Abstract:
A method for manufacturing an electric device by connecting a wiring board to an object is disclosed. This method for manufacturing an electric device comprises: applying a wiring board having a first via hole on a mounting face of an object to fix the wiring board; placing a heater having a recess to the wiring board, the heater being adjusted so that the recess overlaps a boundary between the first via hole and a surface of the wiring board; and melting a soldering metal so that the soldering metal enters into the recess and the first via hole.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a method for manufacturing an electric device by connecting a wiring board to an object, and an electric device including the wiring board. 
       BACKGROUND 
       [0002]    A semiconductor device such as an optical semiconductor device is packaged. A board such as a flexible printed board (hereinafter, described as a flexible board) is connected to a lead of a semiconductor package, and power supply, input and output of signals, or the like is performed through the board. The board is connected to the lead using a soldering metal. Connection using the soldering metal is performed through soldering (Japanese Patent Application Laid-Open Publication No. Hei7-273435). 
       SUMMARY 
       [0003]    However, it is difficult to realize stable connection using soldering depending on the amount of the soldering metal, wettability of the soldering metal, a temperature profile, or the like. 
         [0004]    One aspect of the present application relates to a method for manufacturing an electric device. The method for manufacturing the electric device comprises: applying a wiring board having a first via hole on a mounting face of an object to fix the wiring board; placing a heater having a recess to the wiring board, the heater being adjusted so that the recess overlaps a boundary between the first via hole and a surface of the wiring board; and melting a soldering metal so that the soldering metal enters into the recess and the first via hole. 
         [0005]    Another aspect of the present application relates to an electric device. The electric device comprising: a wiring board having a first via hole on a mounting face of an object to fix the wiring board; and a soldering metal extending inside the first via hole and on a surface of the wiring board, wherein the soldering metal has a first projection and a recess of the wiring board located on an outside of the first via hole, and a thickness of the first projection is larger than that of the recess. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The foregoing and other purposes, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, in which: 
           [0007]      FIG. 1  is a cross-section view illustrating a method for manufacturing an optical module according to a first embodiment; 
           [0008]      FIG. 2  is a plan view illustrating a semiconductor package; 
           [0009]      FIG. 3A  is a plan view illustrating an upper face of a flexible board,  FIG. 3B  is a plan view illustrating a lower face of a heater,  FIG. 3C  is a cross-section view along a line IIIc-IIIc in  FIG. 3B ; 
           [0010]      FIG. 4A  is a plan view illustrating soldering,  FIG. 4B  is a plan view illustrating a flexible board after soldering; 
           [0011]      FIG. 5A  is a cross-section view along a line Va-Va in  FIG. 4B ,  FIG. 5B  is a cross-section view along a line Vb-Vb in  FIG. 4B ; 
           [0012]      FIG. 6A  is a plan view illustrating a heater in a comparative example,  FIG. 6B  is a cross-section view along a line VIb-VIb in  FIG. 6A ; 
           [0013]      FIG. 7A  is a plan view illustrating a flexible board after soldering,  FIG. 7B  is a cross-section view along a line VIIb-VIIb in  FIG. 7A ,  FIG. 7C  is a cross-section view along a line VIIc-VIIc in  FIG. 7A , 
           [0014]      FIG. 8A  is a plan view illustrating a lower face of the heater,  FIG. 8B  is a cross-section view along a line VIIIb-VIIIb in  FIG. 8A ; and 
           [0015]      FIG. 9A  is a plan view illustrating a flexible board after soldering,  FIG. 9B  is a cross-section view along a line IXb-IXb in  FIG. 9A , and  FIG. 9C  is a cross-section view along a line IXc-IXc in  FIG. 9A . 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Embodiments of the present invention will be described. 
         [0017]    One aspect of the present embodiment relates to a method for manufacturing an electric device. The method for manufacturing the electric device comprises disposing a wiring board on a mounting face, the wiring board having a first terminal provided on a first face, a second terminal provided on a second face which is an opposite side of the first face, and a first via hole connecting the first terminal to the second terminal; adjusting a position of a heater having a first recess so that the first recess overlaps with the first via hole and a portion of the wiring board outside of the first via hole; making the heater abut on the wiring board after the adjusting; melting a soldering metal in a state the heater abuts on the wiring board so that the melted soldering metal intrudes into the first via hole and the first recess of the heater; and solidifying the melted soldering metal so as to connect the wiring board to the mounting face. 
