are connected to each other through the signal surface layer wiring  32   c  of the microstrip line  32   g  of the auxiliary substrate  32 . 
   Namely, since thin-type ball electrodes  34  used as external connecting terminals are formed on a main surface  4   a  on the flip-chip connection side, of the package substrate  4 , the main surface  4   a  of the package substrate  4  and its corresponding main surface  32   a  of the auxiliary substrate  32  are disposed in an opposing relationship. Consequently, the signal surface layer wiring  4   c  of the package substrate  4 , and the signal surface layer wiring  32   c  of the auxiliary substrate  32  can be connected to each other via the thin-type ball electrodes  34  made up of solder or the like. Thus, the microstrip line  4   g  of the package substrate  4  and the microstrip line  32   g  of the auxiliary substrate  32  are connected to each other via the thin-type ball electrodes  34 . 
   Accordingly, the high-frequency package  1  according to the modification shown in  FIG. 41  is also capable of directly introducing a signal of a high frequency (e.g., 40 Gbps) sent from the coaxial cable  7  into the corresponding semiconductor chip  2  via the signal surface layer wiring  32   c  of the auxiliary substrate  32  and the thin-type ball electrodes  34 . The high-frequency signal can be transmitted by only the microstrip line at the whole surface layer of the package substrate  4  via the auxiliary substrate  32 . 
   Consequently, the high-frequency signal is transmitted by only the microstrip lines at the surface layers of the auxiliary substrate  32  and the package substrate  4  without through via-based wirings or the like in a manner similar to the high-frequency package  1  according to the first embodiment, whereby the high-frequency signal can be transmitted without causing a loss in frequency characteristic. 
   Incidentally, a signal on the low frequency side passes through an internal signal wiring  4   d  of the package substrate  4  and then passes through an internal signal wiring  32   d  of the auxiliary substrate  32  via the corresponding thin-type ball electrode  34 . Further, the signal is transmitted to a module substrate  13  or the like via a pin member (connecting terminal)  33 . 
   The semiconductor chip  2  is disposed in an opening  32   h  of the auxiliary substrate  32  in a state of being flip-chip connected to the package substrate  4 . Further, a cap  9  is attached to a back surface  2   b  of the semiconductor chip  2  with a thermal conductive adhesive  10  interposed therebetween. Furthermore, a radiating block (radiating member)  26  is mounted on the surface of the cap  9 . Accordingly, the radiating block  26  is disposed on the back surface  32   b  side of the auxiliary substrate  32 . 
   The high-frequency package  1  according to the second embodiment is divided into parts on the coaxial cable  7  side and parts on the semiconductor chip  2  side and respectively sorted, and the non-defective parts are connected to one another, whereby the yield of the high-frequency package  1  can be improved. 
   Namely, a chip-side structural body  36  shown in  FIG. 42  wherein a semiconductor chip  2  with a cap  9  mounted thereon is flip-chip connected, and a cable-side structural body  37  shown in  FIG. 43  wherein a coaxial cable  7  is connected to an auxiliary substrate  32  by solder connection  31 , are respectively assembled. The respective structural bodies are selected and tested separately. 
   Thus, since both the structural bodies include microstrip lines, a high-frequency test can be effected on their parts, and the non-defective parts are connected to one another, so that their yields can be divided. As a result, the chip-side structural body  36  and the cable-side structural body  37  can share yield risks respectively, and the yield of the high-frequency package  1  shown in  FIG. 41  to which both structural bodies are connected, can be improved. 
   Further, the chip-side structural body  36  and the cable-side structural body  37  can be respectively put in circulation as singular parts, and they are available as parts. 
   Since all the external connecting terminals are provided on the main surface  4   a  on the flip-chip connection side, of the package substrate  4 , a screening test can be easily performed upon screening of semiconductor chips  2  each used for the high frequency of 40 Gbps. 
   Namely, since all the external connecting terminals for the high and low frequencies are provided on one-sided surface (main surface  4   a ) of the package substrate  4 , a probe becomes easy to contact upon the screening test. The test can be performed without using a jig having a complex shape. 
   As a result, a test time interval can be shortened. 
   Incidentally, the auxiliary substrate  32  may be used as a testing substrate  35  as shown in FIG.  44 . Alternatively, it may be used as a socket upon a screening test of each package substrate  4 . 
   At this time, the package substrate  4  and the testing substrate  35  are electrically brought into contact with each other with an interposer  35   a  such as an ACF (Anisotropic Conductive Film) or the like. A signal is transmitted to the outside through a corresponding pin member  35   b  to thereby test the package substrate  4 . 
   Incidentally, the testing substrate  35  is formed with a signal surface layer wiring  35   c , an internal signal wiring  35   d , GND layers  35   f  disposed through the signal surface layer wiring  35   c  and an insulating layer  35   e , and a microstrip line  35   g  in a manner similar to the auxiliary substrate  32 . 
   The chip-side structural body  36  shown in FIG.  42  and the cable-side structural body  37  shown in  FIG. 43  are respectively selected and tested in several. Non-defective products are obtained for them. Thereafter, the chip-side structural body  36  and the cable-side structural body  37  are connected and assembled. The resultant one is a high-frequency package  1  illustrative of a modification of the second embodiment shown in FIG.  45 . 
   Further, one wherein a thermal conductive adhesive  10  is applied onto the surface of a cap  9 , a radiating block  26  is mounted thereon with the thermal conductive adhesive  10  interposed therebetween, and the high-frequency package  1  is mounted on its corresponding module substrate  13  of an optical module  14  through pin members  35   b , is a mounting structure shown in FIG.  41 . 
   Incidentally, the cap  9  is first mounted onto its corresponding back surface  2   b  of the semiconductor chip  2  with the thermal conductive adhesive  10  interposed therebetween, and the radiating block  26  is mounted on the surface of the cap  9  with the thermal conductive adhesive  10  interposed therebetween in the high-frequency package  1  shown in FIG.  41 . In the optical module  14 , however, a module case  15  shares the role of the radiating block  26 . Further, the cap  9  is formed with an opening (wall escape portion)  9   a  for isolating the cap  9  and the surface wirings such as the signal surface layer wiring  4   c  or the like from one another. 
   Thus, since the radiating block  26  (module case  15 ) is provided on the cap  9  as well as the cap  9 , the high-frequency package  1  shown in  FIG. 41  is also capable of further enhancing dissipation or radiation thereof and preventing degradation of high-frequency characteristics. 
