Patent Publication Number: US-2011048796-A1

Title: Connector, Package Using the Same and Electronic Device

Description:
TECHNICAL FIELD 
     The present invention relates to a connector (or a connecting terminal), a package using the same and an electronic device. 
     BACKGROUND ART 
       FIG. 12(   a ) is a plan view showing a conventional electronic device  100  having a connector  103 , and  FIG. 12(   b ) is a sectional view of the electronic device  100 . 
     The electronic device  100  comprises a package having a frame  102  and the connector  103 , and an electronic component  115  such as semiconductor element housed in the package. 
     The connector (input/output terminal)  103  is disposed below the frame  102  of the container of the package. One end of the connector  103  located outside of the frame  102  is connected via a lead  116  to an external circuit, while the other end located inside of the frame  102  is connected via a bonding wire  114  to the electronic component (internal circuit)  115 . Thus the external circuit and the electronic component  115  are electrically connected with each other. 
     The connector  103  has two kinds of conductor; first conductor  111  and second conductor  112 . 
     The first conductor  111  is disposed on a first flat portion (top surface of a first dielectric layer)  103   a  formed from ceramics extending from the outside of the frame  102  toward the inside, and extends from the outside of the frame  102  toward the inside similarly to the first dielectric layer. 
     The first conductor  111  has a first external connecting terminal connected to the lead  116  outside of the frame  102 , and has a first internal connecting terminal connected to the bonding wire  114  in the frame  102 . 
     The second conductor  112  extends on a second flat portion (top surface of a second dielectric layer)  103   b  formed from ceramics on the outside of the frame  102 . Within the frame  102 , the second conductor  112  extends on the first flat portion  103   a  similarly to the first conductor  111 . 
     The second conductor  112  has a second external connecting terminal connected to the lead  116  outside of the frame  102 , and has a second internal connecting terminal connected to the bonding wire  114  in the frame  102 . 
     The second flat portion  103   b  is disposed above the first flat portion  103   a , with a step existing between the second flat portion  103   b  and the first flat portion  103   a.    
     As described above, since the first and second external connecting terminals are disposed on the top surface of the first flat portion  103   a  and the top surface of the second flat portion  103   b  which are separate planes, the connector tends to protrude to the outside. 
     The first and second internal connecting terminals, on the other hand, are arranged along the frame  102  on the same plane, and the length of the arrangement tends to be longer. 
     As a result, the connector described above is likely to become large, and may cause the package using the connector and the electronic device  100  using the package to become large. 
     Patent Document 1: JP2004-356391A 
     SUMMARY OF INVENTION 
     Technical Problem 
     The present invention has been made to solve the problem described above and an object thereof is to provide a connector that can be reduced in size. Another object of the present invention is to provide a package and an electronic device that can be reduced in size. 
     Solution to Problem 
     A connector according to an embodiment of the present invention is for the purpose of electrically connecting an internal circuit formed in a frame-like container and an external circuit provided outside the container. 
     The connector comprises a stacked body having a first top surface, a second top surface positioned at a height different from the first top surface and a bottom surface positioned opposite to the second top surface, and the stacked body comprises a plurality of dielectric layers. 
     The connector further comprises a first conductor and a second conductor. The first conductor comprises a first external connecting terminal disposed on the first top surface of the stacked body and for connecting to the external circuit, and a first internal connecting terminal disposed on the first top surface of the stacked body and for connecting to the internal circuit. The second conductor comprises a second internal connecting terminal disposed on the second top surface and for connecting to the internal circuit and a second external connecting terminal disposed on the bottom surface and for connecting to the external circuit. 
     A connector according to another embodiment of the present invention comprises a plurality of first conductors each comprising a first internal connecting terminal and a first external connecting terminal, a plurality of second conductors each having a second internal connecting terminal and a second external connecting terminal, and a stacked body comprising a plurality of dielectric layers and provided with the first and the second conductors. 
     The stacked body comprises a first top surface whereon the first internal connecting terminal and the first external connecting terminal of the first conductor are disposed, a second top surface positioned in a plane different from the first top surface whereon the second internal connecting terminal is disposed, and a bottom surface whereon the second external connecting terminal disposed and corresponding to the back of the second top surface. 
     Advantage 
     Use of the connector described above enables it to make the connector smaller. Use of the connector described above also enables it to make the package and the electronic device smaller. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a connector  6  according to the first embodiment of the present invention,  FIG. 1(   a ) is a sectional view of the connector  6  taken along lines X-X′ in  FIG. 1(   b ), and  FIG. 1(   b ) is a plan view of the connector  6 . 
         FIG. 2  is a sectional view showing a connector  6   a  according to the first embodiment of the present invention. 
         FIG. 3  shows a connector  6   a ,  FIG. 3(   a ) is a perspective view thereof, and  FIG. 3(   b ) is an exploded perspective view thereof. 
         FIG. 4  is a plan view showing a connector  6   b  according to the first embodiment of the present invention. 
         FIG. 5  shows a connector  6   c  according to the first embodiment of the present invention,  FIG. 5(   a ) is a perspective view thereof, and  FIG. 5(   b ) is an exploded perspective view thereof. 
         FIG. 6  show a connector  6   d  according to the second embodiment of the present invention,  FIG. 6(   a ) is a sectional view of the connector  6   d  taken along lines X-X′ in  FIG. 6(   b ), and  FIG. 6(   b ) is a plan view of the connector  6   d.    
