Optical Module

Abstract

The optical module involved in the invention of the present application comprises: an optical semiconductor element; a package that accommodates the optical semiconductor element; a first pattern that is arranged on the upper surface of the package; a second pattern that is arranged on the side surface of the package connected to the upper surface; a flexible substrate that is arranged on the first pattern and extends from the upper surface of the package to the side surface; and solder that joins the first pattern and the flexible substrate together, and the solder extends between a portion of the flexible substrate that extends from the upper surface of the package to the side surface and the second pattern.

Description

Technical Field

[0001] The invention relates to an optical module. Background Art

[0002] Patent document 1 discloses a connection structure of printed wiring boards in which a pad group of a first printed wiring board is connected to a pad group of a second printed wiring board by solder. The second printed wiring board is a flexible printed wiring board. The solder arranged between the pad group of one wiring board and the pad group of another wiring board spreads to a soldering pattern formed in an area corresponding to the back side of the pad group of the other wiring board. Thus, the solder surrounds the end edge of the first printed wiring board.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2005-302824

[0004] When the FPC (Flexible Printed Circuit) and the optical module are soldered, the FPC may deform, causing a force to be applied vertically to the solder joint to separate from the optical module. As a result, there is a possibility that the solder joint will be separated and stress will be concentrated at the end of the solder joint, causing the FPC to break.

[0005] In order to prevent the above situation, it is considered to cover the solder joint with an adhesive. However, in order to fix the joint with an adhesive, an adhesive coating process or bonding process is required. Therefore, there is a concern that the increase in manufacturing processes will lead to an increase in costs.

[0006] In Patent Document 1, the peel strength is improved by spreading the solder to the back side of the pad group of the wiring board. However, there is a case where the portion of the optical module where the electrode circuit is formed is thicker than the general circuit substrate. In addition, there is a case where the electrode circuit is formed on the portion of the optical module where the FPC is soldered to the electrode circuit formed on both sides. Therefore, in the optical module, it may be difficult to spread the solder infiltration to the side opposite to the electrode circuit side. Summary of the invention

[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain an optical module capable of improving the strength of a solder joint portion.

[0008] The optical module involved in the invention of the present application comprises: an optical semiconductor element; a package that accommodates the optical semiconductor element; a first pattern that is provided on the upper surface of the package; a second pattern that is provided on the side surface of the package that is connected to the upper surface; a flexible substrate that is provided on the first pattern and extends from the upper surface of the package to the side surface; and solder that joins the first pattern to the flexible substrate, the solder extending between a portion of the flexible substrate that extends from the upper surface of the package to the side surface and the second pattern.

[0009] In the optical module involved in the invention of the present application, the flexible substrate is joined to the upper surface of the package by solder. The solder extends between the portion of the flexible substrate extending from the upper surface of the package to the side surface and the second pattern provided on the side surface of the package. Therefore, the solder can be thickened at the end of the package where a peeling force is likely to act on the flexible substrate. Therefore, the strength of the solder joint can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a cross-sectional view of the optical module according to the first embodiment.

[0011] Figure 2 This is another cross-sectional view of the optical module according to the first embodiment.

[0012] Figure 3 This is a cross-sectional view showing the structure of the flexible substrate according to the first embodiment.

[0013] Figure 4 is a cross-sectional view of an optical module according to a comparative example.

[0014] Figure 5 This is a perspective view of an optical module according to a modification of the first embodiment.

[0015] Figure 6 This is a perspective view of an optical module according to the second embodiment.

[0016] Figure 7 It is a top view of the flexible substrate involved in Embodiment 2.

[0017] Figure 8 This is a perspective view of an optical module according to Embodiment 3.

[0018] Fig. 9 It is a top view of the flexible substrate involved in Embodiment 3.

[0019] Fig.10 It is a cross-sectional view of an optical module according to the fourth embodiment.

[0020] Fig.11 It is a top view of the flexible substrate involved in the fourth embodiment.

[0021] Fig.12 It is a top view of a flexible substrate according to a modification of the fourth embodiment. DETAILED DESCRIPTION

[0022] The optical module involved in the embodiment of the present invention is described with reference to the accompanying drawings. There are cases where the same or corresponding components are marked with the same figure mark and repeated description is omitted. The following description and the contents of the drawings are not limited to the claims. In addition, in each drawing, the size or scale of the corresponding components is independent. For example, in a figure in which a part of the structure is changed and a figure in which it is not changed, there is a case where the size or scale of the corresponding components is different.

[0023] Implementation method 1.

[0024] Figure 1 It is a cross-sectional view of the optical module 100 according to the first embodiment. Figure 2 1 is another cross-sectional view of the optical module 100 according to Embodiment 1. The optical module 100 can be used for optical communication, for example. Figure 1 , 2 Only basic components of the optical module 100 are shown in the figure, and other components such as capacitors are omitted from the figure.