   (Third Embodiment) 
     FIG. 46  is a plan view showing one example of a layout of parts built in an optical module according to a third embodiment of the present invention,  FIG. 47  is a cross-sectional view illustrating one example of the layout of the parts built in the optical module shown in  FIG. 46 ,  FIG. 48  is a cross-sectional view showing a modification of a connecting method of a transmission line section employed in the optical module shown in  FIG. 46 ,  FIG. 49  is a plan view depicting a layout of parts built in an optical module illustrative of a modification of the third embodiment of the present invention,  FIG. 50  is a cross-sectional view showing one example of the layout of the parts built in the optical module shown in  FIG. 49 ,  FIG. 51  is a plan view illustrating a structure of a tape-shaped transmission line section showing one example of the transmission line section employed in the third embodiment of the present invention,  FIG. 52  is a cross-sectional view showing a structure of a cross-section cut along line A—A shown in  FIG. 51 ,  FIG. 53  is a cross-sectional view illustrating a structure of a cross-section cut along line B—B shown in  FIG. 51 ,  FIG. 54  is a back view showing a structure of a back surface of the tape-shaped transmission line section shown in FIG.  51 ,  FIG. 55  is a cross-sectional view illustrating a structure of a cross-section cut along line C—C shown in  FIG. 51 ,  FIG. 56  is a plan view showing a structure of a tape-shaped transmission line section illustrative of a modification of the third embodiment of the present invention,  FIG. 57  is a cross-sectional view illustrating a structure of a cross-section cut along line A—A shown in  FIG. 56 ,  FIG. 58  is a cross-sectional view showing a structure of a cross-section cut along line B—B shown in  FIG. 56 ,  FIG. 59  is a back view depicting a structure of a back surface of the tape-shaped transmission line section shown in  FIG. 56 ,  FIG. 60  is a cross-sectional view illustrating a structure of a cross-section cut along line C—C shown in  FIG. 56 ,  FIG. 61  is a plan view showing a structure of a tape-shaped transmission line section illustrative of another modification of the third embodiment of the present invention,  FIG. 62  is a cross-sectional view depicting a structure of a cross-section cut along line A—A shown in  FIG. 61 ,  FIG. 63  is a cross-sectional view showing a structure of a cross-section cut along line B—B shown in  FIG. 61 ,  FIG. 64  is a back view showing a structure of a back surface of the tape-shaped transmission line section shown in  FIG. 61 ,  FIG. 65  is a cross-sectional view illustrating a structure of a cross-section cut along line C—C shown in  FIG. 61 ,  FIG. 66  is a cross-sectional view showing one example of a mounting structure of a high-frequency package provided with the tape-shaped transmission line section according to the third embodiment of the present invention,  FIG. 67  is an enlarged partly cross-sectional view showing, in a developed form, a structure of a portion D shown in  FIG. 66 ,  FIG. 68  is a cross-sectional view illustrating a structure of a cross-section cut along line E—E shown in  FIG. 67 ,  FIG. 69  is a cross-sectional view showing a modification of the structure shown in  FIG. 68 ,  FIG. 70  is a cross-sectional view illustrating a modification of the structure shown in  FIG. 66 ,  FIG. 71  is a cross-sectional view showing another modification of the structure shown in  FIG. 66 ,  FIG. 72  is a plan view showing a structure of a tape-shaped transmission line section illustrative of a further modification of the third embodiment of the present invention,  FIG. 73  is a plan view showing a connected state of the tape-shaped transmission line section illustrative of the modification shown in  FIG. 72 ,  FIG. 74  is a cross-sectional view showing a mounting structure of a still further modification of the tape-shaped transmission line section according to the third embodiment of the present invention, and  FIG. 75  is a cross-sectional view illustrating a mounting structure of a still further modification of the tape-shaped transmission line section according to the third embodiment of the present invention, respectively. 
   The third embodiment describes high-frequency packages (semiconductor devices)  38  each mounted to a piece of an electronic device such as an optical module  39  or the like shown in  FIG. 46  having a structure similar to the optical module  14  described in the first embodiment. 
   Namely, the high-frequency package  38  is also of a semiconductor package equipped with an optical communication IC. This is a semiconductor device capable of performing high-speed transmission at 1 GHz or more, e.g., 40 Gbps. Incidentally, the high-frequency package  38  has a tape-shaped line section  40  corresponding to such a tape-like transmission line section as shown in  FIGS. 51 through 55  as a transmission line section for a high-frequency signal. The input or output of the high-frequency signal to and from a semiconductor chip  2  is performed via the tape-shaped line section  40 . Accordingly, the tape-shaped line section  40  is a member which performs the transfer of a high-speed signal. 
   The high-frequency package  38  comprises a package substrate (wiring board)  4  formed with such a signal surface layer wiring (surface layer wiring)  4   c  as shown in  FIG. 66 , a high-frequency semiconductor chip  2  electrically connected to and mounted onto a main surface  4   a  of the package substrate  4  by flip-chip connection with a plurality of solder bump electrodes  5  interposed therebetween, a tape-shaped line section  40  electrically connected to the signal surface layer wiring  4   c  of the package substrate  4 , an underfill resin  6  poured between a main surface  2   a  (see  FIG. 1 ) of the semiconductor chip  2  and the main surface  4   a  of the package substrate  4  to protect the flip-chip connected portion, and ball electrodes  3  used as a plurality of external connecting terminals disposed within a back surface  4   b  located on the side opposite to the main surface  4   a  of the package substrate  4 . 
   Further, the tape-shaped line section  40  according to the third embodiment has plate-shaped leads  40   a  which are transmission lines and high-frequency wirings as shown in FIG.  51 . The plate-shaped lead  40   a  is electrically connected to the signal surface layer wiring  4   c  of the package substrate  4 . 
   Incidentally, the package substrate  4  is formed with a microstrip line  4   g  made up of a signal surface layer wiring  4   c  and GND layers (ground conductor layers)  4   f  formed inside via the signal surface layer wiring  4   c  and an insulating layer  4   e  as shown in FIG.  1 . 
