JP4807091B2 - Connector structure for optical transmission module - Google Patents

Description

  The present invention relates to a connector structure for an optical transmission module.

  Conventionally, as described in Patent Document 1, for example, an optical transmission module mounted on a wiring board is known. This optical transmission module includes a mount substrate mounted on a wiring board, a light emitting element that converts an electrical signal into an optical signal or a light receiving element that converts an optical signal into an electrical signal, and an IC for transmitting the electrical signal to the light emitting element. And an IC circuit for receiving an electrical signal from the circuit or the light receiving element.

In this optical transmission module, waveguides that are optically coupled to the light emitting element or the light receiving element are formed on the mount substrate, respectively, and these waveguides extend from the mount substrate and extend.
JP 2003-222746 A

  If the waveguide extends from the mount substrate and extends as described above, it is necessary to route the waveguide when the mount substrate is mounted on the wiring substrate, so mounting the mount substrate becomes a complicated operation. Therefore, it is conceivable that the waveguide is formed on the mount substrate so as not to protrude from the mount substrate, and an external waveguide is newly provided to optically couple the waveguide and the external waveguide.

  However, when optically coupling the waveguide and the external waveguide in this way, it is required to position the waveguide and the external waveguide with high accuracy from the viewpoint of optical coupling efficiency.

  In view of such circumstances, an object of the present invention is to provide a connector structure for an optical transmission module that can optically couple a waveguide and an external waveguide in a state of being positioned with high accuracy.

In order to solve the above problems, an optical transmission module connector structure according to the present invention is an optical transmission module connector structure for optically coupling a waveguide formed on a mount substrate and an external waveguide. Te, the mounting substrate, provided with a first fitting part towards direction along said waveguide, an optical connector provided at the end of the outer waveguide, fitted to the first fitting portion at the tip of the optical connector A second fitting portion capable of being joined, and either one of the first fitting portion and the second fitting portion is a trapezoidal concave portion in plan view, and the other is a trapezoidal convex portion in plan view. It is characterized by this.

  In order to position the external waveguide with high accuracy with respect to the optical connector, the optical connector has a first base portion and a second base portion that sandwich and hold the external waveguide. It is preferable to provide a positioning convex part and to provide a positioning concave part fitted to the positioning convex part in the first base part or the second base part.

  In order to be applicable to a bent portion of a device, the external waveguide is preferably a flexible film.

  In order to maintain a state where the fitting convex portion and the fitting concave portion are fitted, it is preferable to attach an adapter to which the optical connector is detachably attached to the mount substrate.

  In order to prevent the optical connector from coming off, the optical connector is preferably provided with a hook portion that engages with the adapter when the optical connector is attached.

  In order to prevent positional deviation between the waveguide and the external waveguide due to vibration, repeated insertion and removal, etc., when fitting the second fitting portion of the optical connector to the first fitting portion, It is preferable to provide a guide portion that guides the second fitting portion and presses it against the mount substrate.

According to the present invention, the mount substrate, provided with a first fitting part towards direction along the waveguide, an optical connector provided at the end of the outer waveguide, the tip of the optical connector, the first fitting portion Since the second fitting portion that can be fitted to the second fitting portion is provided, when the second fitting portion is fitted to the first fitting portion, the external waveguide is positioned with high accuracy with respect to the waveguide. Therefore, optical coupling can be performed in a state where the waveguide and the external waveguide are positioned with high accuracy.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a photoelectric conversion apparatus 1A that employs a connector structure for an optical transmission module according to an embodiment of the present invention. The photoelectric conversion device 1 includes a light-emitting side light transmission module 1A and a light-receiving side light transmission module 1B mounted on a wiring board 2, and an external waveguide 9 that optically connects these light transmission modules 1A and 1B. It has. 1, the vertical direction in FIG. 1 is referred to as the vertical direction, the direction orthogonal to the paper surface is referred to as the horizontal direction, and for the light-emitting side optical transmission module 1A, the right side in FIG. For the side light transmission module 1B, the left side in FIG.

