JP4779920B2 - Photoelectric conversion device - Google Patents

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. In place of the light emitting element, a light receiving element that converts a received optical signal into an electric signal may be used.

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.

  In such a photoelectric conversion device, an interposer substrate (intermediate substrate) is disposed between the mount substrate and the electrical connector, and the electrode pattern is converted by the interposer substrate to electrically connect the mount substrate and the electrical connector. However, since the number of parts increases by the amount corresponding to the interposer substrate and the cost increases, it is desired to further reduce the number of parts.

  In view of such a demand, an object of the present invention is to provide a photoelectric conversion apparatus that can reduce the number of components while protecting a wiring pattern of a mount substrate.

  The invention of claim 1 is an optical element that converts an electrical signal into an optical signal or an optical signal into an electrical signal, and an IC circuit that transmits an electrical signal to or receives an electrical signal from the optical element, A mounting board on which the optical element is mounted; an electrical connector that can be attached to and detached from an external connector; and a waveguide that is optically coupled to the optical element, wherein the electrical connector is provided on one surface of the mounting board. The waveguide is a photoelectric conversion device provided on the mount substrate along one surface of the mount substrate or the other surface on the opposite side thereof, and the substrate-side wiring formed on the one surface of the mount substrate Columnar wiring standing on the pattern, an insulating sealing body that covers one surface of the mount substrate with a thickness that allows the columnar wiring to be included without leaving the tip, and exposed to the outer surface of the sealing body Columnar arrangement A sealing body-side wiring pattern formed on the outer surface of the sealing body in a state of being electrically connected to the sealing body, and the sealing body-side wiring pattern is disposed at an arrangement interval corresponding to the terminals of the electrical connector. It has a stationary-side terminal portion.

  According to a second aspect of the present invention, in the photoelectric conversion apparatus according to the first aspect, the optical element and the IC circuit are provided on one surface of the mount substrate and are covered by the sealing body. It is characterized by.

  According to the first aspect of the present invention, the mounting substrate and the electrical connector can be electrically connected by rationally using the sealing body that seals and protects the wiring pattern on the substrate side of the mounting substrate. The interposer substrate (intermediate substrate) becomes unnecessary, and the number of parts can be reduced.

  In addition, since the columnar wiring is erected on the mounting substrate and the mounting substrate and the electrical connector are electrically connected via the columnar wiring, the diameter of the columnar wiring is usually 100 microns or less. Unlike the case where the mount substrate and electrical connector are connected using an interposer substrate connected to the mount substrate with a solder ball of about several hundred microns, the area occupied by the wiring pattern on the substrate side of the mount substrate is used with the above interposer substrate. Can be made smaller. Thereby, the size of the mount substrate can be easily reduced.

  Further, the substrate-side wiring pattern of the mount substrate can be sealed by the sealing body to protect it from moisture and dust.

  According to the invention of claim 2, the optical element and the IC circuit are further sealed and protected by the sealing body, and the heat generated in the optical element and the IC circuit is quickly transferred to the sealing body, thereby releasing heat. Can be improved.

  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 4 A of light emitting elements, LED etc. are difficult to oscillate at high speed compared with laser diodes, such as VCSEL, and use in the transmission band below several hundred MHz is a condition, and in that case 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. In addition to silicon, the mount substrate 3 is made of a compound semiconductor such as GaAs of the same system as the VCSEL material or a ceramic such as aluminum nitride. May be.

  The mirror part 33 can be formed by depositing gold, silver, copper or aluminum on a 45 ° inclined surface formed by etching the mount substrate 3 by a method such as vapor deposition or sputtering. The 45 ° inclined surface can be formed by anisotropic etching utilizing the difference in the etching rate of silicon crystals. For the anisotropic etching, for example, a strong alkali such as a potassium hydroxide aqueous solution or a TMAH (tetramethylammonium hydroxide) aqueous 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 part 1B1 of this embodiment, as shown in FIG. 8, a sealing body 37 is provided on one surface 3a of the mount substrate 3 made of silicon resin. The mount substrate 3 and the header 6 are electrically connected.

  That is, as shown in FIG. 9, the wiring pattern (substrate-side wiring pattern) 36 formed on the one surface 3a of the mount substrate 3 includes the external electrical connection terminal portion 36a, the wiring portion 36b, the light emitting element 4A and It is comprised by the terminal part 36c for IC board 5A. As shown in FIGS. 8 and 10, columnar wiring 38 is erected on the external electrical connection terminal portion 36 a of the wiring pattern 36 so as to extend substantially perpendicular to the one surface 3 a of the mount substrate 3. Yes. The columnar wiring 38 is formed by stacking metal in a columnar shape on each external electrical connection terminal portion 36a of the mount substrate 3 by a plating method or the like.

  Further, a sealing body 37 made of an insulating resin (commercially available chip size package sealing resin, for example, “CV8710” material or “CV8510” material manufactured by Matsushita Electric Works) is provided on one surface 3a of the mount substrate 3. Is provided. The sealing body 37 wraps the entirety of the light emitting element 4A and the IC substrate 5A, and includes the columnar wiring 38 leaving the tip end portion 38a. Accordingly, the columnar wiring 38 has a form in which the tip end portion 38 a is exposed on the outer surface (lower surface) of the sealing body 37. The sealing body 37 has a function of sealing the wiring pattern 36, the light emitting element 4A, and the IC substrate 5A on the mount substrate 3 and protecting them from moisture, dust, and the like.