   Accordingly, the high-frequency package  38  according to the third embodiment directly inputs a signal of a high frequency (e.g., 40 Gbps) sent from the tape-shaped line section  40  to the semiconductor chip  2  through the corresponding solder bump electrode  5  by way of the signal surface layer wiring  4   c  of the package substrate  4  or outputs a high-frequency signal sent from the semiconductor chip  2  to the outside via the tape-shaped line section  40  in reverse in a manner similar to the high-frequency package  1  according to the first embodiment. The high-frequency package  38  has a structure wherein the high-frequency signal can be transmitted by only the microstrip line at the whole surface layer of the package substrate  4 . 
   As a result, the high-frequency signal can be transmitted without a loss in frequency characteristic owing to the transmission of the high-frequency signal by only the microstrip line at the surface layer of the package substrate  4  without through via-based wirings or the like. 
   Described specifically, reflective characteristics at high-frequency transmission can be reduced and penetrative or transmissive characteristics can be enhanced owing to the transmission of the high-frequency signal by only the microstrip line at the surface layer. Thus, a loss at the high-frequency transmission can be reduced and a high-quality high-frequency signal can be transmitted. 
   It is further possible to reduce disturbance in the waveform of the signal of the high frequency at the high-frequency transmission. Accordingly, the transmission of a high-quality high-frequency signal is enabled. 
   Namely, since a characteristic impedance mismatch occurs when vias are provided upon high-frequency transmission as described in the first embodiment, it can result in a transmission loss. However, if the microstrip line is used, then a desired characteristic impedance can be obtained with the design of parameters such as a wiring width, the thickness of an insulating layer, a space between adjacent patterns, etc. Accordingly, the uniform characteristic impedance can be designed between the input side and the output side and hence a transmission loss can be reduced. 
   Incidentally, the surface layer wirings of the package substrate  4 , such as the signal surface layer wiring  4   c , the GND surface layer wiring  4   h , etc. are formed of, for example, copper or the like. The surface layer wirings correspond to wirings disposed in the top layer on the main surface  4   a  side of the package substrate  4 , which may be exposed onto the surface of the main surface  4   a . Alternatively, they may be coated with a non-conductive thin film or the like. 
   In the high-frequency package  38  as well, a plurality of ball electrodes (bump electrodes)  3  provided as external connecting terminals are disposed on a back surface  4   b  of the package substrate  4  in an array form in a manner similar to the high-frequency package  1 . Accordingly, the high-frequency package  38  is also of a semiconductor package of a ball grid array type. 
   Thus, the package can be brought into less size as compared with an outer-lead protrusion type high-frequency package wherein outer leads protrude outwards from a package main body. 
   The optical module  39  shown in  FIG. 46 , which is equipped with the high-frequency packages  38 , will next be explained. 
   The optical module  39  according to the third embodiment is similar in structure to the optical module  14  according to the first embodiment. The optical module  39  converts an input light signal to an electric signal by means of an optoelectronic transducer (other semiconductor device)  20 , amplifies the same by means of an amplifier device (other semiconductor device)  19 , and thereafter performs arithmetic processing inside the semiconductor chip according to the electric signal, and further converts the result of its processing to a light signal again, followed by output to the following module product. 
   In the optical module  39  shown in  FIG. 46 , a signal of a high frequency on the order of a giga (G) Hz is inputted/outputted to the following stages of the amplifier devices  19 . Accordingly, the high-frequency packages  38  and the amplifier devices  19  corresponding to other semiconductor devices are respectively connected via the tape-shaped line sections  40 . 
   A description will now be made to the connections made via the tape-shaped line sections  40 . Upon the connection between the high-frequency packages  38  and the amplifier devices  19  mounted on the same module substrate  13 , the respective tape-shaped line sections  40  are connected to the module substrate  13  once, and the high-frequency packages  38  and the amplifier devices  19  are respectively electrically connected to one another through surface layer wirings on the module substrate  13  and the tape-shaped line sections  40 . 
   As shown in  FIG. 48 , the high-frequency packages  38  and the amplifier devices  19  can be directly connected to one another by their corresponding tape-shaped line sections  40 . 
   Namely, since the tape-shaped line sections  40  have flexibility, they are shaped in a bent form in advance. It is thus possible to easily package the high-frequency packages  38  or the amplifier devices  19 . 
   On the other hand, since the tape-shaped line section  40  has flexibility, both parts different in height can be directly connected by the tape-shaped line section  40  even if the parts are used. Accordingly, the distance between both parts can be shortened as shown in  FIG. 48 , and a packaging area can be reduced. Since the surface layer wirings of the module substrate  13  are not interposed between the parts upon transmission of a high-frequency signal between the parts, a loss at the transmission of the high-frequency signal can be further reduced, and the quality of transmission of the high-frequency signal can be enhanced. 
   The optical module  39  shown in  FIGS. 49 and 50  has a structure wherein tape-shaped line sections  40  are respectively interposed between amplifier devices  19  and optoelectronic transducers (other semiconductor devices)  20  as well as between high-frequency packages  38  and the amplifier devices  19 . Further, a packaging area of each part can be reduced and the quality of transmission of a high-frequency signal can be enhanced. 
   Incidentally, a circuit for dividing, for example, an input signal having a first frequency into a plurality of signals each having a second frequency smaller than the first frequency and outputting the same is built in the semiconductor chip  2  provided with the tape-shaped line section  40  on the signal input side in the optical module  39  shown in FIG.  46 . On the other hand, a circuit for integrating or combining, for example, a plurality of input signals each having a third frequency into a signal having a fourth frequency larger than the third frequency and outputting the same is incorporated into the semiconductor chip  2  provided with the tape-shaped line section  40  on the signal output side. The first and fourth frequencies are 1 GHz or more. 
   Since other structures other than the tape-shaped line sections  40 , of the structures of the optical modules  39  shown in  FIGS. 46 through 50  related to the third embodiment are similar to the optical module  14  shown in  FIG. 4 , the description of common ones will be omitted. 
   A configuration of the tape-shaped line section  40  mounted to the high-frequency package  38  according to the third embodiment will next be described. 
   The tape-shaped line section  40  shown in  FIGS. 51 through 55  is such a four-layer structured tape-shaped member as shown in  FIG. 52 , which comprises a single base metal layer (ground conductor layer)  40 b set to a ground potential shown in  FIG. 54 , an insulating layer  40   c  disposed thereon, a surface layer metal layer  40   d  formed thereon, and a cover coat layer  40   e  corresponding to a solder resist for covering the surface layer metal layer  40   d.    
