JP2016004130A - Optical transmission module and method for manufacturing optical transmission module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical transmission module with a high efficiency of combining an optical element and an optical fiber.SOLUTION: An optical transmission module 1 includes an optical element 10, a wiring board 20 equipped with the optical element 10, an optical fiber 60 transmitting an optical signal, and a holding member 50 holding the optical fiber 60. Further, the holding member 50 has a fixing part 40 and a holding part 30 with a side surface 30SA bonded to the wiring board 20 with a first adhesive layer 29 interposed therebetween, holds the optical fiber 60 between the fixing part 40 and the holding part 30, and a counter surface where the optical fiber 60 is not held between the fixing part 40 and the holding part 30 is bonded with a second adhesive layer 39 interposed therebetween.

Description

  The present invention provides an optical transmission module comprising: an optical element that generates an optical signal; a wiring board on which the optical element is mounted; an optical fiber that transmits the optical signal; and a holding member that holds the optical fiber. And an endoscope having the light transmission module.

The electronic endoscope has an image sensor such as a CCD at the distal end of the elongated insertion portion. In recent years, use of an imaging device having a high pixel number for an endoscope has been studied. When an image sensor with a large number of pixels is used, the amount of signal transmitted from the image sensor to the signal processing device (processor) increases. Therefore, instead of electric signal transmission via metal wiring using electric signals, optical signals are used. Optical signal transmission through a thin optical fiber is preferred. For optical signal transmission, an optical transmission module that converts an electrical signal into an optical signal is used.
For example, Japanese Patent Laid-Open No. 2013-025092 discloses an optical element that inputs or outputs an optical signal, a substrate on which the optical element is mounted, and an optical fiber insertion that transmits an optical signal that is input and output from the optical element. An optical transmission module having a through hole and a holding portion (ferrule) arranged side by side in the thickness direction of the optical element is disclosed.

  In the above conventional optical transmission module, the diameter of the through hole of the holding portion is considerably larger than the outer diameter of the optical fiber, and due to this tolerance, the optical fiber is kinked in the through hole, and the light emitting portion of the optical element and the end face of the optical fiber are There was a risk that the optical axis would shift between the two. The deviation of the optical axis reduces the optical coupling efficiency between the optical element and the optical fiber and causes the transmission quality of the optical transmission module to deteriorate.

JP 2013-025092 A

  An object of an embodiment of the present invention is to provide an optical transmission module having high optical coupling efficiency between an optical element and an optical fiber, and a method for manufacturing the optical transmission module.

  An optical transmission module according to an embodiment of the present invention includes: an optical element having a light emitting unit that outputs an optical signal; a connection terminal electrically connected to the light emitting unit on a light emitting surface; A wiring board mounted on a surface and having a hole at a position facing the light emitting portion, an optical fiber for transmitting the optical signal, and a second main surface of the wiring board, and bonded to the tip of the optical fiber A holding member holding the surface so as to face the light emitting part, and a side surface of the holding part of the holding member having a fixing part and a holding part has the wiring board and the second adhesive layer. The holding member holds the optical fiber between the fixing portion and the holding portion, and the opposing surface where the fixing portion and the holding portion do not hold the optical fiber. It adhere | attaches through the 1st contact bonding layer.

  In another embodiment of the method for manufacturing an optical transmission module, an optical element having a light emitting portion for outputting an optical signal and a connection terminal electrically connected to the light emitting portion on a light emitting surface is provided on the first main surface. A wiring board that is mounted and has a hole at a position facing the light emitting part is adhered to the side surface of the holding part having the first groove part and the first through hole communicating with the first groove part by an adhesive. A step of inserting an optical fiber into the third through hole of the holding jig having a step, a third groove portion, and a third through hole communicating with the third groove portion; The optical fiber is sandwiched between the groove portion of the holding jig and the third groove portion of the holding jig, and the outer surface of the fixing portion on the entrance side of the second groove portion is bonded to the optical fiber with an adhesive. And the tip of the optical fiber protruding from the third through hole of the holding jig A step of cutting the holding jig, the step of removing the holding jig from the fixed part to which the optical fiber is bonded, and the holding part bonded to the wiring board instead of the holding jig. The step of inserting the optical fiber bonded to the fixing portion into the first through hole, and the opposing surface where the fixing portion and the holding portion do not sandwich the optical fiber are interposed via an adhesive layer And a step of bonding.

