JP2019113784A - Optical transceiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently discharge heat generated from an electronic component. An optical transceiver 1 is directed from a main circuit board 6 to which an IC 26 is attached, an outer shell portion 22 defining an accommodating portion S accommodating the main circuit board 6, and an outer shell portion 22 toward the accommodating portion S. A housing 8 having a separation wall 21 extending from the wall is provided. The isolation wall 21 includes a heat recovery unit 31 to which the IC 26 is thermally connected. The outer shell portion 22 includes a heat radiating unit 33 that dissipates heat recovered from the IC 26, and a heat conductive unit 32 that receives the heat recovered by the heat recovery unit 31 and transmits it to the heat radiating unit 33. [Selection diagram] Fig. 2

Description

  The present invention relates to an optical transceiver.

  Patent Document 1 discloses an optical transceiver. The optical transceiver has a metal case body, an optical module, and a substrate. The number of substrates corresponds to the number of light modules. Patent Document 2 discloses an optical transmitter / receiver. This optical transmitter / receiver accommodates two printed circuit boards inside the case.

JP, 2012-42719, A JP, 2016-6927, A

  As the communication capacity of optical communication increases, the speed of signals used for optical communication is increased. As a result, the components mounted on the optical transceiver also need to have high-speed performance according to the speed of the signal. On the other hand, electronic components having such high-speed performance tend to have increased power consumption as compared to those having relatively low high-speed performance. As the power consumption of electronic components increases, the amount of heat generated by the electronic components also increases. When the temperature of the electronic component rises due to this heat generation, a situation may occur where the temperature of the electronic component exceeds the upper limit of the operating temperature.

  An object of the present invention is to provide an optical transceiver capable of efficiently dissipating heat generated from an electronic component.

  One embodiment of the present invention is an optical transceiver including an optical device that performs signal conversion between an electrical signal and an optical signal, which accommodates a circuit board to which a semiconductor element for processing the electrical signal is attached and the circuit board. A heat recovery system comprising: an outer shell defining a rectangular parallelepiped housing space; and a case having a partition extending from the outer shell toward the housing space, the partition being thermally connected to the semiconductor element The heat sink includes a heat sink that radiates the heat conducted from the semiconductor element, and a heat conducting section that conducts the heat conducted from the semiconductor chip to the heat recovery station to the heat sink.

  According to the present invention, an optical transceiver capable of efficiently dissipating the heat generated from the electronic component is provided.

FIG. 1 is a perspective view showing a part of a system to which an optical transceiver according to an embodiment is applied. FIG. 2 is an exploded perspective view of the optical transceiver shown in FIG. FIG. 3 is a perspective view showing a cross section of the optical transceiver. FIG. 4 is a perspective view showing a connection structure of the main circuit board and the sub circuit board. FIG. 5 is a cross-sectional view showing the structure of the optical transceiver according to the comparative example.

Description of the embodiment of the present invention
One embodiment of the present invention is an optical transceiver including an optical device that performs signal conversion between an electrical signal and an optical signal, which accommodates a circuit board to which a semiconductor element for processing the electrical signal is attached and the circuit board. A heat recovery system comprising: an outer shell defining a rectangular parallelepiped housing space; and a case having a partition extending from the outer shell toward the housing space, the partition being thermally connected to the semiconductor element The heat sink includes a heat sink that radiates the heat conducted from the semiconductor element, and a heat conducting section that conducts the heat conducted from the semiconductor chip to the heat recovery station to the heat sink.

  When the semiconductor element attached to the circuit board generates heat, the heat is transferred to a heat recovery unit to which the semiconductor element is thermally connected. Since the partition wall portion including the heat recovery portion extends from the outer shell portion, the heat transferred to the heat recovery portion further moves toward the heat conduction portion which is a part of the outer shell portion. The heat transferred to the heat conducting part further moves to the heat radiating part which is a part of the outer shell part. And the heat which moved to the thermal radiation part is discharged to the exterior of a case. As described above, the heat generated in the semiconductor element immediately moves to the heat recovery unit which is a part of the housing, and then moves to the heat dissipation part via the heat conducting part which is a part of the housing. Therefore, the thermal resistance that hinders the heat transfer is reduced, so that the heat generated in the semiconductor element can be efficiently discharged.

  In one form, the partition part divides the housing space into a first housing space and a second housing space located between the first housing space and the heat dissipation portion, and the first housing space is a circuit board. A first circuit board may be disposed, a second circuit board different from the circuit board may be disposed in the second accommodation space, and the second circuit board may be thermally connected to the heat dissipation unit. According to this configuration, the housing can accommodate two substrates. Therefore, it is possible to increase the density since it is possible to increase the number of components that can be accommodated in the housing.

