JP5982457B2 - Manufacturing method of optical module - Google Patents

Description

  The present invention relates to a method for manufacturing an optical module, and is suitable for manufacturing a highly reliable optical module.

  As one of the optical modules, an optical module in which light emitted from a laser diode is emitted via an optical fiber is known. In this optical module, an optical fiber is led out from the inside of the casing, and optical components such as a laser diode, a mirror, a lens, and an optical fiber are arranged in the casing. The light emitted from each laser diode is collected and then incident on the optical fiber, and is emitted from the optical fiber outside the housing.

  As such an optical module, there is an optical module in which an optical component is arranged on a submount and then the submount is arranged on a bottom plate of a housing. In such an optical module, a submount in which optical components are arranged is arranged in a casing, and the bottom surface of the submount is fixed on the bottom plate of the casing by soldering.

  Patent Document 1 listed below describes such an optical module. In the optical module described in Patent Document 1, spacers interposed between the submount and the bottom plate are arranged at the four corners of the submount, and the submount is joined to the bottom plate by the solder spread between the bottom plate. Yes.

JP2013-4752A

  In general, the submount is made of a material having a relatively small linear expansion coefficient, such as aluminum nitride, so that the relative position between optical components does not change even when the temperature rises during use. On the other hand, the casing is generally made of a material having a relatively large linear expansion coefficient such as copper because of ease of handling and cost. For this reason, after fixing the submount to the bottom plate of the housing by soldering, when the temperature of the submount and the bottom plate decreases, the bottom plate deforms so that the vicinity of the center of the submount on the bottom plate rises to the submount side due to the bimetal effect. Tend. Therefore, the bottom plate tends to be separated from the submount on the outer peripheral side of the solder connecting the submount and the bottom plate. For this reason, the solder connecting the submount and the bottom plate is subjected to a stronger tensile stress on the outer peripheral portion than in the vicinity of the center of the submount. When tensile stress is applied on the outer peripheral side of the solder in this way, there is a possibility that the solder may crack, and there is a concern that the reliability of the optical module may be reduced.

  Then, an object of this invention is to provide the manufacturing method of the optical module which can manufacture a reliable optical module.

  In order to solve the above problems, the optical module manufacturing method of the present invention is such that the bottom surface serving as the bottom plate of the housing has a flat base plate on the heater having a convex heating surface so that the bottom surface follows the heating surface. A plate fixing step for fixing, a submount soldering step for soldering a submount having a smaller linear expansion coefficient than the base plate onto the base plate, and fixing the base plate on which the submount is soldered to the heater. And a plate releasing step for releasing.

  The base plate is warped by fixing the base plate having a flat bottom surface along the convex heating surface. When the base plate and the submount are soldered in this state, the distance between the base plate and the submount near the outer periphery of the solder becomes larger than the distance between the base plate and the submount near the center of the solder. Thereafter, when the base plate is released from the heater, the base plate tries to return to the original flat plate state from the warped state, and the base plate moves toward the submount near the outer periphery of the solder, and compressive stress is applied to the solder. On the other hand, when the temperature of the base plate is lowered after the soldering is completed, the base plate tends to move away from the submount near the outer periphery of the solder due to the bimetal effect, and a tensile stress is applied to the solder. As described above, since the force that the base plate tries to return to and the force due to the bimetal effect work in opposite directions, the tensile stress in the outer peripheral portion of the solder is relieved. Therefore, according to the method for manufacturing an optical module of the present invention, it is possible to reduce the risk of cracks in the solder and to manufacture a highly reliable optical module.

  In the submount soldering step, it is preferable that the submount is pressed toward the base plate.

  By pressing the submount as described above, the thickness near the center of the solder can be reduced, and soldering between the base plate and the submount can be performed more appropriately.

  The submount is preferably vibrated in the submount soldering step.

  Examples of the failure mode of the optical module include an interface peeling mode that fails between the base plate or submount and the solder, and a cohesive failure mode that fails inside the solder. By performing scrubbing that vibrates the submount, bubbles inside the molten solder can be discharged to the outside, and the cohesive failure mode can be prevented. In particular, when the submount is vibrated while pressing the submount toward the base plate, it is preferable because the oxide film of the solder can be broken, and the interface breakdown mode can be prevented.

  Moreover, it is preferable that a compressive stress is applied to the outer peripheral side of the solder connecting the submount and the base plate after the plate releasing step.

