Photoelectric conversion device

Abstract

In a photoelectric conversion device (1), an optical element (2) converts a received transmission electric signal into a transmission optical signal by emitting light on the basis of the transmission electric signal, or converts a received reception optical signal into a reception electric signal. An integrated circuit (3) transmits the transmission electric signal to the optical element (2) or receives the reception electric signal from the optical element (2). The optical element (2) is mounted on a first substrate (4). An electrical connector (5) is configured to be detachable from an external connector (CN1) and is electrically connected to the integrated circuit (3). A second substrate (6) has a first surface (61) and a second surface (62) that faces the first surface (61), with the first substrate (4), the integrated circuit (3), and the electrical connector (5) being mounted on the first surface (61).

Description

Photoelectric conversion device

[0001] The present disclosure relates to optical-to-electrical conversion devices.

[0002] The photoelectric conversion device disclosed in Patent Document 1 includes an interposer substrate, a mount substrate, an IC substrate, a light-emitting element, and an electrical connector. The IC substrate and the light-emitting element are mounted on the mount substrate. The mount substrate and the electrical connector are physically and electrically connected to the interposer substrate by solder balls.

[0003] The IC substrate outputs an electrical signal to the light-emitting element. The light-emitting element converts the electrical signal into an optical signal by emitting light in response to the received electrical signal. The IC substrate is electrically connected to the interposer substrate via the mount substrate and solder balls.

[0004] JP 2008-65287 A

[0005] In a photoelectric conversion device such as that disclosed in Patent Document 1, an integrated circuit (IC substrate) is electrically connected to an electrical connector and optical elements (light-emitting elements, light-receiving elements). Further reduction of electrical loss is required in such a photoelectric conversion device.

[0006] An optical-electrical conversion device according to one aspect of the present disclosure includes an optical element, an integrated circuit, a first substrate, an electrical connector, and a second substrate. The optical element converts a received transmission electrical signal into a transmission optical signal by emitting light based on the received transmission electrical signal, or converts a received optical signal into a reception electrical signal. The integrated circuit transmits the transmission electrical signal to the optical element or receives the reception electrical signal from the optical element. The optical element is mounted on the first substrate. The electrical connector is configured to be detachable from an external connector and is electrically connected to the integrated circuit. The second substrate has a first surface and a second surface opposite the first surface, and the first substrate, the integrated circuit, and the electrical connector are mounted on the first surface.

[0007] The present disclosure has an effect of reducing electrical loss.

[0008] Fig. 1 is a side view showing an opto-electrical conversion device according to an embodiment. Fig. 2 is a bottom view showing the same opto-electrical conversion device. Fig. 3 is a side view showing a modified example of an optical element in the same opto-electrical conversion device. Fig. 4 is a bottom view showing the same opto-electrical conversion device. Fig. 5 is a side view showing a waveguide of the same opto-electrical conversion device. Fig. 6 is a cross-sectional view showing a waveguide of the same opto-electrical conversion device. Fig. 7 is a diagram showing an opto-electrical conversion system including the same opto-electrical conversion device.

[0009] The present disclosure generally relates to an optical-electrical conversion device, and more particularly to an optical-electrical conversion device having at least one of a function of converting an electrical signal into an optical signal and a function of converting an optical signal into an electrical signal.

[0010] Photoelectric conversion devices according to embodiments will be described below with reference to the drawings. However, the following embodiment is merely one of various embodiments of the present disclosure. The following embodiment can be modified in various ways depending on the design, etc., as long as it can achieve the object of the present disclosure and does not deviate from the technical concept of the present disclosure. Furthermore, each figure described in the following embodiment is a schematic diagram, and the ratios of the sizes and thicknesses of the components in the figures do not necessarily reflect the actual dimensional ratios.

[0011] (Embodiment) (1) Overview FIG. 1 shows a photoelectric conversion device 1 according to this embodiment.

[0012] The optical-electrical conversion device 1 includes an optical element 2, an integrated circuit 3, a first substrate 4, an electrical connector 5, and a second substrate 6. The optical element 2 has at least one of the following functions: converting a transmitted electrical signal into a transmitted optical signal by emitting light based on a received transmitted electrical signal, and converting a received optical signal into a received electrical signal. That is, the optical element 2 (1) can convert a transmitted electrical signal into a transmitted optical signal by emitting light based on a received transmitted electrical signal, (2) can convert a received optical signal into a received electrical signal, or (3) can convert a transmitted electrical signal into a transmitted optical signal and convert a received optical signal into a received electrical signal by emitting light based on a received transmitted electrical signal. The integrated circuit 3 has at least one of the following functions: transmitting a transmitted electrical signal to the optical element 2 and receiving a received electrical signal from the optical element 2. That is, the integrated circuit 3 (1) can transmit a transmitted electrical signal to the optical element 2, (2) can receive a received electrical signal from the optical element 2, or (3) can transmit a transmitted electrical signal to the optical element 2 and receive a received electrical signal from the optical element 2. The optical element 2 is mounted on the first substrate 4. The electrical connector 5 is configured to be detachable from the external connector CN1 and is electrically connected to the integrated circuit 3. The second substrate 6 has a first surface 61 and a second surface 62 opposing the first surface 61, and the first substrate 4, the integrated circuit 3, and the electrical connector 5 are mounted on the first surface 61.