  In one embodiment, the outer shell has a surface covering the upper part of the accommodation space, a back surface covering the lower part of the accommodation space, and a pair of side parts covering the sides of the accommodation space, The heat recovery unit includes a heat dissipation unit, and the heat recovery unit is formed to extend from one of the pair of side surfaces to the other of the pair of side surfaces, and the first accommodation space is sandwiched between the back surface and the heat recovery unit. The space may be sandwiched between the surface portion and the heat recovery portion. According to this configuration, it is possible to arrange the second circuit board on the first circuit board. Therefore, the optical transceiver can be suitably densified.

  In one form, the thermal conductivity of the housing may be greater than the thermal conductivity of the circuit board. According to this configuration, the heat generated in the semiconductor element can be suitably discharged.

  In one form, the semiconductor device further comprises a first heat transfer member in contact with the semiconductor element attached to the first circuit board and in contact with the heat recovery portion, and the semiconductor element attached to the first circuit board is via the first heat transfer member May be thermally connected to the heat recovery unit. According to this configuration, even when there is unevenness due to the height of the semiconductor element on the first circuit board, the unevenness can be absorbed by the first heat transfer member. Therefore, the heat flow area from the first circuit board to the heat recovery portion can be increased, so that the thermal resistance can be reduced.

  In one embodiment, the heat transfer unit may further include a second heat transfer member in contact with the heat dissipation portion while in contact with the second circuit board, and the second circuit substrate may be connected to the heat dissipation portion via the second heat transfer member. According to this configuration, even when there is unevenness due to the height of the semiconductor element on the second circuit board, the unevenness can be absorbed by the second heat transfer member. Therefore, it is possible to increase the heat flow passage area from the second circuit board to the heat dissipation portion, and thus the heat resistance can be reduced.

  In one embodiment, a first semiconductor element group including a semiconductor element is attached to the first circuit board, and a second semiconductor element group including a semiconductor element different from the semiconductor element is attached to the second circuit board. The calorific value of the first semiconductor element group may be larger than the calorific value of the second semiconductor element group. According to this configuration, the heat caused by the first semiconductor element group can be efficiently discharged.

Details of the Embodiment of the Present Invention
Hereinafter, an optical transceiver according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to these exemplifications, but is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. Further, in the drawings, the same or corresponding portions are denoted by the same reference numerals, and redundant description will be omitted.

  The optical transceiver 1 shown in FIG. 1 is an optical transceiver module used for optical communication. The optical transceiver 1 is inserted into a cage 101 provided in a host system 100 (transmission system) along the longitudinal direction D1. The optical transceiver 1 has an electrical connector (edge connector) at the end of the side (cage side) to be inserted into the cage 101 in the longitudinal direction D1. On the other hand, at the back of the cage 101, an electrical connector is provided. The optical transceiver 1 and the host system 100 are electrically connected by the respective electrical connectors being engaged with each other. As a result, the optical transceiver 1 receives supply of power necessary for operation from the host system 100, and can communicate with each other by electrical signals. The optical transceiver 1 may be removed (hot-lined) while the electrical connector at the back of the cage 101 is energized. The optical transceiver 1 also has two optical receptacles 2 at the end of the longitudinal direction D1 opposite to the cage side (optical fiber side). An optical connector 200 for holding the optical fiber 201 is inserted into the optical receptacle 2. The optical transceiver 1 is optically connected to the optical fiber 201 by fitting the optical receptacle 2 and the optical connector 200 to each other. Thereby, the optical transceiver 1 can perform two-way communication (two-core full-duplex communication) with another optical transceiver, for example, using an optical signal. The optical transceiver 1 converts an electrical signal supplied from the host system 100 into an optical signal, and outputs the optical signal to one of the optical connectors 200. Also, the optical transceiver 1 converts an optical signal transmitted from another optical connector 200 into an electrical signal and outputs the electrical signal to the host system 100. The portion inserted into the cage 101 of the optical transceiver 1 has a rectangular parallelepiped shape which is long in the longitudinal direction D1, so the rectangular portion is also long in the longitudinal direction D1. Since the optical receptacle 2 is not inserted into the cage 101, the optical receptacle 2 may not have a rectangular parallelepiped shape.