[0025] In the optical module 100, the thermoelectric module 40 is fixed to the bottom of the housing 80. The metal block 30 is fixed to the upper surface of the thermoelectric module 40. The auxiliary fixture 20 is fixed to the upper surface of the metal block 30. In this way, the auxiliary fixture 20 is mechanically fixed to the inside of the housing 80 at the surface opposite to the optical semiconductor element 10.

[0026] The optical module 100 includes an optical semiconductor element 10 . The optical semiconductor element 10 is a semiconductor laser chip. The optical semiconductor element 10 is bonded to the upper surface of the auxiliary fixture 20 by solder 60 . The optical semiconductor element 10 is accommodated in a housing 80 .

[0027] A feedthrough 81 is provided on the side of the housing 80 opposite to the laser output direction of the optical semiconductor element 10. The housing 80 and the feedthrough 81 constitute a package for accommodating the optical semiconductor element 10. The feedthrough 81 penetrates from the inside to the outside of the housing 80. The feedthrough 81 electrically connects the outside and the inside of the housing 80. The feedthrough 81 is formed in a stepped shape on the inside and outside of the housing 80, respectively.

[0028] A first pattern 85 is provided on the upper surface 81a of the feed-through member 81. Figure 2 As shown, the first pattern 85 penetrates from the inside to the outside of the housing 80. Thus, the outside and the inside of the housing 80 are electrically connected. The second pattern 86 is provided on the side surface 81b of the feedthrough 81 connected to the upper surface 81a. The first pattern 85 and the second pattern 86 are connected.

[0029] The first pattern 85 and the second pattern 86 are electrode circuits of the optical semiconductor element 10. One of the anode and cathode of the optical semiconductor element 10 is electrically connected to the first pattern 85 on the upper side of the feedthrough 81 via the wire 84. The other of the anode and cathode of the optical semiconductor element 10 is electrically connected to the first pattern 85 on the lower side of the feedthrough 81 via the solder 60, the auxiliary fixture 20, and the wire 84. In this way, the first pattern 85 is electrically connected to the optical semiconductor element 10 on the inner surface of the housing 80.

[0030] On the outside of the housing 80, one end of the flexible substrate 90 is connected to the first pattern 85 of the upper section and the lower section of the feedthrough 81, respectively. The first pattern 85 and the flexible substrate 90 are joined by solder 70. The flexible substrate 90 is provided on the first pattern 85 and extends from the upper surface 81a to the side surface 81b. The other end of the flexible substrate 90 is electrically connected to an external electronic circuit not shown. Thus, the optical semiconductor element 10 is electrically connected to the external electronic circuit. The flexible substrate 90 electrically connects the optical semiconductor element 10 in the housing 80 to the external electronic circuit.

[0031] Each component is described in detail. The optical semiconductor element 10 converts an electrical signal into an optical signal, and also performs the reverse conversion. In the present embodiment, the optical semiconductor element 10 is an LD (Laser Diode), but the optical semiconductor element 10 may also be a PD (Photo Diode) or the like. In addition, in Embodiment 1, a laser generating unit is formed in the optical semiconductor element 10. However, it is not limited to this, and a plurality of laser generating units may be formed in the optical semiconductor element 10. In addition, in Embodiment 1, there is one optical semiconductor element 10. However, it is not limited to this, and there may be a plurality of optical semiconductor elements 10.

[0032] The auxiliary fixture 20 includes a ceramic substrate 21, an electrode pattern 22 formed on one of two surfaces in the thickness direction of the ceramic substrate 21, and an electrode pattern 23 formed on the other surface. The ceramic substrate 21 is an electrical insulator. The ceramic substrate 21 is preferably formed of a material with a high thermal conductivity in order to effectively cool the optical semiconductor element 10. As the ceramic substrate 21, for example, a ceramic plate such as AlN or Al2O3 with a thickness of 0.3 mm can be used.

[0033] In the first embodiment, only one optical semiconductor element 10 is bonded to the auxiliary fixture 20, but a plurality of optical semiconductor elements 10 may be bonded to one auxiliary fixture. Although the number of auxiliary fixtures 20 is one in the first embodiment, the number of auxiliary fixtures 20 is not limited to one.

[0034] The semiconductor element 10 is bonded to the electrode pattern 23 on the upper surface side of the auxiliary fixture 20 corresponding to the circuit surface side by solder 60. In addition, a bonding portion is formed on the electrode pattern 23 by Au wire or the like. Thus, the electrode pattern 23 is electrically connected to surrounding components or the surface of the optical semiconductor element 10.