  According to the embodiments of the present invention, it is possible to provide an optical transmission module having high optical coupling efficiency between an optical element and an optical fiber, and a method for manufacturing the optical transmission module.

It is an exploded view of the optical transmission module of 1st Embodiment. It is a perspective view of the optical transmission module of a 1st embodiment. It is a fragmentary sectional view in alignment with the III-III line of FIG. 2 of the optical transmission module of 1st Embodiment. It is an exploded view of the optical transmission module of 2nd Embodiment. It is an exploded view of the optical transmission module of 3rd Embodiment. It is an exploded view of the optical transmission module of 4th Embodiment. It is a perspective view of the optical transmission module of a 5th embodiment. It is sectional drawing of the optical transmission module of 5th Embodiment. It is a flowchart of the manufacturing method of the optical transmission module of 5th Embodiment. It is a side view for demonstrating the manufacturing method of the optical transmission module of 5th Embodiment. It is a side view for demonstrating the manufacturing method of the optical transmission module of 5th Embodiment. It is a side view for demonstrating the manufacturing method of the optical transmission module of 5th Embodiment. It is a side view for demonstrating the manufacturing method of the optical transmission module of 5th Embodiment. It is a side view for demonstrating the manufacturing method of the optical transmission module of 5th Embodiment.

<First Embodiment>
The optical transmission module 1 according to the first embodiment will be described with reference to FIGS. 1 to 3. The optical transmission module 1 is an E / O module that converts an electrical signal into an optical signal and transmits the optical signal. In the following description, the drawings based on each embodiment are schematic, and the relationship between the thickness and width of each part, the thickness ratio of each part, and the like are different from the actual ones. It should be noted that the drawings may include portions having different dimensional relationships and ratios between the drawings.

<Configuration of optical transmission module 1>
The optical transmission module 1 includes an optical element 10, a wiring board 20, a holding member 50, and an optical fiber 60. In the optical transmission module 1, the optical element 10, the wiring board 20, and the holding member 50 are arranged side by side in the thickness direction of the optical element 10.

  The optical element 10 is a surface emitting laser having a light emitting unit 11 that outputs light of an optical signal. For example, the ultra-small optical element 10 having a dimension in plan view of 250 μm × 300 μm transmits a light emitting unit 11 having a diameter of 20 μm and a connection terminal 12 for supplying a drive signal electrically connected to the light emitting unit 11. It is provided on the exit surface 10SA.

  The flat wiring board 20 having the first main surface 20SA and the second main surface 20SB has a hole 25H serving as an optical path. The optical element 10 is flip-chip mounted on the first main surface 20SA in a state where the light emitting portion 11 is disposed at a position facing the hole 25H of the wiring board 20. The wiring board 20 has electrode pads (not shown) joined to the connection terminals 12 of the optical element 10. As the base of the wiring board 20, an FPC board, a ceramic board, a glass epoxy board, a glass board, a silicon board, or the like is used.

  On the other hand, for example, the optical fiber 60 having a diameter of 125 μm includes a core 61 having a diameter of 50 μm for transmitting light and a clad 62 covering the outer periphery of the core 61. The optical fiber 60 may be covered with an outer skin made of resin.

  The holding member 50 is bonded to the second main surface 20SB of the wiring board 20 by a first adhesive layer 29 made of, for example, a thermosetting adhesive, and the tip surface of the optical fiber 60 faces the light emitting unit 11. To hold.