[0013] In the photoelectric conversion device 1 having the above-described configuration, a large number of electrical paths (pattern portion 63 described below) for transmitting a large number of signals exist between the integrated circuit 3 and the electrical connector 5. Meanwhile, an electrical path (pattern portion 43 described below) for transmitting at least one of a transmission electrical signal and a reception electrical signal exists between the integrated circuit 3 and the optical element 2. In other words, the number of electrical paths existing between the integrated circuit 3 and the electrical connector 5 is greater than the number of electrical paths existing between the integrated circuit 3 and the optical element 2.

[0014] Therefore, in the photoelectric conversion device 1, the integrated circuit 3, the first substrate 4, and the electrical connector 5 are mounted on the first surface 61 of the second substrate 6. As a result, the electrical distance (wiring length) between the integrated circuit 3 and the electrical connector 5 in this embodiment is shorter than in a configuration in which the integrated circuit 3 is mounted on the first substrate 4 (corresponding to the configuration of Patent Document 1). However, the electrical distance between the integrated circuit 3 and the optical element 2 is longer than in a configuration in which the integrated circuit 3 is mounted on the first substrate 4 (corresponding to the configuration of Patent Document 1). However, as described above, the number of electrical paths between the integrated circuit 3 and the electrical connector 5 is greater than the number of electrical paths between the integrated circuit 3 and the optical element 2. Therefore, by shortening the electrical distance between the integrated circuit 3 and the electrical connector 5, the photoelectric conversion device 1 can reduce electrical loss.

[0015] 1 and 2 is a photoelectric conversion device 1A that includes a light-emitting element 2A as the optical element 2. The photoelectric conversion device 1A includes the light-emitting element 2A (optical element 2), an integrated circuit 3, a first substrate 4, an electrical connector 5, a second substrate 6, and a heat dissipation member 7.

[0016] 1 is defined as the up-down direction, the side of the second substrate 6 as viewed from the first substrate 4 is defined as the top, and the side of the first substrate 4 as viewed from the second substrate 6 is defined as the bottom. Also, in the following description, the direction in which the first substrate 4 and the electrical connector 5 are aligned is defined as the left-right direction, with the side of the electrical connector 5 as viewed from the first substrate 4 being the left, and the side of the first substrate 4 as viewed from the electrical connector 5 being the right. Also, the direction perpendicular to the up-down and left-right directions is defined as the front-rear direction. However, these definitions are intended to facilitate understanding of the photoelectric conversion device 1 and are not intended to define the direction in which the photoelectric conversion device 1 is used.

[0017] (2.1) Second Substrate The second substrate 6 is a rectangular plate-shaped interposer substrate, and has a first surface 61 and a second surface 62 that face each other in the vertical direction. In FIG. 1 , the first surface 61 corresponds to the bottom surface, and the second surface 62 corresponds to the top surface. Therefore, in the following description, the first surface 61 may be referred to as the bottom surface 61, and the second surface 62 may be referred to as the top surface 62. The bottom surface 61 and the top surface 62 are each rectangular. However, the second substrate 6 may have a shape other than a rectangular plate, and may be, for example, a circular plate, an elliptical plate, or a polygonal plate.

[0018] The integrated circuit 3, the first substrate 4, and the electrical connector 5 are mounted on the lower surface 61. The electrical connector 5 is mounted on the left side of the lower surface 61, the first substrate 4 is mounted on the right side of the lower surface 61, and the integrated circuit 3 is mounted between the electrical connector 5 and the first substrate 4 in the left-right direction. The methods for mounting the integrated circuit 3, the first substrate 4, and the electrical connector 5 on the lower surface 61 will be described later.

[0019] A pattern portion 63 is formed on the lower surface 61 of the second substrate 6. The pattern portion 63 forms an electrical path including conductors electrically connected to each pin of the electrical connector 5. In this embodiment, the number of pattern portions 63 forming the electrical path is the same as the number of pins of the electrical connector 5, which is three or more. The pattern portion 63 includes, as electrical paths, a signal path for transmitting signals and a power path for transmitting drive power. The second substrate 6 may be a multilayer substrate, a single-sided substrate, or a double-sided substrate.

[0020] (2.2) Electrical Connector The electrical connector 5 is a header-type connector having pin contacts. The electrical connector 5 is configured to be detachable from the external connector CN1 (see FIG. 1), which is a socket-type connector having socket contacts. Note that the electrical connector 5 may be a socket-type connector and the external connector CN1 may be a header-type connector.

