JP2008091474A - Photoelectric conversion device - Google Patents

Abstract

Provided is a photoelectric conversion device capable of improving the degree of freedom of a wiring pattern of a mount substrate and reducing the height of the device.
A photoelectric conversion apparatus includes a mount substrate on which a light emitting element is mounted on one surface. The mount substrate 3 is provided with an internal waveguide 31 that is optically coupled to the light emitting element 4A along the one surface 3a. With respect to this photoelectric conversion device 1B, the external connector 7 is detachably attached to the one surface 3a of the mount substrate 3, and the electrode pattern is changed between the electrical connector portion 8a and the mount substrate 3. The three-dimensional circuit board 8 integrally having the wiring board portion 8b is provided.
[Selection] Figure 8

Description

  The present invention relates to a photoelectric conversion apparatus including an optical element.

  Conventionally, as a photoelectric conversion device, for example, as described in FIG. 9 of Patent Document 1, a light emitting element that emits light by converting an electric signal into an optical signal, and an electric signal for transmitting the light signal to the light emitting element An IC circuit is formed, the substrate mounted on one surface from the side opposite to the light emitting element emits light, and disposed so as to extend from the light emitting element in a direction perpendicular to one surface of the substrate, so that the light emitting element emits light. One having a waveguide for transmitting light is known. Instead of the light emitting element, it is also possible to use a light receiving element that receives light and converts an optical signal into an electric signal.

Moreover, in the photoelectric conversion apparatus described in FIG. 9 of Patent Document 1, a female electrical connector provided on the wiring board and a detachable male electrical connector are provided on the other surface of the substrate. By connecting these electrical connectors, the substrate and the wiring substrate are electrically connected.
JP 2001-42170 A

  However, in the configuration as described above, since the waveguide is disposed so as to extend from the light emitting element in a direction orthogonal to the one surface of the substrate, the height of the entire apparatus becomes considerably high.

  Here, as described in FIG. 3 of Patent Document 1, an electrical connector may be provided on the end face of the substrate so that the light emitting element emits light in a direction parallel to the wiring substrate. However, the height of the device is at least as large as the size of the light emitting element and the size of the control IC element, so that the height of the device cannot be suppressed so much.

  Therefore, the applicant of the present application mounts the optical element on one side of the mount substrate from the light emitting side or the light receiving side so that the apparatus can be reduced in height, and the optical element is mounted on the mount substrate. An IC circuit for the element is provided and an electrical connector that can be attached to and detached from the external connector is provided on one surface of the mount substrate or the other surface on the opposite side, and a waveguide that is optically coupled to the optical element is provided on one surface of the mount substrate or A photoelectric conversion device provided on the mount substrate along the other surface has been proposed.

  With this photoelectric conversion device, the overall height of the device in the thickness direction of the mount substrate can be suppressed, and the device can be reduced in height.

  Further, the applicant of the present application may improve the degree of freedom of the wiring pattern of the mounting substrate by interposing a wiring substrate that changes the electrode pattern between one surface or the other surface of the mounting substrate and the electrical connector. It has also been proposed to make it possible, but in such a photoelectric conversion device, it is desired to further reduce the height of the device.

  In view of such a demand, an object of the present invention is to provide a photoelectric conversion device that can improve the degree of freedom of the wiring pattern of the mount substrate and can reduce the height of the device.

  The present invention relates to an optical element that converts an electrical signal into an optical signal or an optical signal into an electrical signal, an IC circuit for transmitting an electrical signal to or receiving an electrical signal from the optical element, and the optical element And a waveguide optically coupled to the optical element, the waveguide being along one surface of the mount substrate on which the optical element is mounted or the other surface on the opposite side. In this way, the photoelectric conversion device provided on the mount substrate, on the one surface on which the optical element of the mount substrate is mounted or on the other surface on the opposite side, an external connector and an electrical connector portion that can be attached and detached, A three-dimensional circuit board is provided, in which an electrode pattern is changed between an electrical connector part and the mount board, and a wiring board part electrically connected to the mount board is integrally provided. It is.