[0035] Such an electrode pattern 23 is a wiring component for electrically connecting the optical semiconductor element 10 to an external circuit. Therefore, the electrode pattern 23 is preferably formed of a metal with a relatively low resistance. In addition, the electrode patterns 22 and 23 formed on both surfaces of the ceramic substrate 21 may also be formed of the same material. The electrode patterns 22 and 23 formed on both surfaces of the ceramic substrate 21 may use a metallized film such as Au with a thickness of about 3.0 μm or less, for example.

[0036] The electrode pattern 22 on the lower surface side of the auxiliary fixture 20 corresponding to the heat dissipation surface side is mechanically and thermally connected to the inner wall of the housing 80 via solder or the like.

[0037] After the optical semiconductor element 10 and the auxiliary fixture 20 are joined by the solder 60, the auxiliary fixture 20 and the housing 80 are joined. In addition, after the optical semiconductor element 10 and the auxiliary fixture 20 are joined by the solder 60, the flexible substrate 90 and the feedthrough 81 are joined. Therefore, the material of the solder 60 is preferably a metal having a higher melting point than the solder 70 and a larger thermal conductivity so that the solder 60 does not melt when the solder 70 is joined. The solder 60 can use an alloy mainly containing Au, Sn, or Ge, etc., and having a melting point of 250°C or more. In addition, from the viewpoint of heat dissipation, the thickness of the solder 60 is preferably 0.1 mm or less.

[0038] The solder 70 joins the first pattern 85 to the electrode circuit provided at one end of the flexible substrate 90. When the flexible substrate 90 is joined by the solder 70, the auxiliary fixture 20 to which the optical semiconductor element 10 is joined by the solder 60 is joined in the housing 80. Therefore, the material of the solder 70 is preferably a metal having a lower melting point than the solder 60 and a higher thermal conductivity so that the solder 60 does not melt again during the joining of the solder 70. Therefore, the solder 70 can use an alloy mainly containing Sn, Ag, Cu, etc., and having a melting point of 250°C or less.

[0039] The housing 80 has a flat bottom and a plurality of side portions connected to the outer edge of the bottom. The bottom of the housing 80 is mechanically and thermally connected to the auxiliary fixture 20 by solder or the like. An opening portion surrounded by a plurality of side portions is formed on the upper surface side of the housing 80. The housing 80 is, for example, a flat box.

[0040] A socket 82 is provided on one side of the housing 80 for guiding the laser light emitted from the optical semiconductor element 10 to an optical fiber (not shown). The light emitting portion of the package is sealed by a lens 83. A feedthrough 81 is provided on the side of the housing 80 opposite to the side on which the socket 82 is provided.

[0041] The feed-through 81 is an input / output port for inputting and outputting electrical signals to and from an external electronic circuit (not shown). The feed-through 81 is formed, for example, by stacking ceramics. The upper surface 81a of the feed-through 81 is parallel to the opening and bottom of the housing 80. In addition, the side surface 81b of the feed-through 81 is parallel to the side of the housing 80.

[0042] Figure 3 1 is a cross-sectional view showing the structure of a flexible substrate 90 according to Embodiment 1. The flexible substrate 90 is an electrical interface component. The flexible substrate 90 is in a strip shape. One end of the flexible substrate 90 is electrically connected to the first pattern 85 and the second pattern 86 via the solder 70, and the other end is electrically connected to a substrate of a transceiver (not shown).

[0043] The flexible substrate 90 has a base 91 as a substrate member. The base 91 is formed of, for example, polyimide and can be bent. In addition, the flexible substrate 90 has electrodes 92 and 93 on both surfaces of the base 91. The electrodes 92 and 93 are formed of a metal material with low resistance such as Au or Cu. The electrodes 92 and 93 are patterns formed by methods such as electroplating or printing.

[0044] The lower surface of the electrode 92 is covered by a cover film 94. In addition, the upper surface of the electrode 93 is covered by a cover film 95. The cover films 94 and 95 protect the electrodes 92 and 93. The cover films 94 and 95 are formed of a dielectric material such as polyimide, similarly to the base 91. The electrodes 92 and 93 have a covering portion covered by the cover films 94 and 95. In addition, the end portions of the electrodes 92 and 93 on the feedthrough 81 side are exposed from the cover films 94 and 95.

[0045] The electrode 92 has a first exposed portion 92a, a second exposed portion 92b and a covering portion 92c. The first exposed portion 92a is disposed directly above the upper surface 81a of the feed-through 81, exposed from the cover film 94, and joined to the first pattern 85 through the solder 70. The covering portion 92c is covered by the cover film 94. The second exposed portion 92b connects the first exposed portion 92a and the covering portion 92c, is exposed from the cover film 94, and is disposed on the outer side of the upper surface 81a when viewed from a direction perpendicular to the upper surface 81a of the feed-through 81. The solder 70 extends from between the first exposed portion 92a and the first pattern 85 to the second exposed portion 92b. In the present embodiment, the solder 70 extends to the end of the second exposed portion 92b adjacent to the covering portion 92c.

