Patent Document

[0001]    The present application is a divisional of application Ser. No. 09/804,035 filed Mar. 13, 2001, now allowed. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention generally relates to a method of molding resin on a substrate, and particularly relates to a method of molding resin on a thin-film resin substrate that works well for high-frequency characteristics and a high-frequency module.  
           [0004]    2. Description of the Related Art  
           [0005]    There is a rapid decrease in size, thickness and weight of electronic equipment such as portable mobile communication terminals. The portable mobile terminals are installed with high-frequency modules, such as power amplifiers and high-frequency circuit boards.  
           [0006]    Thus, it is necessary to reduce size, thickness and weight of the high-frequency modules to further reduce the size, thickness and weight of such portable mobile terminals. For this purpose, it has been proposed to select a thin-film resin substrate that can achieve further reduction of size, thickness and weight and can improve the high-frequency characteristics.  
           [0007]    However, due to its reduced thickness, the thin-film resin substrates are often deformed during a manufacturing process of the high-frequency module. Accordingly, there is a need for a resin molding method which can restrict the deformation of the thin-film resin substrate during the manufacturing process.  
           [0008]    [0008]FIGS. 1A and 1B are diagrams showing an example of a high-frequency module  1  of the related art. FIG. 1A is a plan view showing general structure of the high-frequency module  1 . FIG. 1B is a cross-sectional view showing general construction of the high-frequency module  1 . Such high-frequency module  1  may be used, for example, as a power amplifier of a portable mobile terminal. It is desirable to further reduce the size, thickness and weight of the high-frequency module  1 .  
           [0009]    Generally, the high-frequency module  1  includes a high-frequency circuit board  2 , a high-frequency active chip  3 , chip components  4 , and a resin package  5 . The high-frequency circuit board  2  includes a base material  15  of ceramics, glass-ceramics, or glass-epoxy. On a first (upper) surface of the base material  15 , high-frequency circuit interconnections  6  and  7 , direct-current (DC) circuit interconnections  8  and  9 , and pad portions  12  to  14  are provided in a predetermined pattern. On a second (lower) surface of the base material  15 , a ground layer  18  and land portions  19  are provided.  
           [0010]    The high-frequency circuit board  2  of the above structure is provided with an opening  16  formed at a predetermined position of the base material  15 . The high-frequency active chip  3  is mounted in the opening  16 . Also, the high-frequency active chip  3  and each of the interconnections  6  to  9  are electrically connected by wires  17 .  
           [0011]    Also, a plurality of chip components  4  are mounted on the high-frequency circuit board  2 . Each chip component  4  is joined to the interconnections  6  to  9  by means of a conductive material. Further, the pad portions  12  to  14  are electrically connected to the ground layer  18  formed on the second (lower) surface of the base material by means of via holes  20  formed through the base material  15 .  
           [0012]    A high-frequency input terminal RFIn, a high-frequency output terminal RFout and bias terminals  10  and  11  are provided at predetermined end portions of respective interconnections  6  to  9 . The terminals RFIn, RFout,  10  and  11 , respectively, are electrically connected to land portions  19  serving as external connection terminals by means of the via holes  20  formed through the base material  15 .  
           [0013]    When the high-frequency module  1  is mounted on the mounting board, the land portions  19  will be electrically connected to the mounting board. Also, a first (upper) surface of the high-frequency circuit board  2  is sealed, for example, using a metal cap (not shown).  
           [0014]    However, if the base material  15  of the high-frequency circuit board  2  is made of ceramics, the cost of the high-frequency module will be increased since a ceramics material is more expensive than a resin material. If the base material  15  of the high-frequency circuit board  2  is made of materials such as ceramics, glass-ceramics or glass-epoxy, it is difficult to reduce the thickness of the base material  15  below 100 μm. Thus, this is contrary to the aim of reducing the thickness of the high-frequency module  1 .  
           [0015]    Also, it is difficult to implement a machining process on the prior art material used for the base material  15  with high accuracy. This is particularly problematic when forming the via holes  20 . With the high-frequency module  1  for processing high-frequency signals, it is preferable to reduce impedance. However, since it is difficult to optionally select the thickness of the base material  15  and the diameter of the via hole  20 , the impedance could not be reduced with the high-frequency module  1  of the related art. Accordingly, with the high-frequency module  1  of the related art, it is not possible to avoid any degradation of the characteristics due to the via holes  20 .  
           [0016]    Also, with the high-frequency module  1 , it is desired to achieve a broader band with the same signal line width. In order to achieve broader band with the same signal line width, it is necessary to reduce the thickness of the base material  15  comprising the high-frequency circuit board  2  and to reduce the relative permittivity.  
           [0017]    However, since the base material  1  has comparatively great thickness and relative permittivity, it is difficult to achieve broader band using the same signal line width. Therefore, with the circuit layout in a millimeter wave region using ceramics having high relative permittivity, the width of a 50 Ω signal line becomes extremely small and thus becomes difficult to form such signal line.  
           [0018]    In order to solve the problems described above, the inventor has proposed a high-frequency module  30 A as shown in FIGS.  2  to  6  (JP 11-310159 A1).  
           [0019]    Generally, the high-frequency module  30 A includes a high-frequency circuit board  32 A, a high-frequency active chip  33 , chip components  34 , and a resin package  35 . The characteristic feature of the high-frequency circuit board  32 A is that it includes a base material  45  of polyimide.  
           [0020]    On a first (upper) surface of the base material  45 , high-frequency circuit interconnections  36 A and  37 A (microstrip lines, coplanar lines etc.), direct-current (DC) circuit interconnections  38 A and  39 A, and pad portions  42  to  44  are formed in a predetermined pattern. The high-frequency circuit interconnections  36 A and  37 A are formed as so-called 50 Ω lines.  
           [0021]    The interconnections  36 A to  38 A,  39  and the pad portions  42  to  44 , respectively, are made of a copper film or a gold film with a thickness of, for example, 35 microns. The predetermined regions of the high-frequency circuit interconnections  36 A,  37 A and the DC circuit interconnections  38 A and  39  constitute microstrip lines and a bias circuit of λ/4. A second (lower) surface of the base material  45  is provided with a grounded ground layer  48 A and land portions  49 A to serve as external connection terminals.  
           [0022]    A high-frequency active chip  33  is mounted on the high-frequency circuit board  32 A of the above structure. An opening  46  is formed in the base material  45  at a position at which the active chip  33  is to be mounted. Also, a bottom open end of the opening  46  is closed by the ground layer  48 A. Therefore, at a predetermined position of the high-frequency circuit board  32 A at which the high-frequency active chip  33  is to be mounted, a recessed portion is defined by the opening  46  and the ground layer  48 A.  