  According to the present invention, since the three-dimensional circuit board integrally having the electrical connector portion and the wiring board portion is provided on one side or the other side of the mounting board, the wiring board is provided on one side or the other side of the mounting board. It is possible to reduce the height of the apparatus as compared with providing an electrical connector. In addition, since the wiring board portion of the three-dimensional circuit board changes the electrode pattern between the electrical connector portion and the mounting board, the degree of freedom of the wiring pattern of the mounting board can be improved. In addition, since the number of parts can be reduced, the manufacturing process of the device can be simplified.

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

  First, with reference to FIGS. 1 to 7, the photoelectric conversion apparatus 1A previously proposed by the applicant will be described as a reference example. This photoelectric conversion device 1A includes a light emitting side photoelectric conversion unit (also referred to as an E / O module) 1A1 that is mounted on one wiring board 2 by fitting electrical connectors 6 and 7, and another wiring board 2. Similarly, a light-receiving side photoelectric conversion part (also referred to as an O / E module) 1A2 that is mounted by fitting the electrical connectors 6 and 7 and an external waveguide 9 that optically connects these conversion parts 1A1 and 1A2. I have.

  In the present specification, the vertical direction in FIG. 1 is referred to as the vertical direction, the direction orthogonal to the paper surface in FIG. 1 is referred to as the horizontal direction, and the right side in FIG. The left side of FIG. 1 is referred to as the front side and the right side is referred to as the rear side with respect to the light-receiving side photoelectric conversion unit 1A2.

  The light emission side photoelectric conversion unit 1A1 includes a mount substrate 3 having a rectangular shape extending in the front-rear direction in plan view. As shown in FIG. 2, a light emitting element 4A that converts an electric signal into an optical signal to emit light and an IC for transmitting the electric signal to the light emitting element 4A are provided on one surface 3a that is the lower surface of the mount substrate 3. An IC substrate 5A on which a circuit 50A is formed is mounted, and a header type electrical connector (hereinafter simply referred to as “header”) 6 is provided so as to cover these 4A and 5A from below. In addition, on one surface 3a of the mount substrate 3, a driving power supply line and a signal line for the light emitting element 4A are formed by a wiring pattern 36 (see FIG. 4). Further, the mount substrate 3 is provided with a mirror portion 33 that converts an optical path of light emitted by the light emitting element 4A by approximately 90 ° at a position directly above the light emitting element 4A, and optically connected to the light emitting element 4A. An internal waveguide 31 to be coupled is provided so as to extend from the mirror portion 33 to the front end surface 3 b of the mount substrate 3.

  The light emitting element 4A has a shape of a square plate that is flat in the vertical direction, emits light upward from the upper surface, and is mounted on the one surface 3a of the mount substrate 3 from the light emitting side. As the light emitting element 4A, a VCSEL (Vertical Cavity Surface Emitting Laser) which is a semiconductor laser is employed. The IC substrate 5A is a driver IC that drives the VCSEL, has a shape of a square plate that is flat in the vertical direction, 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 wiring pattern 36 of the mount substrate 3 by bumps 11 (see FIG. 3) made of gold or solder. In addition, although LED etc. are employable as the light emitting element 4A, since LED etc. have no directivity and the ratio of optical coupling to the internal waveguide 31 is small, it is a condition that there is a margin in light efficiency, In that case, it is advantageous in terms of low price.

  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. Further, in the case of optical transmission, since optical 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 due to the influence of heat 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 mirror part 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 by anisotropic etching utilizing the difference in the etching rate of silicon crystals. For anisotropic etching, for example, a potassium hydroxide solution is used.

  The internal waveguide 31 is provided along one surface 3 a of the mount substrate 3, and transmits light emitted from the light emitting element 4 </ b> A in a direction parallel to the one surface 3 a of the mount substrate 3. The internal waveguide 31 is composed of two types of resins having different refractive indexes. Specifically, as shown in FIG. 3, the internal waveguide 31 includes a core 31a made of a resin having a high refractive index and a clad 31b made of a low refractive index resin that covers the core 31a from the periphery. These are disposed in a waveguide forming groove 32 formed in the mount substrate 3. The sizes of the core 31a and the clad 31b are determined from light loss calculation based on the divergence angle of the light emitting element 4A and the light receiving diameter of the light receiving element 4B described later. In addition to the resin, the internal waveguide 31 may be made of an inorganic material as long as it is a light transmissive material such as quartz.