  The light emission side optical transmission module 1 </ b> A includes a mount substrate 3 that is mounted on the upper surface of the wiring substrate 2 at a predetermined interval. On one surface 3a which is the lower surface of the mount substrate 3, an IC substrate 5A on which a light emitting element 4A for converting an electric signal into an optical signal and an IC circuit 50A for transmitting the electric signal to the light emitting element 4A are formed. Has been implemented. Further, the mount substrate 3 is formed with a waveguide 31 that is optically coupled to the light emitting element 4A.

  As the light emitting element 4A, a VCSEL (Vertical Cavity Surface Emitting Laser) that emits light upward from the upper surface is employed. The IC substrate 5A is a driver IC that drives the VCSEL, and is disposed in the vicinity of the light emitting element 4A. The light emitting element 4A and the IC substrate 5A are connected to the one surface 3a of the mount substrate 3 by a gold bump 11 (see FIG. 2). As the light emitting element 4A, an LED or the like can also be adopted. However, the LED or the like has no directivity, and the ratio of optical coupling to the waveguide 31 is small. In some cases, it is advantageous in terms of low price.

  The mount substrate 3 has a rectangular shape extending in the front-rear direction in plan view (see FIG. 3), and is connected to the upper surface of the wiring substrate 2 by solder bumps 10. The mount substrate 3 needs to be rigid in order to avoid the influence of heat during mounting and the influence of stress due to the use environment. In the case of optical transmission, since light transmission efficiency from the light emitting element to the light receiving element is required, it is necessary to mount the optical element with high accuracy and to suppress position fluctuation during use as much as possible. For this reason, a silicon substrate is employed as the mount substrate 3. The mount substrate 3 is preferably made of a material having a linear expansion coefficient close to that of the light emitting element 4A, and may be made of a compound semiconductor such as GaAs of the same system as the VCSEL material other than silicon.

  The mount substrate 3 is formed with a mirror portion 33 for bending the optical path by 90 ° at a position directly above the light emitting element 4A. The mirror portion 33 can be formed by evaporating gold or aluminum on a 45 ° inclined surface formed by etching the mount substrate 3. The 45 ° inclined surface can be formed, for example, by anisotropic etching with a potassium hydroxide solution.

  The waveguide 31 extends forward from the mirror portion 33 and has an end surface that is flush with the front end surface of the mount substrate 3. As shown in FIG. 2, the waveguide 31 includes a core 31 a having a substantially square cross section and a clad 31 b that covers the core 31 a from the periphery. The waveguide 31 is formed in the waveguide forming groove 32 formed in the mount substrate 3. It is arranged. The waveguide forming groove 32 is formed by etching the mount substrate 3.

  A pair of left and right resin structure portions 6 that are separated from each other with the waveguide 31 interposed therebetween is provided on the front end portion of the mount substrate 3 (see FIG. 4), and an adapter 7A is attached. Then, the external waveguide 9 is optically coupled to the waveguide 31 by attaching the optical connector 8A provided at the end of the external waveguide 9 to the adapter 7A.

  Each resin structure 6 is composed of, for example, an epoxy resin, an acrylic resin, a silicon resin, or a photocurable material such as an epoxy resin, an acrylic resin, or a silicon resin, which is a thermosetting material. As shown in FIG. 4, it has a trapezoidal plate shape in plan view. Specifically, the facing surface 61 on the side where the resin structure portions 6 face each other is an inclined surface that spreads outward as it goes forward. The opposing surface 61 and the one surface 3 a of the mount substrate 3 constitute a fitting recess (first fitting portion) 35 that is closed upward and opens forward along the waveguide 31. ing. Further, a fitting hole 62 is provided on the lower surface of each resin structure portion 6. Each resin structure 6 can be easily formed by using a molding method or a photolithography method.