           [0023]    The high-frequency active chip  33  is mounted in the opening  46  and is joined to the bottom ground layer  48 A by means of gold-tin alloy or conductive adhesive agent. With the base material  45  provided with the ground layer  48 A and the opening  46  and by mounting the high-frequency active chip  33  on the ground layer  48 A in the opening  46 , heat produced by the high-frequency active chip  33  can be dissipated in an efficient manner.  
           [0024]    Also, the high-frequency active chip  33  and each interconnection  36 A to  39 A are electrically connected by wires  47 . Since the high-frequency active chip  33  is positioned inside the opening  46 , the wire bonding level of the high-frequency active chip  33  and the wire bonding level of the respective interconnections  36 A to  39  are equal. Thus, wire bonding characteristic can be improved and the height of the wire loop can be reduced.  
           [0025]    Also, a plurality of chip components  34  are mounted on a first (upper) surface of the high-frequency circuit board  32 A. Each chip component  34  is joined to respective interconnection  36 A to  38 A and  39  or to the pad portions  42  to  44  by means of solder or conductive adhesive agent. The chip component  34  is a chip capacitor which together with the high-frequency circuit interconnections  36 A and  37 A form an input/output matching circuit. Although not shown in the diagrams referred to in the above description, a hybrid circuit (branch-line, coupler, rat-race, phase-reversion type hybrid, high-frequency filter, etc.) may be provided the first surface of the high-frequency circuit board  32 A.  
           [0026]    Also, the pad portions  42  to  44  are electrically connected to the ground layer  48 A formed on the second surface of the base material  45  by means of via holes (not shown) formed through the base material  45 . Further, a high-frequency input terminal  53 , a high-frequency output terminal  54  and bias terminals  40  and  41  are formed at predetermined positions of the respective interconnections  36 A to  38 A. By means of the via holes  50  formed through the base material  45 , the respective interconnections  40 ,  41 , 53 , and  54  are electrically connected to land portions  49 A serving as external terminals.  
           [0027]    As shown in FIG. 6, the land portions  49 A are formed on the second surface of the base material  45  so as to be electrically separated from the ground layer  48 A. The land portions  49 A are electrically connected to the mounting board (not shown) when mounting the high-frequency module  30 B. It is to be noted that, for ease of understanding, the via holes  50  are illustrated in FIG. 3, which is a cross-sectional diagram of FIG. 2 along line A-A, but practically, the via holes  50  do not appear in such a cross-sectional diagram.  
           [0028]    Also, a resin package  35  is formed on the first surface of the high-frequency circuit board  32 A. The resin package  35  is formed by, for example, transfer molding (hereinafter referred to as molding) and serves to protect the high-frequency active chip  33 , the chip component  34 , and the interconnections  36 A to  38 A and  39  that are formed on the first surface of the high-frequency circuit board  32 A.  
           [0029]    The high-frequency module  30 A of the above structure uses a thin-film resin board of polyimide as the base material  45  of the high-frequency circuit board  32 A. Since polyimide is less expensive compared to ceramics, the cost can be reduced in comparison to the high-frequency circuit board  2  with base material  15  of material such as ceramics (see FIG. 1).  
           [0030]    Also, by using the base material  45  of polyimide, the thickness of the base material  45  can be reduced to about 25 to 75 μm. Thus, the width of the 50 Ω lines can be reduced to about 50 to 150 μm, which in turn gives reduced area occupied by the 50 Ω lines on the high-frequency circuit board  32 A. Accordingly, it is possible to achieve reduced size and thickness of the high-frequency module  30 A.  
           [0031]    Also, although polyimide has a low relative permittivity of about 3.1, when the thin-film resin board of polyimide is used, the width of the 50 Ω lines can be reduced by reducing its thickness. Therefore, it is no longer necessary to use a base material having high relative permittivity (e.g., ceramics, glass-ceramics, glass-epoxy etc.) which gives comparatively large thickness of the base material. This also serves to reduce the size and thickness of the high-frequency module  30 A.  
           [0032]    In general, as the frequency used becomes higher, the impedance of the interconnections  36 A and  37 A becomes greater. The less the thickness of the base material  45 , the rate of increase of the impedance becomes smaller. Therefore, by using the polyimide having low relative permittivity as the base material  45 , with a small thickness, low impedance can be maintained at a broad band frequency. Thus, an improved high-frequency circuit having high-frequency characteristics at broad band frequency can be achieved.  
           [0033]    As has been described above, with the high-frequency module  30 A shown in FIGS.  2  to  6 , by using a thin-film resin board of polyimide as the base material  45 , it is possible to provide a high-frequency circuit board  32 A having an improved high-frequency characteristic at broad band frequency, low thermal resistivity and low cost. Thus, by incorporating the high-frequency module  30 A of the present embodiment into a portable mobile terminal, a portable mobile terminal with reduced thickness can be achieved at a low cost.  
           [0034]    Also, the base material  45  is a flexible substrate. Therefore, the high-frequency module  30 A can be provided which can be provided at a low cost and which is not affected by the shape of the portable mobile terminal when the high-frequency module  30 A is mounted on a portable mobile terminal.  
           [0035]    However, the inventor has found that the base material  45  may be deformed during a molding step for forming the resin package  35 . This will be described in detail in the following description.  
           [0036]    As has been described above, the ground layer  48 A and the land portions  49 A are formed on the second surface of the high-frequency circuit board  32 A. As shown in FIGS. 5 and 6, the land portions  49 A are spaced apart at a predetermined interval (e.g., 600 μm).  
           [0037]    Thus, the base material  45  is exposed at positions between neighboring land portions  49 A. Also, the thickness of the ground layer  48 A and the land portions  49 A is, for example, 35 μm. Therefore, since the land portions  49 A are raised and the portions where the base material  45  is exposed are recessed, the second surface of the high-frequency circuit board  32 A becomes unleveled, or uneven.  
           [0038]    [0038]FIG. 7 shows a resin molding step for forming the resin package  35 . During the resin molding step, the high-frequency circuit board  32 A is placed in mold  60 A. The mold  60 A comprises an upper mold  61 A and a lower mold  62 A. Cavities  63 A and  64 A are formed in the upper and lower molds  61 A and  62 A, respectively.  
           [0039]    The cavity  63 A of the upper mold  61 A corresponds to the shape of the resin package  35  and the cavity  64 A of the lower mold  62 A has a planar shape. Therefore, when the high-frequency circuit board  32 A is placed in the mold  60 A, the land portions  49 A touches the cavity  64 A and gaps are formed at portions where the recessed portions  51  face the cavities  64 A.  
           [0040]    When resin  66  is injected into the cavities  63 A,  64 A from a gate  65  of the mold  64 A, the base material  45  which is a thin-film resin substrate will be pressed by an injection pressure exerted by the resin  66 . Since the gaps are formed at positions where the recessed portions  51  face the cavities  64 A, the base material  45  deforms and sags at the gaps as indicated by dash-dot lines in FIG. 7.  
