JP2020053567A - Optical module - Google Patents

Abstract

To secure a sufficient heat dissipation property.SOLUTION: An optical module 10 comprises: a printed board 22 on whose first surface 24, an electronic component is mounted and which has a through hole 46 overlapping the electronic component; a housing 58 that includes a first case 60 and a second case 62 combined with each other, with the first case 60 opposing the first surface 24 and the second case 62 opposing a second surface 26; a first heat conduction member 48 disposed inside a through hole 46 of the printed board 22 so as to thermally contact the electronic component; and a second heat conduction member 64 that integrally includes a first portion 66 existing between the first case 60 and the first surface 24, a second portion 70 existing between the second case 62 and the second surface 26, and a third portion 72 that establishes connection of the first portion 66 and the second portion 70 at a side of the printed board 22. The first heat conduction member 48 and the second heat conduction member 64 thermally contact with each other. The first portion 66 of the second heat conduction member 64 thermally contact the first case 60.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an optical module.

  An optical module (transceiver) having a transmission / reception function is used by being inserted into a cage provided in a host device. A heat sink (heat spreader) is attached to the cage to cool the optical module (Patent Document 1). Since the bottom surface of the cage is fixed to the printed circuit board, the heat sink is provided only on the upper surface of the cage, and heat is transmitted from the upper surface of the case of the optical module. Alternatively, a heat sink may be provided on the case of the optical module. Patent Literature 2 discloses an example in which a heat sink is attached to an upper surface of an optical module. In any case, the heat sink is provided only on one side of the cage or the optical module.

JP-A-2017-111421 JP 2004-63861 A

  The optical module has built-in electronic components including a heating element, and when it is difficult to transmit heat from the upper side due to its structure, heat is radiated from the bottom. However, when radiating heat from the bottom surface of the electronic component, since the heat radiation is on the opposite side to the heat sink, the heat radiation is insufficient, and the optical module cannot be sufficiently cooled. Characteristics may not be obtained.

  An object of the present invention is to ensure sufficient heat dissipation.

  (1) An optical module according to the present invention has an optical subassembly for converting an optical signal and an electric signal from at least one to the other, an electronic component that generates heat, and first and second surfaces that are opposite to each other. And a printed circuit board having the electronic component mounted on the first surface, electrically connected to the optical subassembly, and having a through hole overlapping the electronic component, and a first case and a second case combined with each other; The first case faces the first surface, the second case faces the second surface, and a housing for housing the optical subassembly, the electronic component, and the printed circuit board; A first heat conductive member disposed inside the through-hole of the printed circuit board so as to make contact with the first case, a first portion between the first case and the first surface, and the second case. The second between the second surfaces And a second heat conducting member integrally including a third portion connecting the first portion and the second portion on the side of the printed circuit board. The second heat conductive member is in thermal contact with the first heat conductive member, and the first portion of the second heat conductive member is in thermal contact with the first case.

  According to the present invention, the electronic component is mounted on the first surface of the printed circuit board, and heat can be transmitted from the second surface on the opposite side to the first surface by the second heat conducting member. Thereby, sufficient heat dissipation can be ensured.

  (2) The optical module according to (1), wherein the first heat conductive member includes a metal layer provided on an inner surface of the through hole to form a thermal via. .

  (3) The optical module according to (1) or (2), wherein the first heat conductive member includes a metal block.

  (4) The optical module according to any one of (1) to (3), wherein the second portion of the second heat conductive member is in thermal contact with the second case. It may be characterized.

  (5) The optical module according to any one of (1) to (4), wherein heat conductive grease interposed between the first case and the first portion of the second heat conductive member is removed. It may be further characterized by having.

  (6) The optical module according to any one of (1) to (5), wherein the printed circuit board has a notch next to the third portion of the second heat conductive member. May be a feature.

  (7) The optical module according to any one of (1) to (6), wherein the optical module is in thermal contact between the first heat conductive member and the second portion of the second heat conductive member. And a third heat conductive member interposed so as to perform the heat treatment.

  (8) In the optical module described in (7), the second portion of the second heat conductive member may be larger than the third heat conductive member.

  (9) The optical module according to (8), further including a second electronic component mounted on the second surface of the printed circuit board, adjacent to the third heat conductive member. (2) The second portion of the heat conducting member may extend between the second electronic component and the second case.

  (10) In the optical module described in (9), the third heat conductive member includes a base portion facing the first heat conductive member, and a flange portion protruding from the base portion. May be a feature.