         FIG. 7  shows a connector  6   d ,  FIG. 7(   a ) is a perspective view thereof, and  FIG. 7(   b ) is an exploded perspective view thereof. 
         FIG. 8  shows a connector  6   e  according to the second embodiment of the present invention,  FIG. 8(   a ) is a sectional view of the connector.  6   e  taken along line Y-Y′ of  FIG. 8(   b ), and  FIG. 8(   b ) is a perspective view showing the connector  6   e.    
         FIG. 9  shows a connector  6   e ,  FIG. 9(   a ) is a perspective view thereof, and  FIG. 9(   b ) is an exploded perspective view thereof. 
         FIG. 10  shows a connector  6   f  according to the second embodiment of the present invention,  FIG. 10(   a ) is a perspective view of thereof, and  FIG. 10(   b ) is an exploded perspective view thereof. 
         FIG. 11  shows a package  30  and an electronic device  50  according to the third embodiment of the present invention,  FIG. 11(   a ) is a schematic plan view thereof, and  FIG. 11(   b ) is a schematic sectional view thereof. 
         FIG. 12  shows a conventional package and a conventional electronic device  100 ,  FIG. 12(   a ) is a plan view thereof, and  FIG. 12(   b ) is a sectional view thereof. 
     
    
    
     REFERENCE SIGNS LIST 
     
         
           1 : Dielectric substrate layer 
           1   a : First dielectric layer 
           1   b : Second dielectric layer 
           1   c : Third dielectric layer 
           1   d : Fourth dielectric layer 
           1   e : Fifth dielectric layer 
           1   f : Sixth dielectric layer 
           2   a : First conductor 
           2   a - 1 : First external connecting terminal 
           2   a - 2 : First internal connecting terminal 
           2   b , 2   b   1 , 2   b   2 : Second conductor 
           2   b - 1 : Second external connecting terminal 
           2   b - 2 : Second internal connecting terminal 
           2   b - 3 : Internally extended portion of the second conductor 
           2   c : Third conductor 
           2   c - 1 : Third external connecting terminal 
           2   c - 2 : Third internal connecting terminal 
           2   c - 3 : Internally extended portion of the third conductor 
           3 : Grounding conductor 
           4 : Metal layer 
           5 : Via hole conductor 
           6 , 6   a , 6   b , 6   c , 6   d , 6   e , 6   f : connector 
           7   a : Flat part 
           7   b : Step portion 
           8 : Notch 
           9   a : First end of the connector 
           9   b : Second end of the connector 
           10 : Container 
           11 : Cavity 
           12 : Frame 
           13 : Aperture 
           14 : Bonding wire 
           15 : electronic component 
           20 : Lid 
           30 : Package 
           50 : Electronic device 
       
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. While terms indicating particular directions or positions (such as top, bottom, right, left and other phrases including these) are used in the following description, these terms are used for making it easier to understand the present invention with reference to the accompanying drawings. It should be noted that meanings of these terms do not limit the technical scope of the present invention. Identical reference numerals used in plural drawings denote the identical portions or members. 
     The connector of the present invention, and the package and the electronic device using the same will be described in detail below. 
     1. First Embodiment 
       FIG. 1  is a view showing the connector  6  according to the first embodiment of the present invention.  FIG. 1(   a ) is a sectional view of the connector  6  taken along lines X-X′ in  FIG. 1(   b ), and  FIG. 1(   b ) is a plan view of the connector  6 . 
     As shown in  FIG. 1 , the connector  6  of the first embodiment comprises conductors comprising the first conductor  2   a  and the second conductor  2   b  provided on the surface and inside of a dielectric substrate  1 . 
     Specifically, the dielectric substrate  1  has multi-layer structure wherein three dielectric layers of first dielectric layer  1   a , second dielectric layer  1   b  and third dielectric layer  1   c  are disposed in parallel in this order from the bottom as shown in  FIG. 1(   a ). It is preferable that a fourth dielectric layer  1   d  is disposed on the third dielectric layer  1   c  as shown in  FIG. 1(   a ),  1 ( b ) in the present embodiment. 
     Providing the fourth dielectric layer  1   d  enables it to reinforce the connector  6 . As a result, the connector  6  can be made less likely to be damaged even when the connector  6  is bonded onto the frame  12  as shown in  FIGS. 11(   a ) and  11 ( b ) and is subjected to a stress caused by the difference in thermal expansion with the frame  12 . 
     Disposed on the top surface of the second dielectric layer  1   b  is one or more, preferably a plurality of the first conductors  2   a  extending from a first end  9   a  to a second end  9   b  of the connector  6 . 
     In the dielectric substrate  1 , positions of both ends of the first dielectric layer  1   a  and the second dielectric layer  1   b  are aligned in the extending direction of the first conductor  2   a . In contrast, both ends of the third dielectric layer  1   c  are positioned inward from both ends of the second dielectric layer  1   b . As a result, a step portion  7   b  is formed on the side of the second end  9   b.    
     Moreover, ends of the third and fourth dielectric layers  1   c ,  1   d  are aligned on the first end  9   a  side, and end of the fourth dielectric layer  1   d  is positioned inward from the end of the third dielectric layer  1   c  on the second end  9   b  side. The first conductor  2   a  has exposed portions not covered by the third dielectric layer  1   c  or the fourth dielectric layer  1   d  on the first end  9   a  side and on the second end  9   b  side. 
     The exposed portion of the first conductor  2   a  on the first end  9   a  side functions as a first external connecting terminal  2   a - 1  that connects to lead or the like connected to an external circuit. The exposed portion of the first conductor  2   a  on the second end  9   b  side, on the other hand, functions as a first internal connecting terminal  2   a - 2  that connects to a bonding wire connected to an internal circuit such as electronic component disposed in the package. 