         [0018]    According to this embodiment, the soldering metal is melted by way of soldering, and the melted soldering metal flows on the first face through the first via hole. The soldering metal flowing into the first recess of the heater forms the projection. Because the soldering metal has the projection, the soldering metal is thick on the first via hole. Therefore, the wiring board is rigidly bonded to another board. Because a surface area of the soldering metal becomes larger than one in which there is no projection, heat is efficiently transferred from the heater to the soldering metal. As a result, heat circulation efficiency between the soldering metal on the first face side and the soldering metal on the second face side is improved, and the soldering metal is effectively melted. By this means, wettability between the soldering metal and the electronic component is improved. As described above, according to the above-described embodiment, it is possible to provide a method for manufacturing an electric device by connecting a wiring board to another board which realizes connection with high reliability. 
         [0019]    In the above-described embodiment, it is also possible that the wiring board has a second via hole connecting the first terminal to the second terminal, and the heater is adjusted so that the first recess is provided over both of the first and the second via holes in the adjusting. According to this embodiment, a projection is provided over the first and the second via holes. Compared to a case where one projection is formed on one via hole, strength of bonding is improved. Accordingly, reliability of connection increases. 
         [0020]    Another aspect of the present embodiment relates to an electric device. The electric device comprising a wiring board having a first terminal provided on a first face, a second terminal provided on a second face which is an opposite side of the first face, and a first via hole connecting the first terminal to the second terminal; another board having a mounting face; a soldering metal extending between the second terminal of the wiring board and the mounting face of the another board, inside the first via hole and on a surface of the first terminal, wherein the soldering metal has a first projection provided on the first via hole and on a portion of the wiring board located on an outside of the first via hole, the first projection projecting from the first face. 
         [0021]    According to this embodiment, because the soldering metal has a projection, the soldering metal is thick on the first via hole. Therefore, the wiring board is rigidly bonded to another board. Because a surface area of the soldering metal becomes larger than one in which there is no projection, heat is efficiently transferred to the soldering metal. As a result, heat circulation efficiency between the soldering metal on the first face side and the soldering metal on the second face side is improved, and the soldering metal is effectively melted. By this means, wettability between the soldering metal and the electronic component is improved. As described above, according to the above-described embodiment, it is possible to provide an electric device including a wiring board which realizes connection with high reliability. 
         [0022]    A more detailed example of an embodiment according to the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same element will be designated by the same reference numeral and a duplicate description thereof will be omitted. Further, in each drawing used for the following description, a scale is properly changed in order to illustrate each member with an identifiable size. 
       First Embodiment 
       [0023]      FIG. 1  is a cross-section view illustrating a method for manufacturing an optical module (optical device) according to a first embodiment. As illustrated in  FIG. 1 , a semiconductor package  20  (electronic component) is mounted on jigs  10  and  12 . A ceramic heater  14  is disposed below the jig  12 . A flexible hoard  60  (wiring board) is disposed on a lead not illustrated in  FIG. 1 ) of the semiconductor package  20 . A heater  16  presses the flexible board  60  against the lead of the semiconductor package  20  from above to perform soldering. By way of soldering, the flexible board  60  is electrically connected to the lead using a soldering metal. The jig  10  is formed with a metal such as, for example, aluminum (Al). The jig  12  is formed with a metal such as, for example, copper (Cu). The jigs  10  and  12  may be formed with an insulating material. 
         [0024]      FIG. 2  is a plan view illustrating the semiconductor package  20 . As illustrated in  FIG. 2 , a temperature control unit such as a TEC (Thermoelectric Cooler)  24  is disposed on a bottom face of a housing  21 . of the semiconductor package  20 . On the TEC  24 , a carrier  28  and a lens holder  26  are disposed. The carrier  28  is made of a material with an insulating properties and high thermal conductivity. The carrier  28  is, for example, aluminum oxide or ceramics. A lens  27  is held in the lens holder  26 . On an upper face of the carrier  28 , ground patterns  28   a  and  28   b  are provided. On the ground pattern  28   a,  boards  42  and  30 , a subcarrier  32  and a capacitor  40  are provided. A resistor  38  is connected between the ground patterns  28   a  and  28   b.  A capacitor  36  is provided on the ground pattern  28   b.    