  A rearrangement wiring pattern (sealing body side wiring pattern) 39 is formed on the lower surface of the sealing body 37. The rearrangement wiring pattern 39 includes a rearrangement wiring portion 39a and a rearrangement terminal portion 39b. The rearrangement wiring portion 39a is electrically connected to the tip end portion 38a of the columnar wiring 38 exposed on the outer surface of the sealing body 37. Connected to. Thereby, the wiring pattern 36 and the rearranged wiring pattern 39 are electrically connected by the columnar wiring 38.

  Further, the rearrangement terminal portions 39b are positioned and formed so that the arrangement interval (pitch) thereof is substantially equal to the pitch of the terminals 61 of the header 6. Therefore, in this embodiment, the sealing body 37, the columnar wiring 38, and the rearrangement wiring pattern 39 also serve as an interposer substrate (intermediate substrate). In the present embodiment, for convenience of illustration, the number of terminals 61 of the header 6 is different from that of the reference example.

  In the above configuration, the number of the external electrical connection terminal portions 36a and the rearrangement terminal portions 39b do not necessarily correspond one-to-one, and the outer surface of the sealing body 37 while collecting the plurality of columnar wires 38 together. It is also possible to connect to the rearranged wiring pattern 39 on the outer surface of the sealing body 37. Therefore, it is possible to reduce the number of terminals of the header 6 and the socket 7 by consolidating the electric lines with the columnar wiring 38.

  With this configuration, the degree of freedom of the wiring pattern 36 of the mount substrate 3 can be improved. That is, since the light emitting element 4 </ b> A and the IC substrate 5 </ b> A are mounted on the mount substrate 3, it is difficult to match the external electrical connection terminal portion 36 a of the wiring pattern 36 of the mount substrate 3 with the terminal 61 of the header 6. In such a case, the above terminal number conversion method is particularly effective.

  In the embodiment, since the sealing body 37 that seals and protects the wiring pattern 36 of the mount substrate 3 can be rationally used, the mount substrate 3 and the header 6 can be electrically connected. The interposer substrate (intermediate substrate) is not required, and the apparatus can be further reduced in height and the number of components can be reduced.

  Further, by arranging the columnar wiring 38 on the mount substrate 3 and electrically connecting the mount substrate 3 and the header 6 via the columnar wiring 38, the diameter of the columnar wiring 38 is usually one hundred microns. Unlike the case where the mount substrate and the electrical connector are connected using an interposer substrate connected to the mount substrate with a solder ball of about several hundred microns, the external electrical connection terminal portion 36a on the mount substrate 3 is as follows. Can be made smaller than when the interposer substrate is used. Thereby, the size of the mount substrate 3 can be reduced as shown in FIG.

  Further, the wiring pattern 36 of the mount substrate 3 can be sealed by the sealing body 37 to protect it from moisture and dust.

  In addition, the sealing body 37 further seals and protects the light emitting element 4A and the IC substrate 5A, and also quickly dissipates heat generated in the light emitting element 4A and the IC substrate 5A to the sealing body 37. Can be improved.

  In the present embodiment, as the photoelectric conversion device 1B, 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 shown. 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. There may be. 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.

  Further, both the light emitting element 4A and the IC substrate 5A are provided on the one surface 3a of the mount substrate 3. However, the present invention is not limited to this, and both or either of the light emitting element 4A and the IC substrate 5A is the other of the mount substrate 3. It may be provided in the direction 3c.

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. It is the schematic front view which showed the mount board | substrate and header of the photoelectric conversion apparatus which concern on one Embodiment of this invention. It is the schematic perspective view which looked at the mount board of the photoelectric conversion apparatus concerning one embodiment of the present invention from the lower part. It is the schematic perspective view which showed the state which provided the sealing body in the mount board | substrate of the photoelectric conversion apparatus which concerns on one Embodiment of this invention. It is the schematic perspective view which looked at the mount board | substrate of the photoelectric conversion apparatus which concerns on the modification of one Embodiment of this invention from the downward direction.

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 36 Wiring pattern 36a Terminal part for external electrical connection 37 Sealing body 38 Columnar wiring 38a Tip part 39 Relocation wiring pattern 39a Relocation wiring Part 39b Rearrangement terminal part 4A Light emitting element 4B Light receiving element 5A, 5B IC substrate 50A, 50B IC circuit 6 Header type electrical connector 7 Socket type electrical connector 9 External waveguide

Claims (2)

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 mounting substrate; an electrical connector that can be attached to and detached from an external connector; and a waveguide that is optically coupled to the optical element, wherein the electrical connector is provided on one surface of the mounting substrate, and the waveguide is A photoelectric conversion device provided on the mount substrate along one surface of the mount substrate or the other surface on the opposite side,
Columnar wiring standing on a substrate-side wiring pattern formed on one surface of the mounting substrate;
An insulating sealing body that covers one surface of the mount substrate with a thickness that can include the columnar wiring leaving the tip; and
A sealing body-side wiring pattern formed on the outer surface of the sealing body in a state of being electrically connected to the columnar wiring exposed on the outer surface of the sealing body;
The said sealing body side wiring pattern has the sealing body side terminal part arrange | positioned by the arrangement space | interval corresponding to the terminal of the said electrical connector, The photoelectric conversion apparatus characterized by the above-mentioned.   2. The photoelectric conversion apparatus according to claim 1, wherein the optical element and the IC circuit are provided on one surface of the mount substrate and are enclosed by the sealing body.

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