   As shown in  FIG. 51 , the surface layer metal layer  40   d  has a surface layer signal lead  40   g  corresponding to a plate-shaped lead  40   a  disposed along its longitudinal direction in the vicinity of the center thereof as viewed in its transverse direction, and surface GND leads  40   h  disposed along the longitudinal direction thereof on both sides thereof. Further, the base metal layer  40   b  and the two surface layer GND leads  40   h  are respectively connected to one another by a plurality of vias  40   f  as shown in  FIGS. 53 and 55  and brought to the ground potential corresponding to the same potential. 
   Namely, the surface layer GND leads  40   h  are respectively disposed on both sides of the surface layer signal lead  40   g  of the surface layer metal layer  40   d  through the insulative cover coat layer  40   e . Further, the base metal layer  40   b  is disposed on the back side of the surface layer signal lead  40   g  with the insulating layer  40   c  interposed therebetween. Thus, the tape-shaped line section  40  is formed with a microstrip line  40   i  as shown in FIG.  55 . 
   As a result, a high-frequency signal is transmitted to other semiconductor device such as the amplifier device  19 , and the module substrate  13  or the like via the signal surface layer wiring  4   c  of the package substrate  4  and the surface layer signal lead  40   g  of the microstrip line  40   i  of the corresponding tape-shaped line section  40 , whereby the loss at high-frequency transmission is reduced and high-quality transmission of a high-frequency signal can be performed. 
   Incidentally, the base metal layer  40   b  is formed of stainless steel (SUS) or the like. The thickness thereof ranges from about 0.1 mm to about 0.2 mm, for example. The surface layer metal layer  40   d  is a thin film of copper, for example, and the thickness thereof ranges from about several tens of μm to about 35 μm, for example. The insulating film  40   c  is formed of a polyimide resin or the like, for example. 
   However, the quality and thickness or the like of each of the constituent members of each tape-shaped line section  40  are not limited to the above ones. 
   Incidentally, while the surface layer metal layer  40   d  is formed on the surface of the insulating layer  40   c  in the tape-shaped line section  40  shown in  FIGS. 51 through 55 , the surface layer metal layer  40   d  is formed of a wiring pattern of copper or the like. Further, the base metal layer  40   b  on the back side of the insulating layer  40   c  is one obtained by lining a metal thin plate having elasticity, for example. 
   Owing to the placement of the base metal layer  40   b  on the back side of the insulating layer  40   c , the tape-shaped line section  40  is easy to bend and mold, and its bent shape can be keep uniform. It is thus easy to shape a gull-wing form. As a result, the tape-shaped line sections  40  can be disposed with respect to the high-frequency package  38  to the module substrate  13  or the like or the high-frequency package  38  to other semiconductor device with high accuracy. An improvement in workability at packaging can be achieved and the packaging property of the high-frequency package  38  can be enhanced. 
   The tape-shaped line section  40  according to the modification shown in  FIGS. 56 through 60  includes a metal layer  40   j  set to a ground potential, which is provided over a base metal layer  40   b  with an adhesive  40   l  interposed therebetween as shown in FIG.  60 . The metal layer  40   j  is electrically connected to surface layer GND leads  40   h  via a plurality of vias  40   f . Since one layer is increased as the layer formed of copper foil set to the ground potential as compared with the tape-shaped line section  40  shown in  FIGS. 51 through 55 , a resistance value can be reduced as compared with the provision of the base metal layer  40   b  alone, and electric characteristics can be enhanced. 
   However, since the tape-shaped line section  40  shown in  FIGS. 51 through 55  is simple in structure as compared with the tape-shaped line section  40  illustrative of the modification shown in  FIGS. 56 through 60 , a cost reduction can be achieved. 
   The tape-shaped line section  40  shown in  FIGS. 61 through 65  includes a surface layer metal layer  40   d  and a metal layer  40   j  provided as wiring patterns. Both are electrically connected to each other by a plurality of vias  40   f . The surface layer metal layer  40   d  and the metal layer  40   j  are respectively covered with a cover coat layer  40   e  corresponding to an insulative solder resist. 
   In the tape-shaped line section  40  illustrative of the modification shown in  FIGS. 61 through 65 , the metal layer  40   j  can be also patterned because of copper foil. The tape-shaped line section  40  is capable of further improving electric characteristics as compared with the tape-shaped line section  40  shown in  FIGS. 51 through 55 . Since the tape-shaped line section  40  is simple in structure as compared with the tape-shaped line section  40  illustrative of the modification shown in  FIGS. 56 through 60 , the cost thereof can be reduced. Since the tape-shaped line section  40  also has flexibility, parts different in height can be easily connected to each other. 
   With the use of such tape-shaped line sections  40  as shown in  FIGS. 51 through 65  as high-frequency signal transmission line sections, the high-frequency package  38  according to the third embodiment can be reduced in size and thinned as compared with the high-frequency package  1  using the coaxial cable  7 , according to the first embodiment. Since the tape-shaped line section  40  is considerably low in cost as compared with the coaxial cable  7 , the cost of the high-frequency package  38  can be lowered. 
   Since the transmission lines such as the surface layer signal lead  40   g  and the surface layer GND leads  40   h  or the metal layer  40   j  formed in the tape-shaped line section  40  can be formed as the wiring patterns by a photolitho technology, the dimensions of each transmission line can be formed with high accuracy, and the design thereof can be facilitated. 
   Next,  FIGS. 66 through 71  respectively show mounting structures (electronic devices) of high-frequency packages  38 , which are ones wherein the high-frequency packages  38  equipped with tape-shaped line sections  40  each formed with being bent in a gull-wing fashion are respectively packaged over mounting boards  41 . 
   Since the tape-shaped line sections  40  are formed with being bent in the gull-wing fashion, packaging work is easy and packageability can be improved. When the tape-shaped line sections  40  are formed with being bent in the gull-wing form in this way, the tape-shaped line sections  40  provided with the lined base metal layers  40   b  may preferably be used as in the tape-shaped line section  40  shown in  FIGS. 51 through 55  and the tape-shaped line section  40  illustrative of the modification shown in  FIGS. 56 through 60 . 