[0021] The electrical connector 5 is mounted on the left side of the lower surface 61 of the second substrate 6. Each pin of the electrical connector 5 is electrically connected to a pattern portion 63 formed on the second substrate 6. Specifically, each pin of the electrical connector 5 is electrically and physically (mechanically) connected to the pattern portion 63 by a solder ball (not shown). The pattern portion 63 has a rectangular shape extending to the right from the electrical connector 5. It is preferable that the length of the pattern portion 63 in the left-right direction is as short as possible. Note that the pattern portion 63 is not limited to a rectangular shape extending to the right from the electrical connector 5, and may have a bent shape, for example.

[0022] The external connector CN1 is electrically connected to an external device 100 (see FIG. 1). The external device 100 supplies driving power to the photoelectric conversion device 1A, transmits signals, and receives signals from the photoelectric conversion device 1A via the external connector CN1 and the electrical connector 5. The external device 100 is formed, for example, by a motherboard that monitors and controls the transmission operation of the photoelectric conversion device 1A.

[0023] (2.3) First Substrate and Optical Element The first substrate 4 is mounted on the right side of the lower surface 61 of the second substrate 6. The first substrate 4 is a rectangular plate-shaped mounting substrate, such as a silicon substrate. The first substrate 4 has a lower surface 41 and an upper surface 42 that face each other in the vertical direction. The lower surface 41 and the upper surface 42 are each rectangular. The first substrate 4 is mounted on the lower surface 61 of the second substrate 6 so that the upper surface 42 faces the lower surface 61 of the second substrate 6. However, the first substrate 4 may have a shape other than a rectangular plate, and may be, for example, a circular plate, an elliptical plate, or a polygonal plate.

[0024] The first substrate 4 is preferably physically connected to the second substrate 6 by adhesion. In this embodiment, the first substrate 4 is physically connected to the second substrate 6 by an adhesive 81. The adhesive 81 is a non-conductive adhesive with high thermal conductivity. The adhesive 81 may contain a metal or the like as a filler, but in this case, it is also preferable that the adhesive does not exhibit high conductivity. Specifically, the upper surface 42 of the first substrate 4 faces the lower surface 61 of the second substrate 6, and the upper surface 42 is physically connected to the lower surface 61 via the adhesive 81. In other words, the adhesive 81 is sandwiched between the lower surface 61 and the upper surface 42, physically connecting the first substrate 4 and the second substrate 6.

[0025] The optical element 2 is mounted on the lower surface 41 of the first substrate 4. Two pattern portions 43 are formed on the lower surface 41 of the first substrate 4 as electrical paths, and the optical element 2 is connected to the two pattern portions 43. The two pattern portions 43 form a pair of signal paths (signal line, ground line) as electrical paths. Specifically, the optical element 2 is electrically connected to the two pattern portions 43 formed on the lower surface 41 by gold bumps 9, and is also physically connected to the first substrate 4. The pattern portions 43 form an electrical path including a conductor electrically connected to the optical element 2. The pattern portions 43 are rectangular and extend leftward from the optical element 2. In this embodiment, the number of pattern portions 43 is two, which is the same as the number of terminals of the optical element 2.

[0026] The optical element 2 has at least one of the functions of converting a received transmission electrical signal into a transmission optical signal by emitting light based on the received transmission electrical signal, and the function of converting a received optical signal into a reception electrical signal. In Figures 1 and 2, the optical element 2 is configured with a light-emitting element 2A that has the function of converting a transmission electrical signal into a transmission optical signal. The light-emitting element 2A includes a light-emitting diode (LED: Light Emitting Diode), a laser diode (LD: Laser Diode), or a VCSEL (Vertical Cavity Surface Emitting Laser).

[0027] The light-emitting element 2A generates a transmission optical signal by emitting light in response to a transmission electrical signal received via the pattern portion 43. An internal waveguide 44 for transmitting an optical signal is formed in the first substrate 4, and the transmission optical signal is input to the internal waveguide 44. A first end 441 of the internal waveguide 44 is formed on the bottom surface 41, positioned above the light-emitting element 2A, and vertically opposed to the light-emitting portion on the top surface of the light-emitting element 2A. A second end 442 of the internal waveguide 44 is formed at a position inside an end surface (right side surface) 45 connecting the bottom surface 41 and the top surface 42 of the first substrate 4. In other words, the internal waveguide 44 is formed between the bottom surface 41 and the end surface 45. An external waveguide EX for transmitting an optical signal is bonded to the second end 442 of the internal waveguide 44. The external waveguide EX is bonded to the internal waveguide 44 at a position inside the end surface 45 of the first substrate 4 and optically coupled to the internal waveguide 44. The internal waveguide 44 and the external waveguide EX constitute the waveguide X. That is, the waveguide X is optically coupled to the light emitting element 2A and transmits the transmission optical signal. The external waveguide EX may be coupled to the internal waveguide 44 using, for example, an adhesive. The adhesive may be, for example, an adhesive for optical fiber.