           [0041]    Such deformation of the base material  45  may cause various problems. For example, the chip components  34  may fall off from the high-frequency circuit board  34 A and the interconnections  36 A,  37 A,  38 A,  39  may peel off from the base material  45 . Further, the interconnections  36 A,  37 A,  38 A,  39  may be disconnected due to stress applied thereto.  
         SUMMARY OF THE INVENTION  
         [0042]    Accordingly, it is a general object of the present invention to provide a method which can solve or at least reduce the problems described above.  
           [0043]    It is another and more specific object of the present invention to provide a method of resin molding for a thin-film resin substrate which can restrict deformation of the high-frequency circuit board (thin-film resin substrate) during the step of forming a resin package.  
           [0044]    In order to achieve the above objects according to the present invention, a method of molding resin on a thin-film resin substrate is provided, the thin-film resin substrate having a first surface provided with an electronic circuit and a second unleveled surface opposite the first surface, the second surface having raised portions and recessed portions, the method including the steps of:  
           [0045]    a) providing deformation restricting means for the substrate; and  
           [0046]    b) molding the resin on the first surface.  
           [0047]    With the such a method, the recessed parts of the second unleveled surface are reinforced by the deformation restricting means. Therefore, the deformation of the thin-film resin substrate is restricted even if the thin-film resin substrate is biased due to the pressure exerted by the resin during the molding step.  
           [0048]    It is still another object of the present invention to provide a high-frequency module that can be manufactured with reduced deformation of the thin-film resin substrate.  
           [0049]    In order to achieve the above object, a high-frequency module includes:  
           [0050]    a thin-film resin substrate having a first surface provided with high-frequency circuit components including high-frequency circuit connections and a second unleveled surface opposite the first surface, the second surface having raised portions and recessed portions;  
           [0051]    a resin sealing formed on the first surface of the thin-film resin substrate; and  
           [0052]    deformation restricting means.  
           [0053]    With the high-frequency module described above, the recessed parts of the second unleveled surface are reinforced by the deformation restricting means. Therefore, the deformation of the thin-film resin substrate is restricted even if the thin-film resin substrate is biased due to the pressure exerted by the resin during the molding step.  
           [0054]    The deformation restricting means may be a sub-member is made of a thermally resistive hard resin having an unleveled surface including raised portions and recessed portions with the raised portions and recessed portions being provided in a negative pattern of the configuration of the second surface.  
           [0055]    Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0056]    [0056]FIGS. 1A and 1B are a plan view and a partial cross-sectional view, respectively, showing a high-frequency module of the related art.  
         [0057]    [0057]FIG. 2 is a plan view showing a high-frequency module which includes a thin-film resin substrate as its high-frequency circuit board.  
         [0058]    [0058]FIG. 3 is a partial cross-sectional diagram along line A-A of FIG. 2 viewed in the direction shown by the arrows.  
         [0059]    [0059]FIG. 4 is a partial cross-sectional diagram along line C-C of FIG. 2 viewed in the direction shown by the arrows.  
         [0060]    [0060]FIG. 5 is a cross-sectional diagram along line B-B of FIG. 2.  
         [0061]    [0061]FIG. 6 is a bottom plan view of the high-frequency module shown in FIG. 2.  
         [0062]    [0062]FIG. 7 is a diagram showing a resin molding step for forming a resin package of the high-frequency module shown in FIG. 2.  
         [0063]    [0063]FIG. 8 is a schematic cross-sectional diagram of a first embodiment of the present invention showing how upper and lower molds are clamped in the resin molding process.  
         [0064]    [0064]FIG. 9 is a schematic cross-sectional diagram of a first embodiment of the present invention showing how resin is injected in the resin molding step.  
         [0065]    [0065]FIG. 10 is a schematic cross-sectional diagram of a second embodiment of the present invention showing how upper and lower molds are clamped in the resin molding step.  
         [0066]    [0066]FIG. 11 is a schematic cross-sectional diagram of a second embodiment of the present invention showing how resin is injected the resin molding step.  
         [0067]    [0067]FIG. 12 is a schematic cross-sectional diagram of a third embodiment of the present invention showing how upper and lower molds are clamped in the resin molding step.  
         [0068]    [0068]FIG. 13 is a schematic cross-sectional diagram of a third embodiment of the present invention showing how resin is injected in the resin molding step.  
         [0069]    [0069]FIG. 14 is a plan view showing a high-frequency module of the fourth embodiment of the present invention.  
         [0070]    [0070]FIG. 15 is a partial cross-sectional diagram along line A-A of FIG. 14 viewed in the direction shown by the arrows.  
         [0071]    [0071]FIG. 16 is a cross-sectional diagram along line B-B of FIG. 14.  
         [0072]    [0072]FIG. 17 is a bottom plan view of the high-frequency module shown in FIG. 14.  
         [0073]    [0073]FIG. 18 is a schematic cross-sectional diagram of a fourth embodiment of the present invention showing how resin is injected in the resin molding step.  
         [0074]    [0074]FIG. 19 is a bottom plan view of the high-frequency module of a variant of the fourth embodiment of the present invention.  
         [0075]    [0075]FIG. 20 is a plan view showing a high-frequency module of the fifth embodiment of the present invention.  
         [0076]    [0076]FIG. 21 is a cross-sectional diagram along line B-B of FIG. 20.  
         [0077]    [0077]FIG. 22 is a schematic cross-sectional diagram of a fifth embodiment of the present invention showing how resin is injected in the resin molding step.  
         [0078]    [0078]FIG. 23 is a plan view showing a high-frequency module of the sixth embodiment of the present invention.  
         [0079]    [0079]FIG. 24 is a partial cross-sectional diagram along line A-A of FIG. 23 viewed in the direction shown by the arrows.  
         [0080]    [0080]FIG. 25 is a cross-sectional diagram along line B-B of FIG. 23.  
         [0081]    [0081]FIG. 26 is a bottom plan view of the high-frequency module shown in FIG. 23.  
         [0082]    [0082]FIG. 27 is a schematic cross-sectional diagram of a sixth embodiment of the present invention showing how resin is injected in the resin molding step.  
         [0083]    [0083]FIG. 28 is a plan view showing a high-frequency module of the seventh embodiment of the present invention.  
         [0084]    [0084]FIG. 29 is a cross-sectional diagram along line B-B of FIG. 28.  
         [0085]    [0085]FIG. 30 is a schematic cross-sectional diagram of a seventh embodiment of the present invention showing how resin is injected step in the resin molding step.  
         [0086]    [0086]FIGS. 31A to  31 D are schematic diagrams showing various steps of a manufacturing process high-frequency module of the seventh embodiment of the present invention.  
         [0087]    [0087]FIGS. 32A to  32 E are schematic diagrams showing various steps subsequent to the steps shown in FIG. 31D.  
         [0088]    [0088]FIGS. 33A to  33 C are schematic diagrams showing various steps subsequent to the steps shown in FIG. 32E.  