   Incidentally,  FIGS. 67 and 68  respectively show the details of a connected state of the tape-shaped line section  40  and the mounting board  41 . A surface layer signal lead (transmission line)  40   g  of the tape-shaped line section  40  and a signal surface layer wiring (electrode)  41   a  of the mounting board  41 , and surface layer GND leads (transmission lines)  40   h  of the tape-shaped line section  40  and their corresponding GND surface layer wirings (electrodes)  41   b  of the mounting board  41  are respectively connected to one another with solder  42  interposed therebetween. 
     FIG. 69  shows a case in which an anisotropic conductive resin  43  is used as an alternative to the solder  42 . A surface layer signal lead  40   g  of a tape-shaped line section  40  and a signal surface layer wiring  41   a  of a mounting board  41 , and surface layer GND leads  40   h  of the tape-shaped line section  40  and GND surface layer wirings  41   b  of a mounting board  41  are respectively electrically connected to one another by conductive particles  43   a.    
   Using the solder  42  and the anisotropic conductive resin  43  in this way makes it possible to detach the respective tape-shaped line sections  40 . Consequently, each high-frequency package  38  can be easily repaired. 
   When the high-frequency package  38  is packaged as shown in  FIG. 70 , ball electrodes  3  used as its external connecting terminals and tape-shaped line sections  40  may be connected to different discrete mounting boards  41  without being connected to the same mounting board  41 . Namely, since the shape of the tape-shaped line section  40  has a degree of freedom, such mounting structures can be realized. 
     FIG. 71  shows a structure wherein a high-frequency package  38  and other semiconductor package (other semiconductor device)  44  are electrically connected to each other by a tape-shaped line section  40 . Since the high-frequency package  38  and other semiconductor package  44  are often different in height in this case, such a tape-shaped line section  40  as indicated by the modification shown in  FIGS. 61 through 65 , having relatively flexibility may preferably be used. Thus, even if the difference in height occurs between the two, they can be easily connected. 
   Incidentally, the high-frequency package  38  provided with the tape-shaped line section  40  in advance is mounted on its corresponding mounting substrate  41 . Thereafter, the tape-shaped line section  40  and other semiconductor package  44  may be connected to each other. Alternatively, the high-frequency package  38  having no tape-shaped line section  40 , and other semiconductor package  44  are packaged on the corresponding mounting board  41 , and thereafter the tape-shaped line section  40  may be connected to the two. In either case, the tape-shaped line section  40  having relatively ductility (flexibility) may preferably be used. 
   Further, since the tape-shaped line section  40  is directly connected to the high-frequency package  38  and other semiconductor package  44  without being connected to the mounting board  41  in the mounting structure shown in  FIG. 71 , the distance between the packages can be shortened, and a packaging area can be reduced. 
   Next,  FIG. 72  shows a modification of the transmission line section, which is a bifurcated tape-shaped line section (differential line) used upon input/output of a high-frequency signal among a plurality of packages. Two surface layer signal leads  40   g  are disposed and surface layer GND leads  40   h  are respectively disposed on both sides thereof and between the two. 
   In this case, a structure is taken wherein as shown in  FIG. 73 , one end of the bifurcated tape-shaped line section  45  is connected to one high-frequency package  38 , whereas other divided ends are respectively connected to discrete other semiconductor packages  44  or the like. 
     FIGS. 74 and 75  respectively show structures wherein high-frequency packages  38  with no tape-shaped line sections  40  attached thereto, and other semiconductor packages  44  or the like are first packaged to mounting boards  41  respectively and thereafter a user or the like connects the tape-shaped line sections  40  thereto. 
   In this case, the user is capable of easily turning ON/OFF electrical connections between the packages by mounting and demounting the tape-shaped line section  40  and changing applications. 
   (Fourth Embodiment) 
     FIG. 76  is a perspective view showing one example of a structure of a high-frequency package according to a fourth embodiment of the present invention,  FIG. 77  is a plan view illustrating the structure of the high-frequency package shown in  FIG. 76 ,  FIG. 78  is a perspective view showing a structure of a back side of a frame-shaped transmission line section mounted to the high-frequency package shown in  FIG. 76 ,  FIG. 79  is a cross-sectional view depicting one example of a mounting structure of the high-frequency package shown in  FIG. 76 ,  FIG. 80  is a plan view showing a structure of a high-frequency package illustrative of a modification of the fourth embodiment of the present invention,  FIG. 81  is s perspective view illustrating the structure of the high-frequency package shown in  FIG. 80 ,  FIG. 82  is a perspective view showing a structure of a back side of a transmission line section mounted to the high-frequency package shown in  FIG. 81 ,  FIG. 83  is a plan view depicting a structure of a high-frequency package illustrative of another modification of the fourth embodiment of the present invention,  FIG. 84  is a perspective view showing the structure of the high-frequency package shown in  FIG. 83 ,  FIG. 85  is a perspective view illustrating a structure of a back side of a transmission line section mounted to the high-frequency package shown in  FIG. 84 , and  FIG. 86  is a cross-sectional view showing the structure of the high-frequency package shown in  FIG. 83 , respectively. 
   In the fourth embodiment, a transmission line section of a high-frequency package (semiconductor device)  47  is disposed so as to protrude in two opposite directions of a package substrate  4  as shown in FIG.  76 . At this time, the transmission line section is provided with a connecting portion  46   g  which protrudes from the transmission line section in a direction to cross its transmission lines and is formed integrally with the transmission line section. 
   Incidentally, the connecting portion  46   g  is shaped in a frame form according to an outer peripheral shape of the package substrate  4  as shown in FIG.  78 . Plate-shaped line portions  46  each corresponding to the transmission line section protrude in two opposite directions of the frame-shaped connecting portion  46   g  and are formed integrally with the connecting portion  46   g.    
   Even in the case of the plate-shaped line sections  46 , base metal layers (ground conductor layers)  46   b  and surface layer metal layers  46   e  (see  FIG. 78 ) are disposed with an insulating layer  46   f  formed of a polyimide resin or the like interposed therebetween. Further, each of the surface layer metal layers  46   e  is a plate-shaped lead (wiring)  46   a  made up of a surface layer signal lead (transmission line)  46   c  and a surface layer GND lead (transmission line)  46   d.    
   Incidentally, since the connecting portion  46   g  is frame-shaped, a semiconductor chip  2  takes a structure exposed within the frame as shown in  FIGS. 76 and 77  when the connecting portion  46   g  is mounted on the package substrate  4 . 