[0046] The solder 70 extends between the portion of the flexible substrate 90 extending from the upper surface 81a of the feedthrough 81 toward the side surface 81b and the second pattern 86. That is, the second pattern 86 and the electrode 92 are bonded by the solder 70. The solder 70 extends to the lower end of the second pattern 86.

[0047] Next, the effects of the optical module 100 will be described. Figure 4 2 is a cross-sectional view of an optical module 101 according to a comparative example. In the optical module 101 , the second pattern 86 is not provided. In addition, the solder 70 is provided between the electrode 92 and the first pattern 85 .

[0048] The cover films 94 and 95 are generally used to protect the electrodes 92 and 93 in order to suppress breakage and disconnection during deformation. However, there is a case where a portion of the electrode 92 that is not covered by the cover film 94 is formed adjacent to the end of the first pattern 85. This is caused by manufacturing errors of the cover films 94 and 95 or deviations in the positional accuracy of the first pattern 85 and the flexible substrate 90.

[0049] When the end of the flexible substrate 90 is connected to the substrate of the transceiver, the position of the optical module 101 is generally determined based on the socket 82. Therefore, the assembly tolerance of the optical module 101 and the transceiver is absorbed by the flexible substrate 90. In addition, the deformation corresponding to the difference in thermal expansion coefficient of the transceiver is also absorbed by the flexible substrate 90. Therefore, the flexible substrate 90 is easily bent.

[0050] Generally, when the flexible substrate 90 is bent, stress in the direction of peeling from the package is easily applied. That is, stress is easily applied in the direction perpendicular to the upper surface 81a of the feedthrough 81. At this time, the gap indicated by arrows A and B of the electrode 92 that is not protected by the cover film 94 and not bonded to the first pattern 85, that is, the second exposed portion 92b, becomes a bending point.

[0051] For example, it is considered that the flexible substrate 90 starts to deform from the end of the solder 70 that wets and spreads in the flexible substrate 90. In addition, it is considered that when the solder thickness is thin, the solder 70 that wets and spreads in the flexible substrate 90 is destroyed, causing the flexible substrate 90 to deform from the end of the first pattern 85. Therefore, stress is easily concentrated in the gaps indicated by arrows A and B, which may cause the flexible substrate 90 to break or disconnect.

[0052] In order to prevent this, it is considered that the solder 70 is allowed to wet and spread to the boundary of the coating film 94 of the electrode 92 as shown by the arrow B, and the solder thickness is increased so that the solder 70 wet and spread to the electrode 92 does not break during bending. Figure 4In the optical module 101 shown, the pattern for the solder 70 to wet and spread is provided only on the upper surface 81 a . Therefore, it is difficult to wet and spread the solder 70 thickly to the electrode 92 protruding from the first pattern 85 .

[0053] In contrast, in this embodiment, if Figure 3 As shown, in addition to the first pattern 85, the feedthrough 81 is provided with a second pattern 86 in a manner that extends the first pattern 85 toward the side surface 81b. Therefore, the solder 70 that wets and spreads in the first pattern 85 further wets and spreads in the second pattern 86. At this time, the portion of the solder 70 that wets and spreads in the second pattern 86 and the portion that wets and spreads in the second exposed portion 92b form a solder fillet having a substantially triangular cross-section. That is, a solder fillet having a substantially triangular cross-section is formed with the contact point between the feedthrough 81 and the flexible substrate 90, the end of the second exposed portion 92b adjacent to the covering portion 92c, and the lower end of the second pattern 86 as vertices.

[0054] Here, the second pattern 86 is formed substantially perpendicular to the electrode 92. Therefore, the solder 70 that wets and spreads in the second exposed portion 92b can be formed thicker by the length of the second pattern 86. That is, the solder 70 can be provided thicker in the perpendicular direction to the direction in which the flexible substrate 90 extends from the first pattern 85. Therefore, a thick solder 70 can be formed in the second exposed portion 92b.

[0055] Furthermore, even in the portion that becomes the bending point when the flexible substrate 90 is bent, it is considered that Figure 4 The stress is concentrated most at the contact point between the feedthrough 81 and the flexible substrate 90 as indicated by the arrow A. In the present embodiment, the solder 70 can be formed to be thickest at this portion.

[0056] According to the above, the concentration of stress can be suppressed with respect to the bending, stretching or rotation of the flexible substrate 90. Therefore, the separation or breakage of the solder 70 can be suppressed, and the strength of the solder joint can be improved. In addition, the portion where the stress is concentrated in the flexible substrate 90 is reinforced by the solder 70. Therefore, the strength of the flexible substrate 90 can be improved. Therefore, the reliability of the optical module 100 can be improved, and the life span can be extended.