[0028] (2.4) Integrated Circuit The integrated circuit 3 is mounted on the lower surface 61 between the electrical connector 5 and the first substrate 4 in the left-right direction. In this case, it is preferable that the integrated circuit 3 is mounted on the lower surface 61 as close as possible to the right end of the pattern portion 63. The integrated circuit 3 is an IC (Integrated Circuit) substrate on which an integrated circuit is formed. The integrated circuit 3 is electrically connected to the pattern portion 63 formed on the second substrate 6, and thereby electrically connected to each pin of the electrical connector 5.

[0029] The integrated circuit 3 has a bottom surface 31 and a top surface 32 that face each other in the vertical direction. The bottom surface 31 and the top surface 32 are each rectangular. The integrated circuit 3 is mounted on the bottom surface 61 of the second substrate 6 so that the top surface 32 faces the bottom surface 61 of the second substrate 6. However, the integrated circuit 3 may have a shape other than a rectangular plate, and may be, for example, a circular plate, an elliptical plate, or a polygonal plate.

[0030] The integrated circuit 3 is preferably physically connected to the second substrate 6 by adhesion. In this embodiment, the integrated circuit 3 is physically connected to the second substrate 6 by an adhesive 82. The adhesive 82 is a non-conductive adhesive with high thermal conductivity. The adhesive 82 may contain a metal or the like as a filler, but in this case, it is also preferable that the adhesive 82 does not exhibit high conductivity. Specifically, the upper surface 32 of the integrated circuit 3 faces the lower surface 61 of the second substrate 6, and the upper surface 32 is physically connected to the lower surface 61 via the adhesive 82. In other words, the adhesive 82 is sandwiched between the lower surface 61 and the upper surface 32, physically connecting the integrated circuit 3 and the second substrate 6.

[0031] The integrated circuit 3 is electrically connected to the second substrate 6 by bonding wires W1. That is, the second substrate 6 is electrically connected to the integrated circuit 3 by the bonding wires W1. The bonding wires W1 are thin wires made of metal such as gold, silver, copper, or aluminum. Specifically, three or more electrodes 33 are provided on the left portion of the lower surface 31 of the integrated circuit 3. A first end of the bonding wire W1 is connected to the electrode 33 of the integrated circuit 3, and a second end of the bonding wire W1 is connected to the right end of the pattern portion 63 of the second substrate 6. That is, each electrode 33 of the integrated circuit 3 is electrically connected to each pin of the electrical connector 5 via the bonding wires W1 and the pattern portion 63 of the second substrate 6. The multiple electrodes 33 constitute input terminals, output terminals, power supply terminals, etc. of the integrated circuit 3.

[0032] The integrated circuit 3 receives driving power and signals from the external device 100 via the external connector CN1, the electrical connector 5, the pattern portion 63, and the bonding wire W1. The integrated circuit 3 transmits signals to the external device 100 via the bonding wire W1, the pattern portion 63, the electrical connector 5, and the external connector CN1. In this embodiment, the number of electrodes 33 is the same as the number of pins on the electrical connector 5.

[0033] The integrated circuit 3 is electrically connected to the first substrate 4 via bonding wires W2. That is, the first substrate 4 is electrically connected to the integrated circuit 3 via the bonding wires W2. The bonding wires W2 are thin wires made of metal such as gold, silver, copper, or aluminum. Specifically, two electrodes 34 are provided on the right portion of the lower surface 31 of the integrated circuit 3. A first end of the bonding wire W2 is connected to the electrode 34 of the integrated circuit 3, and a second end of the bonding wire W2 is connected to the left end of the pattern portion 43 of the first substrate 4. That is, the electrodes 34 of the integrated circuit 3 are electrically connected to the input terminals of the light-emitting element 2A via the bonding wires W2 and the pattern portion 43 of the first substrate 4. The integrated circuit 3 then outputs a transmission electrical signal from the two electrodes 34 to the light-emitting element 2A based on a signal input to the electrode 33. The light-emitting element 2A receives the transmission electrical signal via the bonding wires W2 and the pattern portion 43 and emits light in response to the received transmission electrical signal. The light emitted by the light emitting element 2A enters the internal waveguide 44 as a transmission optical signal, propagates through the waveguide X consisting of the internal waveguide 44 and the external waveguide EX, and is transmitted to an external receiving device.

[0034] The technique of electrically connecting two components using bonding wires W1, W2, etc. is called wire bonding.

[0035] (2.5) Heat Dissipation Member The heat dissipation member 7 is made of a metal such as aluminum or copper, and is provided on the upper surface 62 of the second substrate 6. The heat dissipation member 7 has the function of dissipating heat generated by the light emitting element 2A and the integrated circuit 3. The heat dissipation member 7 preferably has a plurality of fins.

[0036] In this embodiment, the first substrate 4 and the integrated circuit 3 are mounted on the lower surface 61 of the second substrate 6, and the heat dissipation member 7 is mounted on the upper surface 62 of the second substrate 6. Heat generated by the light emitting element 2A is transferred to the heat dissipation member 7 via the first substrate 4, adhesive 81, and second substrate 6, and is dissipated from the heat dissipation member 7. Heat generated by the integrated circuit 3 is transferred to the heat dissipation member 7 via the adhesive 82 and second substrate 6, and is dissipated from the heat dissipation member 7.

