JP2012150222A - Photoelectric conversion module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion module in which a photoelectric converting element having an incidence/emission part and a first electrode on one surface and a second electrode on the other surface is mounted on a substrate by employing a simple connection structure with high productivity and high space efficiency.SOLUTION: A photoelectric conversion module comprises: a translucent circuit substrate 30 having a substrate-side first electrode 56 and a substrate-side second electrode 64 on a mounting surface; a photoelectric converting element 38 mounted on the mounting surface of the circuit substrate 30 and having an incidence/emission part and an element-side first electrode 44 connected to the substrate-side first electrode 56 on a first surface opposing the mounting surface and an element-side second electrode 62 on a second surface opposite to the first surface; a filling member 40 filled between the photoelectric converting element 38 and the circuit substrate 30; and a film-shaped conductive member 42 extending from the element-side second electrode 62 to the substrate-side second electrode 64.

Description

  The present invention relates to a photoelectric conversion module.

  For example, in a connection between a server and a switch in a data center or a connection between digital AV (audio / visual) devices, an optical fiber is used as a transmission medium in addition to a metal wire. In recent years, the use of an optical fiber as a transmission medium (optical interconnect) has also been studied in information processing devices such as mobile phones and personal computers.

  When an optical fiber is used, a photoelectric conversion module that converts an electrical signal into an optical signal or an optical signal into an electrical signal is required. As a photoelectric conversion module, for example, a printed circuit board unit for light transmission disclosed in Patent Document 1 includes an optical waveguide substrate, and a light emitting element or a light receiving element is mounted on the optical waveguide substrate as a photoelectric conversion element. The photoelectric conversion element is mounted by mounting the photoelectric conversion element on the submount chip in advance and then mounting the submount chip on the optical waveguide substrate.

JP 2004-12803 A

The printed circuit board unit for optical transmission disclosed in Patent Document 1 requires a submount chip, has a large number of parts, and has a large mounting area.
In addition, when manufacturing the photoelectric conversion element, it is necessary to align the photoelectric conversion element with respect to the submount chip at the stage of mounting the photoelectric conversion element on the submount chip, and to the optical waveguide substrate at the stage of mounting the submount chip on the optical waveguide substrate. The positioning of the submount chip is necessary, and the manufacturing is complicated.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a photoelectric conversion element having an input / output portion and a first electrode on one surface and a second electrode on the other surface. Another object of the present invention is to provide a photoelectric conversion module mounted on a substrate with a simple connection structure excellent in space efficiency.

  In order to achieve the above object, according to one aspect of the present invention, a circuit board having translucency and having a mounting surface and a substrate-side first electrode and a substrate-side second electrode provided on the mounting surface; A photoelectric conversion element mounted on the mounting surface of the circuit board, the element side first connected to the input / output part and the first electrode on the substrate side provided respectively on the first surface facing the mounting surface A photoelectric conversion element having one electrode and an element-side second electrode on a second surface opposite to the first surface; and a filling member filled between the photoelectric conversion element and the circuit board; There is provided a photoelectric conversion module including a film-like conductive member extending from the element side second electrode to the substrate side second electrode.

  According to the present invention, a photoelectric conversion element having an input / output portion and a first electrode on one surface and a second electrode on the other surface is a substrate with a simple connection structure excellent in productivity and space efficiency. A photoelectric conversion module mounted on is provided.

It is a perspective view which shows schematic structure of an optical active cable provided with the photoelectric conversion module of one Embodiment. FIG. 2 is an enlarged perspective view showing the vicinity of an optical transmitter of the optical active cable of FIG. 1. FIG. 3 is a schematic perspective view showing the optical transmitter of FIG. 2 in an exploded manner. FIG. 4 is a perspective view schematically showing one side of the photoelectric conversion module in FIG. 3. FIG. 5 is a perspective view schematically showing the other side of the photoelectric conversion module of FIG. 4. FIG. 6 is an enlarged perspective view schematically showing the vicinity of the IC chip and the photoelectric conversion element in FIG. 5. It is a top view which shows roughly the output surface of the photoelectric conversion element in FIG. It is a figure which shows schematically the longitudinal cross-section of IC chip and the photoelectric conversion element vicinity in the photoelectric conversion module of FIG.4 and FIG.5. It is a figure which shows schematically the longitudinal cross-section of an IC chip and photoelectric conversion element vicinity in the photoelectric conversion module of a modification. It is a perspective view which expands and schematically shows the circumference of an IC chip and a photoelectric conversion element in a photoelectric conversion module of a modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view schematically showing the external appearance of the optical active cable 10.
The optical active cable 10 includes a photoelectric composite cable 11 and an optical transmitter 12 and an optical receiver 14 attached to both ends of the photoelectric composite cable 11. The optical active cable 10 is applied to a connection between digital AV devices, for example.