         [0089]    [0089]FIGS. 34A and 34B are schematic diagrams showing various steps subsequent to the steps shown in FIG. 33C.  
         [0090]    [0090]FIGS. 35A and 35B are schematic diagrams showing various steps subsequent to the steps shown in FIG. 34B. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0091]    In the following, principles and embodiments of the present invention will be described with reference to the accompanying drawings.  
         [0092]    [0092]FIGS. 8 and 9 are diagrams showing a first embodiment of the present invention. The present embodiment relates to a method of manufacturing a high-frequency module  30 A which is characterized in that a sub-member  70  is used in a molding process of a resin package  35 . FIG. 8 shows a high-frequency circuit board  32 A in a state before being clamped in a mold  60 A. FIG. 9 shows the high-frequency circuit board  32 A in a state after being clamped in a mold  60 A and also shows how the resin  66  is injected.  
         [0093]    In FIGS. 8 and 9, those elements that are similar to elements shown in FIG. 7 are indicated by similar reference numerals and will not be described in detail in the following description. Also, since the high-frequency circuit board  32 A used in the present invention is identical to what is used for the high-frequency module  30 A, no further detailed explanation is made for the high-frequency circuit board  32 A.  
         [0094]    The sub-member  70  is made of a material such as a thermally resistive hard resin and is provided with raised parts  71  and recessed portions  72  on its surface facing towards the high-frequency circuit board  32 A. The raised parts  71  and the recessed portions  72  are configured such that it forms a negative of (or has a reversed shape of) the configuration of the land portions  49 A and the recessed portions  51  provided on the second surface of the high-frequency circuit board  32 A.  
         [0095]    In other words, when the high-frequency circuit board  32 A and the sub-member  70  are placed opposite each other, the land portions  49 A of the high-frequency circuit board  32 A face the recessed portions  72  of the sub-member  70 , and, the recessed portions  51  of the high-frequency circuit board  32 A face the raised parts  71  of the sub-member  70 . Also, the height of the raised parts  71  is made equal to the height of the land portions  49 A.  
         [0096]    In order to implement molding process using the sub-member  70  of the above structure, firstly, the sub-member  70  is joined with the high-frequency circuit board  32 A. Thus, the land portions  49 A of the high-frequency circuit board  32 A engage with the recessed portions  72  of the sub-members  70 , and, the recessed portions  51  of the high-frequency circuit board  32 A engage with the raised parts  71  of the sub-members  70 . In other words, the recessed portions  51  formed in the high-frequency circuit board  32 A are filled with the sub-member  70 .  
         [0097]    Accordingly, when implementing a molding process as shown in FIG. 9, the recessed portions  51  are filled with the raised parts of the sub-member  70 . There is no gap between the cavity  64 A and the high-frequency circuit board  32 A while injecting the resin  66 . Therefore, even if the base material  45  is biased due to pressure exerted by the resin  66  during molding, the base material  45  is supported by the raised parts  71  of the sub-member  70  and its deformation will be restricted.  
         [0098]    Thus, during a molding process, deformation of the high-frequency circuit board  32 A can be restricted (or reduced). Therefore, it is possible to prevent the chip components  34  from falling off from the high-frequency circuit board  32 A and the interconnections  36 A,  37 A,  38 A,  39  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  36 A,  37 A,  38 A,  39  from being disconnected due to stress applied thereto.  
         [0099]    Now, a second embodiment of the present invention will be described with reference to FIGS. 10 and 11.  
         [0100]    In the first embodiment described above, the deformation of the high-frequency circuit board  32 A during the molding process is restricted by supporting the base material  45  using the sub-member  70  having raised parts  71  that engage with the recessed portions  51  of the high-frequency circuit board  32 A. Whereas in the present embodiment, in order to restrict (or reduce) the deformation of the high-frequency circuit board  32 A, a further high-frequency circuit board  32 A is used in place of the sub-member  70  of the first embodiment.  
         [0101]    [0101]FIG. 10 shows a high-frequency circuit board  32 A in a state before being clamped in a mold  60 A. FIG. 11 shows the high-frequency circuit board  32 A in a state after being clamped in a mold  60 A and also shows how the resin  66  is injected. In FIGS. 10 and 11, those elements that are similar to elements shown in FIGS. 8 and 9 are indicated by similar reference numerals and will not be described in detail in the following description.  
         [0102]    As has been described above, the second surface of the high-frequency circuit board  32 A is unleveled since a plurality of land portions  49 A are provided thereon. In the present embodiment, two high-frequency circuit boards  32 A are situated such that the second surfaces thereof are opposing each other and offset by a distance corresponding to a pitch between neighboring land portions  49 A. Thus, the land portions  49 A of a first high-frequency circuit board  32 A face with the recessed portions  51  of the second high-frequency circuit board  32 A placed below the first high-frequency circuit board  32 A. Similarly, the recessed portions  51  of the first high-frequency circuit board  32 A face with the land portions  49 A of a second high-frequency circuit board  32 A.  
         [0103]    In the present embodiment, a molding process is implemented as follows. Firstly, the high-frequency circuit boards  32 A are placed in the mold  60 B. The first high-frequency circuit board  32 A is placed in the cavity  63 B of the upper mold  61 B and the second high-frequency circuit board  32 A is placed in the cavity  64 B of the lower mold  62 B.  
         [0104]    When placed in the mold  60 B, the second surfaces of the high-frequency circuit boards  32 A are opposing each other and the high-frequency circuit boards  32 A are offset by a distance corresponding to a pitch of the land portions  49 A.  
         [0105]    Then, the upper mold  61 B and the lower mold  62  are joined together. The land portions  49 A of the first high-frequency circuit board  32 A placed in the upper mold  61  B engages the recessed portions  51  of the second high-frequency circuit board  32 A placed in the lower mold  62 B. Similarly, the recessed portions  51  of the first high-frequency circuit board  32 A placed in the upper mold  61  B engages the land portions  49 A of the second high-frequency circuit board  32 A placed in the lower mold  62 B. In other words, the recessed portions  51  of one of the first and second high-frequency circuit boards  32 A are filled with the land portions  49 A of another one of the first and second high-frequency circuit boards  32 A.  
         [0106]    As shown in FIG. 11, during a molding process, since the recessed portions  51  are filled with the land portions  49 A of the opposing high-frequency circuit board  32 A, the resin  66  is injected in a state where there is no space between a pair of high-frequency circuit board  32 A.  
         [0107]    Accordingly, during a molding step, even if the base materials  45  of the first and second high-frequency circuit boards  32 A are biased due to a pressure exerted by the resin  66 , a pair of high-frequency circuit boards  32 A will mutually support the recessed portions  51 . Thus, during a molding step, the deformation of each of the high-frequency circuit boards  32 A can be restricted. Therefore, it is also possible in the present embodiment to prevent the chip components  34  from falling off from the high-frequency circuit board  32 A and the interconnections  36 A,  37 A,  38 A,  39  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  36 A,  37 A,  38 A,  39  from being disconnected due to stress applied thereto.  