[0037] In the photoelectric conversion device 1A, by mounting the heat dissipation member 7 on the upper surface 62 of the second substrate 6, the contact area between the heat dissipation member 7 and the second substrate 6 can be made larger than in a configuration in which the heat dissipation member 7 is mounted on the lower surface 61 of the second substrate 6. As a result, the photoelectric conversion device 1A can improve the heat dissipation efficiency of the light emitting element 2A (optical element 2) and the integrated circuit 3. Note that the heat dissipation member 7 may be provided directly on the upper surface 62 of the second substrate 6, or a thermal interface material may be interposed between the heat dissipation member 7 and the upper surface 62 of the second substrate 6. This can reduce the gap between the heat dissipation member 7 and the upper surface 62 of the second substrate 6, thereby further improving the heat dissipation efficiency.

[0038] (2.6) Modified Examples of Optical Element FIGS. 3 and 4 show a photoelectric conversion device 1B including a light-receiving element 2B as the optical element 2. FIG.

[0039] The light receiving element 2B has a function of converting a received optical signal received from an external transmitting device via the waveguide X into a received electrical signal. The light receiving element 2B includes a photodiode or a phototransistor. The waveguide X is optically coupled to the light receiving element 2B and transmits the received optical signal.

[0040] The light-receiving element 2B is mounted on the lower surface 41 of the first substrate 4, and a light-receiving portion on the upper surface of the light-receiving element 2B faces the first end 441 of the internal waveguide 44. The light-receiving element 2B receives an incoming optical signal transmitted from the external waveguide EX through the internal waveguide 44 and converts the received optical signal into an incoming electrical signal. The light-receiving element 2B outputs the incoming electrical signal to the integrated circuit 3 via the pattern portion 43 and bonding wire W2. The integrated circuit 3 outputs a signal based on the incoming electrical signal from the electrode 33, and the signal is transmitted to the external device 100 via the bonding wire W1, the pattern portion 63, the electrical connector 5, and the external connector CN1.

[0041] The external device 100 is configured, for example, by a motherboard that monitors and controls the receiving operation of the photoelectric conversion device 1B.

[0042] The heat dissipation member 7 has a function of dissipating heat generated by the light receiving element 2B and the integrated circuit 3.

[0043] Other configurations of the photoelectric conversion device 1B are similar to those of the photoelectric conversion device 1A, and therefore description thereof will be omitted.

[0044] (2.7) Summary As described above, the photoelectric conversion device 1 (1A, 1B) has the integrated circuit 3, first substrate 4, and electrical connector 5 mounted on the underside 61 of the second substrate 6. As a result, the electrical distance (wiring length) between the integrated circuit 3 and the electrical connector 5 in this embodiment is shorter than in a configuration in which the integrated circuit 3 is mounted on the first substrate 4 (corresponding to the configuration of Patent Document 1). However, the electrical distance between the integrated circuit 3 and the optical element 2 is longer than in a configuration in which the integrated circuit 3 is mounted on the first substrate 4 (corresponding to the configuration of Patent Document 1). However, the number of pattern portions 63 (three or more) constituting the electrical path between the integrated circuit 3 and the electrical connector 5 is greater than the number of pattern portions 43 (two) constituting the electrical path between the integrated circuit 3 and the optical element 2. Therefore, the photoelectric conversion device 1 can reduce electrical loss by shortening the electrical distance between the integrated circuit 3 and the electrical connector 5.

[0045] Furthermore, in the photoelectric conversion device 1, the integrated circuit 3 and the first substrate 4 are physically connected to the second substrate 6 by adhesive bonding. In this case, compared to a configuration in which the integrated circuit 3 and the first substrate 4 are physically and electrically connected to the second substrate 6 by solder balls, problems caused by scattering of solder or flux can be suppressed and high-density wiring is possible.

[0046] Specifically, in a configuration in which the integrated circuit 3 and the first substrate 4 are physically and electrically connected to the second substrate 6 by solder balls, problems may occur due to the scattering of solder or flux. For example, if solder or flux adheres to the optical element 2 mounted on the first substrate 4, the light emitted from the optical element 2 or the light incident on the optical element 2 may be blocked by the solder or flux, which may cause problems with the electrical-to-optical conversion function and the optical-to-electrical conversion function. In addition, the scattered solder may cause short circuits between pattern portions and between electrodes. On the other hand, in the photoelectric conversion device 1, the integrated circuit 3 and the first substrate 4 are physically connected to the second substrate 6 by adhesion, so problems due to the scattering of solder or flux can be suppressed.

[0047] Furthermore, in a configuration in which the first substrate 4 is physically and electrically connected to the second substrate 6 by solder balls, the heat used to melt the solder balls applies thermal stress to the optical elements 2 mounted on the first substrate 4. On the other hand, in the photoelectric conversion device 1, the first substrate 4 is physically connected to the second substrate 6 by adhesive bonding, so that the thermal stress applied to the optical elements 2 can be suppressed.