     The connector  6  also has one or more, preferably a plurality of the second conductors  2   b . The second conductor  2   b  comprises a second external connecting terminal  2   b - 1  formed on the bottom surface of the first dielectric layer  1   a , a second internal connecting terminal  2   b - 2  disposed on the top surface of the third dielectric layer  1   c , and an internal connection conductor connecting between the second external connecting terminal  2   b - 1  and the second internal connecting terminal  2   b - 2 . 
     The internal connection conductor comprises a via hole conductor  5  connected to the second external connecting terminal  2   b - 1  and penetrating through the first dielectric layer  1   a , an extension  2   b - 3  connected to the via hole conductor  5  and formed on the top surface of the first dielectric layer  1   a , and via hole conductor  5  connected to the extension  2   b - 3  and penetrating through the second dielectric layer  1   b  and the third dielectric layer  1   c , as shown in  FIG. 1(   a ). 
     While the via hole conductor  5  penetrating through the first dielectric layer  1   a  and the via hole conductor  5  penetrating through the third dielectric layer are shown in the drawing as each being constituted from one conductor, such a constitution may also be employed that each comprises a plurality of via hole conductors  5  depending on the current capacity of the second conductor  2   b . 
     The extension  2   b - 3  is formed on the top surface of the first dielectric layer  1   a , for the consideration of a case where the frame  12  of the package  30  shown in  FIG. 11  to be described later is formed from a metal. That is, the first dielectric layer  1   a  is provided for the purpose of insulating between the extension  2   b - 3  and the metallic frame  12  by means of the first dielectric layer  1   a . Therefore, when the frame  12  is an insulating material, the extension  2   b - 3  may also be disposed on the bottom surface of the first dielectric layer  1   a  similarly to the second external connecting terminal  2   b - 1 , or the second external connecting terminal  2   b - 1  and the extension  2   b - 3  may be disposed on the bottom surface of the second dielectric layer  1   b  while omitting the first dielectric layer  1   a.    
     As described above, the second conductor  2   b  is formed on a plane different from that of the first conductor  2   a . Also because the extending direction of the first conductor  2   a  and the extending direction of the second conductor  2   b  do not become parallel to each other on the same plane, it is easier to decrease the width of the connector  6  in a direction perpendicular to the line X-X′ of  FIG. 1(   b ). This contributes to the size reduction of the connector. 
     The second external connecting terminal  2   b - 1  is disposed on the bottom surface of the first dielectric layer  1   a , and is in a plane different from that of the first external connecting terminal  2   a - 1 . Also as shown in  FIG. 1(   b ), the first and second external connecting terminals  2   a - 1 ,  2   b - 1  are arranged in a direction perpendicular to the line X-X′ of  FIG. 1(   b ) along the first end  9   a , so that positions thereof overlap with each other in the direction parallel to the line X-X′. This configuration enables it to decrease the space for disposing the first external connecting terminal and the second external connecting terminal in the direction parallel to the line X-X′. 
     The lead can be easily connected regardless of whether the external connecting terminal is connected to the top surface or the bottom surface of the dielectric layer in the same manner. Therefore, there occurs no problem for the operation of connecting the lead if the first external connecting terminal  2   a - 1  and the second external connecting terminal  2   b - 1  are disposed on the top surface and the bottom surface, respectively, as described above. 
     Moreover, the second internal connecting terminal  2   b - 2  of the second conductor  2   b  is disposed on the top surface of the third dielectric layer  1   c  at a position higher than and inside (nearer to the fourth dielectric layer  1   d ) the first internal connecting terminal  2   a - 2 . This configuration enables it to easily connect bonding wires to both the first internal connecting terminal  2   a - 2  and the second internal connecting terminal  2   b - 2 . 
     For the bonding wire, unlike the lead, it is very difficult to carry out wire bonding operation with the ordinary wire bonding apparatus if the internal connecting terminal is formed on the bottom surface of the dielectric layer. In contrast, when the first internal connecting terminal  2   a - 2  and the second internal connecting terminal  2   b - 2  are formed on the top surface of the dielectric layer as described above, there is no inconvenience in wire bonding operation despite the presence of the step portion  7   b.    
     Also because the bonding wire is far smaller in diameter than the lead, length of the internal connecting terminal required for connecting the bonding wire is less than that of the external connecting terminal required for connecting the lead. Thus by disposing the first internal connecting terminal  2   a - 2  and the second internal connecting terminal  2   b - 2  stepwise in the connector  6 , it is made easier to make the portion of the first internal connecting terminal  2   a - 2  protruding toward the inside of the package (toward the second end  9   b  side) shorter than the portion of the external connecting terminal protruding toward the outside of the package. 
     The connector  6  is suitable for use as a connector for transmitting high-frequency signals (for example, 10 GHz or more). High-frequency signals are more likely to experience transmission loss as the bonding wire becomes longer. The first conductor  2   a  is formed on the lower surface of the step portion  7   b , and therefore can reach a position nearer to the electronic component within the package, so that the length of the bonding wire can be made shorter. Therefore, it is preferable to transmit high-frequency signals through the first conductor  2   a . In this case, it is preferable to use the second conductor  2   b  to transmit DC signals or low-frequency signals (for example, 1 MHz or less), which are less affected by the length of the bonding wire, rather than high-frequency signals. 