     FIG. 79  shows the mounting structure wherein the high-frequency package  47  is packaged to a mounting board  41 . Signal surface layer wirings  4   c  of a package substrate  4  in the high-frequency package  47  and their corresponding surface layer signal leads  46   c  of plate-shaped line sections  46 , and the surface layer signal leads  46   c  of the plate-shaped line sections  46  and their corresponding signal surface layer wirings  41   a  on the mounting board  41  are respectively electrically connected to one another. 
   In the high-frequency package  47  shown in  FIG. 76 , according to the fourth embodiment, the connecting portion  46   g  protruded from each plate-shaped line section  46  assumes the role of reinforcement upon connection of the plate-shaped line sections  46  and the package substrate  4 . Therefore, the connecting portion  46   g  is capable of enhancing the strength of connection between the plate-shaped line sections  46  and the package substrate  4 . The larger the area for connecting the connecting portion  46   g  and the package substrate  4  at this time, the greater the strength of connection between the two. 
   Further, since the connecting portion  46   g  formed integrally with the plate-shaped line sections  46  is directly connected to the package substrate  4  in a frame-based large area, heat generated from the semiconductor chip  2  can be dissipated into the connecting portion  46   g  through the package substrate  4 , so that the radiation of the high-frequency package  47  can be enhanced. 
   Owing to the connection of the plate-shaped line sections  46  each having the base metal layer  46   b  at a ground potential to the package substrate  4 , the ground of the high-frequency package  47  can be upgraded and a noise margin can be enhanced. 
   When the plate-shaped line sections  46  and the connecting portion  46   g  are integrally formed, the surface layer signal leads  46   c  each corresponding to the transmission line, and the surface layer GND leads  46   d  are formed by etching processing. Further, the central portion of the connecting portion  46   g  is punched out and thereafter the connecting portion  46   g  is formed by press molding. At this time, the bending accuracy of each plate-shaped line section  46  can be set to about ±0.05 mm owing to the accuracy of a press die. 
   Incidentally, the connecting portion  46   g  may not be necessarily formed in such a frame shape so as to couple the two plate-shaped line sections  46  disposed as opposed to each other. The connecting portion  46   g  may be one having areas which protrude in a direction to cross transmission lines of the plate-shaped line sections  46  from the plate-shaped line sections  46  and are connectable to the package substrate  4 . Namely, the two plate-shaped line sections  46  disposed in an opposing relationship may not be necessarily connected to each other. 
   Next,  FIGS. 80 through 82  show a high-frequency package  47  equipped with plate-shaped line sections  46  according to a modification. Transmission lines are formed in association with four directions of a package substrate  4 , and the plate-shaped line sections  46  respectively formed in association with the four sides thereof are brought to an integrally connected structure. 
   Owing to the provision of the structure wherein the plate-shaped line sections  46  corresponding to the four sides of the package substrate  4  are respectively connected at the corners in this way, the degree of flatness of each lead can be enhanced. 
   When the bending accuracy of a press die is about ±0.05 mm, for example, a flatness of 0.05 mm or less can be ensured. Since the integrally-constructed plate-shaped line sections  46  corresponding to the four sides are joined to the package substrate  4 , the degree of flatness of a ball-electrode mounting surface of the package substrate  4  can be set to 0.1 mm or less. 
   Since the lead flatness can be enhanced, the height-control ball electrodes  3  (see  FIG. 76 ) become unnecessary. Therefore, the high-frequency package  47  can be low priced and its connection reliability can be enhanced. 
     FIGS. 83 through 86  show a high-frequency package  47  equipped with plate-shaped line sections  46 , according to another modification. A connecting portion  46   g  is disposed even on a semiconductor chip  2 . As shown in  FIG. 86 , a back surface  2   b  of the semiconductor chip  2  and the connecting portion  46   g  are bonded to each other by an adhesive  48 . 
   Thus, the high-frequency package  47  can be further improved in dissipation. 
   (Fifth Embodiment) 
     FIG. 87  is a plan view illustrating a structure of a tape-shaped transmission line section according to a fifth embodiment of the present invention,  FIG. 88  is a plan view showing a structure of a base metal layer of the tape-shaped transmission line section shown in  FIG. 87 ,  FIG. 89  is a plan view depicting a structure of an insulating layer of the tape-shaped transmission line section shown in  FIG. 87 ,  FIG. 90  is a plan view illustrating a structure of a surface-layer metal layer of the tape-shaped transmission line section shown in  FIG. 87 ,  FIG. 91  is a plan view showing a structure of a cover coat layer of the tape-shaped transmission line section shown in  FIG. 87 ,  FIG. 92  is a cross-sectional view illustrating a structure of a cross-section cut along line A—A shown in  FIG. 87 ,  FIG. 93  is a cross-sectional view depicting a structure of a cross-section cut along line B—B shown in  FIG. 87 ,  FIG. 94  is a partly cross-sectional view showing a connecting structure of the base metal layer of the tape-shaped transmission line section shown in  FIG. 87 ,  FIG. 95  is a partly cross-sectional view illustrating a connecting structure of the surface-layer metal layer of the tape-shaped transmission line section shown in  FIG. 87 ,  FIG. 96  is a plan view depicting a structure of a tape-shaped transmission line section illustrative of a modification of the fifth embodiment of the present invention,  FIG. 97  is a plan view showing a structure of a base metal layer of the tape-shaped transmission line section shown in  FIG. 96 ,  FIG. 98  is a plan view illustrating a structure of an insulating layer of the tape-shaped transmission line section shown in  FIG. 96 ,  FIG. 99  is a plan view depicting a structure of a surface-layer metal layer of the tape-shaped transmission line section shown in  FIG. 96 ,  FIG. 100  is a plan view showing a structure of a cover coat-layer of the tape-shaped transmission line section shown in  FIG. 96 ,  FIG. 101  is a cross-sectional view illustrating a structure of a cross-section cut along line A—A shown in  FIG. 96 ,  FIG. 102  is a cross-sectional view depicting a structure of a cross-section cut along line B—B shown in  FIG. 96 ,  FIG. 103  is a partly cross-sectional view showing a connecting structure of a surface-layer metal layer (GND) of the tape-shaped transmission line section shown in  FIG. 96 ,  FIG. 104  is a partly cross-sectional view illustrating a connecting structure of a surface-layer metal layer (signal) of the tape-shaped transmission line section shown in  FIG. 96 ,  FIG. 105  is a cross-sectional view showing a structure of a tape-shaped transmission line section illustrative of another modification of the fifth embodiment of the present invention,  FIG. 106  is a plan view depicting a structure of a tape-shaped transmission line section illustrative of a further modification of the fifth embodiment of the present invention,  FIG. 107  is a plan view showing a structure of a tape-shaped transmission line section illustrative of a still further modification of the fifth embodiment of the present invention,  FIG. 108  is a plan view showing one example of a connecting structure of the tape-shaped transmission line section according to the fifth embodiment of the present invention,  FIG. 109  is a plan view showing one example illustrative of how a return current flows in the connecting structure shown in  FIG. 108 , and  FIG. 110  is a plan view showing how a return current flows in a connecting structure of a comparative example with respect to the connecting structure shown in  FIG. 108 , respectively. 