[0048] Furthermore, in a configuration in which the integrated circuit 3 and the first substrate 4 are physically and electrically connected to the second substrate 6 by solder balls, taking into consideration deformation of the solder balls when melted, etc., it is necessary to widen the spacing between the pattern portions 63 of the second substrate 6, the spacing between the electrodes 33 of the integrated circuit 3, the spacing between the electrodes 34 of the integrated circuit 3, and the spacing between the pattern portions 43 of the first substrate 4. On the other hand, in the photoelectric conversion device 1, the integrated circuit 3 and the first substrate 4 are physically connected to the second substrate 6 by adhesive bonding, so that the spacing between the pattern portions 63 of the second substrate 6, the spacing between the electrodes 33 of the integrated circuit 3, the spacing between the electrodes 34 of the integrated circuit 3, and the spacing between the pattern portions 43 of the first substrate 4 can be narrower. In other words, the photoelectric conversion device 1 enables high-density wiring.

[0049] Furthermore, in the photoelectric conversion device 1, the integrated circuit 3 is electrically connected to the second substrate 6 by a bonding wire W1, and is electrically connected to the first substrate 4 by a bonding wire W2. In this case, compared to a configuration in which the integrated circuit 3 is physically and electrically connected to the second substrate 6 and the first substrate 4 by solder balls, high-density wiring is possible and problems caused by scattering of solder or flux can be suppressed. Furthermore, by using the bonding wires W1 and W2, it is possible to improve the signal transmission quality.

[0050] (2.8) Waveguide Figures 5 and 6 show the configuration of the waveguide X. Figure 6 is a cross-sectional view taken along the line Y1-Y2 of Figure 5.

[0051] The waveguide X is optically coupled to the optical element 2 (light-emitting element 2A or light-receiving element 2B) and transmits at least one of a transmitted optical signal and a received optical signal. In particular, the waveguide X preferably includes an internal waveguide 44, an external waveguide EX, and a mirror portion 446. The internal waveguide 44 is formed in the first substrate 4. The external waveguide EX is joined to the internal waveguide 44 at a position inside an end face 45 of the first substrate 4 and is optically coupled to the internal waveguide 44. The mirror portion 446 changes the traveling direction of at least one of a transmitted optical signal and a received optical signal in the internal waveguide 44.

[0052] Specifically, a groove 46 extending linearly from the end face 45 to the left is formed in the lower surface 41 of the first substrate 4. The internal waveguide 44 is disposed in the groove 46. The left end of the groove 46 is an inclined surface extending diagonally downward and left toward the lower surface 41, and a mirror 446 is formed on this inclined surface. The mirror 446 is a mirror surface that reflects light and is inclined at an angle of 45 degrees (or approximately 45 degrees) with respect to the lower surface 41. A first end 441 of the internal waveguide 44 is formed on the lower surface 41 of the first substrate 4, between the left end of the groove 46 and the left end of the internal waveguide 44. The internal waveguide 44 is made of glass, plastic, or the like, and includes a core 444 that forms the center of the internal waveguide 44, and a cladding 445 that covers the outer periphery of the core 444 (see FIG. 6 ). By using a silicon substrate for the first substrate 4, the grooves 46 and the mirror portion 446 can be easily processed in the first substrate 4.

[0053] For example, the mirror portion 446 is formed by depositing gold or aluminum on a 45° inclined surface formed by etching the first substrate 4 (for example, anisotropic etching using a potassium hydroxide solution).

[0054] When the optical element 2 is the light-emitting element 2A, the transmission optical signal emitted upward by the light-emitting element 2A enters the first end 441 of the internal waveguide 44. The transmission optical signal traveling upward is reflected by the mirror portion 446, changing the traveling direction of the transmission optical signal from upward to rightward. In other words, the traveling direction of the transmission optical signal is changed by 90 degrees by the mirror portion 446. The transmission optical signal traveling rightward from the mirror portion 446 enters the left end of the optical fiber 443 and travels rightward within the optical fiber 443. The transmission optical signal that reaches the right end of the optical fiber 443 exits from the second end 442 of the internal waveguide 44, enters the external waveguide EX, and propagates within the external waveguide EX.

[0055] When the optical element 2 is a light receiving element 2B, the received optical signal that enters the second end 442 of the internal waveguide 44 from the external waveguide EX travels leftward through the optical fiber 443. The received optical signal traveling leftward is reflected by the mirror portion 446, changing the traveling direction of the received optical signal from leftward to downward. In other words, the traveling direction of the received optical signal is changed by 90 degrees by the mirror portion 446. The received optical signal traveling downward from the mirror portion 446 exits from the first end 441 of the internal waveguide 44, and is received by the light receiving element 2B.