FIG. 2 is an enlarged perspective view showing the optical transmitter 12 together with a part of the photoelectric composite cable 11.
The optical transmitter 12 has a housing 16 made of metal, for example, and the housing 16 has a box shape, for example. The photoelectric composite cable 11 extends from one end of the housing 16 via a seal member 18, while an opening is formed at the other end of the housing 16.
For example, the end of one rigid circuit board 20 is located in the opening of the housing 16. The end of the circuit board 20 can be inserted into a slot provided in the digital AV device.

3 is an exploded perspective view schematically showing the optical transmitter 12, and the housing 16 includes, for example, a first case 16a and a second case 16b that are separable from each other.
The circuit board 20 is a rigid board made of glass epoxy, for example, and is fixed to the second case 16b. A predetermined conductor pattern made of a metal such as copper is formed on the circuit board 20, and the conductor pattern includes a plurality of electrode terminals 22 arranged at the end of the circuit board 20. The electrode terminal 22 is electrically connected to an electrode terminal provided in the digital AV device.

A connector 24 is attached to the circuit board 20 together with an LSI (Large Scale Integrated Circuit) 23 for signal processing.
The photoelectric composite cable 11 includes a plurality of conductive wires 25, and the conductive wires 25 extend through the seal member 18 to the inside of the housing 16. The leading end portion of the conducting wire 25 located inside the housing 16 is soldered to the circuit board 20. The connector 24 and the conductive wire 25 are electrically connected to the LSI 23 through a conductor pattern, and the LSI 23 is electrically connected to the electrode terminal 22.

  On the other hand, the photoelectric composite cable 11 includes, for example, one optical fiber 28, and the optical fiber 28 also extends to the inside of the housing 16 through the seal member 18. And the front-end | tip of the optical fiber 28 located inside the housing 16 is being fixed to the end of the photoelectric conversion module 26 of one Embodiment.

[Photoelectric conversion module]
The other end of the photoelectric conversion module 26 is connected to the connector 24. The photoelectric conversion module 26 of the optical transmitter 12 has a function of converting an electrical signal received from the digital AV device into an optical signal and transmitting the optical signal to the optical fiber 28.
FIG. 4 is a perspective view showing the second case 16 b side of the photoelectric conversion module 26. The photoelectric conversion module 26 includes an FPC board (flexible printed circuit board) 30. The FPC board 30 is, for example, a polyimide-made film 32 having flexibility and translucency, and copper provided on the film 32, for example. And a conductor pattern made of a metal. The translucency may be ensured by making a hole in the film 32.

A polymer optical waveguide member 33 is provided integrally with the film 32 on one end side of the FPC board 30. A groove that opens at one end of the FPC board 30 is formed in the polymer optical waveguide member 33, and the tip of the optical fiber 28 is fixed in the groove.
A metal film is formed on the end surface of the polymer optical waveguide member 33 opposite to the optical fiber 28 by vapor deposition, and the metal film forms a mirror 34.

FIG. 5 is a perspective view showing the first case 16 a side of the photoelectric conversion module 26.
The conductor pattern of the FPC board 30 includes a plurality of electrode terminals 35 formed on the other end of the film 32, and the electrode terminals 35 are electrically connected to the connector 24.
The conductor pattern can be produced, for example, by etching a metal film formed on the film 32.

