JP4899762B2 - 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. 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.

  In such a photoelectric conversion apparatus, it is desired to reduce the height of the apparatus by suppressing the height of the electrical connector that can be attached to and detached from the external connector.

  An object of the present invention is to provide a photoelectric conversion device that can further reduce the height of the device, simplify the number of manufacturing steps, and reduce the number of components.

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 substrate on which the optical element and the IC circuit is mounted on one side, provided on the mount substrate formed waveguide forming groove along this one side, extends to the end surface of the mounting substrate, the mounting substrate An internal waveguide that is joined to the external waveguide at the end face of the mounting board, and an electrical connector that is provided on one side of the mount board and is detachable from the external connector, and the housing of the electrical connector is provided on one side of the mount board. It is characterized by being integrated.

  According to a second aspect of the present invention, in the photoelectric conversion device according to the first aspect, when the mount substrate is formed, the terminals of the electric connector connected to the wiring pattern of the mount substrate are simultaneously insert-molded, so that the housing It is characterized by being integrated.

  According to a third aspect of the present invention, in the photoelectric conversion device according to the first or second aspect, the mount substrate is formed of any one of ceramic, thermoplastic resin, and thermosetting resin, or a combination thereof. It is characterized by this.

According to the present invention, on one surface of the mount substrate and mounting the optical element and the IC circuit, provided inside the waveguide to waveguide forming groove formed in the mounting substrate along this one side In addition, since the housing of the electrical connector is integrated on this one surface, it is not necessary to connect the electrical connector to the wiring pattern of the mount board with solder balls, so that positioning work and connection work are unnecessary. As a result, the number of manufacturing steps is simplified, and a space for connection is not required, so that the height of the apparatus can be further reduced. Further, since an interposer substrate for converting the electrode pitch between the wiring pattern of the mount substrate and the electrical connector is not necessary, the number of components can be reduced.

  According to the second aspect of the present invention, since the terminal of the electrical connector connected to the wiring pattern of the mount board is insert-molded at the same time when the mount board is molded, the housing of the electrical connector can be integrated with the mount board. The housing can be easily integrated.

  As in the third aspect of the invention, the mount substrate and the electrical connector can be injection-molded or press-molded by molding the mount substrate with any one of ceramic, thermoplastic resin, thermosetting resin, or a combination thereof. At the same time, the terminal can be easily insert-molded.

  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 type 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, a housing of a header (header type electrical connector) 6 is integrated with one surface 3a of the mount substrate 3.

  That is, as shown in FIGS. 8A and 8B, a plurality (four in this example) of metal terminals (male terminals) 61 are provided at almost four corners of the one surface 3a of the mount substrate 3, respectively. The rectangular header 6 is integrally formed, and each terminal 61 is connected to the wiring pattern 36 (see FIG. 4) of the mount substrate 3.

  Each terminal 61 is insert-molded at the same time when the mount substrate 3 is formed, so that the housing of the header 6 is integrally formed on the mount substrate 3. Note that it is possible to insert mold simultaneously with the same material as the mount substrate 3 or insert mold simultaneously with a material different from the mount substrate 3.

  Although the mount substrate 3 is made of silicon in the reference example, in the present embodiment in which the header 6 is integrally formed with the mount substrate 3, the mount substrate 3 is made of ceramic, thermoplastic resin, or thermosetting resin from the viewpoint of formability. Any one or a combination thereof is preferable.

  Examples of the ceramic include aluminum oxide, zirconia, and aluminum nitride.

  As thermoplastic resins, polyamide (PA), liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyacetal (POM), polybutylene terephthalate (PBT), polycarbonate (PC), polyether ether ketone (PEEK), ABS resin Etc.

  Examples of the thermosetting resin include epoxy resin, silicone resin, unsaturated polyester resin, phenol resin, polyimide resin, diallyl phthalate resin, polyurethane resin, melanin resin, and fluorine resin.