  In the optical transmission module 1, the holding member 50 includes a fixing portion 40 and a holding portion 30 that are bonded by a second adhesive layer 39 made of, for example, a thermosetting adhesive. The material of the fixing part 40 and the holding part 30 is a metal member such as ceramic, Si, glass or SUS. The material of the fixing part 40 and the material of the holding part 30 may be different. Further, the first adhesive layer 29 and the second adhesive layer 39 may be made of the same material or different.

  The optical fiber 60 sandwiches the optical fiber 60 between the fixing portion 40 and the holding portion 30.

  The holding part 30 has a first groove part 30T and a through hole 30H communicating with the first groove part 30T. The optical fiber 60 is inserted through the through hole 30 </ b> H of the holding unit 30. The inner diameter of the cylindrical through hole 40H is larger than the outer diameter of the optical fiber 60 to be inserted. For example, the inner diameter of the through hole 40H is made larger by 1 μm to 10 μm than the outer diameter of the optical fiber 60.

  The through hole 40H may have a prismatic shape as long as the optical fiber 60 can be held by the wall surface in addition to the cylindrical shape. Further, the cross-sectional shape of the first groove portion 30T is a substantially semicircular shape having the same diameter as the through-hole 30H, but may be a rectangle, and the first groove portion 30T may be a V-groove.

  The fixed portion 40 includes a second groove portion 40T having a substantially semicircular cross-sectional shape that is substantially the same diameter as the through hole 30H. The cross-sectional shape of the second groove portion 40T may be a rectangle, and the second groove portion 40T may be a V-groove. Moreover, the cross-sectional shape of the first groove 30T and the cross-sectional shape of the second groove 40T may be different.

  The holding member 50 holds the optical fiber 60 between the first groove portion 30T and the second groove portion 40T. The opposing surfaces of the fixing unit 40 and the holding unit 30 are bonded via a second adhesive layer 39. However, the second adhesive layer 39 is not disposed in the first groove 30T and the second groove 40T sandwiching the optical fiber 60. For this reason, the optical fiber 60 is in contact with at least the bottom surface of the first groove 30T and the bottom surface of the second groove 40T without any other member such as an adhesive.

  The optical axis O of the optical fiber 60 is defined based on the bottom surface of the first groove 30T and the bottom surface of the second groove 40T, not the wall surface of the through hole 30H. Since the optical transmission module 1 regulates the position of the optical fiber 60 and prevents the optical axis shift between the optical element 10 and the optical fiber 60 regardless of the inner diameter of the through hole 30H, the optical transmission module 1 performs optical transmission with high optical coupling efficiency. Do.

<Method for Manufacturing Optical Transmission Module 1>
Next, a method for manufacturing the optical transmission module 1 will be briefly described.

  First, the optical element 10 is flip-chip mounted in a state where the light emitting unit 11 is disposed at a position facing the hole 25H of the wiring board 20.

  For example, an Au bump that is the connection terminal 12 of the optical element 10 is ultrasonically bonded to the electrode pad 21 of the wiring board 20. In addition, sealing agents, such as an underfill material and a side fill material, may be inject | poured into a junction part. The optical element 10 may be mounted on the wiring board 20 by printing solder paste or the like on the wiring board 20 and placing the optical element 10 at a predetermined position and then melting the solder by reflow or the like.

  Side surface 30SA of holding portion 30 is bonded to second main surface 20SB of wiring board 20 via first adhesive layer 29. The optical fiber 60 is inserted into the through hole 30 </ b> H of the holding unit 30. Since the inner diameter of the through hole 30H is larger than the outer diameter of the optical fiber 60, at this stage, the optical axis of the optical fiber 60 can move up and down and right and left.

  Then, the fixing unit 40 is bonded to the holding unit 30 via the second adhesive layer 39. At this time, the optical fiber 60 is fixed in a state where it is pressed by the first groove 30T and the second groove 40T, that is, in a sandwiched state.

  The optical transmission module 1 can be easily manufactured by the above manufacturing method.