         [0025]    The subcarrier  32  is, for example, a dielectric board. A semiconductor laser  34  (LD (Laser Diode) element) is disposed on the subcarrier  32 . A signal line  30   a  is fowled on an upper face of the board  30 . The signal line  30   a  and the ground pattern  28   a  on the upper face of the carrier  28  form a micro strip line. 
         [0026]    A receptacle  23  is fixed on a front face of the housing  21 . A board  45  is embedded in a rear side wall of the housing  21 . The board  45  serves as a feed-through. On the board  45 , a coplanar line  46  and a signal line  47  are provided. The coplanar line  46  is formed with a signal line  46   a  and ground patterns  46   b  and  46   c.  The signal lines  46   a  and  47  and the ground patterns  46   b  and  46   c  of the board  45  are electrically connected to the signal lines  22 , respectively. On the lower face of the board  45 , a ground pattern (not illustrated) is provided. The ground patterns  46   b  and  46   c  are connected to the ground pattern on the lower face through via holes  48 , respectively. 
         [0027]    The board  42  serves as a bridge between the board  45  and the board  30 . On an upper face of the board  42 , a signal line  43   a  and ground patterns  43   b  and  43   c  are provided. On a lower face of the board  42 , a ground layer which is not illustrated is provided. The signal line  43   a  and the ground patterns  43   b  and  43   c  form a coplanar line  43 . The signal line  43   a  and the ground pattern on the lower face form a micro strip line. The ground patterns  43   b  and  43   c  are connected to the ground pattern on the lower face through via holes  44 , respectively. 
         [0028]    The signal line  43   a  of the board  42  is electrically connected to the signal line  30   a  of the hoard  30  through a bonding wire  50 . The signal line  30   a  is electrically connected to the semiconductor laser  34  through a bonding wire  51 . The semiconductor laser  34  is electrically connected to the capacitor  36  through a bonding wire  52 . The semiconductor laser  34  is electrically connected to the capacitor  40  through a bonding wire  53 . The capacitor  40  is electrically connected to the signal line  47  through a bonding wire  54 . 
         [0029]    A power-supply voltage is supplied to the semiconductor laser  34  through the signal line  22 , the signal line  47  and the capacitor  40 . A laser drive IC (Integrated Circuit, not illustrated) is disposed outside the semiconductor package  20 . The laser drive IC is connected to the signal line  22  through the flexible board  60  illustrated in  FIG. 1 . The laser drive IC amplifies an input signal which is a high frequency signal and outputs the amplified signal. The output input signal is input to the semiconductor laser  34  through the coplanar line  46  of the board  45 , the coplanar line  43  and the micro strip line of the board  42 , and the micro strip line of the board  30 . The output light of the semiconductor laser  34  is focused by the lens  27  and output to an optical fiber (not illustrated) which is inserted into the receptacle  23 . 
         [0030]    The TEC  24  maintains a constant temperature of the semiconductor laser  34 . By this means, it is possible to lock a wavelength of the output light. Because part of the board  45  is exposed to the outside of the housing  21 , the temperature of the board  45  is substantially equal to the outside temperature. The board  42  is cooled down by the TEC  24 . Because the ground pattern of the board  42  is separated from the ground pattern of the board  45 , heat is less likely to be transferred between the boards  42  and  45 , so that increase of the temperature of the semiconductor laser  34  is inhibited. 
         [0031]      FIG. 3A  is a plan view illustrating an upper face of the flexible board  60 . As illustrated in  FIG. 3A , a plurality of terminals  62  and two terminals  64  are provided on the upper face of the flexible board  60 . Two via holes  66  are provided for one terminal  62 . One via hole  68  is provided at each of the terminals  64 . As will be described later with reference to  FIG. 5A  and  FIG. 5B , terminals  63  and terminals  65  are provided on a lower face of the flexible board  60 . The via holes  66  penetrate through the flexible board  60  and connect the terminals  62  on the upper face to the terminals  63  on the lower face, respectively. The via holes  68  penetrate through the flexible board  60  and connect the terminals  64  on the upper face to the terminals  65  on the lower face, respectively. The terminals  62  and  63  are terminals for inputting a power-supply voltage and inputting and outputting a high frequency signal. The terminals  64  and  65  have a reference potential. The soldering metal is preformed on the terminals  63  and  65  (which is not illustrated). It should be noted that the soldering metal does not have to be preformed on the terminals and may be applied upon bonding. 