         [0108]    In the present embodiment, the sub-member  70  used in the first embodiment can be omitted. Therefore, there is no need to design and manufacture the sub-member  70  and the cost required for the molding process can be reduced.  
         [0109]    In the molding process of the present embodiment, the ground layers  48 A formed on the first and second high-frequency circuit boards  32 A must also engage with each other. Accordingly, the ground layers  48 A is configured to engage with each other when the first and second high-frequency circuit boards  32 A are joined together.  
         [0110]    Now, a third embodiment of the present invention will be described with reference to FIGS. 12 and 13.  
         [0111]    In the first embodiment described above, the deformation of the high-frequency circuit board  32 A during the molding process is restricted by supporting the base material  45  using the sub-member  70  of hard resin having raised parts  71  that engage with the recessed portions  51  of the high-frequency circuit board  32 A. Whereas in the present embodiment, in order to restrict the deformation of the high-frequency circuit board  32 A, an elastic sub-member  75  is used in place of the sub-member  70  of the first embodiment.  
         [0112]    [0112]FIG. 12 shows a high-frequency circuit board  32 A in a state before being clamped in a mold  60 A. FIG. 13 shows the high-frequency circuit board  32 A in a state after being clamped in a mold  60 A and also shows how the resin  66  is injected. In FIGS. 12 and 14, those elements that are similar to elements shown in FIGS. 8 and 9 are indicated by similar reference numerals and will not be described in detail in the following description.  
         [0113]    The elastic sub-member  75  is made of a resin material having an elastic property such as polyimide and is configured in a rectangular shape with no protruded parts nor recessed portions. When implementing a molding process using the elastic sub-member  75 , the high-frequency circuit board  32 A is placed in the cavity  63 A of the upper mold  61 A and the elastic sub-member  75  is placed in the cavity  64 A of the lower mold  62 A. Then, the upper mold  61 A and the lower mold  62 A are joined together.  
         [0114]    Accordingly, the high-frequency circuit board  32 A pressed the elastic sub-member  75 . The elastic sub-member  75  elastically deforms into a shape corresponding to an unleveled profile (formed by the land portions  49 A) of a second (lower) surface of the high-frequency circuit board  32 A. Due to such elastic deformation, the elastic sub-member  75  enters the recessed portions  51 .  
         [0115]    As shown in FIG. 13, during a molding process, the recessed portions  51  are filled with the elastic sub-member  75 , the resin  66  is injected in a state where there is no space between the cavity  64 A and the high-frequency circuit board  32 A.  
         [0116]    Accordingly, during a molding step, even if the base materials  45  is biased due to a pressure exerted by the resin  66 , the base material  45  is supported by the elastic sub-member  75  and its deformation is restricted.  
         [0117]    Thus, during a molding step, the deformation of each of the high-frequency circuit boards  32 A can be restricted. Therefore, it is also possible in the present embodiment to prevent the chip components  34  from falling off from the high-frequency circuit board  32 A and the interconnections  36 A,  37 A,  38 A,  39  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  36 A,  37 A,  38 A,  39  from being disconnected due to stress applied thereto.  
         [0118]    Also, in contrast to the sub-member  70 , since the elastic sub-member  75  elastically deforms, only one elastic sub-member  75  is required for various thin-film resin substrate having different number of lands  49 A or different pattern. In other words, with the sub-member  70  with protruded parts  71  and recessed portions  70  of the first embodiment, one wishes to implement the molding process for various high-frequency circuit board with different number of lands  49 A or different pattern, various types of sub-members  70  must be prepared for various types of high-frequency circuit boards.  
         [0119]    With the molding process of the present embodiment, there is no need to prepare different types of elastic sub-member  75  for various types of the land portions  49 A of the high-frequency circuit board  32 A. Accordingly, it is possible to reduce cost required for the molding process.  
         [0120]    Also, in the present embodiment, the elastic sub-member  75  is provided as sheet member of polyimide resin. Therefore, the same material is used for the elastic sub-member  75  and for the base material  45  of the high-frequency circuit board  32 A. Accordingly, in the molding process performed under heated environment, any stress due to the difference of thermal expansion can be prevented from being produced between the base material  45  and the elastic sub-member  75 .  
         [0121]    Now, a fourth embodiment of the present invention will be described with reference to FIGS. 14 through 18.  
         [0122]    In each of the embodiments described above, the deformation of the high-frequency circuit board  32 A during the molding process is restricted by supporting the recessed portions  51  of the base material  45  using the sub-member  70  or the elastic sub-member  75 . Whereas in the present embodiment, in order to restrict the deformation of the high-frequency circuit board  32 A, the recessed portions  51  are reinforced so as to improve the structure of the high-frequency module.  
         [0123]    [0123]FIG. 14 is a plan view of the high-frequency module  30 B of the present embodiment. FIG. 15 is a partial cross-sectional diagram along line A-A of FIG. 14. FIG. 16 is a partial cross-sectional diagram along line B-B of FIG. 14. FIG. 17 is a bottom view of the high-frequency module  30 B. Further, FIG. 18 the high-frequency circuit board  32 B in a state after being clamped in a mold  60 A and also shows how the resin  66  is injected. In FIGS.  14  to  18 , those elements that are similar to elements shown in FIGS.  2  to  6 ,  8  and  9  are indicated by similar reference numerals and will not be described in detail in the following description.  
         [0124]    As has been described above with reference to FIG. 7, during the molding process, the base material  45  is deformed at positions of the recessed portions  51  where the base material  45  is exposed between neighboring land portions  49 A. Thus, by mechanically reinforcing the recessed portions  51 , the deformation of the base material  45  can be reduced.  
         [0125]    In the present embodiment, supporting parts  76 A are formed in the recessed portions  51  of the high-frequency circuit board  32 B constituting the high-frequency module  30 B. As shown in FIG. 17, the supporting parts  76 A are formed integral with the ground layer  48 A. As shown in FIG. 16, the thickness of the supporting parts  76 A and the thickness of the land portions  49 A are equal. When the width L 2  of the recessed part  51  is, for example, 600 μm, the width L 1  of the supporting part  76 A is preferably 100 μm≦L 1 ≦300 μm.  
         [0126]    In the manufacturing process of the high-frequency module  30 B of the above-described structure, the supporting parts  76 A are formed before forming the resin package  35 . As has been described above, since the supporting parts  76 A are formed integral with the ground layer  48 A, the ground layer  48 B and the land portions  49 A may be formed simultaneously. Accordingly, even if the supporting parts  76 A are provided, the manufacturing process of the high-frequency module  30 B will not become complicated. Also, the manufacturing process can be simplified in comparison to a method in which the supporting parts  76 A are formed in a forming process that is separate from the process of forming the ground layer  48 A and the land portions  49 A.  