  (11) The optical module according to (10), wherein the flange portion overlaps the second electronic component.

FIG. 2 is an external view of the optical module according to the embodiment. FIG. 2 is a perspective view illustrating a host device on which the optical module according to the embodiment is mounted. FIG. 2 is a perspective view showing the internal structure of the host device. FIG. 2 is a perspective view of the internal structure of the optical module shown in FIG. 1 as viewed obliquely from above. FIG. 2 is a perspective view of the internal structure of the optical module shown in FIG. 1 as viewed obliquely from below. FIG. 3 is a perspective view illustrating a first surface of a printed circuit board. It is a perspective view showing the 2nd surface of a printed circuit board. FIG. 8 is a sectional view taken along line VIII-VIII of the optical module shown in FIG. 1. It is sectional drawing of the optical module which concerns on the modification 1 of embodiment. It is sectional drawing of the optical module which concerns on the modification 2 of embodiment. FIG. 13 is a perspective view of a third heat conductive member used in Modification Example 2.

  Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the drawings. In all of the drawings, members denoted by the same reference numerals have the same or equivalent functions, and a repeated description thereof will be omitted. Note that the size of the graphic does not always match the magnification.

  FIG. 1 is an external view of the optical module according to the embodiment. The optical module 10 is an optical receiver (optical transceiver) having a transmission function and a reception function with a bit rate of 400 Gbit / s class.

  FIG. 2 is a perspective view illustrating a host device on which the optical module 10 according to the embodiment is mounted. The host device is, for example, a large-capacity router or switch, has a function of, for example, an exchange, and is arranged in a base station or the like.

  FIG. 3 is a perspective view showing the internal structure of the host device. The host device has a circuit board 12. A cage 14 is attached to the circuit board 12. A heat sink 16 is attached to an upper surface side of the cage 14 (an outer surface side opposite to the circuit board 12). The optical module 10 is inserted into the cage 14 and radiates heat via the heat sink 16. The heat is further released from the vent 18 (FIG. 2) of the host device.

  FIG. 4 is a perspective view of the internal structure of the optical module 10 shown in FIG. 1 as viewed obliquely from above. FIG. 5 is a perspective view of the internal structure of the optical module 10 shown in FIG. The optical module 10 includes a plurality of optical subassemblies 20 for converting an optical signal and an electric signal from at least one to the other. The plurality of optical subassemblies 20 include an optical transmitting subassembly (TOSA) having an optical transmitting function, an optical receiving subassembly (ROSA: Receiver Optical Subassembly) having an optical receiving function, and a bidirectional subunit having an optical transmitting and receiving function. Assembly (BOSA: Bi-directional Optical Subassembly). An electric signal is transmitted from the optical receiving subassembly 20A to the circuit board 12 of the host device shown in FIG. An electric signal is transmitted from the circuit board 12 to the optical transmission subassembly 20B.

  The optical module 10 has a printed board 22 on which a wiring pattern (not shown) is formed. The printed circuit board 22 is electrically connected to the optical subassembly 20. The printed circuit board 22 has a first surface 24. The printed circuit board 22 has a second surface 26 opposite to the first surface 24.

  FIG. 6 is a perspective view showing the first surface 24 of the printed circuit board 22. On the first surface 24, a first electronic component 28 that generates heat is mounted. A digital signal processor (DSP) 30 is also mounted on the first surface 24, and is one of the heat sources.

  FIG. 7 is a perspective view showing the second surface 26 of the printed circuit board 22. On the second surface 26, in addition to the power supply IC 32 and the control IC 34, at least one second electronic component 36 is mounted. The second electronic component 36 does not overlap with the first electronic component 28. The first electronic component 28 and the second electronic component 36 are shifted in the width direction of the printed circuit board 22 (a direction orthogonal to the direction between the first electronic component 28 and the optical subassembly 20).

  FIG. 8 is a sectional view taken along line VIII-VIII of the optical module 10 shown in FIG. The first electronic component 28 has a built-in integrated circuit chip 38. The integrated circuit chip 38 is mounted on a package substrate 40 made of an insulator such as a ceramic, so as to establish an electrical connection with the outside through a via 42. Resin is used for the sealing portion 44 in order to reduce costs, and since there is a space inside to prevent deformation of a wire (not shown), heat is hardly transmitted.