         [0032]      FIG. 3B  is a plan view illustrating a lower face of the heater  16 .  FIG. 3C  is a cross-section view along a line IIIc-IIIc in  FIG. 3B . As illustrated in  FIG. 3B  and  FIG. 3C , a plurality of recesses  16   a  and two recesses  16   b  are provided at a tip of the heater  16 . The recesses  16   a  and  16   b  have curved upper faces. The position of the heater  16  is adjusted on the flexible board  60  so that the recesses  16   a  illustrated in  FIG. 3B  and  FIG. 3C  overlap with the via holes  66  and the flexible board  60  on the outside of the via hole  66  illustrated in  FIG. 3A , respectively, and the recesses  16   b  overlap with the via holes  68  and the flexible board  60  on the outside of the via holes  68 , respectively. As illustrated in  FIG. 1 , the flexible board  60  is soldered to the semiconductor package  20  using the heater  16 . 
         [0033]      FIG. 4A  is a plan view illustrating soldering.  FIG. 4B  is a plan view illustrating the flexible board  60  after soldering.  FIG. 5A  is a cross-section view along a line Va-Va in  FIG. 4B .  FIG. 5B  is a cross-section view along a line Vb-Vb in  FIG. 4B . 
         [0034]    As illustrated in  FIG. 4A , the heater  16  is brought into contact with the upper face of the flexible board  60 . The heater  16  applies heat and pressure to the flexible board  60 . As illustrated in  FIG. 4B , a soldering metal  70  having the projection  71  and  73  and the recess  72  wets and spreads over the terminal  62 . A soldering metal  70  having the projections  74  and  73  and the recess  72  wets and spreads over the terminal  64 . It should be noted that the terminals are separated from each other and electrically insulated from each other. Detailed description will be provided with reference to the cross-section view. 
         [0035]    A method for connecting the flexible board  60  to the mounting face of the board  45  will be described with reference to  FIG. 1 . At first, the flexible board  60  is mounted on the mounting face of the board  45 . The heater  16  applies heat and pressure to the flexible board  60 . The soldering metal  70  provided on the lower face of the flexible board  60  is melted by the heat transferred from the heater  16 . The melted soldering metal  70  flows on the upper face through the via holes  66  as illustrated in  FIG. 5A . The melted soldering metal  70  wets and spreads over the terminal  62  provided on the upper face of the flexible board  60  and the terminal  63  provided on the lower face. The terminal  63  is electrically connected to the signal line  22  through the soldering metal  70 . Further, the terminals  63  is electrically connected to the terminal  62  through the soldering metal  70  inside the via holes  66 . The melted soldering metal  70  is solidified after intruding into the recesses  16   a  of the heater  16  and forms the projections  71 . The soldering metal  70  at a portion pressed against an end face (lower face in  FIG. 5A ) of the heater  16  forms recesses  72 . At the outside of the recesses  72 , projections  73  are formed. 
         [0036]    As illustrated in  FIG. 5B , the melted soldering metal  70  wets and spreads over the terminal  64  provided on the upper face of the flexible board  60  and the terminal  65  provided on the lower face. The terminal  65  is electrically connected to the signal line  22  through the soldering metal  70 . Further, the terminal  65  is electrically connected to the terminal  64  through the soldering metal  70  inside the via hole  68 . The soldering metal  70  which has intruded into the recess  16   b  of the heater  16  is solidified and forms a projection  74 . At the outside of the projection  74 , recesses  72  are formed. At the outside of the recesses  72 , projections  73  are formed. The projections  71 ,  73  and  74  project further from the upper face of the flexible board  60 . 
         [0037]    Because the soldering metal  70  has projections  71  and  74 , the soldering metal  70  is thick on the via holes  66  and  68 . Therefore, the flexible board  60  is rigidly bonded to the signal line  22 . Because a surface area of the soldering metal  70  becomes larger than one in which there is no projection, heat is efficiently transferred from the heater  16  to the soldering metal  70 . As a result, heat circulation efficiency between the soldering metal on the upper face side and the soldering metal on the lower face side is improved, and the soldering metal  70  is effectively melted. By this means, wettability between the soldering metal  70  and the terminals is improved and wettability between the soldering metal  70  and the metal patterns is also improved. As described above, according to the first embodiment, it is possible to improve reliability of connection. 