         [0127]    In the molding process, as shown in FIG. 18, the high-frequency circuit board  32 B provided with the supporting parts  76 A is placed in the mold  60 A and then the resin  66  is injected. When the high-frequency circuit board  32 B is placed in the mold  60 A, the land portions  49  touches the cavity  64  of the lower mold  62 A. In this state, the supporting parts  76 A having the same height as the land portions  49 A also touches the cavity  64 . Accordingly, the recessed portions  51  of the high-frequency circuit board  32 A are supported by the supporting parts  76 A.  
         [0128]    Thus, even if the base materials  45  is biased due to a pressure exerted by the resin  66  during the molding step, the base material  45  is supported by the supporting parts  76 A and its deformation is restricted. Thus, deformation of the high-frequency circuit board  32 A can also be restricted with the molding process of the present embodiment. Therefore, it is possible to prevent the chip components  34  from falling off from the high-frequency circuit board  32 B and the interconnections  36 A,  37 A,  38 A,  39  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  36 A,  37 A,  38 A,  39  from being disconnected due to stress applied thereto.  
         [0129]    Accordingly, since the deformation of the high-frequency circuit board  32 B is restricted, the high-frequency module  30 B that is manufactured with the manufacturing process described above can be mounted to a mounting board with an improved mounting ability. When the high-frequency module  30 B is mounted on the mounting board, the land portions  49 A for providing electrical connection touches the mounting board, and the supporting portions  76 A also touches the mounting board. Therefore, the high-frequency module  30 B of the present embodiment can be mounted on the mounting board with a high stability. Accordingly, the land portions  49 A and the mounting board can be soldered with an improved soldering ability.  
         [0130]    Further, as shown in FIG. 17, supporting parts  76 A are positioned between neighboring land portions  49 A. Also, the supporting parts  76 A are formed integral with the ground layer  48 B that is grounded. Thus, since a pair of neighboring land portions  49 A is electro-magnetically separated from the supporting part  76 A, the land portions  49 A can be securely isolated from one another.  
         [0131]    Accordingly, with the high-frequency module  30 B of the present embodiment, it is possible to reduce the interference between the land portions  49 A through which the high-frequency signals are input/output. As shown in FIG. 19 for the high-frequency circuit board  32 V, curved parts  77 ,  78  are formed at corners of the land portions  49 B and the supporting parts  76 B. Thus, it is possible to further reduce the interference between the land portions  49 B.  
         [0132]    Now, a fifth embodiment of the present invention will be described with reference to FIGS. 20 through 22.  
         [0133]    This embodiment is also characterized in that the recessed portions  51  are reinforced by adding improved feature to the structure of the high-frequency module. Accordingly, the deformation of the high-frequency circuit board  32 D is reduced.  
         [0134]    [0134]FIG. 20 is a plan view of the high-frequency module  30 C of the present embodiment. FIG. 21 is a partial cross-sectional diagram along line B-B of FIG. 20. FIG. 16 is a partial cross-sectional diagram along line B-B of FIG. 14. Further, FIG. 22 shows the high-frequency circuit board  32 D in a state after being clamped in a mold  60 A and also shows how the resin  66  is injected. In FIGS.  20  to  22 , those elements that are similar to elements shown in FIGS.  2  to  6 ,  8  and  9  are indicated by similar reference numerals and will not be described in detail in the following description.  
         [0135]    In the fourth embodiment described above, the deformation of the high-frequency circuit boards  32 B,  32 C is restricted by providing the supporting parts  76 A and  76 B in the recessed portions  51 . Whereas in the present embodiment, in order to restrict or to reduce the deformation of the base material  45 , the recessed portions  51  are mechanically reinforced using various interconnections provided on the high-frequency module  30 C.  
         [0136]    In detail, in the present embodiment, the positions of the high-frequency circuit interconnections  36 B,  37 B and the DC circuit interconnection  38 B are altered such that they are provided on the base material  45  at positions opposing the recessed portions  51 . Accordingly, as shown in FIG. 21, the high-frequency circuit interconnections  36 B,  37 B and the DC circuit interconnection  38 B are provided. above the recessed portions  51  with the base material  45  being interposed therebetween.  
         [0137]    The high-frequency circuit interconnections  36 B,  37 B and the DC circuit interconnection  38 B formed simultaneously with the DC circuit interconnection  39 . Also, the positions of the interconnections  36 A to  38 B can be easily altered by altering the mask pattern used for forming the interconnections  36 B to  38 B and  39 . Also, the thickness of each of the interconnections  36 B to  38 B is, for example, 35 μm.  
         [0138]    In the manufacturing process of the high-frequency module  30 C of the above structure, the interconnections  36 B- 38 B and  39 B are formed before forming the resin package  35 . In the molding process, as shown in FIG. 22, the high-frequency circuit board  32 D provided with the interconnections  36 B to  38 B is placed in the mold  60 A and the resin  66  is injected.  
         [0139]    When the high-frequency circuit board  32 D is placed in the mold  60 A, the land portions  49 A touches the cavity  64 A of the lower mold  62 A. In this state, gaps are formed at positions corresponding to the recessed portions  51 . However, as has been described above, the interconnections  36 B to  38 B are formed on the first surface of the base material  45  opposing the recessed portions  51 . Accordingly, the mechanical strength at the recessed portions  51  is increased.  
         [0140]    Therefore, even if the base material  45  is biased due to pressure exerted by the resin  66  during molding, the base material  45  is reinforced by the interconnections  36 B to  38 B and its deformation will be restricted.  
         [0141]    Thus, during a molding process, deformation of the high-frequency circuit board  32 D can be restricted. Therefore, it is also possible in the present embodiment to prevent the chip components  34  from falling off from the high-frequency circuit board  32 A and the interconnections  36 A,  37 A,  38 A,  39  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  36 A,  37 A,  38 A,  39  from being disconnected due to stress applied thereto.  
         [0142]    Accordingly, since the deformation of the high-frequency circuit board  32 D is restricted, the high-frequency module  30 C of the present embodiment can be mounted on the mounting board with a high stability.  
         [0143]    Now, a sixth embodiment of the present invention will be described with reference to FIGS. 23 through 27.  
         [0144]    This embodiment is also characterized in that the mechanical strength at the recessed portions  51  is increased. Accordingly, the deformation of the high-frequency circuit board  32 E is reduced.  
         [0145]    [0145]FIG. 23 is a plan view of the high-frequency module  30 D of the present embodiment. FIG. 24 is a partial cross-sectional diagram along line A-A of FIG. 23. FIG. 26 is a bottom plan view of the high-frequency module  30 D. Further, FIG. 27 shows the high-frequency circuit board  32 E in a state after being clamped in a mold  60 A and also shows how the resin  66  is injected. In FIGS.  23  to  27 , those elements that are similar to elements shown in FIGS.  2  to  6 ,  8  and  9  are indicated by similar reference numerals and will not be described in detail in the following description.  