  The waveguide forming groove 32 can be formed by anisotropic etching as in the case of forming the 45 ° inclined surface. In addition to anisotropic etching, there is a dry etching forming method such as reactive ion etching for forming the waveguide forming groove 32.

  As shown in FIGS. 4 and 5A and 5B, when the waveguide forming groove 32 having a substantially rectangular cross section and the 45 ° inclined surface are formed by anisotropic etching, the etching conditions are different. That is, the composition of the etching solution is different. Therefore, it is necessary to perform etching in two steps. However, either may be performed first.

  Alternatively, when the waveguide forming groove 32 is formed simultaneously with the 45 ° inclined surface, as shown in FIGS. 5C and 5D, the waveguide forming groove 32 has a substantially trapezoidal cross section. The groove width of the waveguide forming groove 32 is increased. The waveguide forming groove 32 has no problem as long as it does not cover the bonding pad for the light emitting element 4A. Therefore, this is also possible.

  The external waveguide 9 is bonded to the front end surface 3b of the mount substrate 3 by an optical adhesive, and the internal waveguide 31 is optically coupled to the external waveguide 9 by this bonding. become. If the distance from the mirror portion 33 to the external waveguide 9 is short, there is a case where the loss is small even if light is simply propagated in the air. In this case, the internal waveguide 31 is omitted. The light may be directly incident on the external waveguide 9 from the mirror unit 33.

  As the external waveguide 9, it is more convenient to use a flexible film-like one in which the resin optical waveguide is thinned. That is, the film-like external waveguide 9 is excellent in flexibility, and there is no problem even if it is used for a bent portion of, for example, a mobile phone. Depending on the bending curvature, light loss may occur, but this can be reduced by increasing the refractive index difference between the core and the cladding. The external waveguide 9 may be a silica fiber or a plastic fiber other than the film-like one.

  The header 6 is detachable from a socket type electrical connector (hereinafter simply referred to as “socket”) 7 which is an external connector provided on the wiring board 2. The header 6 and the socket 7 can be interchanged with each other, the socket 7 is provided on the mount board 3, the header 6 is provided on the wiring board 2, and the header 6 may be an external connector.

  As shown in FIG. 6A, the socket 7 has a substantially rectangular shape extending in the front-rear direction in a plan view. The socket 7 includes a socket main body 72 and a terminal 71 held by the socket main body 72. The socket main body 72 is provided with a fitting recess 72a having a rectangular frame shape in plan view. The terminal 71 is exposed in the fitting recess 72a. Further, the end portion of the terminal 71 protrudes from the socket main body 72 in the left-right direction, and this end portion is connected to a not-illustrated wiring pattern formed on the upper surface of the wiring substrate 2 by unillustrated solder or the like. The socket 7 is usually mounted on the wiring board 2 by reflow.

  On the other hand, as shown in FIG. 6B, the header 6 has a substantially rectangular shape extending in the front-rear direction that is slightly smaller than the socket 7 in a bottom view. The header 6 includes a header main body 62 and terminals 61 held by the header main body 62. The header main body 62 has a rectangular frame in bottom view that can be fitted into the fitting recess 72a of the socket 7. A fitting projection 62a is provided, and the terminal 61 is exposed on the surface of the fitting projection 62a. Further, the end portion of the terminal 61 protrudes in the left-right direction from the header body 62, and this end portion is connected to the wiring pattern 36 of the mount substrate 3 by the solder ball 10. Further, for mounting the header 6 on the mount substrate 3, it is possible to use terminal posts, pins, etc. in addition to the solder balls. The height including the mount substrate 3 and the solder ball 10 is about 1 mm.

  Then, when the fitting convex part 62a of the header 6 is inserted into the fitting concave part 72a of the socket 7 and they are fitted, the terminals 61 and 71 come into contact with each other and the wiring pattern of the wiring board 2 and the wiring pattern of the mount board 3 36 is electrically connected. At this time, the height from the lower surface of the socket 7 to the upper surface of the header 6 is about 1 mm. For this reason, the height from the upper surface of the wiring board 2 to the other surface 3c serving as the upper surface of the mount board 3 when the light emitting side photoelectric conversion part 1A1 is mounted on the wiring board 2 is about 2 mm.