[0057] In addition, as another method of suppressing the breakage of the solder 70, it is conceivable to reinforce the second exposed portion 92b using a resin, an adhesive, etc. However, in the case of reinforcement using a resin, after the feedthrough 81 and the flexible substrate 90 are joined by the solder 70, it is necessary to separately perform a process of applying the resin to the second exposed portion 92b and a process of curing the applied resin. Therefore, it may take a long time to assemble the optical module.

[0058] In contrast, in the present embodiment, in the process of joining the flexible substrate 90 and the feedthrough 81 by the solder 70, which is generally performed in the assembly process of the optical module, a thicker solder 70 can be formed on the second exposed portion 92b. Therefore, the same effect as the case of reinforcement by resin can be obtained in a shorter time than the case of reinforcement by resin. In addition, compared with the case of not reinforcing the flexible substrate 90, the time required for the assembly process can be suppressed from being prolonged. Therefore, a low-cost optical module 100 can be obtained.

[0059] In the present embodiment, the flexible substrate 90 is provided on the side of the package opposite to the light emitting side of the optical semiconductor element 10. However, the present invention is not limited thereto, and when the optical semiconductor element 10 is a PD, the flexible substrate 90 may be provided on the side of the package opposite to the side on which light is incident to the optical semiconductor element 10.

[0060] In the present embodiment, the first pattern 85 and the second pattern 86 form one continuous pattern, but the present invention is not limited thereto, and the first pattern 85 and the second pattern 86 may be separated as long as the solder 70 can spread from the first pattern 85 to the second pattern 86 .

[0061] In addition, in this embodiment, although the optical module 100 is described as an example, this embodiment can also be applied to the connection between a semiconductor device for power or for handling normal current and the flexible substrate 90 .

[0062] Figure 5 1 is a perspective view of an optical module 200 according to a modified example of Embodiment 1. A plurality of first patterns 85 are provided on a feedthrough 81. In addition, a flexible substrate 90 includes a plurality of electrodes 92. The plurality of first patterns 85 are respectively bonded to the plurality of electrodes 92. The plurality of first patterns 85 and the plurality of electrodes 92 are arranged in a direction along a side surface 81 b of the feedthrough 81.

[0063] Here, in the optical module 100, the second pattern 86 is formed for all the first patterns 85. That is, substantially triangular fillets are formed for all the electrodes 92 formed on the flexible substrate 90 for reinforcement.

[0064] On the other hand, the second pattern 86 may not be formed for all the first patterns 85. The second pattern 86 may be formed in the number required to suppress the concentration of stress. Figure 5 As shown, the second pattern 86 only needs to be provided at a position corresponding to the first pattern 85 at both ends among the plurality of first patterns 85. Thus, the solder 70 is formed thicker at both ends of the flexible substrate 90.

[0065] The above-mentioned modifications can be applied to the optical modules according to the following embodiments. In addition, since the optical modules according to the following embodiments have many common points with the first embodiment, the description will be mainly focused on the differences from the first embodiment.

[0066] Implementation method 2.

[0067] Figure 6 It is a perspective view of an optical module 300 according to the second embodiment. Figure 7 FIG. 1 is a top view of a flexible substrate 390 according to Embodiment 2. In Embodiment 1, the portions of the plurality of electrodes 92 exposed from the cover film 94 are all of the same length. In contrast, in this embodiment, Figure 7 As shown, the lengths of the portions of the plurality of electrodes 392 exposed from the cover film 394 differ depending on the position.

[0068] The plurality of electrodes 392 include electrodes 392-1, 392-2, and 392-3. The second exposed portion 92b of the electrode 392-1 at both ends and the center is longer than that of the other electrodes 392-2 and 392-3. In addition, the further away from the electrode 392-1, the shorter the second exposed portion 92b. The second exposed portion 92b of the electrode 392-3 disposed in the center of the two electrodes 392-1 is the shortest. The second exposed portion 92b of the electrode 392-2 between the electrode 392-1 and the electrode 392-3 is shorter than that of the electrode 392-1 and longer than that of the electrode 392-3.

[0069] At this time, if Figure 6 As shown, the plurality of solders 70 are arranged in a direction along the side surface 81b of the feedthrough 81. In addition, the longer the second exposed portion 92b is, the larger the solder fillet 70 can be. Therefore, the solders 70 at both ends and the center of the plurality of solders 70 that are bonded to the first pattern 85 are formed to extend further from the upper surface 81a of the feedthrough 81 than the other solders 70.