Second Embodiment
Next, the optical transmission module 1A of the second embodiment will be described. Since the optical transmission module 1A is similar to the optical transmission module 1, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 4, in the holding member 50A of the optical transmission module 1A, the holding portion 30A has the first groove portion 30AT, and the fixing portion 40A has the second groove portion 40AT. The holding member 50A sandwiches the optical fiber 60 between the first groove portion 30AT and the second groove portion 40AT.

Side surface 30SA of holding portion 30A is bonded to second main surface 20SB of wiring board 20 via first adhesive layer 29A. Further, the holding surface 30A and the fixing portion 40A are bonded to each other by the second adhesive layer 39A at the opposing surface that does not sandwich the optical fiber 60.

  Although the holding portion 30A of the holding member 50A has no through hole, the optical transmission module 1A has the same effect as the optical transmission module 1.

<Third Embodiment>
Next, the optical transmission module 1B of the third embodiment will be described. Since the optical transmission module 1B is similar to the optical transmission module 1 and the like, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 5, in the holding member 50B of the optical transmission module 1B, the holding portion 30B has a first groove portion 30BT and through holes 30BH1 and 30BH2 communicating with the first groove portion 30BT.

  The first groove portion 30BT can be regarded as a concave portion reaching the through hole of the holding portion 30B. In the optical transmission module 1B illustrated in FIG. 5, the through holes 30BH1 and 30BH2 are provided on both sides of the first groove 30BT. However, the through holes may be provided only on one side. In this case, the first groove 30BT can be regarded as a notch that reaches the through hole of the holding portion 30B.

  On the other hand, the fixed portion 40B has a convex portion 45 inserted into the first groove portion 30BT of the holding portion 30B. That is, the width and length of the convex portion 45 are slightly shorter than the width and length of the first groove portion 30BT.

  The side surface 30SA of the holding unit 30B is bonded to the second main surface 20SB of the wiring board 20 via the first adhesive layer 29B. In addition, the holding surface 30B and the fixing portion 40B are bonded to each other by the second adhesive layer 39B at the opposing surface where the optical fiber 60 is not sandwiched.

  The through holes 30BH1 and 30BH2 have substantially the same configuration as the through hole 30H, and the first groove 30BT has substantially the same configuration as the first groove 30T. Further, the cross-sectional shape of the front end surface of the convex portion 45 of the fixed portion 40 </ b> B is substantially semicircle corresponding to the outer surface shape of the optical fiber 60. However, the tip surface of the convex portion 45 of the fixed portion 40B may be a flat surface or the like.

  The side surface 30SA of the holding unit 30B is bonded to the second main surface 20SB of the wiring board 20 via the first adhesive layer 29B. In addition, the holding surface 30B and the fixing portion 40B are bonded to each other by the second adhesive layer 39B at the opposing surface where the optical fiber 60 is not sandwiched.

  That is, the holding member 50B sandwiches the optical fiber 60 between the bottom surface of the first groove portion 30BT of the holding portion 30B and the tip surface of the convex portion 45 of the fixing portion 40B without interposing other members.

  In the optical transmission module 1B, the position of the optical axis O of the optical fiber 60 is defined by the first groove portion 30BT of the holding portion 30B and the 45 convex portion of the fixing portion 40B.

  For this reason, the light transmission module 1 </ b> B has the same effect as the light transmission module 1.

<Fourth embodiment>
Next, an optical transmission module 1C according to the fourth embodiment will be described. Since the optical transmission module 1C is similar to the optical transmission module 1B and the like, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 6, in the holding member 50C of the optical transmission module 1C, the holding portion 30C has the first groove portion 30CT, and the fixed portion 40A has the convex portion 45D. The holding member 50A sandwiches the optical fiber 60 between the bottom surface of the first groove 30CT and the tip surface of the convex portion 45D.