  When the bottom plate of the optical module is fixed to the heat sink in order to use the optical module, the bottom plate tends to be deformed in the same direction as the deformation due to the bimetal effect due to the stress caused by the fixing. When such deformation occurs, tensile stress is applied to the outer peripheral side of the solder connecting the bottom plate and the submount. Therefore, if compressive stress is applied to the outer peripheral side of the solder after the plate releasing step as described above, the tensile stress applied to the outer peripheral side of the solder deforming the bottom plate is relieved. Therefore, an optical module with higher reliability can be obtained.

  As described above, according to the present invention, an optical module manufacturing method capable of manufacturing a highly reliable optical module is provided.

It is a figure which shows the optical module which concerns on embodiment of this invention. It is a figure which shows the optical module shown in FIG. 1 from another viewpoint. It is the figure which removed the cover body of the optical module shown in FIG. It is sectional drawing which shows a mode that the submount was fixed to the baseplate. It is a figure which sees the lid shown in Drawing 1 from the back. It is a flowchart which shows the process of the manufacturing method of an optical module. It is a figure which shows the mode of a component fixing process. It is a figure which shows the mode of a plate fixing process. It is a figure which shows the mode after a plate fixing process. It is a figure which shows the mode after a submount soldering process. It is a figure which shows the mode of a cover body fixing process.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an optical module manufacturing method according to the invention will be described in detail with reference to the drawings.

<Optical module>
First, the optical module of this embodiment will be described.

  FIG. 1 is a diagram illustrating the optical module according to the present embodiment, and FIG. 2 is a diagram illustrating the optical module illustrated in FIG. 1 from another viewpoint.

  As shown in FIGS. 1 and 2, the optical module 1 of the present embodiment includes a housing composed of a base plate 2 and a lid 3, optical components to be described later including an optical fiber 50 fixed in the housing, and a part thereof. And a connector 41 for supplying power to the optical components.

  FIG. 3 is a view in which the cover of the optical module shown in FIG. 1 is removed. In FIG. 3, the state of light is indicated by broken lines. The base plate 2 is a plate having a flat bottom surface serving as a bottom plate of the housing. In the present embodiment, the base plate 2 is a flat plate member as shown in FIG. The base plate 2 is made of metal, and examples of the metal constituting the base plate 2 include copper and stainless steel. A plurality of screw holes 27 are formed in the outer peripheral portion of the base plate 2.

  A submount 4 is fixed on the base plate 2. In the submount 4, the entire bottom surface on the base plate 2 side is fixed to the base plate 2 with solder. The submount 4 is a flat substrate and is made of a material having a smaller linear expansion coefficient than that of the base plate 2. For example, when the base plate 2 is made of copper, the submount 4 is made of aluminum nitride. The reason why the submount 4 is made of a material having a small linear expansion coefficient is that an optical component is disposed on the submount 4, so that the submount 4 expands due to heat generated by the optical component during use, and thus the optical module. This is to prevent the change in the optical characteristics of No. 1.

  An optical component including the optical fiber 50 is fixed on the submount 4. The optical component of the present embodiment includes a laser diode 11, a collimating lens 16, a mirror 13, a first condenser lens 14, a second condenser lens 15, and an optical fiber 50.

  The plurality of laser diodes 11 serving as light sources are elements having a Fabry-Perot structure formed by stacking a plurality of semiconductor layers, and emit laser light having a wavelength of, for example, 900 nm. Each laser diode 11 is fixed on the laser mount 12 with solder or the like, and is fixed on the submount 4 via the laser mount 12. The laser mount 12 is a table for adjusting the height of the laser diode 11, and each laser mount 12 is fixed to a predetermined position on the submount 4 by, for example, soldering. In this way, the laser mount 12 may be separated from the submount 4 and the laser mount 12 may be fixed on the submount 4. Alternatively, the laser mount 12 may be molded integrally with the submount 4. . Alternatively, the laser mount 12 may be omitted when the height adjustment of the laser diode 11 is unnecessary.

  The collimating lens 16 is disposed on the laser mount 12 corresponding to each laser diode 11. The collimating lens 16 is a lens that collimates the light emitted from the laser diode 11 in the fast axis direction and the light in the slow axis direction. In general, the collimating lens 16 collimates the light in the fast axis direction and the light in the slow axis direction. It consists of a combination of collimating lenses. The collimating lens 16 is fixed on the laser mount 12 together with the laser diode 11 by adhesion or the like. When the laser mount 12 is omitted as described above, the collimating lens 16 is fixed on the submount 4 together with the laser diode 11.