   The fifth embodiment describes another embodiment of the tape-shaped transmission line section. 
   A tape-shaped line section (transmission line section)  49  shown in  FIG. 87  is substantially similar in structure to the tape-shaped line section  40  described in the third embodiment. However, the tape-shaped line section  49  is different therefrom in that cut-away portions  40 k are respectively defined in a base metal layer  40   b , an insulating layer  40   c  and a cover coat layer  40   e.    
   A detailed structure of the tape-shaped line section  49  shown in  FIG. 87  will be described. The tape-shaped line section  49  comprises four layers of a base metal layer  40   b  shown in  FIG. 88 , an insulating layer  40   c  shown in  FIG. 89 , a surface metal layer  40   d  shown in  FIG. 90 and a  cover coat layer  40   e  shown in FIG.  91 .  FIG. 92  shows a sectional structure at a GND line, and  FIG. 93  shows a sectional structure at a signal line. 
   Incidentally, the base metal layer  40   b  shown in FIG.  88 , the insulating layer  40   c  shown in FIG.  89  and the cover coat layer  40   e  shown in  FIG. 91  respectively have cut-away portions  40   k  defined in parts of their ends at portions thereof each of which overlaps with a surface layer signal lead  40   g  of the surface layer metal layer  40   d.    
   A longitudinally-extending length of the insulating layer  40   c  is shorter than that of the base metal layer  40   b . An end of the base metal layer  40   b  is exposed so as to be connectable to a surface layer wiring of a wiring board such as a package substrate  4  or the like. 
   Further, the surface layer metal layer  40   d  comprises a surface layer signal lead  40   g  and surface layer GND leads  40   h . The surface layer GND leads  40   h  are shorter than the surface layer signal lead  40   g , and ends of the surface layer GND leads  40   h  are covered with the insulating layer  40   c.    
   The cover coat layer  40   e  shown in  FIG. 91  is disposed on the surface layer metal layer  40   d . Further, the base metal layer  40   b  and the surface layer GND leads  40   h  of the surface layer metal layer  40   d  are electrically connected by a plurality of vias  40   f . At this time, the placement pitch between the adjacent vias  40   f  is set narrower than at spots other than those in the neighborhood of the cut-away portions  40   k  of the respective layers, or successive vias  40   n  are provided. 
     FIGS. 94 and 95  respectively show a state of connection of the tape-shaped line section  49  shown in  FIG. 87  to a package substrate  4 .  FIG. 94  illustrates a state of connection of the base metal layer  40   b  and GND surface layer wirings  4   h  of the package substrate  4  by solder  42  (which may be conductive paste or the like).  FIG. 95  shows a state of connection of the surface layer signal lead  40   g  and its corresponding signal surface layer wiring  4   c  on the package substrate  4  by solder  42  (which may be conductive paste or the like). 
   Incidentally, since the longitudinally-extending length of the insulating layer  40   c  is shorter than the length of the base metal layer  40   b  as shown in  FIGS. 88 and 89 , the ends of the base metal layer  40   b  can be exposed. Accordingly, the base metal layer  40   b  of the tape-shaped line section  49  can be connected to the GND surface layer wirings  4   h  of the package substrate  4  as shown in FIG.  94 . Thus, a GND potential is stabilized so that electric characteristics can be enhanced. 
   In the fifth embodiment, the base metal layer  40   b , the insulating layer  40   c  and the cover coat layer  40   e  respectively have cut-away portions  40   k  defined in parts of their ends at portions thereof each of which overlaps with the surface layer signal lead  40   g  of the surface layer metal layer  40   d.    
   In addition, the placement pitch between the adjacent vias  40   f  is set narrower than at spots other than those in the neighborhood of the cut-away portions  40   k  of the respective layers, or successive vias  40   n  are provided. Thus, as shown in  FIG. 109 , the flow of a return current  54  can be made smoother and hence source impedance can be reduced. 
   A difference in the way of flowing of the return current  54  where the cut-away portions  40   k  are defined in the tape-shaped line section  49  and no cut-away portions  40   k  are not defined therein, will now be explained. 
   As shown in  FIG. 108 , a connecting portion of a surface layer signal lead  40   g  assumes a coplanar structure  50  where a cut-away portion  40   k  is defined in a tape-shaped line section  49  as in the fifth embodiment. However, a GND layer  4   f  corresponding to an inner layer is provided on the substrate side as viewed from the connecting portion. On the other hand, since a base metal layer  40   b  is provided on the lead side as viewed from the connecting portion, both sides of the connecting portion both result in GND coplanar structures  51 . 
   A tape-shaped line section  49  illustrated in a comparative example of  FIG. 110  is not formed with such a cut-away portion  40   k  as shown in FIG.  108 . Namely, a connecting portion of a surface layer signal lead  40   g  results in a GND coplanar structure  51 . Thus, when the surface layer signal lead  40   g  of the GND coplanar structure  51  is connected to a substrate, an end portion of a base metal layer  40   b  is placed on the back surface side of the surface layer signal lead  40   g , and a signal surface layer wiring  4   c  is formed at a portion which overlaps with the surface layer signal lead  40   g . Therefore, the connections between the base metal layer  40   b  and GND surface layer wirings  4   h  are made only in the edge neighborhood of an end of the base metal layer  40   b.    
   Therefore, for example, a return current  54  which has flowed immediately below the corresponding wiring from the lead side to the substrate, abruptly changes its direction in the edge neighborhood (vicinity of Q) of the base metal layer  40   b  (GND) and enters into the substrate side. 