  As shown in FIG. 5, the adapter 7 </ b> A has a rectangular plate-like base portion 71 and a block portion 72 provided in a region approximately two thirds of the front side of the upper surface of the base portion 71. A pair of left and right bosses 73 that can be fitted into the fitting holes 62 of the resin structure portion 6 project from the rear side position of the upper surface of the base portion 71, and the bosses 73 are fitted into the fitting holes 62. As a result, the adapter 7 </ b> A is attached to the mount substrate 3 with the rear end surface of the block portion 72 in contact with or close to the front end surface of the mount substrate 3. Further, the block portion 72 is provided with insertion holes 74 penetrating the block portion 72 in the front-rear direction along the upper surface of the base portion 71 at a position corresponding to the waveguide 31, and concave on both the left and right side surfaces. The engaging portion 75 is provided.

  The optical connector 8A is detachably attached to the front portion of the block portion 72 of the adapter 7A. Specifically, as shown in FIG. 6, the optical connector 8A includes a main part 81 extending in the left-right direction, extending rearward from both ends of the main part 81, and an engaging part of the adapter 7A at the tip. A hook portion 84 having an engaging claw 84a that can be engaged with 75, and an insertion portion 82 that extends rearward from a substantially center in the left-right direction of the main portion 81 and is inserted into the insertion hole 74 of the adapter 7A. Yes.

  When the optical connector 8A is pushed in while the insertion portion 82 is inserted into the insertion hole 74, the engagement claw 84a of the hook portion 84 is engaged with the engagement portion 75 so that the optical connector 8A is attached to the adapter 7A. Become. At this time, the rear end surface of the insertion portion 82 comes into contact with the front end surface of the mount substrate 3 through the insertion hole 74. Further, when the optical connector 8A is pulled out with the hook portion 84 elastically deformed outward, the optical connector 8A can be detached from the adapter 7A.

  More specifically, as shown in FIG. 7, the optical connector 8A includes a first base portion 80A and a second base portion 80B that sandwich and hold the external waveguide 9 from above and below, and the portions 81, 82, and 84 are vertically moved. The structure is divided into two parts (divided into 81A and 81B, 82A and 82B, and 84A and 84B). The external waveguide 9 is held by the first base portion 80A and the second base portion 80B with the end surface being flush with the rear end surface of the insertion portion 82. For this reason, when the optical connector 8A is attached to the adapter 7A, the end face of the external waveguide 9 comes into contact with the end face of the waveguide 31. Further, a plate-like fitting convex portion (second fitting portion) 83 protruding rearward from the rear end surface of the insertion portion 82 is continuously provided at the tip of the lower insertion portion 82B of the second base portion 80B.

  As a material constituting the adapter 7A and the optical connector 8A, for example, a thermoplastic material, a thermosetting resin, a ceramic material such as aluminum oxide or zirconia is applicable. As thermoplastic resins, polyamide (PA), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyacetal (POM), polybutylene terephthalate (PBT), polycarbonate (PC), polyether ketone (PEEK), ABS resin, etc. Examples of the thermosetting resin include epoxy resins, silicone resins, unsaturated polyester resins, phenol resins, polyimide resins, diallyl phthalate resins, polyurethane resins, melanin resins, and fluorine resins.

  As shown in FIG. 8A, the external waveguide 9 is a flexible film having a predetermined width, and a core 92 is placed on the lower clad 91, and the core 92 is the upper clad 93. It is the structure covered with.

  At the end of the external waveguide 9, the upper clad 93 is not provided, the core 92 is exposed, and positioning protrusions 94 extending in parallel with the core 92 are provided on both sides thereof. On the other hand, on the upper surface of the lower insertion portion 82B of the second base portion 80B of the optical connector 8A, a core groove 82a is provided in the center, and positioning grooves 82b are provided on both sides thereof (see FIG. 7). As shown in FIG. 8B, the core 92 is loosely fitted in the core groove 82a, but the positioning protrusion 94 is located on the core groove 82a side of the positioning groove 82b. The outer waveguide 9 and the second base portion 80B are aligned with high accuracy by coming into contact with the side surface and fitting into the positioning groove 82b. Then, with the optical adhesive 12 applied to the upper surface of the lower insertion portion 82B, the external waveguide 9 is pressed with the lower cladding 91 facing upward, whereby the core 92, the positioning protrusion 94, and the core The external waveguide 9 and the second base portion 80B are bonded in a state in which the groove for use 82a and the positioning groove 82b are engaged with each other and the gap between them is filled with the optical adhesive 12.