     It is preferable to form the first conductor  2   a  to run straight from the first end  9   a  side to the second end  9   b  side in a same plane (top surface of the second dielectric layer  1   b ) in the connector  6  as shown in  FIG. 1 . With this configuration, signals transmitted by the first conductor  2   a  propagate without changing the direction of propagation in the same plane, and therefore transmission loss can be suppressed from increasing. This is particularly advantageous in case frequency of the signals transmitted by the first conductor  2   a  is higher than that of the signals transmitted by the second conductor  2   b . Also because the first conductor  2   a  having straight line configuration can be formed altogether on the top surface of the second dielectric layer  1   b  by a printing method such as screen printing, excellent workability can be achieved during manufacturing. 
     When high-frequency signals are transmitted by the first conductor  2   a , it is preferable to provide a grounding conductor (conductor for earth)  3 , to be electrically connected to an external grounding circuit, on the top surface of the second dielectric layer  1   b  to adjoin the first conductor  2   a , as shown in  FIG. 1(   b ). A coplanar transmission line of G (ground)-S (signal)-G (ground) structure can be formed by the first conductor  2   a  and the grounding conductor  3 . 
     Forming the coplanar transmission line of G-S-G structure enables it to stabilize the impedance of the first conductor  2   a  at a predetermined value. In this constitution, the first conductor  2   a  can transmit high-frequency signals with higher efficiency. 
       FIG. 1(   b ) shows the first conductor  2   a  and the conductor for earth  3  arranged in the order of G-S-G, although the first conductor  2   a  and the conductor for earth  3  may also be arranged in the order of G-S-S-G. 
     In this case, the two first conductors  2   a  interposed between the conductors for earth  3  can be functioned as a differential-mode transmission line constituted by a pair of the first conductors  2   a . This constitution enables coupled transmission of the electric signals transmitted by the two first conductors  2   a , so that transmission loss of the electric signals transmitted by the two first conductors  2   a  can be decreased. As a result, electric signals can be transmitted over the two first conductors  2   a  with less attenuation. 
     Dielectric layers adjoining one over another, such as the first dielectric layer  1   a  and the second dielectric layer  1   b , or the second dielectric layer  1   b  and the third dielectric layer  1   c , may be integrated by firing. In this case, some of the conductors (for example, the first conductor  2   a , the second conductor  2   b , the grounding conductor  3 ) that is disposed between the dielectric layers has the form of internal wiring. 
     First Variation of First Embodiment 
     
         
           FIG. 2  is a sectional view showing a connector  6   a  according to a variation of the first embodiment.  FIG. 3(   a ) is a perspective view of the connector  6   a , and  FIG. 3(   b ) is an exploded perspective view of the connector  6   a.    
       
    
     The connector  6   a  has such a constitution as, in addition to the same constitution of the connector  6  shown in  FIG. 1(   a ), a fifth dielectric layer le having a metal layer  4  formed on the top surface thereof is disposed between the second dielectric layer  1   b  and the third dielectric layer  1   a , and a sixth dielectric layer if having the metal layer  4  formed on the top surface thereof is disposed between the second dielectric layer  1   b  and the third dielectric layer  1   c.    
     In this constitution, the metal layers  4  are provided on the upper and lower sides of the first conductor  2   a , so that the metal layers  4  having shielding effect can be interposed between the first conductor  2   a  and the second conductor  2   b.    
     As a result, the metal layers  4  held at a predetermined potential are disposed around the first conductor  2   a , so that noise can be suppressed from entering the first conductor  2   a . Even when conductors such as the second conductor  2   b  are disposed nearby, interference with such conductors can be avoided. Thus impedance of the first conductor  2   a  can be made less susceptible to disturbance, thereby making it easier to design the first conductor  2   a . Therefore the connector  6   a  capable of transmitting high-frequency electrical signals through the first conductor  2   a  having high reliability and less affected by electromagnetic interference is provided. 
     Second Variation of First Embodiment 
       FIG. 4  is a plan view showing a connector  6   b  according to another variation of the first embodiment. 
     In the connector  6   b , it is preferable to dispose the first conductor  2   a  and the second conductor  2   b  at positions offset in the direction perpendicular to the longitudinal direction of the first conductor  2   a , so that the first conductor  2   a  and the second conductor  2   b  do not oppose each other. 
     In the aspect of variation shown in  FIG. 4 , the first conductor  2   a  is disposed to run between adjoining second conductors  2   b  in plan view. The conductor for earth  3  is provided right below or right above the second conductor  2   b.    
     With this arrangement, the via hole conductor  5  forming a part of the second conductor  2   b  can be disposed between the first conductors  2   a.    
     Also because the first conductor  2   a  is disposed in a staggered arrangement in a plane with respect to the second conductor  2   b , distance between the first conductor  2   a  and the second conductor  2   b  can be made larger than in the case of disposing these members to overlap each other. 
     As a result, troubles can be suppressed from being caused by electromagnetic coupling between the first conductor  2   a  and the second conductor  2   b . In other words, it is made possible to suppress electric field from being generated from the first conductor  2   a  to the second conductor  2   b , and suppress the impedance of the first conductor  2   a  to the electrical signals transmitted thereby from deviating from the predetermined value. 
     For a reason similar to the first embodiment, it is preferable to transmit high-frequency signals through the first conductor  2   a  and transmit DC signals or low-frequency signals through the second conductor  2   b.    
     The second conductor  2   b  has a second conductor  2   b   1  having high current capacity and a second conductor  2   b   2  having current capacity lower than that of the second conductor  2   b   1 . 