  The mirror 13 is disposed on the submount 4 corresponding to each laser diode 11. Each mirror 13 reflects the light emitted from the corresponding laser diode 11 and collimated by the collimating lens 16 so as to be emitted vertically along the surface direction of the submount 4 with respect to the light incident on the mirror 13. It has been adjusted. The mirror 13 of this embodiment is composed of a prism and is fixed on the submount 4 with an adhesive. In addition, the mirror 13 may be comprised other than a prism like the glass body in which the reflecting film was formed.

  The first condenser lens 14 and the second condenser lens 15 are each composed of a cylindrical lens, and are fixed to the submount 4 by adhesion. The first condenser lens 14 condenses the light reflected by the respective mirrors 13 in the fast axis direction, and the second condenser lens 15 collects the light emitted from the first condenser lens 14 in the slow axis direction. Shine. Thus, the light emitted from the second condenser lens 15 collects the light at a predetermined position. If the light emitted from the second condenser lens 15 is not condensed at a desired position, a condenser lens that collects the light emitted from the second condenser lens 15 is further disposed on the submount 4. May be.

  The optical fiber 50 is inserted into a pipe-shaped holder 51 and fixed to the holder 51. In the present embodiment, one end serving as the light incident end of the optical fiber 50 is slightly led out from the holder 51. The holder 51 is fixed to the fiber mount 52, and the fiber mount 52 is fixed to the submount 4. One end of the optical fiber 50 is at a position where light emitted from the second condenser lens 15 can enter the core. In this embodiment, the optical fiber 50 is fixed to the holder 51 by an adhesive or soldering, the holder 51 is fixed by being bonded to the fiber mount 52, and the fiber mount 52 is bonded to the submount 4 by bonding. It is fixed.

  The connector 41 is formed of a pair of rod-shaped conductors, and each conductor is fixed to a pair of connector holders 42. Each connector holder 42 is bonded and fixed to the submount 4. One conductor of the connector 41 is connected to the laser diode 11 closest to the connector 41 by a gold wire (not shown), and each laser diode 11 is daisy chain connected by a gold wire (not shown). The laser diode 11 farthest from the connector 41 is connected to the other conductor of the connector 41 by a gold wire (not shown).

  FIG. 4 is a cross-sectional view showing a state in which the submount 4 on which optical components and connectors are arranged is fixed to the base plate 2. 4 is a cross-sectional view of FIG. 3 along the optical path of light emitted from a specific laser diode 11 for easy understanding. As described above, the entire bottom surface of the submount 4 on the side of the base plate 2 is fixed to the base plate 2 with the solder 7. In this state, the base plate 2 is slightly warped so that the vicinity of the center of the submount 4 rises toward the submount 4 side. Therefore, the distance between the base plate 2 and the submount 4 in the vicinity of the outer periphery of the submount 4 is set larger than the distance between the base plate 2 and the submount 4 in the vicinity of the center of the submount 4. Is gradually increased from the center of the submount 4 to the outer periphery of the submount 4. For this reason, the thickness of the solder 7 near the outer periphery of the submount 4 is made larger than the thickness of the solder 7 near the center of the submount 4. In this embodiment, near the outer periphery of the submount 4, that is, near the outer periphery of the solder, the force received from the submount 4 and the base plate 2 with respect to the solder is compressed in a direction perpendicular to the surface direction of the submount and the base plate 2. Stress is applied.

  FIG. 5 is a view of the lid shown in FIG. 1 as seen from the back side. As shown in FIG. 5, the lid 3 according to the present embodiment is formed by pressing a metal plate, and includes a top plate 31, a frame 32, and a flange 33.

  The top plate 31 is a part that becomes a top plate of the casing, and is made of a flat plate-like member. The frame body 32 is a part that is vertically connected to the top plate 31 at the periphery of the top plate 31. The frame body 32 is sized to enclose the submount 4 and the optical components on the submount 4 in a state where the lid body 3 is disposed on the base plate 2 as shown in FIGS. Further, the frame 32 is formed with a notch 35a for leading the optical fiber 50 from the housing to the outside of the housing, and a notch 35b for guiding the connector 41 from the housing to the outside of the housing. The flange portion 33 is a portion connected to the frame body 32 on the side opposite to the top plate 31 side of the frame body 32, and is outside the frame body 32 perpendicular to the frame body 32 (parallel to the top plate 31). It extends to spread. Moreover, the position adjacent to each notch 35a, 35b of the frame 32 in the collar part 33 is each notched. In addition, a plurality of screw holes 37 are formed in the flange portion 33, and the positions where these screw holes 37 are formed are arranged on the base plate 2 with the lid 3 as shown in FIGS. In this state, the position overlaps with the screw hole 27 formed in the base plate 2.