An IC chip 36 is flip-chip mounted, for example, at a predetermined position on one surface (mounting surface) of the FPC board 30 opposite to the polymer optical waveguide member 33.
Further, as shown in an enlarged view in FIG. 6, a light emitting element such as an LD (laser diode) as a photoelectric conversion element 38 is mounted on the mounting surface of the FPC board 30, and the IC chip 36 and the photoelectric conversion element 38 are It is electrically connected to the conductor pattern. The IC chip 36 constitutes a drive circuit for driving the photoelectric conversion element 38.

  Between the photoelectric conversion element 38 and the FPC board 30, a resin filling member 40 having translucency and electrical insulation is provided. The filling member 40 is made of, for example, an epoxy resin or a silicone resin. A film-like conductive member 42 is provided across the conductor pattern of the FPC board 30 from the surface of the photoelectric conversion element 38 opposite to the FPC board 30.

  FIG. 7 is a plan view schematically showing the surface (exiting surface) of the photoelectric conversion element 38 on the FPC substrate 30 side. On the emitting surface, an anode electrode (element-side first electrode) 44 and an emitting unit 46 are provided. Is provided. That is, the light emitting element as the photoelectric conversion element 38 is a surface emitting type. The photoelectric conversion element 38 has a cathode electrode on the side opposite to the emission surface, and emits light from the emission unit 46 when a voltage is applied between the anode electrode 44 and the cathode electrode.

FIG. 8 is a diagram schematically showing a longitudinal section in the vicinity of the IC chip 36 and the photoelectric conversion element 38 of the photoelectric conversion module 26.
The polymer optical waveguide member 33 includes an under cladding layer 48, a core 50, and an over cladding layer 52. The under-cladding layer 48 is laminated on the FPC substrate 30, and a core 50 having a quadrangular cross-sectional shape viewed from the traveling direction of the optical signal extends on the under-cladding layer 48.

The number of cores 50 is one corresponding to the number of optical fibers 28, and is positioned coaxially with the tip of the optical fiber 28. The over clad layer 52 is laminated on the under clad layer 48 and the core 50 so as to surround the core 50 in cooperation with the under clad layer 48.
The material of the under cladding layer 48, the core 50, and the over cladding layer 52 is not particularly limited, and for example, an acrylic resin, an epoxy resin, a polyimide resin, or the like can be used.

  One end of the core 50 is located on the end face of the groove of the polymer optical waveguide member 33 and is in contact with the end of the optical fiber 28 and optically coupled. On the other hand, a mirror 34 is provided at the other end of the core 50, and the mirror 34 is disposed so as to correspond to the emission part 46 of the photoelectric conversion element 38. That is, the optical path is bent by 90 ° by the mirror 34 between the other end of the core 50 and the photoelectric conversion element 38 and penetrates the FPC board 30.

The electrodes of the IC chip 36 are connected to the conductor pattern of the FPC board 30 through bumps 54 made of, for example, Au. More specifically, one electrode of the IC chip 36 is connected via a bump 54 to an anode electrode (substrate-side first electrode) 56 that constitutes a part of the conductor pattern. The anode electrode 56 extends from the IC chip 36 to the photoelectric conversion element 38 on the film 32.
The anode electrode 44 of the photoelectric conversion element 38 is also connected to the anode electrode 56 through a bump 58 made of, for example, Au. The photoelectric conversion element 38 can be said to be flip-chip mounted in that it is mounted on the anode electrode 56 via the bump 58.

The filling member 40 filled between the photoelectric conversion element 38 and the FPC board 30 surrounds the bump 58, and the photoelectric conversion element 38 is firmly fixed to the FPC board 30 by the filling member 40. In addition, the filling member 40 ensures electrical insulation between the anode electrodes 44 and 56 and the bumps 58 and the conductive member 42.
The filling member 40 may protrude from the edge of the photoelectric conversion element 38 or may adhere to the side surface of the photoelectric conversion element 38, but the surface (upper surface) of the photoelectric conversion element 38 on the side opposite to the FPC board 30. ) Is not attached. The filling member 40 adheres to a part of the upper surface of the photoelectric conversion element 38, but may be provided so as not to cover the entire surface.