  The printed circuit board 22 has a plurality or one through hole 46 overlapping the first electronic component 28. A first heat conductive member 48 is arranged inside the through hole 46. The first heat conductive member 48 is a metal layer provided on the inner surface of the through hole 46 for forming a thermal via. The first heat conducting member 48 is in thermal contact with the first electronic component 28 (the bottom surface). For example, the first heat conductive member 48 and the first electronic component 28 may be in direct contact with each other, or a heat conductive adhesive, film, solder, or the like may be interposed.

  Above the printed board 22, a sub-printed board 50 on which a wiring pattern (not shown) is formed is arranged. Specifically, the sub-printed circuit board 50 is placed on the first electronic component 28 via a heat conductive sheet 52 made of a material having heat conductivity such as silicone. The sub-printed circuit board 50 may be fixed above the printed circuit board 22 using another metal fitting or the like. The sub printed board 50 also has a through hole 54 overlapping the first electronic component 28 (heat conductive sheet 52), and a heat conductive member 56 is disposed inside the through hole 54. This heat conductive member 56 may also be a metal layer for forming a thermal via. Although the example using the sub-printed board 50 is shown here, the sub-printed board 50 may be omitted.

  The optical module 10 has a housing 58. The housing 58 houses the optical subassembly 20, the first electronic component 28, and the printed circuit board 22. The housing 58 includes a combined first case 60 and second case 62. The joining may be performed by a fastening means such as a screw, or an adhesive may be used. However, since the first case 60 and the second case 62 are separate members, the thermal conductivity of the contact interface is sufficient. is not. Note that the first case 60 faces the first surface 24 of the printed circuit board 22. The second case 62 faces the second surface 26 of the printed circuit board 22. The outer surface of the first case 60 faces the heat sink 16 of the cage 14.

  The optical module 10 has a second heat conducting member 64. The second heat conducting member 64 includes a first portion 66. The first portion 66 of the second heat conducting member 64 is between the first case 60 and the printed board 22 (the first surface 24) and above the first electronic component 28. The first portion 66 is in thermal contact with the first case 60. The first portion 66 and the first case 60 may be in direct contact with each other, but the heat conductive grease 68 is interposed. The heat conductive grease 68 is also interposed between the first portion 66 and the sub printed circuit board 50. In other words, the first portion 66 is arranged in the heat conductive grease 68 interposed between the first case 60 and the sub printed circuit board 50 in close contact.

  The second heat conduction member 64 includes a second portion 70. The second portion 70 of the second heat conducting member 64 is between the second case 62 and the printed board 22 (the second surface 26). The second part 70 is in thermal contact with the second case 62. For example, the second portion 70 and the second case 62 may be in direct contact with each other, or may be provided with a thermally conductive adhesive or film. Note that the second portion 70 need not be in contact with the second case 62.

  The second heat conductive member 64 includes a third portion 72 connecting the first portion 66 and the second portion 70 on the side of the printed circuit board 22. As shown in FIGS. 4 to 7, the printed circuit board 22 has a notch 74 next to the third portion 72 of the second heat conductive member 64. The third portion 72 is accommodated in the notch 74 so as not to protrude to the side of the printed circuit board 22.

  The first portion 66, the second portion 70, and the third portion 72 are continuously integrated. It is preferable that an electrical insulating film is formed on the surface of the second heat conductive member 64 as long as it does not hinder thermal contact with other members. The second heat conducting member 64 is preferably made of a material having excellent heat conductivity, such as a metal plate or graphite.

  The second heat conducting member 64 is in thermal contact with the first heat conducting member 48. A third heat conductive member 76 such as a metal block is interposed between the first heat conductive member 48 and the second portion 70 so as to be in thermal contact. The second portion 70 of the second heat conducting member 64 is larger than the third heat conducting member 76. A second electronic component 36 is mounted on the second surface 26 of the printed circuit board 22 adjacent to the third heat conductive member 76. The second portion 70 of the second heat conducting member 64 extends between the second electronic component 36 and the second case 62. Although the example in which the third heat conductive member 76 is arranged is shown here, the second portion 70 of the second heat conductive member 64 and the first heat conductive member 48 are thermally connected without the third heat conductive member 76 interposed therebetween. You may come into contact with it.

  According to the present embodiment, the first electronic component 28 is mounted on the first surface 24 of the printed circuit board 22, and is moved in the direction from the opposite second surface 26 to the first surface 24 by the second heat conductive member 64. Can transmit heat. Since the first case 60 on the first surface 24 side is in thermal contact with the heat sink 16, sufficient heat radiation can be ensured. Although not shown, a heat sink may be provided directly on the outer surface of the first case 60. In this case, no heat sink is arranged in the cage 14.