  The optical transceiver 1 has a front surface portion 1a, a back surface portion 1b, and a pair of side surface portions 1c. When the optical transceiver 1 is inserted into the host system 100, the back surface 1 b faces the surface 100 a of the host system 100. A predetermined space is provided on the surface portion 1a and the pair of side surface portions 1c. With this configuration, cooling air is provided from the host system 100 to the surface portion 1a and the pair of side portions 1c. That is, the optical transceiver 1 is cooled by the cooling air applied to the surface portion 1 a and the pair of side surface portions 1 c. The cage 101 may have a mechanism for contacting the surface portion 1 a of the optical transceiver 1 and the pair of side portions 1 c via a metal member. Through such a mechanism, the heat generated inside the optical transceiver 1 may be discharged to the cage 101 by heat conduction.

  As shown in FIG. 2, the optical transceiver 1 includes an optical transmission module 3 (optical device), an optical reception module 4 (optical device), a main circuit board 6, an auxiliary circuit board 7, and a housing 8. Have.

  The optical transmission module 3 is a so-called TOSA (Transmitter Optical Sub-Assembly) that converts an electrical signal into an optical signal. The light receiving module 4 is a so-called ROSA (Receiver Optical Sub-Assembly) that converts an optical signal into an electrical signal.

  The main circuit board 6 and the sub circuit board 7 perform electrical signal processing for the light transmitting module 3 and the light receiving module 4 by the operation of the circuits formed on the respective circuit boards. That is, the main circuit board 6 and the sub circuit board 7 can exhibit various functions such as generation of control signals for controlling the operation of the light transmission module 3 and the light reception module 4, amplification of electric signals, noise removal, and waveform adjustment. . For example, the main circuit board 6 has a laser diode driver (LDD) for driving the light transmission module 3 and an IC (PAM-IC) that performs pulse amplitude modulation (PAM). Further, the main circuit board 6 has an IC for amplifying the electric signal output from the light receiving module 4 and an IC for demodulating the PAM signal. For example, the sub circuit board 7 has a power supply IC for supplying power for the LDD and PAM-IC, and a control IC for controlling the operation of the optical transceiver 1 comprehensively.

  The housing 8 is composed of three parts. That is, the case 8 includes the lower case 11, the first upper case 12, and the second upper case 13.

  The lower housing 11 constitutes the bottom of the optical transceiver 1. The lower housing 11 is a plate-like component extending along the longitudinal direction D1. The lower housing 11 has a front surface 11a and a back surface 11b. The components of the optical transceiver 1 such as the first upper housing 12 and the second upper housing 13 are mounted on the surface 11 a. The back surface 11 b constitutes the back surface portion 1 b of the optical transceiver 1. The light transmitting module 3 and the light receiving module 4 are disposed in front of the lower housing 11 (on the side of the optical fiber). On the lower housing 11, the light transmitting module 3 and the light receiving module 4 are juxtaposed along a width direction D2 intersecting the longitudinal direction D1. More specifically, the light transmitting module 3 and the light receiving module 4 each include an optical coupling system for optically coupling to the optical fiber 201. The light transmitting module 3 and the light receiving module 4 are arranged such that the optical axes of their respective optical coupling systems are parallel to the longitudinal direction D1. Also, the optical transmitter module 3 and the optical receiver module 4 are disposed near the optical receptacle 2 in order to optically couple with the optical fiber 201, respectively. Then, a first upper housing 12 is further disposed in front of the lower housing 11 (on the side of the optical fiber) so as to cover the light transmitting module 3 and the light receiving module 4. The lower housing 11 also has a pair of connection holes 14 provided substantially at the center in the longitudinal direction D1. The screw 16 is inserted into the connection hole 14. The screw 16 integrates the first upper housing 12, the second upper housing 13, and the lower housing 11.

  The first upper housing 12 constitutes the front of the optical transceiver 1. Therefore, the first upper housing 12 has the optical receptacle 2 described above. The first upper housing 12 holds the optical connector 200 (see FIG. 1) inserted in the optical receptacle 2 and the optical transmitter module 3 and the optical receiver module 4 in a state where they are optically coupled to each other.

  The first upper housing 12 has a first surface portion 12 a and a pair of first side portions 12 c. The first surface portion 12 a constitutes a part of the surface portion 1 a of the optical transceiver 1. The first side face 12 c constitutes a part of the side face 1 c of the optical transceiver 1. When viewed from the rear side (cage side) of the longitudinal direction D1, the first upper housing 12 presents a U-shaped cross section in which one surface is open. That is, the bottom side of the first upper housing 12 is open. This opening is closed by the lower housing 11. Here, the conductive elastic body 17 (see FIG. 3) is sandwiched between the first upper housing 12 and the lower housing 11. Furthermore, the first upper housing 12 has a pair of screw holes 18. Each of the screw holes 18 communicates with the connection hole 14 of the lower housing 11. The screw 16 inserted from the lower housing 11 side is screwed into the screw thread formed in the screw hole 18. The connection hole 14 extends along the height direction D3 of the optical transceiver 1.