     As the second conductor  2   b   1  is disposed on the outside to interpose the second conductor  2   b   2 , the second conductor  2   b   1  generating greater amount of heat than the second conductor  2   b   2  does is disposed at a position near the ends of the first dielectric layer  1   a  and the third dielectric layer  1   c . This is not only advantageous for dissipating heat from the second conductor  2   b   1 , but also enables it to suppress the permittivity of the dielectric layer from changing due to heat, thereby achieving stable transmission of electrical signals. 
     Third Variation of First Embodiment 
       FIG. 5(   a ) is a perspective view showing a connector  6   c  according to further another variation of the first embodiment.  FIG. 5(   b ) is an exploded perspective view showing the connector  6   c.    
     The via hole conductor  5  of the connector  6   c  penetrates through vicinities of both ends of the dielectric layers  1   b ,  1   c ,  1   e ,  1   f  (both ends in y-axis direction in  FIG. 5(   b )), so as not to penetrate through the first conductor  2   a , the grounding conductor  3  and the metal layer  4 . 
     Therefore, this configuration makes it easier to insulate the via hole conductor  5  from the first conductor  2   a , the grounding conductor  3  and the metal layer  4 , than in the case of the connector  6  shown in  FIG. 3 , thus providing the advantage of excellent workability during manufacturing. Also because the via hole conductor  5  can be formed at a distance from the first conductor  2   a , this configuration is advantageous also for achieving more stable impedance of the first conductor  2   a . Moreover, the degree of freedom in design can be increased with regard to the interval of disposing the first conductor  2   a , than in the case of disposing the via hole conductor  5  between a plurality of first conductors  2   a.    
     In the connector  6   c , the via hole conductors  5  are positioned near both ends of the dielectric layers  1   a ,  1   b ,  1   c ,  1   e ,  1   f  as described above. As a result, the extension  2   b - 3  of the second conductor  2   b  extends in an oblique direction (at an angle from x-axis direction in  FIG. 5(   b )) on the first end  9   a  side on the top surface of the first dielectric layer  1   a , while it extends in a direction perpendicular to line connecting the first end  9   a  and the second end  9   b  (y-axis direction in  FIG. 5(   b )) on the top surface of the second dielectric layer  1   b , and changes the direction to extend in the direction from the first end  9   a  to the second end  9   b  (x-axis direction in  FIG. 5(   b )). When the second conductor  2   b  is longer than the first conductor  2   a , it is preferable to transmit DC signals or low-frequency signals through the second conductor  2   b.    
     Respective Elements of First Embodiment and First to Third Variations of First Embodiment 
     Elements that constitute connectors  6 ,  6   a ,  6   b ,  6   c  of the first embodiment and first to third variations thereof will be described in detail below. 
     It is possible to use, as the material of dielectric layers  1   a ,  1   b ,  1   c ,  1   d ,  1   e ,  1   f , dielectrics such as ceramics, glass and resin. When the dielectric layers  1   a ,  1   b  are made of ceramics, a step portion  7   b  can be formed by a conventionally known ceramic green sheet stacking method with predetermined dimensional accuracy. 
     A first conductor  2   a , a second conductor  2   b , a grounding conductor for earth  3 , and a third conductor  2   c  can be formed from a metallized layer of tungsten (W), molybdenum (Mo), manganese (Mn) or the like. 
     Furthermore, a via hole conductor  5  may be formed from a metallized layer of W, Mo, Mn or the like. 
     A metal layer  4  can be formed by applying a metal paste, that is prepared by adding an organic solvent, a solvent or the like to a powder of W, Mo, Mn or the like, followed by mixing, in a predetermined pattern by a screen printing method. It is also possible to form a first conductor  2   a , a second conductor  2   b , a grounding conductor for earth  3  and a third conductor  2   c  by this screen printing method. 
     Method for Manufacturing Connector of First Embodiment 
     The method for manufacturing connector  6  will be described in detail below. 
     Dielectric layers  1   a ,  1   b ,  1   c ,  1   d  are preferably formed from dielectrics such as alumina (Al 2 O 3 ) ceramics, aluminum nitride (AlN) ceramics and mullite (3Al 2 O 3 .2SiO 2 ) ceramics and preferably obtained by a ceramic green sheet stacking method. It is possible to improve airtight reliability of the inside and outside of a connector  6  by using ceramics having higher airtight reliability than that of other dielectric materials such as resin and glass. 
     For example, when the dielectric layers  1   a ,  1   b ,  1   c ,  1   d  are Al 2 O 3  sintered bodies, proper organic binders, solvents, plasticizers and dispersants are added to raw powders such as Al 2 O 3 , silicon oxide (SiO 2 ), magnesium oxide (MgO) and calcium oxide (CaO) powders, followed by mixing to obtain a paste, and then ceramic green sheets (ceramic unfired sheets) that are turned into the dielectric layers  1   a ,  1   b ,  1   c ,  1   d  is formed from the paste using a doctor blade method or a calendar roll method. 
     Next, an electrically conductive paste prepared by mixing a metal powder of W, Mo, Mn or the like with a proper binder and solvent is applied in a predetermined pattern by a screen printing method or the like at predetermined positions on the top surface of the ceramic green sheet used to form the second dielectric layer  1   b  thereby to form the electrically conductive paste layer that are turned into the first conductor  2   a  and the conductor  3 . 