[0056] The angle at which the mirror unit 446 changes the direction of travel of the optical signals (transmitted optical signal, received optical signal) is preferably within a range of 89 degrees or more and 91 degrees or less. In other words, the angle at which the mirror unit 446 changes the direction of travel of the optical signal is not limited to 90 degrees, and may be within a range of 89 degrees or more and 91 degrees or less, including tolerances and the like.

[0057] As described above, by changing the traveling direction of optical signals (transmitted optical signals and received optical signals) using the mirror portion 446, it is possible to form the internal waveguide 44 between the lower surface 41 and the end surface 45 of the first substrate 4. In other words, the degree of freedom of the path of the internal waveguide 44 is increased.

[0058] (3) Photoelectric Conversion System FIG. 7 shows a photoelectric conversion system 10 including a photoelectric conversion device 1A and a photoelectric conversion device 1B.

[0059] In the optical-electrical conversion system 10, the optical-electrical conversion device 1A and the optical-electrical conversion device 1B are connected to each other via an external waveguide EX. A light-emitting element 2A of the optical-electrical conversion device 1A generates a transmission optical signal and propagates it through the external waveguide EX. A light-receiving element 2B of the optical-electrical conversion device 1B receives the transmission optical signal output from the optical-electrical conversion device 1A as a reception optical signal via the external waveguide EX. That is, in the optical-electrical conversion system 10, the optical-electrical conversion device 1A functions as a transmitter, and the optical-electrical conversion device 1B functions as a receiver.

[0060] (4) Other Modifications The photoelectric conversion device 1 may use double-sided tape instead of the adhesives 81 and 82. That is, the integrated circuit 3 and the first substrate 4 may be physically connected to the second substrate 6 by double-sided tape.

[0061] The photoelectric conversion device 1 may have functions of both a transmitter and a receiver by including both a light-emitting element 2A and a light-receiving element 2B as the optical element 2. In this case, the number of pattern portions 43 is four, and the number of pattern portions 63 is five or more.

[0062] The pattern portions 43 and 63 may have a shape other than a rectangular shape.

[0063] The photoelectric conversion device 1 does not necessarily have to include the heat dissipation member 7. In other words, the heat dissipation member 7 is not an essential component of the photoelectric conversion device 1.

[0064] (5) Summary The optical-electrical conversion device (1, 1A, 1B) of the first aspect includes an optical element (2), an integrated circuit (3), a first substrate (4), an electrical connector (5), and a second substrate (6). The optical element (2) converts a received electrical signal into an optical signal by emitting light based on the received electrical signal, and / or converts a received optical signal into an electrical signal. The integrated circuit (3) transmits the electrical signal to the optical element (2) or receives the electrical signal from the optical element (2). The optical element (2) is mounted on the first substrate (4). The electrical connector (5) is configured to be detachable from an external connector (CN1) and is electrically connected to the integrated circuit (3). The second substrate (6) has a first surface (61) and a second surface (62) opposite the first surface (61). The first substrate (4), the integrated circuit (3), and the electrical connector (5) are mounted on the first surface (61).

[0065] The above-described photoelectric conversion device (1, 1A, 1B) can reduce electrical loss.

[0066] In the second aspect of the photoelectric conversion device (1, 1A, 1B), it is preferable that the first substrate (4) is electrically connected to the integrated circuit (3) by a bonding wire (W2), and the second substrate (6) is electrically connected to the integrated circuit (3) by a bonding wire (W1).

[0067] The above-described photoelectric conversion device (1, 1A, 1B) enables high-density wiring and can suppress problems caused by scattering of solder or flux.

[0068] In the photoelectric conversion device (1, 1A, 1B) of the third embodiment, the integrated circuit (3) and the first substrate (4) are preferably physically connected to the second substrate (6) by adhesive bonding.

[0069] The above-described photoelectric conversion device (1, 1A, 1B) enables high-density wiring and can suppress defects caused by scattering of solder or flux. Furthermore, it can suppress thermal stress applied to the optical element (2).

[0070] In the photoelectric conversion device (1, 1A, 1B) of the fourth aspect, the integrated circuit (3) and the first substrate (4) are preferably physically connected to the second substrate (6) by adhesive (81, 82).

[0071] The above-described photoelectric conversion device (1, 1A, 1B) enables high-density wiring and can suppress defects caused by scattering of solder or flux. Furthermore, it can suppress thermal stress applied to the optical element (2).

[0072] The photoelectric conversion device (1, 1A, 1B) of the fifth aspect preferably further comprises a heat dissipation member (7) provided on the second surface (62) of the second substrate (6).

[0073] The above-described photoelectric conversion device (1, 1A, 1B) can improve the heat dissipation efficiency of the optical element (2) and the integrated circuit (3).

[0074] The sixth aspect of the photoelectric conversion device (1, 1A, 1B) is preferably any one of the first to fifth aspects, further comprising a waveguide (X) optically coupled to the optical element (2) and transmitting at least one of a transmitted optical signal and a received optical signal.

[0075] The above-described optical-electrical conversion device (1, 1A, 1B) can transmit and receive at least one of a transmission optical signal and a reception optical signal to and from the outside.