  The second upper housing 13 constitutes the rear side of the optical transceiver 1. Therefore, the second upper housing 13 has a structure for connecting with the host system 100 (see FIG. 1) described above. Specifically, the rear side of the second upper housing 13 is open, and the main circuit board 6 is exposed from the opening. When the optical transceiver 1 is inserted into the host system 100, the main circuit board 6 is electrically connected to the electrical connector of the host system 100.

  The second upper housing 13 has a second surface portion 13 a and a pair of second side portions 13 c. The second surface portion 13a constitutes the surface portion 1a of the optical transceiver 1 together with the first surface portion 12a. The second side surface portion 13c constitutes the side surface portion 1c of the optical transceiver 1 together with the first side surface portion 12c. Similar to the first upper housing 12, the second upper housing 13 has a U-shaped cross section with one surface open when viewed from the rear side (cage side) in the longitudinal direction D1. That is, the bottom side of the second upper housing 13 is open. This opening is closed by the lower housing 11. Here, the conductive elastic body 17 is sandwiched between the second upper housing 13 and the lower housing 11. Further, the second upper housing 13 has a pair of screw holes 19. The screw holes 19 extend along the height direction D3 of the optical transceiver 1. Each of the screw holes 19 communicates with the connection hole 14 of the lower housing 11. The screw 16 inserted from the lower housing 11 side is screwed into the screw thread formed in the screw hole 18 through the connection hole 14 of the lower housing 11 and the connection hole 14 of the second upper housing 13 .

  As shown in FIG. 3, the second upper housing 13 has an isolation wall 21 (partition wall portion). That is, the second upper housing 13 differs from the first upper housing 12 in that the second upper housing 13 has the separation wall 21. The separation wall 21 extends from one second side surface portion 13c toward the other second side surface portion 13c. More specifically, one end of the isolation wall 21 is integrated with one second side surface portion 13c, and the other end of the isolation wall 21 is integrated with one second side surface portion 13c. That is, the separation wall 21 is integral with the second side surface portion 13c. The separation wall 21 divides the storage portion S (storage space) into a first storage portion S1 (first storage space) and a second storage portion S2 (second storage space). The housing portion S is a space inside the housing 8 defined by the housing 8. Most of the housing 8 has a rectangular parallelepiped shape which is long in the longitudinal direction D1 so that the housing 101 can be inserted into the cage 101, and the housing portion S has a rectangular parallelepiped shape similar to that. However, the inside of the housing 8 has various asperities etc. by the convenience of attaching a component inside, and it may not be strictly rectangular. Here, the rectangular shape means that the entire appearance can be regarded as a rectangular shape except for the shape of the detail.

  The first accommodation portion S1 is formed on the lower side in the height direction D3 with respect to the second accommodation portion S2. The first accommodation portion S1 accommodates the main circuit board 6. The first housing portion S <b> 1 is surrounded by the lower housing 11, the pair of second side surface portions 13 c, and the separation wall 21. On the other hand, the second accommodation portion S2 accommodates the sub circuit board 7. The second accommodation portion S2 is surrounded by the second surface portion 13a, the pair of second side portions 13c, and the separation wall 21.

  FIG. 4 is an exploded perspective view of the second upper housing 13 as viewed from the back side (the lower housing 11 side). As shown in FIG. 4, the separation wall 21 has an opening 21 d. The opening 21 d is provided on the rear side (cage side) of the separation wall 21. The openings 21 d are for the stacking connector 25. The stacking connector 25 electrically connects the main circuit board 6 and the sub circuit board 7. In the example of FIG. 4, the stacking connector 25 is provided on the surface 6 a of the main circuit board 6 and protrudes toward the sub circuit board 7. The opening 21 d is a region where a part of the separation wall 21 is cut away so as to avoid the protruding portion. Further, the front side 21 f and the rear side 21 g of the separation wall 21 are open ends. For example, the second upper housing 13 has a clearance F for attaching the sub circuit board 7 to the second upper housing 13 on the side 21 g side. By having the clearance F, it is possible to prevent the secondary circuit board 7 from interfering with the second upper housing 13.

  Hereinafter, the heat dissipation structure of the optical transceiver 1 will be described in more detail with reference to FIG. 3 again. The housing 8 has an outer shell 22 and an isolation wall 21. The outer shell 22 is a wall that separates the internal space of the optical transceiver 1 from the outside. The outer shell portion 22 has a second surface portion 13 a, a second side surface portion 13 c, and the lower housing 11. A space surrounded by the second surface portion 13a, the second side surface portion 13c, and the lower housing 11 is a housing portion S. The front and rear of the housing portion S are open. The housing 8 is made of metal. For example, a zinc alloy, an aluminum alloy, a copper alloy or the like can be adopted as a metal material for the housing 8. Then, the thermal conductivity of the housing 8 can be, for example, 120 W / mK or more.