  As shown in FIGS. 9A and 9B, the socket body 72 of the socket 7 has a corresponding number (four in this example) of metal terminals (4 in this example) at positions facing the terminals 61 of the header 6. Female terminal) 71.

  Note that the number of the ends of the terminals 71 projecting from the socket main body 72 in the left-right direction is not the same as the number of the terminals 71 facing the respective terminals 61 of the header 6 (the former is 20 and the latter is 16). This is because a plurality of branches may occur between a terminal 71 at a position facing each terminal 61 of the header 6 and an end portion of the terminal 71 projecting from the socket body 72 in the left-right direction.

  In the socket main body 72, the electrode pitch is converted between the terminal 71 at a position facing each terminal 61 of the header 6 and the end of the terminal 71 projecting from the socket main body 72 in the left-right direction. The socket 7 also serves as an interposer substrate for converting the electrode pitch.

  Then, as shown in FIG. 10, when each terminal 61 of the header 6 of the mount board 3 is inserted into the terminal 71 of the socket 7 of the wiring board 2 and they are fitted, the terminals 61 and 71 come into contact with each other and the wiring board 2 and the wiring pattern 36 of the mount substrate 3 are electrically connected.

  At this time, a space corresponding to the protruding height H of the header 6 is generated between the mount substrate 3 and the socket 7, and the light emitting element 4 </ b> A and the IC substrate 5 </ b> A can be rationally accommodated in this space.

  In the embodiment, since the housing of the header 6 is integrated with the mount substrate 3, it is not necessary to connect the header 6 to the wiring pattern 36 of the mount substrate 3 with solder balls or the like. The connection work is not required and the number of manufacturing steps is simplified, and a space for connection is not required, so that the apparatus can be reduced in height.

  Further, since an interposer substrate for converting the electrode pitch between the wiring pattern 36 of the mount substrate 3 and the header 6 is not necessary, the number of components can be reduced.

  Furthermore, since the terminal 61 of the header 6 connected to the wiring pattern 36 of the mount substrate 3 is insert-molded at the same time when the mount substrate 3 is molded, the housing of the header 6 can be integrated with the mount substrate 3. Can be easily integrated.

  Further, by molding the mount substrate 3 with any one of ceramic, thermoplastic resin, and thermosetting resin, or a combination thereof, the mount substrate 3 and the header 6 can be injection-molded and press-molded. 61 can be easily insert-molded.

  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.

  Furthermore, the header 6 does not need 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 it on the other surface 3c opposite to the one surface 3a. As in the reference example, the header 6 and the socket 7 can be interchanged.

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 mount board | substrate which integrated the housing of the header of the photoelectric conversion apparatus which concerns on one Embodiment of this invention, (a) is a front view, (b) is a bottom view. It is a socket, (a) is a top view, (b) is a front view. It is the front view which made the header and socket of the mount board concerning one embodiment of the present invention fit.

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 4A Light emitting element 4B Light receiving element 5A, 5B IC board 50A, 50B IC circuit 6 Header type electrical connector 61 Terminal 7 Socket type Electrical connector 71 Terminal 9 External waveguide

Claims (3)

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 the IC circuit A mount substrate mounted on one surface, and provided in a groove for forming a waveguide formed on the mount substrate along the one surface, extends to the end surface of the mount substrate, and is connected to the external waveguide on the end surface of the mount substrate. and an internal waveguide to be joined, provided on one surface of the mounting substrate, and an electrical connector detachable and external connector, said electrical connector housing to one surface of said mounting substrate are integrated A photoelectric conversion device.   2. The photoelectric conversion apparatus according to claim 1, wherein the housing is integrated by simultaneously insert-molding the terminals of the electrical connector connected to the wiring pattern of the mount substrate when the mount substrate is formed. .   3. The photoelectric conversion apparatus according to claim 1, wherein the mount substrate is formed of any one of ceramic, thermoplastic resin, and thermosetting resin, or a combination thereof.

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