     Similarly, the electrically conductive paste described above is applied in a predetermined pattern by a screen printing method or the like at predetermined positions on the top surface and bottom surface of the ceramic green sheet that is turned into the first dielectric layer  1   a  and on the top surface of the ceramic green sheet used to form the third dielectric layer  1   c , thereby to form the electrically conductive paste layer becoming a part of the second conductor  2   b  (a part excluding the via hole conductor  5 ). 
     Then the via hole conductors  5  are formed in the dielectric layers  1   a ,  1   b  and  1   c . The via hole conductor  5  is formed by forming a through hole in the ceramic green sheet by using a die or the like, and filling the through hole with the electrically conductive paste described above. 
     After stacking the ceramic green sheets that are turned into the dielectric layers  1   a ,  1   b ,  1   c ,  1   d , having been subjected to the process described above, in a predetermined order, the stack is fired at a temperature of about 1,600° C. to obtain the connector  6 . 
     The connector  6  can be formed easily by the method described above, thus making it possible to provide the connector  6  characterized by high manufacturing efficiency. 
     When manufacturing the connector  6   a , the electrically conductive paste layer that is turned into the metal layer  4  can be formed by applying the electrically conductive paste described above in a predetermined pattern by screen printing or the like at predetermined positions on the top surfaces of the ceramic green sheets that are turned into the dielectric layers  1   e ,  1   f  obtained by the same method as that of the ceramic green sheets used to form the dielectric layers  1   a ,  1   b ,  1   c ,  1   d  described above. 
     Then the via hole conductors  5  are formed by the method described above in the ceramic green sheets that are turned into the dielectric layers  1   e ,  1   f , and the ceramic green sheets that are turned into the dielectric layers  1   a ,  1   b ,  1   c ,  1   d ,  1   e ,  1   f  are stacked in the predetermined order and fired to obtain the connection terminal  6   a.    
     2. Second Embodiment 
       FIG. 6(   a ),  6 ( b ) and  FIG. 7(   a ),  7 ( b ) show a connector  6   d  according to the second embodiment of the present invention.  FIG. 6(   b ) is a plan view of the connector  6   d , and  FIG. 6(   a ) is a sectional view of the connector  6  taken along lines X-X′ in  FIG. 6(   b ).  FIG. 7(   a ) is a perspective view of the connector  6   d , and  FIG. 7(   b ) is an exploded perspective view of the connector  6   d.    
     Of the reference numerals (symbols) used in the drawings according to the second embodiment, those identical with the reference numerals (symbols) used in the drawings according to the first embodiment denote the same members as, or members corresponding to, the members described in the first embodiment, unless otherwise described. 
     The connector  6   d  has the first dielectric layer  1   a  and the second dielectric layer  1   b  disposed thereon. It is the same as the connector  6  of the first embodiment, that the first conductor  2   a  is formed on the top surface of the second dielectric layer  1   b , and the first conductor  2   a  has the first external connecting terminal  2   a - 1  on the first end  9   a  side and the first internal connecting terminal  2   a - 2  on the second end  9   b  side. 
     In the connector  6   d  of the second embodiment, however, notches  8  are formed at corners on both ends of the second dielectric layer  1   b , so that the second conductor  2   b  is exposed through the notches  8 , thereby providing the second internal connecting terminal  2   b - 2 . That is, in the connector  6   d  of the second embodiment, the second internal connecting terminal  2   b - 2  is formed on the top surface of the first dielectric layer  1   a . Thus the second internal connecting terminal  2   b - 2  is formed in a plane different, hence at a different height, from the first internal connecting terminal  2   a - 2  formed on the top surface of the second dielectric layer  1   b.    
     The second conductor  2   b  of the connector  6   d  extends through the end face of the first dielectric layer  1   a  on the first end  9   a  side to reach the bottom surface of the first dielectric layer  1   a , and the second external connecting terminal  2   b - 1  is formed on the bottom surface of the first dielectric layer  1   a  similarly to the first embodiment. 
     Thus the entire path of the second conductor  2   b  of the connector  6   d , from the second external connecting terminal  2   b - 1  to the second internal connecting terminal  2   b - 2 , is disposed on the surface of the first dielectric layer  1   a . That is, the second conductor  2   b  includes the second internal connecting terminal  2   b - 2 , the top-surface extension  2   b - 3  connected to the second internal connecting terminal  2   b - 2  and extending from the second end  9   b  side to the first end  9   a  side on the top surface of the first dielectric layer  1   a , the second external connecting terminal  2   b - 1  formed on the first end  9   a  side of the bottom surface of the first dielectric layer  1   a , and the end-face extension  2   b - 4  positioned on the end face of the first dielectric layer  1   a  on the first end  9   a  side and connecting the top-surface extension  2   b - 3  and the second external connecting terminal  2   b - 1  together. 
     In the connector  6   d  of the second embodiment constituted as described above, it is not necessary to form a via hole conductor penetrating through the dielectric layers such as first dielectric layer  1   a  and the second dielectric layer  1   b  for providing the second external connecting terminal  2   b - 1 , thus providing an advantage in terms of workability during manufacturing. 
     In the connector  6   d  of the second embodiment, the second conductor  2   b  does not run through the third dielectric layer  1   c , unlike the connectors (the connectors  6 ,  6   a ,  6   b ,  6   c ) according to the first embodiment. 
     Further in the connector  6   d  of the second embodiment, as shown in  FIGS. 6(   a ) and  6 ( b ), and  FIGS. 7(   a ) and  7 ( b ), a third conductor  2   c  is provided on the third dielectric layer  1   c , and the fourth dielectric layer  1   d  is provided on the third dielectric layer  1   c  so that both ends of the third conductor  2   c  are exposed. 