  Since the basic configuration of the light-receiving side photoelectric conversion unit 1A2 is the same as that of the light-emitting side photoelectric conversion unit 1A1, detailed description thereof is omitted. The light-emitting side photoelectric conversion unit 1A1 is different from the light-emitting side photoelectric conversion unit 1A1 in that a light receiving element 4B that receives light on one surface 3a of the mount substrate 3 and converts an optical signal into an electric signal, as shown in FIG. An IC substrate 5B on which an IC circuit 50B for receiving an electrical signal from 4B is formed is mounted. PD is adopted 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.

  In the photoelectric conversion apparatus 1A of the reference example as described above, the header 6 is provided on the one surface 3a of the mount substrate 3 on which the light emitting element 4A or the light receiving element 4B is mounted, and the internal waveguide 31 is connected to one of the mount substrates 3. Since it is provided so as to extend in a direction parallel to the direction 3a, the height of the entire device in the plate thickness direction of the mount substrate 3 can be suppressed, and the height of the device can be reduced.

  Next, with reference to FIGS. 8-10, the photoelectric conversion apparatus 1B which concerns on one Embodiment of this invention is demonstrated. Since this photoelectric conversion apparatus 1B is an improvement of the photoelectric conversion apparatus 1A of the reference example, the same components as those of the reference example are denoted by the same reference numerals, and description thereof is omitted. Also in this photoelectric conversion device 1B, the light receiving side photoelectric conversion unit is the same as the light emission side photoelectric conversion unit, and therefore only the light emission side photoelectric conversion unit 1B1 will be illustrated and described.

  In the light emission side photoelectric conversion unit 1B1 of the present embodiment, the three-dimensional circuit board 8 is provided on the one surface 3a of the mount board 3. The three-dimensional circuit board 8 is obtained by forming an electric circuit on the surface of an integrally molded product made of insulating resin, ceramic, or a combination thereof.

  Specifically, the three-dimensional circuit board 8 integrally includes a wiring board part 8b facing the mount board 3 and an electrical connector part 8a protruding downward from the wiring board part 8b.

  The electrical connector portion 8a is detachable from the socket 7 which is an external connector. As shown in FIG. 10, the resin structure portion 81 extending downward while the cross-sectional shape is rectangular, and the resin structure portion A plurality of electrodes 82 formed on the lower surface of 81, and a terminal portion 83 extending upward from the electrode 82 along the side surface of the resin structure portion 81.

  On the other hand, as shown in FIG. 9, the socket 7 has a fitting recess 72a having a rectangular shape in plan view in which the electrical connector portion 8 of the three-dimensional circuit board 8 can be fitted, and the bottom surface of the fitting recess 72a. The terminal 71 is exposed. And when the electrical connector part 8a is inserted in the fitting recessed part 72a and they are fitted, the electrode 82 will contact the terminal 71 from upper direction, and they will come to be electrically connected.

  The wiring board portion 8b has a rectangular plate-like structure portion 84 that is substantially the same size as the one surface 3a of the mount substrate 3, and the electrical connector portion 8a is connected to the center portion of the lower surface of the structure portion 84. The resin structure part 81 protrudes downward. On the upper surface of the structure portion 84 facing the mount substrate 3, electrodes 86 are formed at positions corresponding to the electrodes formed by the wiring pattern 36 (see FIG. 4) of the mount substrate 3. The wiring board portion 8 b is electrically connected to the mount substrate 3 by being individually connected to the electrodes of the mount substrate 3 by the solder balls 10.

  The wiring board portion 8b is formed with a wiring portion 85 extending along the side surface and the lower surface of the structure portion 84 and connecting the electrode 86 and the upper end portion of the terminal portion 83 of the electrical connector portion 8a. That is, the wiring board portion 8 b changes the electrode pattern by converting the electrode pitch between the electrical connector portion 8 a and the mount substrate 3 by the wiring portion 85.

  In the three-dimensional circuit board 8, the number of the electrodes 86 of the wiring board portion 8b and the number of the electrodes 82 of the electric connector portion 8a do not necessarily correspond one-to-one. It is also possible to reduce the number of electrodes 82 of the electrical connector portion 8a.