         [0146]    The present embodiment is characterized in that embedded members  79  are provided in the recessed portions  51  of the high-frequency circuit board  32 E that is provided in the high-frequency module  30 D (see FIGS. 25 and 26 for detailed illustration). The embedded member  79  is made of an insulating material such as a polyimide resin. In order to form the embedded members  79 , the insulating material is heated until it becomes soft, and then the insulating material is filled in the recessed portions  51 . Thus, the recessed portions  51  are filled with the embedded members  79  and the bottom surface of the high-frequency module  30 D becomes flat.  
         [0147]    In the manufacturing process of the high-frequency module  30 D of the above-described structure, the embedded members  79  are formed before forming the resin package  35 . Screen-printing may be used for providing the embedded members  79  so that the embedded members  79  can be easily provided in the recessed portions  51 .  
         [0148]    In the molding process, as shown in FIG. 27, the high-frequency circuit board  32 E provided with the embedded members  79  in the recessed portions  51  is placed in the mold  60 A and then the resin  66  is injected. When the high-frequency circuit board  32 E is placed in the mold  60 A, the land portions  49 A touches the cavity  64 A of the lower mold  62 A. In this state, the embedded members  79  also touches the cavity  64 A. Accordingly, the recessed portions  51  of the high-frequency circuit board  32 E are supported by the embedded members  79 .  
         [0149]    Thus, even if the base materials  45  is biased due to a pressure exerted by the resin  66  during the molding step, the base material  45  is supported by the embedded members  79  and its deformation is restricted. Thus, deformation of the high-frequency circuit board  32 E can also be restricted with the molding process of the present embodiment. Therefore, it is possible to prevent the chip components  34  from falling off from the high-frequency circuit board  32 B and the interconnections  36 A,  37 A,  38 A,  39  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  36 A,  37 A,  38 A,  39  from being disconnected due to stress applied thereto.  
         [0150]    Accordingly, since the deformation of the high-frequency circuit board  32 E is restricted, the high-frequency module  30 D that is manufactured with the manufacturing process described above can be mounted to a mounting board with an improved mounting ability. When the high-frequency module  30 D is mounted on the mounting board, the land portions  49 A for providing electrical connection touches the mounting board, and the embedded members  79  also touches the mounting board. Therefore, the high-frequency module  30 D of the present embodiment can be mounted on the mounting board with a high stability. Accordingly, the land portions  49 A and the mounting board can be soldered with an improved soldering ability.  
         [0151]    Further, as has been described above, the embedded members  79  are made of an insulating material and are provided in the recessed portions  51  each positioned between neighboring land portions  49 A. Thus, with the embedded members  79 , the neighboring land portions  49 A can be securely isolated. Accordingly, the interference may be reduced between the electrodes whereto and wherefrom the high-frequency signals are provided.  
         [0152]    Also, after completing the molding process of the resin package  24 , the embedded members  9  may be removed from the recessed portions  51 . With this structure, since the land portions  49 A will be protruded from the base material  45 , the high-frequency module  30 D may be connected to the mounting board with improved connecting ability.  
         [0153]    Now, a seventh embodiment of the present invention will be described with reference to FIGS. 28 through 30.  
         [0154]    [0154]FIG. 28 is a plan view of the high-frequency module  30 E of the present embodiment. FIG. 29 is a partial cross-sectional diagram along line B-B of FIG. 29. FIG. 30 shows the high-frequency circuit board  32 F in a state after being clamped in a mold  60 A and also shows how the resin  66  is injected. In FIGS.  28  to  30 , those elements that are similar to elements shown in FIGS.  2  to  6 ,  14  to  22  are indicated by similar reference numerals and will not be described in detail in the following description.  
         [0155]    In the present embodiment, in a similar manner to the above-described fourth embodiment, the supporting parts  76 A are formed in the recessed portions  51  of the high-frequency circuit board  32 F (see FIGS.  14  to  18 ). Further, the present embodiment is characterized in that, in a similar manner to the above-described fifth embodiment, the high-frequency circuit interconnections  36 B,  37 B and the DC circuit interconnections  38 B are provided on the first surface of the base material  45  facing the recessed portions  51  (see FIGS.  20  to  22 ).  
         [0156]    With the structure of the present embodiment, the recessed portions  51  are reinforced by the embedded members  79 A and by the high-frequency circuit interconnections  36 B,  37 B and the DC circuit interconnections  38 B. As shown in FIG. 30, in the molding process for forming the resin package  35 , the recessed portions  51  are supported by the supporting parts  76 A and are also reinforced by the interconnections  36 B,  37 B and  38 B. Therefore, even if the base material  45  is biased due to pressure exerted by the resin  66  during molding, the deformation of the base material  45  will be restricted.  
         [0157]    Thus, during a molding step, the deformation of the high-frequency circuit board  32 F can be restricted. Therefore, it is also possible in the present embodiment to prevent the chip components  34  from falling off from the high-frequency circuit board  32 F and the interconnections  36 B,  37 B,  38 B,  39  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  36 B,  37 B,  38 B,  39  from being disconnected due to stress applied thereto. Accordingly, since the deformation of the high-frequency circuit board  32 F is restricted, the high-frequency module  30 E that is manufactured with the manufacturing process described above can be mounted to a mounting board with an improved mounting ability.  
         [0158]    Now, the supporting parts provided in the recessed portions  51  will be described in detail. In order to restrict the deformation of the high-frequency circuit board  32 F (base material  45 ), it is preferable to provide the supporting parts  76 A that extends across the entire surface of the recessed portions  51 . However, as has been described above, the land portions  49 A needs to be isolated from one another. Therefore, if the supporting parts  76 A are made of, for example, a conductive material or a magnetic material and are provided across a great area in the recessed portions, the land portions  49 A will not be sufficiently isolated between each other.  
         [0159]    That is to say, when the supporting parts  76 A are formed by the conductive material or the magnetic material, it is necessary to provide sufficient space within the recessed portions  51  to ensure isolation between the land portions  49 A. The width of the space required is in an order of about 300 μm. Accordingly, with the structure provided with the supporting parts  76 A in the recessed portions  51 , the deformation of the base material  45  may not be restricted for some strength of a pressure exerted by the resin  66  during molding.  
         [0160]    However, in the present embodiment, the high-frequency module  30 E is provided with the supporting parts  76 A and with the interconnections  36 B,  37 B, and  38 B formed on the base material  45  opposing the recessed portions  51 . Thus, even if the supporting parts  76 A are formed in a shape that ensures that the land portions  49 A are isolated from one another, the recessed portions  51  will be reinforced by the interconnections  36 B,  37 B and  38 B. With such a structure, the deformation of the high-frequency circuit board  32 F can be restricted while ensuring isolation between the land portions  49 A.  