[0076] In the optical-electrical conversion device (1, 1A, 1B) of the seventh aspect, the waveguide (X) preferably includes an internal waveguide (44), an external waveguide (EX), and a mirror portion (446). The internal waveguide (44) is formed in the first substrate (4). The external waveguide (EX) is joined to the internal waveguide (44) at a position inside the end face (45) of the first substrate (4) and is optically coupled to the internal waveguide (44). The mirror portion (446) changes the traveling direction of a transmitted optical signal and / or a received optical signal in the internal waveguide (44).

[0077] The above-described photoelectric conversion device (1, 1A, 1B) can increase the degree of freedom of the path of the internal waveguide (44) by including the mirror portion (446).

[0078] In the eighth aspect of the optical-electrical conversion device (1, 1A, 1B), it is preferable that the angle at which the mirror portion (446) changes the direction of propagation of the transmitted optical signal is in the range of 89 degrees or more and 91 degrees or less, and / or the angle at which the mirror portion (446) changes the direction of propagation of the received optical signal is in the range of 89 degrees or more and 91 degrees or less.

[0079] The above-described optical-electrical conversion device (1, 1A, 1B) can change the traveling direction of an optical signal (at least one of a transmitted optical signal and a received optical signal) by approximately 90 degrees.

[0080] In the ninth aspect of the photoelectric conversion device (1, 1A, 1B), it is preferable that the number of electrical paths (63) existing between the integrated circuit (3) and the electrical connector (5) is greater than the number of electrical paths (43) existing between the integrated circuit (3) and the optical element (2).

[0081] The above-described photoelectric conversion device (1, 1A, 1B) can reduce electrical loss.

[0082] In the photoelectric conversion device (1, 1A, 1B) of the tenth aspect, the first substrate (4) is preferably a silicon substrate.

[0083] In the above-described photoelectric conversion device (1, 1A, 1B), the first substrate 4 can be easily processed.

[0084] REFERENCE SIGNS LIST 1, 1A, 1B Opto-electrical conversion device 2 Optical element 3 Integrated circuit 4 First substrate 43 Pattern portion (electrical path) 44 Internal waveguide 446 Mirror portion 5 Electrical connector 6 Second substrate 61 First surface (lower surface) 62 Second surface (upper surface) 63 Pattern portion (electrical path) 7 Heat dissipation member CN1 External connector W1, W2 Bonding wires X Waveguide EX External waveguide

Claims

1. An optical-electrical conversion device comprising: an optical element that converts a received transmitted electrical signal into a transmitted optical signal by emitting light based on the received transmitted electrical signal, or converts a received optical signal that it has received into a received electrical signal; an integrated circuit that transmits the transmitted electrical signal to the optical element or receives the received electrical signal from the optical element; a first substrate on which the optical element is mounted; an electrical connector that is configured to be detachable from an external connector and is electrically connected to the integrated circuit; and a second substrate having a first surface and a second surface opposite to the first surface, with the first substrate, the integrated circuit, and the electrical connector mounted on the first surface.

2. The photoelectric conversion device of claim 1, further comprising: a first bonding wire connected to the integrated circuit; and a second bonding wire connected to the integrated circuit, wherein the first substrate is electrically connected to the integrated circuit by the first bonding wire, and the second substrate is electrically connected to the integrated circuit by the second bonding wire.

3. The optical-electrical conversion device according to claim 1 or 2, wherein the integrated circuit and the first substrate are physically connected to the second substrate by adhesion.

4. The optical-electrical conversion device according to claim 3, wherein said integrated circuit and said first substrate are physically connected to said second substrate by an adhesive.

5. The photoelectric conversion device according to any one of claims 1 to 4, further comprising a heat dissipation member provided on the second surface of the second substrate.

6. The optical-electrical conversion device according to any one of claims 1 to 5, further comprising a waveguide optically coupled to said optical element and transmitting at least one of said transmitted optical signal and said received optical signal.

7. An optical-electrical conversion device as claimed in claim 6, wherein the waveguide comprises: an internal waveguide formed in the first substrate; an external waveguide joined to the internal waveguide at a position inside an end face of the first substrate and optically coupled to the internal waveguide; and a mirror portion which changes the traveling direction of the transmitted optical signal or the traveling direction of the received optical signal in the internal waveguide.

8. An optical-electrical conversion device as described in claim 7, wherein the angle by which the mirror portion changes the propagation direction of the transmitted optical signal is within a range of 89 degrees or more and 91 degrees or less, or the angle by which the mirror portion changes the propagation direction of the received optical signal is within a range of 89 degrees or more and 91 degrees or less.

9. An optical-electrical conversion device according to any one of claims 1 to 8, wherein the number of electrical paths existing between the integrated circuit and the electrical connector is greater than the number of electrical paths existing between the integrated circuit and the optical element.

10. The photoelectric conversion device according to any one of claims 1 to 9, wherein the first substrate is a silicon substrate.

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