  Next, the separation wall 21 extends from one second side surface portion 13c to the other second side surface portion 13c. That is, the separation wall 21 extends in a planar manner in the longitudinal direction D1 and the width direction D2. In other words, the separation wall 21 is orthogonal to the height direction D3 and faces the second surface portion 13a and the lower housing 11. The storage portion S is divided into a first storage portion S1 and a second storage portion S2 by the separation wall 21. That is, the accommodating portion S is divided into two spaces along the height direction D3 by the separation wall 21.

  The main circuit board 6 is disposed in the first accommodation portion S1. The main circuit board 6 is a so-called printed circuit board (PCB) and is made of a material such as glass epoxy or copper. Then, the thermal conductivity of the main circuit board 6 is, for example, about 0.5 to 5 W / mK. The main circuit board 6 is not particularly limited, and may be, for example, a ceramic board or the like. The same applies to the sub circuit board 7.

  A plurality of ICs 26 are attached to the surface 6 a of the main circuit board 6. These ICs 26 consume relatively large amounts of power. That is, the IC 26 has a large amount of heat generation. For example, the total power consumption of the plurality of ICs 26 mounted on the main circuit board 6 is larger than the total power consumption of the ICs 27 mounted on the sub circuit board 7. In other words, the total heat generation amount of the IC 26 attached to the main circuit board 6 is larger than the total heat generation amount of the IC 27 attached to the sub circuit board 7. The main circuit board 6 is thermally connected to the separation wall 21 by the first heat radiation sheet 28 (first heat transfer member) sandwiched between the IC 26 and the back surface 21 b of the separation wall 21.

  The first heat dissipation sheet 28 is a flexible material having flexibility. For example, the first heat radiation sheet 28 is made of a resin material such as silicone or acrylic. The same applies to a second heat radiation sheet 29 (second heat transfer member) described later. That is, the portion of the back surface 21 b of the isolation wall 21 to which the first heat dissipating sheet 28 is attached receives heat from the IC 26. Therefore, the separation wall 21 constitutes the heat recovery unit 31.

  In addition, a connector (not shown) provided at the front end of the main circuit board 6 is inserted into a connecting portion provided in the first upper housing 12. The main circuit board 6 is mechanically held by this structure. A spacer 35 may be disposed between the back surface 6 b of the main circuit board 6 and the lower housing 11.

  The sub circuit board 7 is disposed in the second housing portion S2. A plurality of ICs 27 are attached to the surface 7 a of the sub circuit board 7. Then, the back surface 7 b of the sub circuit board 7 contacts the surface 21 a of the separation wall 21. That is, the sub circuit board 7 is physically attached to the separation wall 21. When electrodes and the like are exposed on the back surface 7 b of the sub circuit board 7, an appropriate space may be provided between the two or the insulating material so that they are electrically isolated from the isolation wall 21. You may insert it. On the other hand, the sub circuit board 7 is thermally connected by the second heat dissipation sheet 29 sandwiched between the front surface 27a of the plurality of ICs 27 and the back surface 13d of the second front surface portion 13a.

  As described above, between the lower housing 11 and the second upper housing 13, more specifically, the surface 11a of the lower housing 11 and the lower end of the second side surface portion 13c of the second upper housing 13 The conductive elastic body 17 is sandwiched between 13 g and 13 g. Accordingly, the conductive elastic body 17 secures conduction between the lower housing 11 and the second upper housing 13. On the other hand, the conductive elastic body 17 has a thermal conductivity lower than that of the housing 8. As an example, the conductive elastic body 17 is made of silicone as a base material, and conductive particles are included in the silicone. As an example, the thermal conductivity of the conductive elastic body 17 is, for example, 0.1 to 1 W / mK or less. Then, compared to the case where the lower housing 11 and the second upper housing 13 are in direct contact with each other, the conductive elastic body 17 is sandwiched between the lower housing 11 and the second upper housing 13 to thereby lower the lower housing. The thermal conductivity between the body 11 and the second upper housing 13 is reduced to 1/100 or less.

  The heat dissipation mechanism in the optical transceiver 1 having the above-described configuration will be described. Specifically, power is applied to the plurality of ICs 26 and 27 attached to the main circuit board 6 and the sub circuit board 7. Then, each of the ICs 26 and 27 starts a predetermined operation. Then, in accordance with the power consumed for each of the ICs 26 and 27, the respective ICs 26 and 27 generate heat.