         [0038]    As illustrated in  FIG. 5A , a radius R 1  of the recess  16   a  is greater than a radius R 2  of the via hole  66 . By this means, the projection  71  which is larger than the via hole  66  is formed. As illustrated in  FIG. 5B , a radius R 3  of the recess  16   b  is greater than a radius R 4  of the via hole  68 . The projection  74  which is larger than the via hole  68  is foamed. Because the projections  71  and  74  are supported on the upper face of the flexible board  60 , the soldering metal  70  is inhibited from flowing out to the lower face side. By this means, shapes of the projections  71  and  74  become stable. Because the shapes of the projections  71  and  74  become stable, it is possible to realize rigid bonding, which improves reliability of connection. As described above, it is preferable that the recess  16   a  of the heater  16  is larger than the via hole  66  and the recess  16   b  is larger than the via hole  68 . 
         [0039]    A comparative example will be described. The flexible board  60  is the same as that illustrated in  FIG. 3A . The semiconductor package is the same as that illustrated in  FIG. 2 .  FIG. 6A  is a plan view illustrating a heater  16 R in the comparative example.  FIG. 6B  is a cross-section view along a line VIb-VIb in  FIG. 6A . As illustrated in  FIG. 6A  and  FIG. 6B , a recess is not provided on the heater  16 R. 
         [0040]    Soldering as illustrated in  FIG. 4A  is also performed in the comparative example.  FIG. 7A  is a plan view illustrating the flexible board  60  after soldering.  FIG. 7B  is a cross-section view along a line VIIb-VIIb in  FIG. 7A . As illustrated in  FIG. 7B , a projection  71  is not formed on a soldering metal  70 R. The soldering metal  70 R on the via hole  66  is pressed by a lower face of the heater  16 R. Therefore, a recess  72  is formed on the via hole  66 .  FIG. 7C  is a cross-section view along a line VIIc-VIIc in  FIG. 7A . As illustrated in  FIG. 7C , a projection  74  is not formed on the soldering metal  70 R The soldering metal  70 R on the via hole  68  is pressed by the lower face of the heater  16 R. Therefore, a recess  72  is formed on the via hole  68 . 
         [0041]    As described above, in the comparative example, the thickness of the soldering metal  70 R on the via holes  66  and  68  is thin. Therefore, strength of bonding is weak. Because a surface area of the soldering metal  70 R is smaller than that in the first embodiment, heat circulation efficiency is low. Therefore, wettability between the soldering metal  70 R and the terminals is degraded and wettability between the soldering metal  70 R and the metal patterns is also degraded. Accordingly, in the comparative example, reliability of connection is degraded. 
       Second Embodiment 
       [0042]    The flexible board  60  according to the second embodiment is the same as that illustrated in  FIG. 3A . The semiconductor package according to the second embodiment is the same as that illustrated in  FIG. 2 . 
         [0043]      FIG. 8A  is a plan view illustrating a lower face of a heater  116 .  FIG. 8B  is a cross-section view along a line VIIIb-VIIIb in  FIG. 8A . As illustrated in  FIG. 8A  and  FIG. 8B , a plurality of recesses  116   c  and two recesses  116   d  are provided at a tip of the heater  116 . The recess  116   c  has a rectangular shape. The recess  116   d  has a trigonal pyramid shape. The heater  116  is disposed on the flexible board  60  so that the recesses  116   c  illustrated in  FIG. 8A  and  FIG. 8B  overlap with the via holes  66  illustrated in  FIG. 3A , respectively and the recesses  116   d  overlap with the via holes  68 , respectively. As illustrated in  FIG. 1  and  FIG. 4A , the flexible board  60  is connected to the semiconductor package through soldering. 
         [0044]      FIG. 9A  is a plan view illustrating the flexible board  60  after soldering.  FIG. 9B  is a cross-section view along a line IXb-IXb in  FIG. 9A .  FIG. 9C  is a cross-section view along a line IXc-IXc in  FIG. 9A . As illustrated in  FIG. 9A , a soldering metal  170  having projections  75  and  73  and a recess  72  wets and spreads the terminal  62 . The soldering metal  170  having projections  76  and  73  and a recess  72  wets and spreads over the terminal  64 . Detailed description will be provided with reference to the cross-section view. 