     Exposed portions of the third conductor  2   c  respectively function as the third external connecting-terminal  2   c - 1  and as the third internal connecting terminal  2   c - 2 . In this case, the third external connecting terminal  2   c - 1  is positioned between the first and second external connecting terminals  2   a - 1 ,  2   b - 1  and the fourth dielectric layer  1   d , and therefore becomes larger in the direction parallel to line X-X′ when compared with the first embodiment. In the second embodiment, however, despite the fact that three kinds of external connecting terminal exist, these external connecting terminals can be arranged in two rows, and therefore size in the direction of line X-X′ can be decreased than that of the conventional art. 
     It goes without saying that the fourth dielectric layer  1   d  and the third conductor  2   c  may be omitted. 
     First Variation of Second Embodiment 
       FIGS. 8(   a ) and  8 ( b ), and  FIGS. 9(   a ) and  9 ( b ) show a connector  6   e  according to a variation of the connector  6   d .  FIG. 8(   a ) is a sectional view of the connector  6   e , FIG.  8 ( b ) and  FIG. 9(   a ) are perspective views of the connector  6   e , and  FIG. 9(   b ) is an exploded perspective view of the connector  6   e.    
     The connector  6   e  of the present variation has the same constitution as that of the second conductor  2   b  of the connector  6  according to the first embodiment. However, the present first variation has a constitution different from that of the connector  6  according to the first embodiment in that the connector  6   e  has the third conductor  2   c , while the third conductor  2   c  extends from the top surface of the third dielectric layer  1   c  through the top surface of the second dielectric layer  1   b  to the bottom surface of the first dielectric layer  1   a , the third external connecting terminal  2   c - 1  is provided on the bottom surface of the first dielectric layer  1   a , and the third internal connecting terminal  2   c - 2  is provided on the top surface of the third dielectric layer  1   c.    
     Specifically, the third conductor  2   c  has the third external connecting terminal  2   c - 1 , the via hole conductor  5  that is connected to the third external connecting terminal  2   c - 1  and penetrates through the first dielectric layer  1   a , an extension  2   c - 3  that is connected to the via hole conductor  5  and extends on the top surface of the first dielectric layer  1   a , another via hole conductor  5  that connects between the extension  2   c - 3  and the third internal connecting terminal  2   c - 2  and penetrates through the second dielectric layer  1   b  and the third dielectric layer  1   c , and the third internal connecting terminal  2   c - 2 . 
     In the connector  6   e  of the second embodiment, the first external connecting terminal  2   a - 1 , the second external connecting terminal  2   b - 1  and the third external connecting terminal  2   c - 1  serving as junctions for connecting the leads, for example, can be disposed along the first end  9   a , and therefore the connector  6   e  can be made smaller in size in the Y-Y′ direction than the connector  6  shown in  FIG. 6 . 
     In the present variation, the extension  2   c - 3  may also be electrically connected to the third external connecting terminal  2   c - 1  via the end-face extension provided on the end face of the first dielectric layer  1   a  on the first end  9   a  side, similarly to the connector  6   d  of the second embodiment. 
     Second Variation of Second Embodiment 
       FIGS. 10(   a ) and  10 ( b ) show a connector  6   f  according to another variation of the connector  6   d .  FIG. 10(   a ) is a perspective view of the connector  6   f , and  FIG. 10(   b ) is an exploded perspective view of the connector  6   f.    
     The via hole conductor  5   b  of the connector  6   f  penetrates through vicinities of both ends of the dielectric layers  1   b ,  1   c  (both ends in y-axis direction in  FIG. 10(   b )), so as not to penetrate the first conductor  2   a  and the grounding conductor  3 . 
     As a result, effects similar to those of the connector  6   c  according to the variation of the first embodiment are obtained. 
     Method for Manufacturing the Connector of Second Embodiment 
     The method for manufacturing the connector  6   d  according to the second embodiment will be described below. 
     Description of parts of the manufacturing method identical to those for the connector according to the first embodiment will be omitted. 
     Ceramic green sheets that are turned into the dielectric layers  1   a ,  1   b ,  1   c ,  1   d  are formed. 
     Then the electrically conductive paste prepared in the same manner as in the first embodiment is applied in a predetermined pattern by screen printing or the like at predetermined positions on the top surface of the ceramic green sheet that is turned into the top surface of the second dielectric layer  1   b , thereby to form the electrically conductive paste layers that are turned into the first conductor  2   a  and the grounding conductor  3 . 
     Similarly, the electrically conductive paste is applied in a predetermined pattern by screen printing or the like on the top surface, bottom surface and on the end face on the first end  9   a  side of the ceramic green sheet that is turned into the first dielectric layer  1   a , thereby to form the electrically conductive paste layer that is turned into the second conductor  2   b.    
     An electrically conductive paste layer that is turned into the third conductor  2   c  may also be formed as required at a predetermined position on the top surface of the ceramic green sheet that is turned into the third dielectric layer  1   c  by the same method. 
     After stacking the ceramic green sheets that are turned into the dielectric layers  1   a ,  1   b ,  1   c ,  1   d  in a predetermined order, the stack is fired at a temperature of about 1,600° C. to obtain the connector  6   d.    
     The connector  6   d  can be formed easily by the method described above, thus making it possible to provide the connector  6   d  characterized by high manufacturing efficiency. 
     When it is necessary to form the via hole conductor  5  as in the connector  6   e ,  6   f , it may be formed by the method described in the first embodiment. 