  As shown in FIGS. 1 and 2, the base plate 2 and the lid body 3 are arranged on the base plate 2, as shown in FIGS. 1 and 2, and the screw holes 27 of the base plate 2 and the lid body 3. It is fixed by a plurality of screws 25 screwed into the screw holes 37. Although not particularly illustrated, in this embodiment, a silicon resin is interposed between the base plate 2 and the flange portion 33 of the lid 3 so that the airtightness between the base plate 2 and the flange portion 33 is maintained.

  Further, with the lid 3 placed on the base plate 2 that is the bottom plate of the housing in this way, the holder 51 is led out from the notch 35a together with the optical fiber 50 as shown in FIG. In the cutout 35 a, a bush 55 is disposed between the holder 51 and the frame body 32 to fill a gap between the holder 51 and the frame body 32. Thus, the gap between the frame 32 and the optical fiber in the notch 35 a is sealed by the bush 55. The bush 55 is configured such that at least a portion in contact with the frame body 32 can be elastically deformed. As a configuration of such a bush 55, for example, a part in contact with the frame body 32, a part in contact with the base plate 2, and a part in contact with the holder 51 are made of an adhesive resin whose main component is a modified silicone resin. It is mentioned that the part surrounded by the resin is made of a hard resin such as polyetheretherketone resin (PEEK). The entire bush 55 may be made of an elastically deformable resin.

  In addition, with the lid 3 placed on the base plate 2, the connector 41 is led out from the notch 35b as shown in FIG. A bush 45 is disposed between the connector 41 and the frame 32, and a gap between the frame 32 and the connector 41 in the notch 35 b is sealed by the bush 45. The bush 45 is made of an elastically deformable resin at least at a portion in contact with the frame body 32, for example, made of the same resin as the bush 55.

  When such an optical module 1 is used, in order to prevent the sub-mout 4 from being deformed by heat generated from the laser diode 11 to change the optical characteristics of the optical module 1, the optical module 1 is provided with a sheet sink. Attached to. When the optical module 1 is attached to the heat sink in this way, the base plate 2 that is the bottom plate of the optical module 1 may be slightly deformed so that the vicinity of the center rises inside the housing. In this case, since the submount 4 tends to maintain a flat plate shape, the base plate 2 and the submount 4 tend to be separated on the outer peripheral side of the submount 4. For this reason, tensile stress is applied to the outer peripheral side of the solder 7 connecting the base plate 2 and the submount 4. However, in the optical module 1 according to the present embodiment, the compressive stress is applied to the outer peripheral side of the solder 7 connecting the submount 4 and the base plate 2 as described above, so that the compressive stress and the tensile stress are offset. The stress in the direction perpendicular to the submount 4 on the solder is reduced. Therefore, the optical module of this embodiment is suppressed from cracking the solder 7 and has high reliability.

  Next, the optical operation of the optical module 1 will be described.

  When desired power is supplied from the connector 41 to each laser diode 11, each laser diode 11 emits light toward each collimating lens 16 corresponding to each laser diode 11 as shown in FIG. 2. Exit. This light is, for example, laser light having a wavelength of 900 nm as described above. Each collimating lens 16 collimates and emits the light emitted from the laser diode 11. The light emitted from each collimator lens 16 enters the corresponding mirror 13. Each mirror 13 reflects incident light and emits the light incident on the mirror 13 in a direction perpendicular to the surface direction of the base plate 2. The light emitted from the mirror 13 enters the first condenser lens 14, and the first condenser lens 14 collects the light in the fast axis direction. The light emitted from the first condenser lens 14 enters the second condenser lens 15, and is condensed in the slow axis direction of the light by the second condenser lens 15. The light collected by the second condenser lens 15 enters the core of the optical fiber 50 and propagates through the optical fiber 50. Thus, light is emitted from the other end of the optical fiber 50.

  Thus, when the optical module 1 operates, a part of the input electric power is emitted as light energy, while the other part becomes thermal energy. Most of this thermal energy is generated from the laser diode 11, and most of the heat generated in the laser diode 11 is transmitted to the base plate 2 via the submount 4 to increase the temperature of the base plate 2. Then, it is cooled by a heat sink installed on the lower surface of the base plate 2.