On the upper surface of the photoelectric conversion element 38, a cathode electrode (element-side second electrode) 62 is provided. The cathode electrode 62 is covered with a film-like conductive member 42. The conductor pattern of the FPC board 30 includes a cathode electrode (substrate-side second electrode) 64, and the conductive member 42 also covers the cathode electrode 64. That is, the conductive member 42 extends from the cathode electrode 62 over the filling member 40 to the cathode electrode 64, and electrically connects the cathode electrode 62 and the cathode electrode 64.
The cathode electrode 64 of the conductor pattern is electrically connected to the IC chip 36, and the IC chip 36 is connected between the anode electrode 44 and the cathode electrode 62 of the photoelectric conversion element 38 via the anode electrode 56 and the cathode electrode 64. Apply voltage to

In the manufacturing process of the photoelectric conversion module 26 described above, the photoelectric conversion element 38 is preferably mounted on the FPC board 30 as follows.
First, bumps 58 are provided on the anode electrode 44 of the photoelectric conversion element 38. Then, the photoelectric conversion element 38 is aligned with the FPC board 30 while being held by a holder. For alignment, for example, an optical camera is used.
Then, the photoelectric conversion element 38 is brought close to the FPC board 30, and the bump 58 is brought into contact with the anode electrode 56. In this state, the anode electrode 56 and the anode electrode 44 are connected via the bump 58 by heating and weighting. At this time, an ultrasonic wave may be applied.

  Thereafter, the filling member 40 is formed by filling the resin between the FPC substrate 30 and the photoelectric conversion element 38 using the filling device and curing the resin. Then, for example, a silver paste is applied from the cathode electrode 62 of the photoelectric conversion element 38 to the cathode electrode 64 of the FPC substrate 30 by using a dispenser, and the conductive material 42 is formed by curing the silver paste. Thereby, the mounting of the photoelectric conversion element 38 is completed.

This is the end of the description of the photoelectric conversion module 26 of the optical transmitter 12, but the optical receiver 14 also has the photoelectric conversion module 26. The photoelectric conversion module 26 of the optical receiver 14 has a function of converting an optical signal received from the optical fiber 28 into an electric signal and transmitting it to an external device through the connector 24 and the electrode terminal 22.
Therefore, in the photoelectric conversion module 26 of the optical receiver 14, the photoelectric conversion element 38 is a light receiving element such as a PD (photodiode), and the IC chip 36 is an amplifier circuit. The light receiving element has an incident part instead of an emission part. In the present specification, the emission part and the incident part are also referred to as an incident / exit part.

  According to the photoelectric conversion module 26 of the embodiment described above, the cathode electrode 62 of the photoelectric conversion element 38 is connected to the cathode electrode 64 of the FPC board 30 by the film-like conductive member 42, and a submount chip is unnecessary. is there. The formation of the film-like conductive member 42 does not require high positional accuracy, and therefore the productivity of the photoelectric conversion module 26 is high. Further, since no subchip is required, space efficiency is high, and the photoelectric conversion module 26 itself can be downsized.

  Further, in the photoelectric conversion element 38 used in the photoelectric conversion module 26 of the above-described embodiment, the anode electrode 44 is provided on one surface and the cathode electrode 62 is provided on the other surface. Compared to the case where the cathode electrode is provided in the same plane, the photoelectric conversion element 38 can be downsized. For this reason, size reduction of the photoelectric conversion module 26 is also achieved.

  Furthermore, in the photoelectric conversion element 38 used in the photoelectric conversion module 26 of the embodiment described above, the cathode electrode 62 of the photoelectric conversion element 38 is connected to the cathode electrode 64 of the FPC board 30 through the film-like conductive member 42. Compared to the case where wires are connected, heat dissipation is excellent.

The present invention is not limited to the above-described embodiment, and includes a form obtained by modifying the embodiment.
For example, in the photoelectric conversion module 26 according to the embodiment described above, the FPC board 30 has flexibility, but a circuit board having no flexibility may be used.