  Attention is focused on the IC 26 attached to the main circuit board 6 and the second surface portion 13a. The IC 26 and the second surface portion 13a constitute a thermal circuit. Specifically, the IC 26 is connected to the second surface portion 13a by the separation wall 21 and the first portion 13e of the second side surface portion 13c. That is, the IC 26 is an input (high temperature side), and the second surface portion 13a can be an output (low temperature side).

  Here, when the optical transceiver 1 is switched from the non-energized state to the energized state, it is assumed that the IC 26 generates heat and the temperature of the IC 26 rises. Then, a thermal gradient is generated in the thermal circuit from the IC 26 to the second surface portion 13a. This thermal gradient causes the transfer of heat. Specifically, the heat generated in the IC 26 first moves to the first heat dissipation sheet 28. Next, the heat transferred to the first heat radiation sheet 28 moves to the separation wall 21 via the back surface 21 b of the separation wall 21. Next, the heat transferred to the separation wall 21 is transferred to the first portion 13 e (the heat conducting portion 32) of the second side surface portion 13 c. The heat transferred to the heat conducting part 32 moves to the second surface part 13a. The heat finally transferred to the second surface portion 13a is removed from the housing 8 by the cooling air provided to the second surface portion 13a. Alternatively, when the housing 8 is connected to the cage 101 via a suitable metal member as described above, the heat of the second surface portion 13 a may be further discharged to the cage 101.

  Thus, the heat generated in the IC 26 is conducted to the housing 8 immediately after the first heat dissipation sheet 28 is interposed. It has already been mentioned that this housing 8 is made of a metallic material and has a relatively high thermal conductivity. Accordingly, the heat transferred to the housing 8 is promptly transferred to the heat dissipation unit 33 and discharged to the outside of the housing 8. In addition, since the second surface portion 13 a contacts the first upper case 12, the heat is also transmitted to the first surface portion 12 a of the first upper case 12. Therefore, the heat of the housing 8 is discharged from the first surface portion 12a constituted by the first surface portion 12a and the second surface portion 13a. In addition, a part of the heat transmitted from the separation wall 21 to the second surface portion 13a is also discharged from the second side surface portion 13c in the middle thereof.

  On the other hand, in the optical transceiver 1, the thermal conductivity between the second upper housing 13 and the lower housing 11 is significantly reduced by the conductive elastic body 17. Then, although the heat transmitted to the second side surface portion 13c is transmitted to the second surface portion 13a via the first portion 13e, the heat transmitted to the lower housing 11 via the second portion 13f and the lower end 13g Transmission is limited. The conductive elastic body 17 can selectively transmit the heat recovered to the housing 8 to the first upper housing 12 and the second upper housing 13. In other words, since heat hardly moves to the lower housing 11 where the cooling air is not provided, the generation of heat accumulation in the lower housing 11 can be suppressed. As a result, the heat generated in the IC 26 can be efficiently discharged to the outside of the housing 8.

  Hereinafter, the operational effects of the optical transceiver 1 according to the embodiment will be described in comparison with the optical transceiver according to the comparative example.

  As shown in FIG. 5, the optical transceiver 300 according to the comparative example includes a housing 308, a main circuit board 306, and a sub circuit board 307. Here, the housing 308 includes an upper housing 312 and a lower housing 311, and the upper housing 312 and the lower housing 311 are integrated with the conductive elastic body 313 interposed therebetween. The housing 308 does not have the separation wall 21. That is, the housing 308 has one housing portion S. First, the sub circuit board 307 is thermally connected to the surface portion of the upper housing 312 via the second heat radiation sheet 329. At this time, the sub circuit board 307 is attached to the housing 308 via a spacer (not shown), another holding mechanism (not shown) or the like. Next, the main circuit board 306 is thermally connected to the back surface of the sub circuit board 307 via the first heat dissipation sheet 328. At this time, the main circuit board 306 is attached to the housing 308 via a spacer (not shown), another holding mechanism (not shown) or the like.

  In the optical transceiver 300, it is assumed that the IC 326 of the main circuit board 306 generates heat. At this time, the heat moves to the surface portion which is a heat dissipation surface through the first heat dissipation sheet 328, the sub circuit board 307, and the second heat dissipation sheet 329. The first heat dissipation sheet 328, the sub circuit board 307, and the second heat dissipation sheet 329 have thermal conductivity lower than that of the housing 308. Therefore, the thermal resistance from the IC 326 having a high calorific value to the upper housing 312 is high. For example, a heat dissipation sheet is used to fill a gap between components such as a circuit board. Since the heat dissipation sheet has a lower thermal conductivity than the housing 308, the heat dissipation property is greatly affected. That is, the heat conductivity of the heat dissipation sheet can become the rate-limiting (bottleneck) of the heat dissipation of the IC 326.