<Optical module manufacturing method>
Next, the manufacturing method of the optical module of this embodiment is demonstrated.

  FIG. 5 is a flowchart showing the steps of the method for manufacturing the optical module 1 of the present embodiment. As shown in FIG. 5, the optical module manufacturing method of the present embodiment includes a component fixing step P1, a plate fixing step P2, a submount soldering step P3, a plate releasing step P4, and a lid fixing step P5. Is provided.

(Part fixing process P1)
In the component fixing step P <b> 1, the optical component including the laser diode 11 and the incident end of the optical fiber 50 are placed on the submount 4 so that the light emitted from the laser diode 11 disposed on the submount 4 enters the optical fiber 50. It is the process of fixing to. FIG. 7 is a diagram showing the state of this process.

  The laser diode 11 is fixed on the submount 4 via the laser mount 12 as described above. Therefore, before the laser diode 11 is placed on the submount 4, the laser diode 11 is placed on the laser mount 12 and fixed. Fixing is performed by soldering, for example. The collimator lens 16 is fixed on the submount 4 via the laser mount 12 in the same manner as the laser diode 11. Accordingly, the collimating lens 16 is fixed on the laser mount 12 so that the light from the laser diode 11 enters the collimating lens 16. The main fixing is performed by adhesion, for example. After the laser diode 11 and the collimating lens 16 are fixed in this way, the laser mount 12 on which the laser diode 11 and the collimating lens 16 are mounted is disposed on the submount 4 and fixed. The main fixing is performed by soldering, for example.

  The connector 41 is disposed on the submount 4 via the connector holder 42 as described above. Therefore, before the connector 41 is disposed on the submount 4, each rod-like conductor is inserted into the connector holder 42, and the conductor is fixed to the connector holder. This fixing is performed by adhesion, for example. Then, each connector holder 42 to which the conductor is fixed is arranged on the submount 4 and fixed. This fixing is performed by adhesion, for example. Next, one conductor of the connector 41 and the laser diode 11 closest to the connector 41 are connected by a gold wire, and further, each laser diode 11 is daisy chain connected by a gold wire, and further away from the connector 41. The laser diode 11 and the other conductor of the connector 41 are connected by a gold wire. Thus, the connector 41 and each laser diode 11 are electrically connected, and power can be supplied to each laser diode 11 via the connector 41.

  As described above, the optical fiber 50 is disposed on the submount 4 via the fiber mount 52 while being fixed to the holder 51. Therefore, the optical fiber 50 is inserted into the holder 51 and fixed before the optical fiber 50 is disposed on the submount 4. At this time, as shown in FIG. 6, a bush 55 is inserted into the optical fiber 50 in advance. Furthermore, when the optical fiber 50 is covered with a coating layer, the coating layer is peeled off by a predetermined distance from one end that is the incident end of the optical fiber 50. Then, the optical fiber 50 is inserted into the holder 51, and the optical fiber 50 is fixed to the holder. At this time, in the present embodiment, the incident end of the optical fiber 50 is slightly led out from the holder 51. The optical fiber 50 may be fixed to the holder 51 by soldering or a resin such as a thermosetting resin. Next, the holder 51 is fixed to the fiber mount 52. This fixing is performed by adhesion, for example. The holder 51 and the fiber mount 52 may be integrally formed. Then, the fiber mount 52 to which the optical fiber 50 is fixed is arranged on the submount 4 and fixed. This fixing is performed by adhesion, for example.

  The first condenser lens 14 and the second condenser lens 15 are directly arranged and fixed on the submount 4 as described above. This fixing is performed by adhesion, for example. Specifically, an adhesive is applied to each position where the first condenser lens 14 and the second condenser lens 15 are arranged on the submount 4, and the first adhesive lens 14 and the second condenser lens 15 are applied on the submount 4 to which the adhesive is applied. The 1 condensing lens 14 and the 2nd condensing lens 15 are arrange | positioned, and it fixes by solidifying an adhesive agent.

  Each mirror 13 is directly arranged and fixed on the submount 4 as described above. This fixing is performed by adhesion, for example. Specifically, an adhesive is applied to each position where the mirror 13 on the submount 4 is disposed, and the mirror 13 is disposed on the submount 4 to which the adhesive is applied, and the adhesive is solidified. To fix.