  Thus, in the photoelectric conversion apparatus 1B of the present embodiment, since the three-dimensional circuit board 8 integrally including the electrical connector portion 8a and the wiring board portion 8b is provided on the one surface 3a of the mount substrate 3, one surface of the mount substrate 3 is provided. The apparatus can be reduced in height compared to providing a wiring board on 3a and providing an electrical connector on the wiring board. Moreover, since the wiring board portion 8b of the three-dimensional circuit board 8 changes the electrode pattern between the electrical connector portion 8a and the mounting board 3, the degree of freedom of the wiring pattern 36 of the mounting board 3 can be improved. it can. In addition, since the number of parts can be reduced, the manufacturing process of the device can be simplified.

  In the present embodiment, the photoelectric conversion device 1B is a one-way communication type in which an optical signal is transmitted from the light emission side photoelectric conversion unit 1B1 to the light reception side photoelectric conversion unit. Is a bidirectional communication type in which the light receiving element 4B is mounted on the light emitting side photoelectric conversion unit 1B1, the light emitting element 4A is mounted on the light receiving side photoelectric conversion unit, and a plurality of waveguides 31 are formed on the mount substrate 3. It may be a thing. Moreover, the photoelectric conversion apparatus 1B should just be equipped with at least one of the light emission side photoelectric conversion part 1B1 or the light reception side photoelectric conversion part. Further, in both the one-way communication type and the two-way communication type, one-channel communication has been described. However, multi-channel communication may be performed by mounting an array-shaped light emitting / receiving element. Alternatively, a structure in which a plurality of waveguides are formed may be used.

  Furthermore, the three-dimensional circuit board 8 does not have to be provided on the one surface 3a of the mount substrate 3. If the through electrode is provided on the mount substrate 3 and a wiring pattern is formed on the other surface 3c, the light emitting element 4A is mounted. It is also possible to provide on the other surface 3c opposite to the one surface 3a.

  Although not shown, a through hole is provided at a position corresponding to the light emitting element 4 </ b> A of the mount substrate 3, the external waveguide 9 is joined to the other surface 3 c of the mount substrate 3, and the end of the external waveguide 9 is further connected. It is also possible to provide the external waveguide 9 along the other surface 3c of the mount substrate 3 and omit the internal waveguide 31 by providing a mirror portion on the through hole.

It is a schematic block diagram of the photoelectric conversion apparatus of a reference example, and the wiring board to which this photoelectric conversion apparatus is connected. It is the figure which decomposed | disassembled the light emission side photoelectric conversion part of the photoelectric conversion apparatus of a reference example. (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 the perspective view which looked at the mount board | substrate of the state before providing a waveguide from the downward direction. (A) is a bottom view of the mount substrate, (b) is a cross-sectional view of (a), (c) is a bottom view of the mount substrate of a modified example, and (d) is a cross-sectional view of (c). (A) is a perspective view of a socket type electrical connector, (b) is a perspective view of a header type electrical connector. It is the figure which decomposed | disassembled the light-receiving side photoelectric conversion part of the photoelectric conversion apparatus of a reference example. 1 is a schematic configuration diagram of a photoelectric conversion apparatus according to an embodiment of the present invention and a wiring board to which the photoelectric conversion apparatus is connected. (A) is a top view of a socket, (b) is the II sectional view taken on the line of (a). It is a bottom view of a three-dimensional circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1B Photoelectric conversion apparatus 2 Wiring board 3 Mount board 3a One side 3c The other side 31 Internal waveguide 4A Light emitting element 4B Light receiving element 5A, 5B IC board 50A, 50B IC circuit 6 Header type electrical connector 7 Socket type electrical connector 8 Three-dimensional circuit Board 8a Electrical connector part 8b Wiring board part 9 External waveguide

Claims (1)

An optical element that converts an electrical signal into an optical signal or an optical signal into an electrical signal, an IC circuit for transmitting an electrical signal to or receiving an electrical signal from the optical element, and the optical element are mounted A mount substrate and a waveguide optically coupled to the optical element, the waveguide being disposed along one surface of the mount substrate on which the optical element is mounted or the other surface on the opposite side. The photoelectric conversion device provided in the
On one surface of the mount substrate on which the optical element is mounted or on the other surface on the opposite side, an external connector and an detachable electrical connector portion, and an electrode pattern between the electrical connector portion and the mount substrate are changed. An optoelectric conversion device comprising a three-dimensional circuit board integrally including a wiring board portion electrically connected to the mount board.

Images