More specifically, the heat dissipation of the optical transceiver 300 was examined. In this examination, power consumption was assumed for the ICs mounted on the optical transceiver 300, and the maximum temperature of each IC was confirmed by thermal analysis calculation. In the thermal analysis, the thermal conductivity of each member constituting the optical transceiver 300 was set as follows.
Upper case and lower case: 120 W / mK.
Conductive elastic body: 1 W / mK.
First heat dissipation sheet: 5 W / mK.
Second heat dissipation sheet: 5 W / mK.
Main circuit board: 5 W / mK.
Secondary circuit board: 5 W / mK.

The following conditions were set as a first examination example.
TOSA and ROSA power consumption (total): 2.5W.
CDR (Clock Data Recovery)-IC power consumption: 1.2W.
The CDR IC corresponds to the IC 326 described above. As a result of calculation based on this condition, it has been found that the operating temperature of the CDR-IC is about 85.degree.

The following conditions were set as a second examination example.
TOSA and ROSA power consumption (total): 2.2W.
Power consumption of LDD and PAM-IC (total): 3.6W.
LDD and PAM-IC correspond to the above IC 326. These elements are elements for improving the high-speed performance of the optical transceiver 300, and consume more power than the CDR-IC in the first studied example. Specifically, the total power consumption of the LDD and PAM is about three times the power consumption of the CDR IC. As a result of calculation based on this condition, it was found that the average value of the operating temperature of the LDD and the operating temperature of the PAM-IC was about 95 ° C.

  As a result of the above examination, it was found that the structure of the optical transceiver 300 tends to increase the temperature of the IC 326 as the power consumption of the IC 326 increases. Since the operating temperature range is defined in the IC 326, it has been found that in the case of an IC with large power consumption, there may be a situation where the upper limit of the operating temperature range is exceeded.

  On the other hand, in the optical transceiver 1 according to the embodiment, when the IC 26 attached to the main circuit board 6 generates heat, the heat is transferred to the heat recovery unit 31 to which the main circuit board 6 is thermally connected. Since the separation wall 21 including the heat recovery portion 31 extends from the outer shell portion 22, the heat transferred to the heat recovery portion 31 further moves toward the heat conducting portion 32 which is a part of the outer shell portion 22. The heat transferred to the heat conducting portion 32 further moves to the heat radiating portion 33 which is a part of the outer shell portion 22. Then, the heat moved to the heat dissipation unit 33 is discharged to the outside of the housing 8. Thus, the heat generated in the IC 26 immediately moves to the heat recovery portion 31 which is a part of the housing 8 and then moves to the heat dissipation portion 33 through the heat conducting portion 32 which is a part of the housing 8 . Therefore, the thermal resistance that impedes the heat transfer is reduced, so the heat generated in the IC 26 can be efficiently discharged.

  In short, by making the first upper housing 12 and the second upper housing 13 into a box shape, the optical transceiver 1 releases heat directly to the housing 8 by using a die-cast portion. According to this configuration, the heat dissipating sheet that affects the heat dissipating property can be at only one place.

  The separation wall 21 divides the housing portion S into a first housing portion S1 and a second housing portion S2. The main circuit board 6 is disposed in the first accommodation portion S1. The sub circuit board 7 is disposed in the second housing portion S2. Sub circuit board 7 is thermally connected to heat dissipation unit 33. According to this configuration, the housing 8 can accommodate two circuit boards. Therefore, the number of components that can be accommodated in the housing 8 can be increased, and therefore, the density can be increased.

  The outer shell portion 22 has a front surface portion 1a, a back surface portion 1b, and a pair of side surface portions 1c. The surface portion 1 a includes a heat dissipation portion 33. The heat recovery portion 31 is formed in a planar shape so as to extend from one side surface portion 1c to the other side surface portion 1c. The first accommodation portion S1 is sandwiched between the back surface portion 1b and the heat recovery portion 31. The second housing portion S2 is sandwiched between the surface portion 1a and the heat recovery portion 31. According to this configuration, the sub circuit board 7 can be disposed on the main circuit board 6. Therefore, the optical transceiver 1 can be suitably densified.

  The thermal conductivity of the housing 8 is larger than the thermal conductivity of the main circuit board 6. According to this configuration, the heat generated by the IC 26 can be suitably discharged.

  The main circuit board 6 is connected to the heat recovery unit 31 via the first heat radiation sheet 28. According to this configuration, even when the main circuit board 6 has unevenness due to the height of the IC 26, the unevenness can be absorbed by the first heat radiation sheet 28. Therefore, the heat flow area from the main circuit board 6 to the heat recovery portion 31 can be increased, so the heat resistance can be reduced.