       3 . Third Embodiment 
     Package 
       FIGS. 11(   a ),  11 ( b ) show a package  30  using the connector  6  according to the first embodiment of the present invention and an electronic device  50  using the package  30 .  FIG. 11(   a ) is a schematic plan view as viewed from above, and  FIG. 11(   b ) is a schematic sectional view. 
     The package  30  of the present invention includes: 
     (a) the connector  6 ; and 
     (b) a container  10  having a cavity, a frame  12  defining the boundary of the cavity, and an aperture  13  provided on the frame  12  and communicating with the cavity. 
     The connector  6  is bonded onto the inner surface of the aperture  13  of the container  10 , with the second end  9   b  positioned respectively on the inside of the container  10  and the first end  9   a  positioned on the outside of the container  10 . 
     The package  30  can be made smaller in size by using the connector  6  of the first embodiment. The package  30  can be made smaller than in the conventional art also by using the connector of any of the first to third variations of the first embodiment, the second embodiment and the first and second variations of the second embodiment described above, instead of the connector  6 . 
     Herein, the container  10  is formed from a metal such as stainless steel (SUS), copper (Cu), copper (Cu)-tungsten (W) alloy, copper (Cu)-molybdenum (Mo) alloy, iron (Fe)-nickel (Ni)-cobalt (Co) alloy or the like. 
     The container  10  may be formed as a predetermined shape of a single piece by applying rolling, pressing, cutting or other machining process to a metal ingot. Alternatively, it may be formed by preparing the base plate  11  forming the bottom of the container  10  and the frame  12  separately and welding the frame  12  onto the top surface of the base plate  11  by using a brazing material such as silver (Ag)-copper (Cu) brazing material. In this case, the frame  12  and the base plate  11  are bonded together by bonding the top surface of the base plate  11  and the bottom surface of frame  12  by means of a preform of a brazing material such as an Ag-Cu brazing material placed on the top surface of the base plate  11 . 
     The frame  12  has the aperture  13  through which the connector  6  is inserted for electrically connecting the electronic device  15  and the external electronic circuit together, as described above. 
     When a semiconductor laser (LD), photodiode (PD) or the like is housed as the electronic device  15  in the package, an optical signal input/output window is formed as an optical transmission path for optically coupling the electronic device  15  to a part of the frame  12 . 
     It is preferable that surface of the container  10  is coated with a metal having high corrosion resistance and high wettability with the brazing material, specifically an Ni layer 0.5 to 9 μm in thickness and a gold (Au) layer 0.5 to 5 μm in thickness formed successively by plating. This enables it to effectively prevent the container  10  from oxidation corrosion and firmly bond the electronic component  15  onto the top surface of the container  10 . 
     Electronic Device 
     The electronic device  50  using the package  30  will be described below. 
     The electronic device  50  of the present invention includes the package  30  described above, the electronic component  15  mounted in the cavity of the package  30  and a lid  20  bonded onto the top surface of the frame  12 . 
     In the cavity of the package  30 , one end of the bonding wire is connected to the first internal connecting terminal  2   a - 2  of the first conductor  2   a  and the second internal connecting terminal  2   b - 2  of the second conductor  2   b , while the other end of the bonding wire is connected to the electronic component  15 . Thus the electronic component  15  and the connector  6  are electrically connected with each other. 
     The first external connecting terminal  2   a - 1  formed on the first conductor  2   a  and the second external connecting terminal  2   b - 1  formed on the second conductor  2   b  can be connected to the leads in the outside of the frame  12  (not shown). Thus electrical connection with the external circuit can be established via the leads. 
     While the lead may be formed from a known electrically conductive material including a metal such as iron (Fe)-nickel (Ni)-cobalt (Co) alloy or copper (Cu), Cu having low resistivity is preferably used. The lead and the external connecting terminal may be bonded together by using a brazing material such as silver (Ag)-copper (Cu) brazing material, or Ag brazing material. Electrical connection of the first external connecting terminal, the second external connecting terminal and, as required, the external connecting terminal of the grounding conductor  3  to the external electrical circuit can be established via the leads with high efficiency of work. 
     It is preferable that surface of the lead is coated with a metal having high corrosion resistance and high wettability with the brazing material, for example, an Ni layer 0.5 to 9 μm in thickness and a gold (Au) layer 0.5 to 5 μm in thickness formed successively by plating. This enables it to effectively prevent the lead from oxidation corrosion and firmly bond the lead and the external connecting terminal of the connector  6  together. 
     It is also preferable to respectively provide the first grounding conductor on the bottom surface of the first dielectric layer  1   a  of the connector  6 , the second grounding conductor on the top surface of the fourth dielectric layer  1   d  and the third grounding conductor on the side face of at least one of the dielectric layers  1   a ,  1   b ,  1   c ,  1   d  disposed in parallel to the first conductor  2   a  and the second conductor  2   b . This constitution enables it to expand the area of the grounding conductor to enhance the grounding potential, while the electrically conductive layer is formed over the entire circumference of the connector  6 , so that hermetically sealed mounting onto the package is made possible via a brazing material such as Ag—Cu brazing material or Ag brazing material around the connector  6 . 
     With this constitution, since the connector  6  is provided in the aperture  13 , the package capable of suppressing the electronic device from increasing in size can be provided. 
     The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present invention. 
     This application claims priority on two patent applications of Japanese Patent Application No. 2008-019795 and Japanese Patent Application No. 2008-019796 in Japan, the disclosure of which is incorporated by reference herein.