         [0045]    As illustrated in  FIG. 9B , the melted soldering metal  170  wets and spreads over the terminal  62  provided on the upper face of the flexible board  60  and the terminal  63  provided on the lower face. The melted soldering metal  170  is solidified after intruding into a recess  116   c  of the heater  116  and forms a rectangular projection  75 . As illustrated in  FIG. 9C , the soldering metal  170  which has intruded into a recess  116   d  of the heater  116  is solidified and forms a projection  76  having a trigonal pyramid shape. 
         [0046]    Because the soldering metal  170  has the projections  75  and  76 , the soldering metal  170  is thick on the via holes  66  and  68 . Therefore, the flexible board  60  is rigidly bonded to the signal line  22 . A surface area of the soldering metal  170  is larger than one in which there is no projection. Because heat circulation efficiency between the soldering metal on the upper face side and the soldering metal on the lower face side is improved, wettability between the terminals and the soldering metal  170  patterns is improved and wettability between the soldering metal  170  and the metal patterns is also improved. According to the second embodiment, reliability of connection is improved. 
         [0047]    As illustrated in  FIG. 9B , a width W 1  of the recess  116   c  is greater than a width W 2  between outer end portions of two via holes  66 . Therefore, the projection  75  is formed over the two via holes  66 . Compared to a case where one projection is fanned on one via hole  66 , strength of bonding becomes high. Therefore, reliability Of connection is improved. Because the projection  75  is supported on the upper face of the flexible board  60 , the shape of the projection  75  becomes stable, which enables rigid bonding. As described above, the recess  116   c  is preferably provided over a plurality of via holes  66  of the flexible board  60 . 
         [0048]    As illustrated in  FIG. 9C , because a width W 3  of a recess  116   d  is greater than a radius R 4  of the via hole  68 , the projection  76  which is larger than the via hole  68  is formed. Because the projection  76  is supported on the upper face of the flexible board  60 , the shape of the projection  76  becomes stable, which enables rigid bonding. As described above, the recess  116   d  is preferably larger than the via hole  68 . 
         [0049]    In the second embodiment, as illustrated in  FIG. 3B  and  FIG. 3C  in the first embodiment, the recesses  116   c  and  116   d  may have curved upper faces. The projections  75  and  76  may also have spherical faces. That is, it is possible to form the projection  75  which is provided over two via holes  68  and which has a spherical upper face. 
         [0050]    In the first embodiment and the second embodiment, the number of via holes  66  formed at one terminal  62  may be one, or three or more. If a plurality of via holes  66  are provided, it is preferable that the recesses of the heaters  16  and  116  overlap with the plurality of via holes  66  as illustrated in the drawings. It is possible to form a projection over the plurality of via holes  66  and improve strength of bonding. It is also possible to provide a plurality of via holes  68  for one terminal  64 . By configuring the recesses of the heaters  16  and  116  so as to overlap with the plurality of via holes  68 , a recess is formed over the plurality of via holes  68 . 
         [0051]    The flexible board  60  is made of an insulating material such as a resin. The terminals  62  to  65  are made of a metal such as a laminated film of for example, nickel (Ni) and gold (Au). The soldering metals  70  and  170  are made of a metal such as an alloy of for example, tin and silver (Sn—Ag). The wettability of the terminals  62  to  65  with respect to the soldering metal (wettability of the soldering metal) is preferably higher than the wettability of the soldering metal of the heaters  16  and  116 , so as to inhibit the soldering metals  70  and  170  from bonding with the heaters  16  and  116 . 
         [0052]    The semiconductor package  20  in  FIG. 2  includes a light emitting element such as the semiconductor laser  34 . According to the first embodiment and the second embodiment, it is possible to form a Transmitter Optical Subassembly (TOSA). The semiconductor package  20  may include, for example, a light receiving element, such as a photodiode. According to the first embodiment and the second embodiment, it is possible to form a Receiver Optical Subassembly (ROSA). As described above, an optical module is formed by soldering the semiconductor package  20  on which optical elements (light emitting element and light receiving element) are mounted to the flexible board  60 . It should be noted that it is also possible to manufacture a semiconductor device and an electronic device other than the optical module. The board to which the semiconductor package is soldered is not limited to the flexible board. The semiconductor package may be soldered to any board such as a printed board, which allows input and output of signals and supply of a power-supply voltage. 
         [0053]    It should be noted that the present invention is not limited to specific embodiments and examples, and various modification and change can be made within the scope of the gist of the present invention described in the claims.