  Before all the optical components and the optical fiber 50 are fixed on the submount 4, the light emitted from the laser diode 11 and incident on the mirror 13 via the collimator lens 16 is incident on the core of the optical fiber 50. The position of any optical component or optical fiber 50 on the submount 4 needs to be finely adjusted. The position of the mirror 13 is finely adjusted. Specifically, the optical component other than the mirror 13 and the connector 41 are fixed on the submount 4 and power is supplied from the connector 41 so that light can be emitted from the laser diode 11. Further, the optical fiber 50 is fixed on the submount 4. Thereafter, the mirror 13 is disposed on the submount 4 to which the adhesive is applied, power is applied from the connector 41 to the laser diode 11, and light is emitted from each laser diode 11. The position of each mirror 13 is finely adjusted so that the light emitted from the laser diode 11 enters the core of the optical fiber 50. For example, the position of the mirror 13 is finely adjusted so that the energy of light emitted from the other end of the optical fiber 50 is maximized. Thus, the position of the mirror 13 is determined. Then, after the position of the mirror 13 is determined, the adhesive on which the mirror 13 is disposed is solidified and the mirror 13 is fixed.

  In this way, as shown in FIG. 2, the optical component including each optical fiber and the connector 41 are fixed on the submount 4.

(Plate fixing process P2)
The plate fixing process P2 is a process of fixing the base plate 2 on the heater. FIG. 8 is a view showing the state of this step, and FIG. 9 is a view showing the state after this step.

  As shown in FIG. 8, the heating surface 8s, which is the upper surface of the heater 8, has a convex shape. The base plate 2 is disposed on the heater 8 so that the center of the region where the submount 4 is disposed is located at the top of the convex heating surface 8s. Since the bottom surface of the base plate 2 is flat as described above, the vicinity of the outer periphery of the base plate 2 is separated from the heating surface 8s of the heater 8, and the vicinity of the center of the base plate 2 is in contact with the heating surface 8s of the heater 8.

  Next, the base plate 2 is fixed to the heater 8. For example, as shown in FIG. 9, the fixing is performed by screwing the screw 81 into the screw hole 27 of the base plate 2 and screwing it to the heater 8. In this case, a screw hole is formed in the heater 8 at a position corresponding to the screw hole 27. Then, the screws 81 are tightened until the base plate 2 is deformed so that the bottom surface of the base plate 2 is along the heating surface 8 s of the heater 8. Thus, as shown in FIG. 9, the base plate 2 is fixed to the heater 8 so that the bottom surface of the base plate 2 is along the heating surface 8s.

(Submount soldering process P3)
The submount soldering process P3 is a process of soldering the submount 4 on which the optical component is mounted on the base plate 2. FIG. 10 is a diagram showing a state after this process. If the optical component is mounted on the submount 4 by this step, the component fixing step P1 and the plate fixing step P2 may be performed in reverse order.

  In this step, a solder paste is applied to a region of the base plate 2 where the submount 4 is disposed. The solder paste may be applied before the plate fixing process P2.

  Next, the submount 4 on which the optical component is mounted is disposed on the solder paste applied to the base plate 2. At this time, it is preferable to arrange the submount 4 so that the center of the submount 4 is located on the uppermost part of the base plate 2.

  Thereafter, the heater 8 is heated to a temperature at which the solder paste melts to melt the solder paste. At this time, it is preferable to press the submount 4 to the base plate 2 side. This pressing may be performed by, for example, fixing the submount 4 to the suction collet and applying a load to the submount 4 so as to press the suction collet against the base plate 2 side. By pressing the submount 4 in this manner, the thickness near the center of the solder 7 can be reduced, and the base plate 2 and the submount 4 can be soldered more appropriately. At this time, it is preferable to vibrate the submount 4. This vibration may be performed by vibrating the collet. Note that only one of pressing and vibration of the submount 4 may be performed. Examples of the failure mode of the optical module 1 include an interface peeling mode that fails between the base plate 2 or the submount 4 and the solder 7 and a cohesive failure mode that fails inside the solder 7. By scrubbing the submount 4 while the solder 7 is melted, bubbles inside the melted solder 7 can be discharged to the outside, and the cohesive failure mode can be prevented. Further, when the submount 4 is vibrated while the submount 4 is pressed toward the base plate 2 as described above, the oxide film of the solder 7 can be broken, so that the interface breakdown mode can be prevented. This is preferable because it is possible.

  Thereafter, the temperature of the heater 8 is lowered to a temperature at which the solder is solidified to solidify the solder. Thus, the submount 4 is fixed on the base plate 2 by the solder 7 as shown in FIG.

(Plate release process P4)
The plate release process P4 is a process of releasing the fixing of the base plate 2 to the heater 8.