[0070] In this embodiment, the position of the boundary of the cover film 394 is different for each of the plurality of electrodes 392. Thus, the position where the stress is concentrated after the deformation of the flexible substrate 390 can be dispersed. Therefore, it is possible to prevent the flexible substrate 390 from being greatly bent at one point as a whole, and to prevent the electrode 392 from being disconnected.

[0071] Furthermore, the portions of the electrodes 392 at both ends of the flexible substrate 390 that are joined by the solder 70 can be made longer. Here, at both ends of the flexible substrate 390, the deformation amount in bending, stretching, and especially rotation is the largest. In this embodiment, the solder fillets are formed larger in the electrodes 392 at the portions where the deformation amount of the flexible substrate 390 is large, and the solder joints can be strengthened. Therefore, the disconnection of the flexible substrate 390 can be suppressed, and the life of the optical module 300 can be extended.

[0072] In addition, in this embodiment, if Figure 6 As shown in FIG. 1 , the second pattern 86 is provided at positions corresponding to the electrodes 392 - 1 and 392 - 3 among the plurality of electrodes 392 . However, the present invention is not limited thereto, and the second pattern 86 may be provided at positions corresponding to all the electrodes 392 .

[0073] In this embodiment, the length of the second exposed portion 92b of the plurality of electrodes 392 is changed to adjust the size of the solder fillet 70. However, the present invention is not limited thereto, and the length of the second pattern 86 may be adjusted to adjust the size of the solder fillet 70.

[0074] In addition, in the present embodiment, the second exposed portion 92b is formed longer in the electrodes 392-1 at both ends and the center. However, the present invention is not limited thereto, and the lengths of the second exposed portions 92b of the plurality of electrodes 392 may be different. Thus, the portions of the plurality of solders 70 extending between the flexible substrate 390 and the second pattern 86 are formed to have different lengths from the upper surface 81a. Therefore, the effect of dispersing the stress when the flexible substrate 390 is deformed can be achieved.

[0075] Implementation method 3.

[0076] Figure 8 It is a perspective view of an optical module 400 according to the third embodiment. Fig. 9 1 is a plan view of a flexible substrate 490 according to Embodiment 3. In Embodiment 1, all electrodes 92 of a flexible substrate 90 have the same width. In contrast, in this embodiment, the width of an electrode 492 varies depending on the position.

[0077] The plurality of electrodes 492 include electrodes 492 - 1 and 492 - 2 . The electrodes 492 - 1 at both ends and the center of the plurality of electrodes 492 are wider in the direction along the side surface 81 b of the feedthrough 81 than the other electrodes 492 - 2 .

[0078] As the width of the electrode 492-1 increases, the width of the fillet formed by the solder 70 also increases. That is, the solder 70 at both ends and the center of the plurality of solders 70 bonded to the first pattern 85 is formed to be wider than the other solders 70 in the direction along the side surface 81b.

[0079] Therefore, the fillets of the electrode 492-1 formed at both ends of the flexible substrate 490 where the deformation amount is large can be reinforced. Therefore, the breakage of the flexible substrate 490 can be suppressed, and the life of the optical module 400 can be extended.

[0080] In the present embodiment, the width of the plurality of electrodes 492 is changed to adjust the width of the fillet of the solder 70 . However, the present invention is not limited thereto, and the width of the fillet of the solder 70 may be adjusted by adjusting the width of the second pattern 86 .

[0081] In addition, the plurality of electrodes 492 may have different widths in the direction along the side 81b of the feedthrough 81 according to the deformation of the flexible substrate 490. Thus, the portions of the plurality of solders 70 extending between the flexible substrate 490 and the second pattern 86 are formed to have different widths in the direction along the side 81b. Therefore, the solder fillet can be reinforced according to the deformation of the flexible substrate 490.

[0082] In addition, the structure of this embodiment can be used in combination with the structure of the second embodiment to further enhance the effect thereof.

[0083] Implementation method 4.

[0084] Fig.10 It is a cross-sectional view of an optical module 500 according to the fourth embodiment. Fig.11 1 is a plan view of a flexible substrate 590 according to Embodiment 4. Through holes 596 are formed in the first exposed portion 92 a and the second exposed portion 92 b of the flexible substrate 590 . The solder 70 is provided in the through holes 596 .

[0085] The flexible substrate 590 includes a base 591, electrodes 592 and 593 provided on both surfaces of the base 591, and cover films 94 and 95 covering the electrodes 592 and 593. The through holes 596 penetrate the base 591 and the electrodes 592 and 593. A plurality of through holes 596 are formed to the vicinity of the end portion of the second exposed portion 92b adjacent to the cover film 94.