  The sub circuit board 7 is connected to the heat dissipation unit 33 via the second heat dissipation sheet 29. According to this configuration, even when there is unevenness due to the height of the IC 27 on the sub circuit board 7, the unevenness can be absorbed by the second heat radiation sheet 29. Therefore, it is possible to increase the heat flow passage area from the sub circuit board 7 to the heat dissipation portion 33, so that the heat resistance can be reduced.

  The first semiconductor element group is attached to the main circuit board 6. The second semiconductor element group is attached to the sub circuit board 7. The calorific value of the first semiconductor element group is larger than the calorific value of the second semiconductor element group. According to this configuration, the heat caused by the first semiconductor element group can be efficiently discharged.

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Optical transceiver, 1a ... Surface part, 1b ... Back surface part, 1c ... Side part, 2 ... Optical receptacle, 3 ... Optical transmission module (optical apparatus), 4 ... Optical reception module (optical apparatus), 6 ... Main circuit board (1st circuit board), 7 ... secondary circuit board (2nd circuit board), 8 ... case, 11 ... lower case, 12 ... first upper case, 13 ... second upper case, 14 ... connection hole Reference numeral 16 screw, 17 conductive elastic body 18, 19 screw hole 21 separating wall (partition wall portion) 22 shell portion 25 stacking connector 26 27 IC (semiconductor element) 28 ... First heat dissipation sheet (first heat transfer member), 29 ... second heat dissipation sheet (second heat transfer member), 31 ... heat recovery portion, 32 ... heat conduction portion, 33 ... heat dissipation portion, 35 ... spacer, 100 ... Host system, 101: cage, 200: optical connector, 201: optical fiber, 300: light tiger Siva, 306: main circuit board, 307: secondary circuit board, 308: housing, 311: lower housing, 312: upper housing, 313: conductive elastic body, 328: first heat dissipation sheet, 329: second heat dissipation Sheet, D1 ... longitudinal direction, D2 ... width direction, D3 ... height direction, F ... clearance, S ... accommodation portion, S1 ... first accommodation portion, S2 ... second accommodation portion.

Claims (7)

An optical transceiver comprising an optical device for performing signal conversion between an electrical signal and an optical signal, comprising:
A circuit board on which a semiconductor element for processing the electrical signal is attached;
And a case having an outer shell defining a rectangular parallelepiped housing space for housing the circuit board, and a partition extending from the outer shell toward the housing space.
The partition portion includes a heat recovery portion thermally connected to the semiconductor element,
The outer shell portion includes a heat dissipation portion which dissipates heat conducted from the semiconductor element, and a heat conducting portion which conducts heat conducted from the semiconductor element to the heat recovery portion to the heat dissipation portion. Transceiver. The partition portion divides the housing space into a first housing space, and a second housing space located between the first housing space and the heat radiating portion.
A first circuit board, which is the circuit board, is disposed in the first accommodation space.
A second circuit board different from the circuit board is disposed in the second accommodation space,
The optical transceiver according to claim 1, wherein the second circuit board is thermally connected to the heat dissipation unit. The outer shell portion has a surface portion covering an upper portion of the accommodation space, a back surface portion covering a lower portion of the accommodation space, and a pair of side portions covering side portions of the accommodation space.
The surface portion includes the heat dissipation portion,
The heat recovery portion is formed to extend from one of the pair of side portions to the other of the pair of side portions.
The first accommodation space is sandwiched between the back surface portion and the heat recovery portion,
The optical transceiver according to claim 2, wherein the second accommodation space is sandwiched between the surface portion and the heat recovery portion.   The optical transceiver according to claim 2, wherein the thermal conductivity of the housing is larger than the thermal conductivity of the circuit board. The semiconductor device further comprises a first heat transfer member in contact with the semiconductor element attached to the first circuit board and in contact with the heat recovery portion.
The optical transceiver according to any one of claims 2 to 4, wherein the semiconductor element attached to the first circuit board is thermally connected to the heat recovery unit via the first heat transfer member. And a second heat transfer member in contact with the heat dissipation portion while in contact with the second circuit board,
The optical transceiver according to any one of claims 2 to 5, wherein the second circuit board is connected to the heat dissipation unit via the second heat transfer member. A first semiconductor element group including the semiconductor element is attached to the first circuit board,
A second semiconductor element group including a semiconductor element different from the semiconductor element is attached to the second circuit board,
The optical transceiver according to any one of claims 2 to 6, wherein a calorific value of the first semiconductor element group is larger than a calorific value of the second semiconductor element group.

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