  As described above, in this embodiment, the base plate 2 is screwed to the heater 8. Therefore, the base plate 2 is released from the heater 8 by removing the screw 81. Thus, as shown in FIGS. 3 and 4, the submount 4 on which the optical components and the like are mounted is fixed on the base plate 2 by the solder 7.

  In the state where the base plate 2 is fixed to the heater 8, the base plate 2 is deformed along the heating surface 8 s of the heater 8 as described above. For this reason, when the base plate 2 is released from the heater 8, the base plate 2 tends to return to the original state due to the elastic force of the base plate 2. A compressive stress is applied to the vicinity of the outer periphery of the solder 7 from the base plate 2 and the submount 4 due to the force of returning to the base plate 2. Further, in the vicinity of the center portion of the solder 7, the base plate 2 and the submount 4 are about to be separated from each other, so that a tensile stress is applied to the solder 7.

  On the other hand, when the solder 7 is solidified and the temperature of the base plate 2 further decreases, a bimetallic effect is generated due to the difference between the linear expansion coefficient of the base plate 2 and the linear expansion coefficient of the submount 4. Due to this bimetal effect, the base plate 2 tends to be deformed so that the vicinity of the center of the soldered region of the base plate 2 rises to the submount side. On the other hand, the submount 4 does not attempt to be deformed compared to the base plate 2. A tensile stress is applied to the vicinity of the outer peripheral portion of the solder 7 due to the force that the base plate is deformed by the bimetal effect. Also, compressive stress is applied to the solder 7 near the center of the solder 7.

  For this reason, the stress applied to the solder 7 due to the elastic force of the base plate 2 and the stress applied to the solder 7 due to the deformation of the base plate 2 due to the bimetal effect cancel each other, and the stress is reduced in the solder 7. In this embodiment, after the base plate 2 is released from the heater 8 and the base plate 2 is cooled, a compressive stress is applied to the vicinity of the outer peripheral portion of the solder 7. That is, the stress applied to the solder 7 due to the elastic force of the base plate 2 is greater than the stress applied to the solder 7 due to the bimetal effect.

(Cover fixing process P5)
The lid fixing step is a step of fixing the lid 3 including the frame 32 and the top plate 31 on the base plate 2. FIG. 11 is a diagram showing the state of this process.

  In this step, first, the lid 3 is disposed on the base plate 2 on which the submount 4 on which the optical component and the connector 41 are mounted is fixed by the solder 7. At this time, the optical fiber 50 is led out of the frame 32 together with the holder 51 from the notch 35a so that the frame 32 surrounds the submount 4, and the connector 41 is led out of the frame 32 from the notch 35b. . Further, the base plate 2 and the lid 3 are aligned so that the respective screw holes 27 of the base plate 2 and the respective screw holes 37 of the flange portion 33 penetrate. In addition, when a silicon resin is interposed between the base plate 2 and the flange portion 33 of the lid 3 as described above, the silicon resin is previously attached to the surface of the flange portion 33 on the base plate 2 side. Thus, the lid 3 is arranged on the base plate 2.

  Next, the screw 25 is screwed into each of the screw hole 27 of the base plate 2 and the screw hole 37 of the flange portion 33 that penetrate each other, and the lid 3 is fixed on the base plate 2. Further, the bush 55 previously inserted into the optical fiber 50 as described above is fitted into the notch 35a and fixed. Further, each conductor of the connector 41 is inserted into the hole of the bush 45, and the bush 45 is fitted into the notch 35b and fixed. The bush 55 and the bush 45 are fixed by, for example, adhesion.

  In this way, the optical module shown in FIGS. 1 and 2 is obtained.

  As described above, in the method for manufacturing the optical module 1 of the present embodiment, the base plate 2 and the submount 4 are fixed in a state where the base plate 2 having a flat bottom surface is fixed to the heater 8 along the convex heating surface 8s. Then, the base plate 2 is released. For this reason, the base plate applies a compressive stress to the solder in the vicinity of the outer periphery of the solder in an attempt to return from the warped state to the original state by elastic force. On the other hand, when the temperature of the base plate 2 decreases due to the completion of soldering, a tensile stress is applied to the solder near the outer periphery of the solder due to the bimetal effect. For this reason, in the outer peripheral part of the solder 7, the tensile stress by said bimetal effect is relieve | moderated by the compressive stress by the elastic force of said base plate. For this reason, according to the manufacturing method of the optical module 1 of this embodiment, the fear that a crack will enter into the solder 7 is reduced, and a highly reliable optical module can be manufactured.