[0086] like Fig.11 As shown in FIG. 1 , a plurality of through holes 596 are provided in all electrodes 592. The plurality of through holes 596 are formed at equal intervals from the end of the electrode 592 on the side to be soldered to the first pattern 85 to the vicinity of the boundary of the cover film 94. Solder 70 is provided in the through hole 596, so that the electrode 592 and the electrode 593 are electrically connected and have the same potential. The end of the electrode 593 on the side of the feedthrough 81 is exposed from the cover film 95.

[0087] When the flexible substrate 590 is soldered to the feedthrough 81, the solder 70 supplied to the first pattern 85 and melted first infiltrates and spreads toward the second exposed portion 92b of the electrode 592 of the flexible substrate 590. Thereafter, the solder 70 infiltrates and spreads toward the through-hole 596. Thus, the through-hole 596 is filled with the solder 70. Furthermore, the remaining solder 70 infiltrates and spreads from the through-hole 596 toward the electrode 593. When the solder 70 infiltrates and spreads to other adjacent through-holes 596, the adjacent through-holes 596 are also filled with the solder 70 due to the surface tension of the solder 70.

[0088] Similarly, the solder 70 is filled into the through hole formed near the boundary of the cover film 94. Thus, the solder 70 wets and spreads over the entire portion of the electrodes 592 and 593 that is not protected by the cover films 94 and 95. A solder fillet is formed by the portion and the portion where the solder 70 wets and spreads over the second pattern 86. Thus, the solder 70 can form a solder fillet more effectively.

[0089] On this basis, compared with the first embodiment, the heat capacity of the electrodes 592 and 593 is reduced by the amount corresponding to the through hole 596. Therefore, the temperature of the electrodes 592 and 593 is easily increased by heating. Therefore, the solder 70 can be easily wetted and spread to the entire surface of the portion of the electrodes 592 and 593 exposed from the cover films 94 and 95.

[0090] Furthermore, the solder 701 also infiltrates and spreads to the electrode 593 through the through hole 596. Thus, both surfaces of the flexible substrate 590 are protected by the solder 70. Therefore, the solder 70 is less likely to be damaged by bending, stretching, and rotating the flexible substrate 590. Therefore, disconnection of the electrodes 592 and 593 can be further suppressed, and the life of the optical module 500 can be further extended.

[0091] In addition, in the present embodiment, the through hole 596 is circular, and three of the through holes are provided for one electrode 592. The three through holes 596 are formed at both ends and the center of the portion of the electrode 592 that is not protected by the cover film 94. The shape, position, and number of the through holes 596 are not limited thereto, as long as the solder infiltrates and extends to the entire surface of the portion of the electrode 592, 593 that protrudes from the feedthrough 81 and is not protected by the cover films 94, 95. In addition, the through holes 596 are provided in a manner that does not disconnect the electrodes 592, 593.

[0092] For example, the through hole 596 may be formed in one of the first exposed portion 92a and the second exposed portion 92b of the flexible substrate 590. In this case, it is preferred that the through hole 596 is formed in the second exposed portion 92b. In addition, the through hole 596 may be formed in a longitudinal shape in a direction perpendicular to the side surface 81b of the feedthrough 81. For example, an elliptical through hole 596 having a width of 0.15 mm and a length of 0.25 mm may be provided on each electrode 598 at a position 0.25 mm from the end of the feedthrough 81 toward the outside of the feedthrough 81. At this time, the width of the electrode 592 is set to 0.3 mm, and the length of the second exposed portion 92b is set to 0.5 mm.

[0093] Fig.12 : is a top view of a flexible substrate 690 according to a modification of Embodiment 4. A plurality of through holes 696 are formed in an electrode 692 of the flexible substrate 690. A through hole 696a closest to the covering portion 92c among the plurality of through holes 696 is longer than the other through holes 696b in a direction perpendicular to the side surface 81b of the feedthrough 81.

[0094] The through hole 696a is a long hole that is long in the direction in which the electrode 692 extends. Therefore, when the molten solder 70 infiltrates and spreads to the end of the through hole 696a on the side of the feedthrough 81, the solder 70 infiltrates and spreads to the covering portion 92c while filling the through hole 696a due to the capillary phenomenon caused by the surface tension of the solder 70. Therefore, the solder 70 can be more easily infiltrated and spread to the entire surface of the second exposed portion 92b.

[0095] In addition, the structure of the fourth embodiment can be used in combination with the second or third embodiment to further enhance the effect thereof.

[0096] Furthermore, the technical features described in each embodiment may be used in combination as appropriate.

[0097] Description of Reference Numerals

[0098] 10...optical semiconductor element; 20...auxiliary fixing member; 30...metal block; 40...thermoelectric module; 60, 70...solder; 80...housing; 81...feedthrough; 82...socket; 83...lens; 84...wire; 85...first pattern; 86...second pattern; 90, 390, 490, 590, 690...flexible substrate; 91, 591...base; 92, 93, 392, 392-1, 392-2, 392-3, 492, 492-1, 492-2, 592, 593, 692...electrode; 94, 95...cover film; 596, 696, 696a, 696b...through hole; 100, 200, 300, 400, 500...optical module.