  Side surface 30SA of holding portion 30C is bonded to second main surface 20SB of wiring board 20 via first adhesive layer 29C. Further, the holding surface 30C and the fixing portion 40C are bonded to each other by the second adhesive layer 39C at the opposing surface that does not sandwich the optical fiber 60.

  Although the holding portion 30C of the holding member 50C has no through hole, the optical transmission module 1C has the same effect as the optical transmission module 1B.

<Fifth Embodiment>
Next, an optical transmission module 1D of the fifth embodiment will be described. Since the optical transmission module 1D is similar to the optical transmission module 1 and the like, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 7 and FIG. 8, in the optical transmission module 1D, the optical fiber 60 is fixed to the fixing portion 40D by the adhesive 69 on the outer surface on the inlet side of the second groove portion 40DT of the fixing portion 40D.

  The configuration of the light transmission module 1D is substantially the same as that of the light transmission module 1. For example, the optical fiber 60 is inserted into the through hole 30DT of the holding unit 30D. The side surface 30SA of the holding unit 30D is bonded to the second main surface 20SB of the wiring board 20 via the first adhesive layer 29D. In addition, the holding surface 30D and the fixing portion 40D are bonded to each other with the second adhesive layer 39D at the opposing surface that does not sandwich the optical fiber 60.

  Here, in the optical transmission module, the distance L between the front end surface of the optical fiber 60 and the light emitting surface 10SA of the optical element 10 is managed extremely accurately in order to improve the optical coupling efficiency between the optical element 10 and the optical fiber 60. It is preferable. The light transmission module 1D has the effect of the light transmission module 1, and the distance L is very accurately arranged by a manufacturing method described later.

<Manufacturing method>
A method for manufacturing the optical transmission module 1D will be described with reference to the flowchart of FIG.

<Step S11>
First, a holding jig 70 having a third groove portion 70T and a third through hole 70H communicating with the third groove portion 70T is prepared. Then, the optical fiber 60 is inserted into the third through hole 70 </ b> H of the holding jig 70.

<Step S12>
As shown in FIG. 10A, the optical fiber 60 is sandwiched and fixed by the second groove portion 40DT of the fixing portion 40D and the third groove portion 70T of the holding jig 70. The holding jig 70 is substantially the same as the holding unit 30 and the like already described, but the side surface of the fixing unit 40D and the side surface of the holding jig 70 are different from each other by a length L.

<Step S13>
As shown in FIG. 10B, the outer surface on the entrance side of the second groove portion 40DT of the fixing portion 40D and the optical fiber 60 are bonded by an adhesive (second adhesive layer 39). That is, the optical fiber 60 is fixed to the fixing portion 40D.

<Step S14>
As shown in FIG. 10C, the tip end portion of the optical fiber 60 protruding from the third through hole 70H of the holding jig 70 is cut.

<Step S15>
As shown in FIG. 10D, the holding jig 70 is removed from the fixing portion 40D to which the optical fiber 60 is bonded.

<Step S16>
Separately, a member including the optical element 10, the wiring board 20, and the holding portion 30D shown in FIG. 10E is manufactured. The optical element 10 includes a light emitting unit 11 that outputs an optical signal and a connection terminal 12 that is electrically connected to the light emitting unit 11 on the light emitting surface 10SA. The holding part 30D includes a first groove part 30DT and a first through hole 30DH communicating with the first groove part 30DT.

  That is, the optical element 10 is mounted on the first main surface 20SA, and the wiring board 20 having a hole at a position facing the light emitting unit 11 is bonded to the side surface of the holding unit 30D via the first adhesive layer 29D. .

<Step S17>
Instead of the holding jig 70,
The optical fiber 60 fixed to the fixing portion 40D is inserted into the first through hole 30DH of the holding portion 30D. The distance between the front end surface of the optical fiber 60 and the light emitting surface 10SA of the optical element 10 is the amount L of difference in length between the side surface of the fixing portion 40D and the side surface of the holding jig 70.