  The external waveguide 9 may be a silica-based fiber or a plastic fiber other than the flexible film-like one. The external waveguide 9 and the second base portion 80B only need to be provided with a structure for positioning them. For example, the external waveguide 9 is provided with a cylindrical convex portion as a positioning convex portion, The 2 base part 80B may be provided with a circular concave part into which the convex part can be fitted as a positioning concave part.

  The fitting convex portion 83 of the second base portion 80B is tapered so that both side surfaces 83a can come into surface contact with the opposing surface 61 of the resin structure portion 6, respectively, and the optical connector 8A is attached to the adapter 7A. The fitting convex portion 83 is inserted into the fitting concave portion 35 through the insertion hole 74, both side surfaces 83a are in surface contact with the opposing surface 61, and the upper surface 83b is in surface contact with the one surface 3a of the mounting substrate 3, so that the fitting convex portion The part 83 comes to fit into the fitting recess 35. Thus, the positioning of the waveguide 31 and the external waveguide 9 in the vertical direction and the horizontal direction is performed, and the position of the core 31a of the waveguide 31 and the position of the core 92 of the external waveguide 9 are matched.

  The basic configuration of the light receiving side optical transmission module 1B is the same as that of the light emitting side optical transmission module 1A. That is, also in the light-receiving side optical transmission module 1B, when the optical connector 8A is attached to the adapter 7A, the fitting convex portion 83 is fitted into the fitting concave portion 35, whereby the waveguide 31 and the external waveguide 9 are Positioning is performed.

  The light receiving side optical transmission module 1B is different from the light emitting side optical transmission module 1A in that a light receiving element 4B for converting an optical signal into an electric signal is provided on one surface 3a of the mount substrate 3, and an electric signal from the light receiving element 4B. And an IC substrate 5B on which an IC circuit 50B for receiving the signal is mounted. A PD (photodiode) is employed as the light receiving element 4B, and the IC substrate 5B is a TIA (Trans-impedance Amplifier) element that performs current / voltage conversion. In addition, an amplifier element may be mounted on the mount substrate 3. Since other configurations are the same as those of the light-emitting side optical transmission module 1A, detailed description thereof is omitted.

  In the optical transmission module connector structure of the present embodiment, the mounting substrate 3 is provided with a fitting recess 35 that opens forward along the waveguide 9, and an optical connector 8 A is provided at the end of the external waveguide 9. Since the fitting convex portion 83 that can be fitted into the fitting concave portion 35 is provided at the tip of the optical connector 8A, when the fitting convex portion 83 is fitted into the fitting concave portion 35, the external waveguide 9 is connected to the waveguide 31. Is positioned with high accuracy. Therefore, optical coupling can be performed with the waveguide 31 and the external waveguide 9 positioned with high accuracy.

  Further, since the positioning protrusion 94 is provided in the external waveguide 9, and the positioning groove 82b to be fitted to the positioning protrusion 94 is provided in the second base portion 80B of the optical connector 8A, the external waveguide 9 is external to the optical connector 8A. The waveguide 9 can be positioned with high accuracy.

  Further, since the external waveguide 9 is a flexible film, it can be applied to a bent portion of a mobile device such as a mobile phone or a PDA (Personal Digital Assistance), for example. High-speed signal transmission becomes possible.

  Further, since the adapter 7A to which the optical connector 8A is detachably attached is attached to the mount substrate 3, the adapter 7A can hold the fitting convex portion 83 and the fitting concave portion 35 in a fitted state. .

  Further, since the optical connector 8A is provided with the hook portion 84 that engages with the engaging portion 75 of the adapter 7A when attached to the adapter 7A, the hook portion 84 can prevent the optical connector 8A from coming off.

  The light-emitting side light transmission module 1A and the light-receiving side light transmission module 1B are not limited to those having the above-described configurations, and various configurations can be employed. For example, the IC circuits 50A and 50B may be directly formed on the mount substrate 3.