  Moreover, in the manufacturing method of the optical module 1 of this embodiment, the compressive stress is applied to the outer peripheral side of the solder 7 connecting the submount 4 and the base plate 2 after the plate releasing step P4. For this reason, even when the base plate 2 is deformed in the same manner as the deformation due to the bimetal effect when fixing the bottom plate of the optical module 1 to a heat sink (not shown) in order to use the optical module 1, Such tensile stress is relieved. Therefore, the optical module 1 can further increase the reliability.

  As mentioned above, although the said embodiment was demonstrated to the example about this invention, this invention is not limited to these.

  For example, after the plate releasing step P4, the solder 7 may be in a state where no stress is applied, or a tensile stress due to the bimetal effect may remain on the outer peripheral side of the solder 7. However, as described above, it is preferable that compressive stress is applied to the outer peripheral side of the solder 7 after the plate releasing step P4.

  Moreover, in the said embodiment, it was set as the structure which has the base plate 2 used as the baseplate of a housing | casing in flat form, and arrange | positions the cover body 3 which has the frame 32 on the base plate 2. FIG. However, the present invention is not limited to such a configuration, and for example, the frame body 32 may be joined to the base plate 2 in advance. In this case, the base plate 2 is fixed on the heater 8 in the same manner as in the above embodiment. Thereafter, the submount 4 is placed on the base plate 2 coated with the solder paste so as to be accommodated in the frame 32, and the optical fiber 50 and the connector 41 are led out from the holes provided in the frame 32 in advance. Thereafter, as in the above embodiment, the submount 4 is fixed to the base plate 2 with the solder 7, and the base plate 2 is released from the heater 8. Thereafter, the top plate 31 serving as the top plate of the housing is fixed to the frame body 32. The optical module can be manufactured by such a process, but from the viewpoint of facilitating fixing of the base plate 2 on the heater 8 along the heating surface 8s, the base plate 2 attaches the frame body 32 as in the above embodiment. It is preferable that it is a separate body and is flat.

  Moreover, the collar part 33 does not have an essential structure. When there is no flange 33, the frame body 32 is directly fixed on the base plate 2. In this case, it may be fixed by soldering, or a screw hole may be formed in the frame 32 and fixed to the base plate 2 by screwing. Thus, when it does not have the collar part 33, the optical module 1 can be reduced in size. However, by having the flange portion 33, the frame body 32 can be fixed on the base plate 2 stably and easily.

  In the above embodiment, the solder 7 is gradually thickened from the center of the submount 4 to the outer periphery of the submount 4. However, the present invention is not limited to this. For example, in the optical module 1 manufactured using the above-described optical module manufacturing method, the force of returning to the base plate 2 results in the overall thickness of the solder 7. May be uniform.

  As described above, according to the present invention, an optical module manufacturing method capable of manufacturing a highly reliable optical module is provided, and can be used, for example, in the field of fiber laser devices and the like.

DESCRIPTION OF SYMBOLS 1 ... Optical module 2 ... Base plate 3 ... Cover body 4 ... Submount 8 ... Heater 8s ... Heating surface 11 ... Laser diode 12 ... Laser mount 13 ... Mirror 14 ... first condenser lens 15 ... second condenser lens 31 ... top plate 32 ... frame 33 ... collar 41 ... connector 42 ... connector holder 45 ··· Bush 50 ··· Optical fiber 51 ··· Holder 52 ··· Fiber mount 55 ··· Bush P1 · · · Part fixing step P2 · · Plate fixing step P3 · · · Submount soldering step P4 · · ..Plate release process P5 ... Lid fixing process

Claims (4)

A plate fixing step of fixing a base plate having a flat bottom surface serving as a bottom plate of the housing on a heater having a convex heating surface so that the bottom surface follows the heating surface;
A submount soldering step of soldering a submount having a smaller linear expansion coefficient than the base plate onto the base plate;
A plate releasing step for releasing the fixing of the base plate to which the submount is soldered to the heater;
An optical module manufacturing method comprising: The method of manufacturing an optical module according to claim 1, wherein the submount is pressed toward the base plate in the submount soldering step. 3. The method of manufacturing an optical module according to claim 1, wherein the submount is vibrated in the submount soldering step. 4. The optical module according to claim 1, wherein a compressive stress is applied to an outer peripheral side of the solder connecting the submount and the base plate after the plate releasing step. 5. Method.

Images