   Thus, since there is a possibility that the moving distance of the return current  54  becomes long, thus leading to an increase in source impedance, this is not desirable. 
   On the other hand, when the cut-away portion  40   k  is provided as shown in  FIG. 109 , the return current  54  that has flowed immediately below the wiring from the lead side to the substrate, gently changes its direction. Therefore, an increase in source impedance at an end (in the vicinity of P) of a base metal layer  40   b  (GND) is reduced as compared with FIG.  110 . 
   Thus, the formation of the GND coplanar structure  51 +coplanar structure  50 +GND coplanar structure  51  by the provision of the cut-away portion  40   k  for the tape-shaped line section  49  enables a further reduction in transmission loss of a signal of a high frequency. Further, the mounting pitch between the adjacent vias  40   f  is set narrower than at spots other than those in the neighborhood of the cut-away portion  40   k , or successive vias  40   n  are provided. Thus, the flow of the return current  54  can be made smoother so that source impedance can be further reduced, thus making it possible to further improve electric characteristics. 
   Next,  FIG. 96  shows a tape-shaped line section  49  illustrative of the modification of the fifth embodiment. Configurations of the tape-shaped line section  49  and its sectional structures are respectively illustrated in  FIGS. 97 through 102 . 
   Incidentally, the tape-shaped line section  49  of the modification shown in  FIG. 96  is substantially similar in structure to the tape-shaped line section  49  shown in FIG.  87  and formed with a cut-away portion  40   k . However, the length of each surface layer GND lead  40   h  in a surface layer metal layer  40   d  is longer than that of a base metal layer  40   b.    
   In this case, as shown in  FIG. 103 , the surface layer GND leads  40   h  of the surface metal layer  40   d , and their corresponding GND surface layer wirings  4   h  of a package substrate  4  are connected to one another by means of solder  42  or conductive paste or the like. On the other hand, as shown in  FIG. 104 , a surface layer signal lead  40   g  of the surface layer metal layer  40   d  and its corresponding signal surface layer wiring  4   c  of the package substrate  4  are connected to each other by solder  42  or conductive paste or the like. 
   Now, as shown in  FIGS. 103 and 104 , a semiconductor chip  2  is mounted on the package substrate  4  with solder ball electrodes  5  interposed therebetween. Each of the GND surface layer wirings  4   h  and a predetermined solder bump electrode  5 , and the signal surface layer wiring  4   c  and a predetermined bump electrode  5  are respectively connected to one another. 
   Incidentally, assuming that in each of the package substrates  4  shown in  FIGS. 103 and 104 , an area (corresponding to an area in which no GND layer  4   f  is formed) up to a substrate end on the left side toward from the GND layer  4   f  in each drawing is defined as a first area, and an area in which the GND layer  4   f  is formed, is defined as a second area, no other wiring layer is formed between GND surface layer wirings  4   h  and the GND layer  4   f  in the second area. Further, no GND layer  4   f  is formed below the GND surface layer wirings  4   h  and the signal surface layer wiring  4   c  formed in the first area. 
   Thus, since the cut-away portion  40   k  is formed even in the case of the tape-shaped line section  49  shown in  FIG. 96 , a GND coplanar structure  51 +coplanar structure  50 +GND coplanar structure  51  can be brought about. In a manner similar to the tape-shaped line section  49  shown in  FIG. 87 , a reduction in transmission loss of a signal of a high frequency can be achieved. As a result, an improvement in electric characteristic can be achieved. 
   Incidentally, when it is possible to form the base metal layer  40   b  thick fully, the tape-shaped line section  49  shown in  FIG. 87  is capable of enhancing the strength of GND connection. 
   Next, a tape-shaped line section  52  illustrative of another modification shown in  FIG. 105  is one wherein other metal layer  40   j  made up of a wiring pattern or the like is provided between a base metal layer  40   b  and an insulating layer  40   c , and a surface protective layer  40   m  is formed on the surface of the base metal layer  40   b.    
   Since the metal layer  40   j  made up of the wiring pattern and high in metal purity can be formed in this case, source impedance can be further reduced, and electric characteristics can be enhanced. 
   Incidentally, while the fifth embodiment has described the case in which one signal line is disposed in each of the tape-shaped line sections  49  and  52  and GND lines are formed on both sides one by one as three wirings in total, the numbers of signal lines and GND lines are respectively not limited to the above. Therefore, two surface layer signal leads  40   g  may be provided as shown in  FIGS. 106 and 107 . A tape-shaped line section  53  shown in  FIG. 106  is one wherein two surface layer signal leads  40   g  are disposed between the surface layer GND leads  40   h  at both ends. A tape-shaped line section  55  shown in  FIG. 107  is one wherein surface layer GND leads  40   h  are disposed on both sides of two surface layer signal leads  40   g  respectively, and a surface layer GND lead  40   h  is disposed even between the two surface layer signal leads  40   g . The two surface layer signal leads  40   g  and the three surface layer GND leads  40   h  are provided. 
   Since the tape-shaped line section  53  and the tape-shaped line section  55  are also provided with cut-away portions  40   k , an advantage similar to the tape-shaped line section  49  shown in  FIG. 87  can be obtained. 
   While the invention made above by the present inventors has been described specifically based on the illustrated embodiments, the present invention is not limited to the embodiments. It is needless to say that many changes can be made thereto within the scope not departing from the substance thereof. 
   While each of the first through fifth embodiments has described the case in which the semiconductor device is of the ball grid array type semiconductor package, for example, the semiconductor device may be an LGA (Land Grid Array) or the like, for example, if one having a structure wherein a plurality of external connecting terminals are disposed within a plane of a package substrate, is adopted. 
   Further, while each of the first through fifth embodiments has described the case in which the semiconductor chip  2  is flip-chip connected to the package substrate  4 , the method of connecting the semiconductor chip  2  and the package substrate  4  is not limited to such a flip-chip connection. It may be ribbon bonding using flat plate-shaped metal wires, etc. 
   Advantageous effects obtained by a typical one of the inventions disclosed in the present application will be described in brief as follows: 
   A high-frequency signal is transmitted via a transmission line section connected to each surface layer wiring on a wiring board. Therefore, a transmission loss in high frequency is reduced and thereby its signal can be transmitted. As a result, a high-quality high-frequency signal can be transmitted.