  Moreover, in the said embodiment, although the form which comprises the fitting recessed part 35 with the resin structure part 6 was shown, as shown to Fig.9 (a), a fitting recessed part is removed by removing a part of mount substrate 3. As shown in FIG. It is also possible to provide 35 directly on the mount substrate 3. The fitting recess 35 in this case can be formed simultaneously with the waveguide forming groove 32 when etching for forming the waveguide forming groove 32 is performed.

  Further, an adapter fitting groove 34 is formed on the one surface 3a of the mount substrate 3, and as shown in FIG. 9B, a protrusion 76 that can be fitted into the adapter fitting groove 34 is provided on the adapter 7A. If provided, the resin structure 6 can be omitted. The adapter fitting groove 34 can also be formed simultaneously with the waveguide forming groove 32 when etching for forming the waveguide forming groove 32 is performed.

  Moreover, in the said embodiment, it can replace with the adapter 7A and the optical connector 8A, and can also employ | adopt the adapter 7B and the optical connector 8B of the modification shown in FIG. In the adapter 7A and the optical connector 8A, the optical connector 8A is externally fitted to the adapter 7A. However, in the modified adapter 7B and optical connector 8B, the optical connector 8B is internally fitted to the adapter 7B. It has come to be.

  Specifically, in the adapter 7B, as shown in FIG. 10A, the block portion 72 is provided over the entire width of the base portion 71, and the width of the insertion hole 74 is set large. The engaging portion 75 is provided on both side surfaces of the block portion 72 so as to communicate with the insertion hole 74.

  On the other hand, in the optical connector 8B, as shown in FIG. 10B, the hook portions 84 are provided so as to extend forward from the rear ends of both side surfaces of the insertion portion 82, and the engaging claws 84a are provided. Facing outward. Then, as shown in FIG. 11A, when the optical connector 8B is inserted into the adapter 7B, the engaging claw 84a is engaged with the engaging portion 75.

  As shown in FIG. 11 (b), the optical connector 8B can be mounted by inclining the surface of the engaging claw 84a that engages with the engaging portion 75 and providing the engaging claw 84a with the pressing surface 84b. Even after being attached to the adapter 7B, the pressing force for pressing the optical connector 8B against the mount substrate 3 as shown by the arrow a by the restoring force of the hook portion 84 always acts on the optical connector 8B. Can be suppressed. When the optical connector 8B is pressed against the mount substrate 3, the waveguide 31 formed on the mount substrate 3 and the external waveguide 9 are in close contact with each other, the gap between the waveguides is reduced, and optical loss is suppressed. It becomes a possible structure.

  In addition, as shown in FIG. 12C, it is possible to provide two fitting protrusions 83 at a position sandwiching the external waveguide 9. In this case, as shown in FIG. 12A, the fitting recess 35 is formed in each of the resin structure portions 6. In this way, since there is no fitting projection 83 below the end face of the external waveguide 9, the end face of the external waveguide 9 is polished while the external waveguide 9 is held by the optical connector 8B. Can be facilitated, and handling at the time of assembly can be improved. Further, by providing a plurality of fitting protrusions 83, the positioning accuracy is improved as compared with the case of one.

  Furthermore, the thickness of the resin structure portion 6 is not necessarily the same as that of the fitting convex portion 83, and may be set thin as shown in FIG. In this case, as shown in FIG. 12B, a stepped portion 78 having a shape that allows the fitting convex portion 83 to escape is provided at the rear end portion of the upper surface of the base portion 71 of the adapter 7 </ b> B. What is necessary is just to project the boss | hub 73. The configuration shown in FIG. 12 is also applicable to the adapter 7A and the optical connector 8A.

  Further, as in the adapter 7 </ b> C of the modified example shown in FIG. 13A, a guide portion 77 having an upward slope toward the rear may be provided at a rear position on the upper surface of the base portion 71. As shown in FIG. 13B, the guide portion 77 guides the fitting convex portion 83 when fitting the fitting convex portion 83 of the optical connector 8A into the fitting concave portion 35, and mount substrate 3 It is for pushing against.