Claims

1. An optical module, characterized in that: have: Optical semiconductor components; a package that houses the optical semiconductor element; a first pattern disposed on the upper surface of the package; a second pattern disposed on a side surface of the package connected to the upper surface; a flexible substrate, which is disposed on the first pattern and extends from the upper surface of the package to the side surface; as well as solder that joins the first pattern and the flexible substrate together, The solder extends between a portion of the flexible substrate extending from the upper surface of the package toward the side surface and the second pattern, The flexible substrate includes electrodes and a cover film covering the electrodes. The electrode has: a first exposed portion, which is disposed just above the upper surface of the package, exposed from the cover film, and bonded to the first pattern through the solder; a covering portion, which is covered by the covering film; a second exposed portion connecting the first exposed portion and the covering portion, exposed from the cover film, and disposed outside the upper surface when viewed from a direction perpendicular to the upper surface of the package, The solder further spreads toward the second exposed portion.

2. The optical module according to claim 1, characterized in that: The first pattern is connected to the second pattern.

3. The optical module according to claim 1 or 2, characterized in that: The solder extends to a lower end of the second pattern.

4. The optical module according to claim 1, characterized in that: The solder extends to an end portion of the second exposed portion adjacent to the covering portion.

5. The optical module according to claim 1 or 4, characterized in that: The flexible substrate includes a plurality of electrodes. The plurality of electrodes are arranged in a direction along the side surface of the package, and the second exposed portions have different lengths.

6. The optical module according to claim 1 or 4, characterized in that: The flexible substrate includes a plurality of electrodes. The plurality of electrodes are arranged in a direction along the side surface of the package, and have different widths in the direction along the side surface.

7. The optical module according to claim 1 or 4, characterized in that: A through hole is formed in the first exposed portion or the second exposed portion, The solder is disposed in the through hole.

8. The optical module according to claim 7, characterized in that: The through hole is formed in the second exposed portion.

9. The optical module according to claim 7, characterized in that: The through hole is formed in a vertically elongated shape in a direction perpendicular to the side surface of the package.

10. The optical module according to claim 9, characterized in that: A plurality of through holes are formed, A through hole closest to the covering portion among the plurality of through holes is longer than the other through holes in a direction perpendicular to the side surface of the package.

11. The optical module according to claim 1 or 2, characterized in that: The flexible substrate is provided on a side of the package opposite to a light emitting side of the optical semiconductor element, or on a side of the package opposite to a light incident side on which light is incident on the optical semiconductor element.

12. An optical module, characterized in that: have: Optical semiconductor components; a package that houses the optical semiconductor element; a plurality of first patterns, which are arranged on the upper surface of the package; a second pattern disposed on a side surface of the package connected to the upper surface; A flexible substrate, which is disposed on the plurality of first patterns and extends from the upper surface of the package to the side surface; as well as a plurality of solders that bond the plurality of first patterns to the flexible substrate, The plurality of solders extend between a portion of the flexible substrate extending from the upper surface of the package toward the side surface and the second pattern, The plurality of first patterns and the plurality of solders are arranged in a direction along the side surface of the package, Portions of the plurality of solders extending between the flexible substrate and the second pattern have different lengths from the upper surface.

13. An optical module, characterized in that: have: Optical semiconductor components; a package that houses the optical semiconductor element; a plurality of first patterns, which are arranged on the upper surface of the package; a second pattern disposed on a side surface of the package connected to the upper surface; A flexible substrate, which is disposed on the plurality of first patterns and extends from the upper surface of the package to the side surface; as well as a plurality of solders that bond the plurality of first patterns to the flexible substrate, The plurality of solders extend between a portion of the flexible substrate extending from the upper surface of the package toward the side surface and the second pattern, The plurality of first patterns and the plurality of solders are arranged in a direction along the side surface of the package, Portions of the plurality of solders extending between the flexible substrate and the second pattern have different widths in a direction along the side surface.

14. An optical module, characterized in that: have: Optical semiconductor components; a package that houses the optical semiconductor element; a plurality of first patterns, which are arranged on the upper surface of the package; a second pattern disposed on a side surface of the package connected to the upper surface; A flexible substrate, which is disposed on the plurality of first patterns and extends from the upper surface of the package to the side surface; as well as solder that joins the plurality of first patterns and the flexible substrate together, The solder extends between a portion of the flexible substrate extending from the upper surface of the package toward the side surface and the second pattern, The plurality of first patterns are arranged in a direction along the side surface of the package, The second pattern is disposed at a position corresponding to the first patterns at both ends of the plurality of first patterns.

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