  The photoelectric conversion module 26 according to the embodiment described above may further include a buffer member 66 as illustrated in FIG. 9. The buffer member 66 is provided between the photoelectric conversion element 38 and the filling member 40 and the conductive member 42, and is softer than the filling member 40 and the conductive member 42. The buffer member 66 relieves stress even when stress is generated due to the difference in linear expansion among the photoelectric conversion element 38, the filling member 40, and the conductive member 42. As a result, failure of the photoelectric conversion element 38 due to stress is prevented.

  In the photoelectric conversion module 26 according to the embodiment described above, one photoelectric conversion element 38 is mounted on the FPC board 30, but a plurality of photoelectric conversion elements 38 may be mounted. Alternatively, as shown in FIG. 10, an array of photoelectric conversion elements 68 in which a plurality of photoelectric conversion elements are integrally formed may be mounted.

  In the photoelectric conversion module 26 according to the embodiment described above, the film-like conductive member 42 extends from the upper surface of the photoelectric conversion element 38 only in the direction toward the cathode electrode 64 of the FPC board 30. It may extend in the direction. That is, the conductive member 42 may have a dome shape so as to cover the photoelectric conversion element 38. In this case, heat dissipation is further improved.

  In the photoelectric conversion element 38 used in the photoelectric conversion module 26 of the above-described embodiment, the anode electrode 44 is provided on the same surface as the input / output unit 46, and the cathode electrode 62 is provided on the opposite surface. Depending on the configuration of the photoelectric conversion element 38, a cathode electrode may be provided on the same surface as the input / output portion 46, and an anode electrode may be provided on the opposite surface.

In the photoelectric conversion module 26 of one embodiment described above, the FPC substrate 30 is provided with the under cladding layer 48 on the film 32, but the film 32 may also serve as the under cladding layer.
Although the photoelectric conversion module 26 according to the embodiment described above includes the polymer optical waveguide member 33 that is integral with the FPC board 30, the polymer optical waveguide member 33 may not be included. That is, the optical fiber 28 and the photoelectric conversion element 38 may be optically coupled by another means.

  Finally, the optical active cable 10 including the photoelectric conversion module 26 of the present invention can be applied to a network device such as a switching hub in addition to a digital AV device. In addition to the optical active cable 10, the photoelectric conversion module of the present invention is also applicable to an optical interconnect built in information processing equipment such as a personal computer.

DESCRIPTION OF SYMBOLS 10 Optical active cable 12 Optical transmitter 14 Optical receiver 16 Housing 20 Circuit board 26 Photoelectric conversion module 28 Optical fiber 30 FPC board (circuit board)
32 Film 33 Polymer optical waveguide member 36 IC chip 38 Photoelectric conversion element 40 Filling member 42 Conductive member 44 Anode electrode (element side first electrode)
46 Outgoing part (Incoming / outgoing part)
56 Anode electrode (substrate side first electrode)
62 Cathode electrode (element-side second electrode)
64 Cathode electrode (Substrate side second electrode)

Claims (6)

A circuit board having translucency and having a mounting surface and a substrate-side first electrode and a substrate-side second electrode provided on the mounting surface;
A photoelectric conversion element mounted on a mounting surface of the circuit board, and provided on a first surface facing the mounting surface, an incident / exit portion that is a light incident portion or an emission portion, and the substrate side first A photoelectric conversion element having an element-side first electrode connected to one electrode and having an element-side second electrode on a second surface opposite to the first surface;
A filling member filled between the photoelectric conversion element and the circuit board;
A photoelectric conversion module comprising a film-like conductive member extending from the element-side second electrode to the substrate-side second electrode.   The photoelectric conversion module according to claim 1, further comprising a buffer member softer than the filling member between the conductive member and the filling member. A polymer optical waveguide member integrally provided on the back surface of the circuit board opposite to the mounting surface;
The photoelectric conversion module according to claim 1, further comprising a mirror that optically couples the polymer optical waveguide member and the photoelectric conversion element.   The photoelectric conversion module according to claim 3, wherein the circuit board has flexibility.   The photoelectric conversion module according to claim 4, wherein the circuit board also serves as a part of a clad layer of the polymer optical waveguide member.   The photoelectric conversion module according to claim 1, wherein the conductive member is made of a silver paste.

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