         [0161]    Now, a seventh embodiment of the present invention will be described with reference to FIGS. 31 through 35.  
         [0162]    In each of the embodiments described above, the land portions  49 A are formed on the second surface of the base material  45 , and then the resin package  35  is formed. Whereas in the present embodiment, the resin package  35  is formed before forming the land portions  49 A.  
         [0163]    With this method, since the resin package  35  is formed while there is no land portions  49 A, there will be no unleveled portions formed on the second surface of the base material  45 . Accordingly, the deformation of the base material  45  can be restricted. In the following description, a method of manufacturing the high-frequency module  30 F of the present embodiment will be described in detail. In FIGS.  31  to  35 , those elements that are similar to elements shown in FIGS.  2  to  6 ,  8  and  9  are indicated by similar reference numerals and will not be described in detail in the following description.  
         [0164]    A method of manufacturing the resin package  35 F is as follows. As shown in FIG. 31A, the base material  45  is prepared. The base material  45  is a polyimide film of a thickness of about 25 μm to 70 μm. As shown in FIG. 31B, a copper layer  80  is provided on a surface of the base material  45 . In order to provide this copper layer  80 , firstly, a thin layer of copper is formed by copper sputtering process and then a flush copper plating is implemented.  
         [0165]    Then, as shown in FIG. 31C, a dry film  1  is provided over the copper layer  80 . The dry film  81  is a photo-sensitive resin layer of a negative type.  
         [0166]    Then, the method proceeds to an exposure process. As shown in FIG. 31D, a glass mask  82  having a predetermined pattern is provided and a light (such as an ultra-violet ray) is illuminated thereto.  
         [0167]    Then, the method proceeds to a development process. Since the dry film  81  is a photo-sensitive resin layer of a negative type, the development process serves to leave only the portions of the dry film  81  that have been irradiated by light. FIG. 32A shows a state after the exposure process has been completed.  
         [0168]    Then, the base material  45  is placed in an electrolytic plating vessel. Electrolytic plating process of copper is carried out using the copper layer  80  as electrodes. Accordingly, using the dry film  81  as a mask, a copper plating body  83  with a predetermined pattern is formed. FIG. 32B shows a state where the copper plating body  83  have been formed.  
         [0169]    Then, as shown in FIG. 32C, the dry film  81  is removed. Subsequently, the copper plating body  83  is subjected to flush etching so as to form independent copper patterns  84 . FIG. 32D shows a state where the copper patterns  84  have been formed.  
         [0170]    Then, a finishing plating layer  85  of, for example, gold, is formed on over the copper patterns  84  such that interconnections  86  shown in FIG. 32E are formed. The interconnections  86  will serve as the high-frequency circuit interconnections  36 A,  37 A, the DC circuit interconnections  38 A,  39 , and the bias terminals  40  to  44 . After forming the interconnections  86 , the chip components  34  are soldered between the predetermined interconnections  86  as shown in FIG. 33A.  
         [0171]    After the interconnections  86  and the chip components  34  are provided on the base material  45 , a molding process is implemented for forming the resin package  35  on the base material  35 . In the molding process, as shown in FIG. 33B, the base material  45  is placed in the mold  60 C and the resin  66  is injected on the upper surface of the base material whereon the chip components  34  and the interconnections  86  are formed.  
         [0172]    Then, after the above-described molding process when the resin package is provided on the base material  45 , the dry film  87  of photo-sensitive resin is provided on the lower surface of the base material  45  as shown in FIG. 33C. Then, the dry film  87  undergoes an exposure process using a glass mask  88  having a predetermined pattern.  
         [0173]    The dry film  87  used herein is also a photo-sensitive resin of a negative type. The pattern formed on the glass mask  88  is configured such that the light is irradiated at portions where via holes  50  are not formed.  
         [0174]    After exposure, a development process is implemented. As shown in FIG. 34A, the dry film  87  is provided with openings  89  provided at positions opposing the via holes  50 . Then, polyimide etching is implemented using the dry film  87  as a mask. Thus, as shown in FIG. 34B, through-holes  90  are formed in the base material  45 .  
         [0175]    Then, as shown in FIG. 34C, a copper layer  91  is formed on the second surface of the base material  45  having the through-holes  90 . In order to provide the copper layer  91 , firstly, a thin film of copper is formed by copper sputtering and then a flush copper plating is implemented.  
         [0176]    When the copper layer  91  is formed, processes similar to those described with reference to FIGS. 31C to  32 B are implemented. As shown in FIG. 35A, using the dry film  92  as a mask, a copper plating body  93  is formed. The copper plating body  93  is formed by electrolytic plating using the copper layer  91  as electrodes. Also, since the copper plating body  93  is also formed in the through-holes  90 , the via holes  50  are formed.  
         [0177]    After the copper plating body  93  is formed in the above-described manner, the dry film  92  is removed. Then, the copper plating body  93  undergoes a flush etching process, so as to provide independent copper patterns. Then, a finishing plating layer  94  of, for example, gold is formed over the copper patterns. Accordingly, as shown in FIG. 35B, the high-frequency module  30 F having the via holes  50  and the land portions  49 A is manufactured.  
         [0178]    Now, a molding process of the resin package  35  of the above-described method will be described in detail.  
         [0179]    As has been described above, the deformation of the base material  45  during the molding process is due to unleveled portions produced before molding as a result of the formation of the land portions  49 A of the second surface of the base material  45 . However, with the manufacturing method of the present embodiment, the resin package  35  is formed before forming the land portions  49 A on the base material, or, before the second surface of the base material  45  becomes unleveled.  
         [0180]    Thus, as shown in FIG. 33B, during the molding process, the second surface of the base material  45  is flat and thus there is no gap between the lower mold  62 C of the mold  60 C and the base material  45 . Therefore, even if the base material  45  is biased due to pressure exerted by the resin  66  during molding, the base material  45  is supported by the lower mold  62 C and its deformation will be restricted. The present embodiment also restricts the deformation of the base material  45  during molding. Therefore, it is also possible in the present embodiment to prevent the chip components  34  from falling off from the interconnections  86  and the interconnections  86  from peeling off from the base material  45 . Further, it is possible to prevent the interconnections  86  from being disconnected due to stress applied thereto.  
         [0181]    In the embodiments described above, a transfer molding process has been described as an example of a method of forming the resin package  35 . However, it is to be noted that the method of forming the resin package  35  is not limited thereto. Instead, it can be widely applied for cases where a resin forming method is used in which biasing force is exerted on a high frequency circuit board while forming the resin package  35  by method such as compression molding.  
         [0182]    Further, the present invention is not limited to these embodiments, but variations and modifications may be made without departing from the scope of the present invention.  
         [0183]    The present application is based on Japanese priority application No. 2000-196965 filed on Jun. 29, 2000, the entire contents of which are hereby incorporated by reference.

Technology Category: h