  In this way, when the fitting convex portion 83 is fitted in the fitting concave portion 35, the mounting substrate 3 and the optical connector 8A are fixed in contact with each other. It is possible to prevent the positional deviation between the waveguide 31 and the external waveguide 9 due to the above. Note that the configuration shown in FIG. 13 is also applicable to the adapter 7B.

  The first fitting portion according to the present invention does not need to be the fitting concave portion 35 having a concave shape in the direction along the waveguide 31 as described above, and has a shape convex in the direction along the waveguide 31. It may be. The first fitting portion in this case can be easily formed by removing the portions on both sides of the waveguide 31 in the mount substrate 3 by etching. In such a case, a bifurcated fork-like protrusion may be formed at the tip of the insertion part 82 of the optical connector 8A, 8B, and this protrusion may be used as the second fitting part according to the present invention. Further, when the first fitting portion is formed in a convex shape, the first fitting portion may be provided so as to protrude outward from a region where the mount substrate 2 exists in a plan view.

1 is a schematic configuration diagram of a photoelectric conversion apparatus according to a first embodiment of the present invention. (A) is a side view of a mount substrate on which an optical element is mounted, and (b) is a cross-sectional view taken along line AA of (a). It is a perspective view of the photoelectric conversion apparatus of 1st Embodiment. It is a perspective view when the mount substrate is viewed from below. It is a perspective view of an adapter. It is a perspective view of an optical connector. It is a disassembled perspective view of an optical connector. (A) is a perspective view of an external waveguide, (b) is a sectional view when the external waveguide is sandwiched between a first base portion and a second base portion. (A) is a perspective view when the mount substrate of a modification is viewed from below, and (b) is a perspective view of an adapter of a modification. (A) is a perspective view of the adapter of a modification, (b) is a perspective view of the optical connector of a modification. (A) is a top view when the optical connector of a modification is mounted | worn with the adapter of a modification, (b) is a partially expanded front sectional view when a pressing surface is provided in an engaging claw. (A) is a perspective view when the mount substrate of the modification is viewed from below, (b) is a perspective view of the adapter of the modification, and (c) is a perspective view of the optical connector of the modification. (A) The perspective view of the adapter of a modification, (b) is a schematic sectional side view when attaching an optical connector to the adapter of a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A Light emission side optical transmission module 1B Light reception side optical transmission module 2 Wiring board 3 Mount board 31 Waveguide 33 Mirror part 35 Fitting recessed part (1st fitting part)
4A Light-Emitting Element 4B Light-Receiving Element 50A, 50B IC Circuit 6 Resin Structure 61 Opposing Surface 7A, 7B Adapter 8A, 8B Optical Connector 83 Fitting Protrusion (Second Fitting Part)
9 External waveguide

Claims (6)

A connector structure for an optical transmission module for optically coupling a waveguide formed on a mounting substrate and an external waveguide,
Said mounting substrate, provided with a first fitting part towards direction along said waveguide, said optical connector provided at the end of the outer waveguide, fittable on the tip of the optical connector in the first fitting portion A second fitting portion is provided,
One of the first fitting portion and the second fitting portion is a trapezoidal concave portion in plan view, and the other is a trapezoidal convex portion in plan view. .   The optical connector includes a first base portion and a second base portion that sandwich and hold the external waveguide. The optical connector is provided with a positioning convex portion on the external waveguide, and is provided on the first base portion or the second base portion. The connector structure for an optical transmission module according to claim 1, further comprising a positioning recess that fits into the positioning protrusion.   3. The connector structure for an optical transmission module according to claim 1, wherein the external waveguide is a flexible film.   The connector structure for an optical transmission module according to claim 1, wherein an adapter to which the optical connector is detachably attached is attached to the mount substrate.   The optical transmission module connector structure according to claim 4, wherein the optical connector includes a hook portion that engages with the adapter when the adapter is attached to the adapter.   When the second fitting portion of the optical connector is fitted to the first fitting portion, the adapter is provided with a guide portion that guides the second fitting portion and presses it against the mount substrate. The connector structure for an optical transmission module according to claim 4 or 5.

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