[Modification 1]
FIG. 9 is a cross-sectional view of an optical module according to a first modification of the embodiment. In this modification, the printed circuit board 122 has a first through hole 146A and a second through hole 146B. A metal layer 178 for forming a thermal via is provided on the inner surface of the first through hole 146A. The metal block 180 is disposed in the second through hole 146B. The first heat conducting member 148 includes a metal layer 178 and a metal block 180.

[Modification 2]
FIG. 10 is a cross-sectional view of an optical module according to Modification 2 of the embodiment. In this modification, the shape of the third heat conductive member 276 is different. FIG. 11 is a perspective view of the third heat conductive member 276 used in the present modification. Third heat conductive member 276 includes a base portion 282 facing first heat conductive member 248 and in thermal contact therewith. Third heat conductive member 276 includes a flange portion 284 protruding from base portion 282. The flange portion 284 overlaps the second electronic component 236.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the configuration described in the embodiment can be replaced with a configuration having substantially the same configuration, a configuration having the same operation and effect, or a configuration capable of achieving the same object.

Reference Signs List 10 optical module, 12 circuit board, 14 cage, 16 heat sink, 18 vent, 20 optical subassembly, 20A optical receiving subassembly, 20B optical transmitting subassembly, 22 printed circuit board, 24 first surface, 26 second surface, 28 1st electronic component, 30 digital signal processor, 32 power supply IC, 34 control IC, 36 second electronic component, 38 integrated circuit chip, 40 package substrate, 42 via, 44 sealing portion, 46 through hole, 48 first heat conduction Member, 50 sub printed circuit board, 52 heat conductive sheet, 54 through hole, 56 heat conductive member, 58 housing, 60 first case, 62 second case, 64 second heat conductive member, 66 first part, 68 heat conductive Grease, 70 second part, 72 third part, 74 cutout, 76 third heat conductive member, 122 printed circuit board, 146A first Through hole, 146B Second through hole, 148 First heat conductive member, 178 metal layer, 180 metal block, 236 Second electronic component, 248 First heat conductive member, 276 Third heat conductive member, 282 Base portion, 284 Flange Department.

Claims (11)

An optical subassembly for converting optical and electrical signals from at least one to the other;
Electronic components that generate heat,
A printed circuit board having opposite first and second surfaces, the electronic component being mounted on the first surface, being electrically connected to the optical subassembly, and having a through hole overlapping the electronic component;
A first case facing the first surface, the second case facing the second surface, the optical subassembly, the electronic component, and the printed circuit board; A housing for accommodating the
A first heat conductive member disposed inside the through hole of the printed circuit board so as to thermally contact the electronic component;
A first portion between the first case and the first surface; a second portion between the second case and the second surface; and the first portion and the second portion on a side of the printed circuit board. A second heat conductive member integrally including a third portion connecting the two portions;
Has,
The first heat conductive member and the second heat conductive member are in thermal contact,
The optical module according to claim 1, wherein the first portion of the second heat conductive member is in thermal contact with the first case. The optical module according to claim 1,
The optical module according to claim 1, wherein the first heat conductive member includes a metal layer provided on an inner surface of the through hole for forming a thermal via. The optical module according to claim 1, wherein:
The optical module according to claim 1, wherein the first heat conductive member includes a metal block. The optical module according to claim 1, wherein:
The optical module according to claim 2, wherein the second portion of the second heat conductive member is in thermal contact with the second case. The optical module according to claim 1, wherein:
The optical module according to claim 1, further comprising a heat conductive grease interposed between the first case and the first portion of the second heat conductive member. The optical module according to claim 1, wherein:
The optical module according to claim 1, wherein the printed circuit board has a notch next to the third portion of the second heat conductive member. The optical module according to any one of claims 1 to 6, wherein
The optical module according to claim 1, further comprising a third heat conductive member interposed between the first heat conductive member and the second portion of the second heat conductive member so as to be in thermal contact with each other. The optical module according to claim 7,
The optical module according to claim 2, wherein the second portion of the second heat conductive member is larger than the third heat conductive member. The optical module according to claim 8, wherein:
A second electronic component mounted on the second surface of the printed circuit board adjacent to the third heat conductive member;
The optical module according to claim 1, wherein the second portion of the second heat conductive member extends between the second electronic component and the second case. The optical module according to claim 9, wherein:
The optical module according to claim 1, wherein the third heat conductive member includes a base portion facing the first heat conductive member, and a flange protruding from the base portion. The optical module according to claim 10,
The optical module, wherein the flange portion overlaps the second electronic component.

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