As shown in FIG. 10E, the fixing portion 40D and the holding portion 30D are bonded to each other on the opposite surface not sandwiching the optical fiber 60 via the second adhesive layer 39D, and the optical transmission module 1D shown in FIG. Manufactured.

  In the method for manufacturing the optical transmission module 1D, the distance L between the front end surface of the optical fiber 60 and the light emitting surface 10SA of the optical element 10 is a desired distance depending on the length between the side surface of the fixing portion 40D and the side surface of the holding jig 70. L can be managed with high accuracy.

  In the above description, an optical transmission module that is an E / O module that converts an electrical signal into an optical signal and transmits the optical signal has been described. However, it is obvious that an O / E module that converts an optical signal into an electrical signal has the same effect by adopting a configuration similar to that of the optical transmission module of the embodiment or the like.

  The present invention is not limited to the above-described embodiments and modifications, and various modifications, combinations, and applications are possible without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1, 1A-1D ... Optical transmission module 10 ... Optical element 20 ... Wiring board 29 ... Adhesive layer 30 ... Holding part 39 ... Adhesive layer 40 ... Fixing part 50 ... -Holding member 60 ... Optical fiber 70 ... Holding jig

Claims (7)

An optical element having a light emitting surface for outputting an optical signal and a connection terminal electrically connected to the light emitting unit on a light emitting surface;
The optical element is mounted on the first main surface, and a wiring board having a hole at a position facing the light emitting unit,
An optical fiber for transmitting the optical signal;
A holding member that is bonded to the second main surface of the wiring board with an adhesive and holds the front end surface of the optical fiber so as to face the light emitting portion;
A side surface of the holding portion of the holding member having a fixing portion and a holding portion is bonded to the wiring board via a first adhesive layer,
The holding member holds the optical fiber between the fixing portion and the holding portion, and an opposing surface where the fixing portion and the holding portion do not hold the optical fiber is interposed via a second adhesive layer. An optical transmission module characterized by being bonded together. The holding part has a first groove part, and the fixing part has a second groove part,
The optical transmission module according to claim 1, wherein the holding member holds the optical fiber between the first groove portion and the second groove portion. The holding portion has a through hole communicating with the first groove portion;
The optical transmission module according to claim 2, wherein the optical fiber is inserted through the through hole. The holding portion has a first groove portion;
The fixed part has a convex part inserted in the first groove part of the holding part,
The optical transmission module according to claim 1, wherein the holding member holds the optical fiber between the first groove portion of the holding portion and the convex portion of the fixing portion. The holding portion has a through hole communicating with the first groove portion;
The optical transmission module according to claim 4, wherein the optical fiber is inserted through the through hole.   6. The optical transmission module according to claim 3, wherein the optical fiber is fixed to the fixing portion with an adhesive on an outer surface of the fixing portion on an inlet side of the second groove portion. An optical element having a light emitting portion for outputting an optical signal and a connection terminal electrically connected to the light emitting portion on a light emitting surface is mounted on the first main surface, and a hole is formed at a position facing the light emitting portion. A step of bonding a wiring board to a side surface of a holding portion having a first groove and a first through hole communicating with the first groove via a first adhesive layer;
A step of inserting an optical fiber into the third through hole of the holding jig having a third groove portion and a third through hole communicating with the third groove portion;
A step of sandwiching the optical fiber by the second groove portion of the fixing portion and the third groove portion of the holding jig;
A step of adhering an outer surface of the second groove portion of the fixing portion on an entrance side and the optical fiber with an adhesive;
Cutting the tip of the optical fiber protruding from the third through hole of the holding jig;
A step of removing the holding jig from the fixed portion to which the optical fiber is bonded;
In place of the holding jig, the step of inserting the optical fiber bonded to the fixing portion into the first through hole of the holding portion;
A step in which the facing surface where the fixing portion and the holding portion do not sandwich the optical fiber is bonded via a second adhesive layer;
A method of manufacturing an optical transmission module comprising: