JP4826889B2 - Optical transceiver heat dissipation structure - Google Patents

Description

  The present invention relates to a structure for fixing a light emitting module in an optical transceiver in consideration of heat dissipation characteristics.

The first patent document discloses an optical transceiver in which a pigtail type optical module (transmission and reception) is mounted. That is, each module (64, 94) is a pigtail type module, and a connector attached to the tip of the pigtail fiber is mounted on the housing for an interface with the outside of the transceiver. X2 was established as a standard for this type of multifunctional optical transceiver under the large number of participants (X2-MSA). According to the standard, the electrical speed is 10 GHz, the pin assignment is mechanical, the mechanical size is the housing size, the type of optical connector to be used, the installation conditions between the transceiver and the host device, etc. Is stipulated.
US Pat. No. 5,943,461 X2 MSA Rev. 1.0b “A Cooperation Agreement for a Small Versatile 10 Gigabit Transceiver Package”, published February 28, 2003

  In order to realize high-speed communication of 10 GHz, a special one is required for the electric circuit. In particular, the power consumption of the electronic device to be used is expected to be significantly higher than when only a communication speed of GHz or less is required. Furthermore, since multifunctional optical communication characteristics are required, optical coupling characteristics with optical fibers must be more precise. For the increasing power consumption, the two propositions are that the assembly of each part must be rigorous and the thermal coupling characteristics must be satisfied, while the optical coupling characteristics require a higher level of precision. Must be satisfied.

  In the conventional optical transceiver, these two propositions are contradictory. When assembling each component with a focus on thermal coupling, there is no guarantee that the desired characteristics can be obtained in terms of optical coupling, but rather only inferior values from the optimal optical coupling characteristics. There were many cases. On the other hand, when the optical coupling characteristics are satisfied, there are many cases in which it is difficult to take measures for heat dissipation. The present invention is a new optical transceiver structure that satisfies both the optical coupling characteristic and the thermal coupling characteristic at the same time. A new mechanism for the assembly structure to the transceiver is provided.

  The optical transceiver according to the present invention is an optical transceiver in which an optical module having a sleeve portion and a box portion is mounted on a housing. The sleeve portion is directly fixed to the housing rigidly, but the box portion is indirectly fixed to the housing via an auxiliary member. The optical transceiver is characterized in that the relative position between the box portion and the auxiliary member is held freely.

  When the box part is in intimate contact with the housing in order to maintain the heat dissipation effect, which is a problem with conventional optical transceivers, because the box part is indirectly fixed to the housing via an auxiliary member. In addition, the module can be fixed to the housing without causing mechanical distortion due to the positional shift between the sleeve portion and the box portion, which is induced by fixing the optical module to the housing at two locations.

  The auxiliary member fixes the box part to itself so as to sandwich the box part. Furthermore, between the two, heat conduction grease is applied and an elastic member is sandwiched so that the box portion can always be brought into contact with the auxiliary member due to the stress of the elastic member. Since the auxiliary member is rigidly fixed to the housing, the heat generated inside the box portion can be efficiently transmitted to the housing via the auxiliary member.

  Furthermore, the position of the auxiliary member is freely fixed with respect to the housing in the direction perpendicular to the main surface of the housing. On the other hand, the position of the box portion is freely fixed with respect to the auxiliary member in two directions parallel to the main surface of the housing. Accordingly, the position of the box portion is freely fixed in three directions with respect to the main surface of the housing. Therefore, even if the sleeve portion is rigidly fixed to the housing, the box portion traces the sleeve portion. Therefore, no mechanical distortion occurs between the sleeve portion and the box portion.

  The auxiliary member can be a metal material having good heat conductivity such as aluminum (Al). Since it is a metal material, there is no difficulty in its processing. The elastic member can be formed only by providing an elastic claw on the metal thin plate. It can be a form that is a material that can suppress an increase in price due to a component material or its processing.

  According to the mounting form of the module to the housing according to the present invention, even if the positional relationship between the sleeve portion of the module and the housing is rigidly defined from the optical coupling surface, the heat generated in the module is efficiently transferred to the housing. It is possible to dissipate heat.

  FIG. 1 shows the appearance of an optical transceiver 1 on which an optical module according to the present invention is mounted. The optical transceiver 1 is roughly divided into a receptacle part 1a, a flange part 1b, and an electronic circuit part 1c. The receptacle portion 1a has two openings 1d and 1e, which correspond to the transmission receptacle 1d and the reception receptacle 1e, respectively. A grip 2 is provided so as to surround the opening, and the transceiver 1 can be removed from the host system on which the transceiver 1 is mounted by moving the grip 2 back and forth.

  A flange 8 is provided on the flange portion 1b. When the transceiver 1 is mounted on the host system, the front side (receptacle side) from the flange 8 is exposed from the face panel of the host system, and the receptacle openings 1d and 1e are opened. Therefore, the optical connector can be engaged with the receptacle from the front side of the host system. An electronic circuit portion 1c is provided on the rear side of the flange portion 1b. An electronic circuit is mounted on the circuit board 6 in the electronic circuit unit 1b, and this electronic circuit is mounted at the forefront of the electronic circuit unit 1c so that the tip protrudes into the receptacle openings 2a and 2b. Electrically coupled to the receiving module. The circuit board 6, the transmission module, and the reception module are assembled with respect to the upper housing 4. Further, the transmission module and the reception module are mounted so as to be sandwiched between the lower housing 5 assembled integrally with the upper housing 4. From the side of the lower housing 5, when the transceiver 1 is mounted on the host system, an engagement pin 5 a that ensures the engagement state of both protrudes. By moving the grip 2 back and forth, the engaging pin 5a can be moved left and right to release the engaged state with the host system.

  When the operating speed exceeds the GHz band, it becomes increasingly difficult to directly modulate the semiconductor laser (LD) by turning the supply current on / off. Although there is no problem in supplying to the LD in terms of electrical signals, the light emission pattern obtained from the LD is not sufficiently turned on / off. That is, the deterioration of the extinction ratio becomes remarkable in such a high frequency region.

  As one solution, an external modulation method is known in which the LD emits light in a DC manner and the emitted light is modulated outside the LD. As an external modulator, for example, a method using a Mach-Zehnder type waveguide or a semiconductor modulator using an electro-absorption effect is known. FIG. 2 shows the appearance of an EA-DFB module that employs a DFB-LD (Distributed Feedback-LD) excellent in monochromaticity as an LD and an EA modulator as a modulator. 2A is a perspective view, and FIG. 2B is a side view.

The EA-DFB module 10 includes a large box-shaped box portion 12 and a sleeve portion 11 extending forward from one side surface 12a of the box portion 12. Here, the forward direction simply refers to the direction in which the sleeve portion 11 extends as the forward direction for convenience, and is not functionally distinguished. The box portion 12 has a size of about 10 × 5.7 × 5.7 mm ³ and has a side surface 12a from which the sleeve portion 11 extends and a surface 12c facing this surface on the rear side. Rear surface 12c, side surfaces 12g, 12h. The upper surface in FIG. 2A is made of an integrally shaped ceramic, and the front surface 12a is formed of a metal such as Kovar. Although hidden in FIG. 2 (a), a part of the upper surface 12d is opened, and the opening is covered with a seal lid 12b. The seal lid 12b is formed by side surfaces 12c, 12g, and 12h of the front surface 12a. The inner space of the box portion 12 is sealed. A plurality of lead pins 12g and 12f extend from the two ceramic side surfaces 12c and 12g, respectively.

  In the internal space of the box portion 12, the EA-DFB element is incorporated, and a TEC (Thermo-Electric Controller) element for controlling the temperature of the EA-DFB element, for example, a Peltier element, corresponds to the upper surface 12d. And is directly in contact with the seal lid 12b. The seal lid 12b is a good heat conductive material, and for example, CuW can be used. On the upper surface 12d, a drive circuit for driving the EA section at a high frequency is mounted. FIG. 2A shows the inside of the box portion 12 upside down. A high frequency signal supplied to a built-in drive circuit from a lead pin 12e formed on the side wall 12c (rear wall), and a power supply to the drive circuit and the ED-DFB element from a lead pin 12f provided on the side surface 12g A DC or relatively low frequency signal such as a line or a power line to a built-in Peltier element is transmitted and received. In the examples of FIGS. 2A and 2B, these signal lines and power lines use flexible printed circuit boards 13a and 13b.

  In recent years, the speed of signals in an optical communication system has been increased, and several years ago, an optical transceiver capable of sufficiently responding to a 2.5 GHz signal as a standard signal speed has already been commercialized. Trying to exceed 10 GHz. As the operation speed becomes higher in this way, the power consumed by the drive circuit mounted on the box portion has also increased. In the example of FIG. 2, the power consumption in the box unit 12 incorporating the drive circuit and the TEC element is 1 W. For this reason, heat dissipation in this box part must also be considered.

  The sleeve portion 11 is an assembly of cylindrical parts extending from one side surface 12 a of the box portion 12. The tip portion forms a metal sleeve 11a, and the sleeve 11a receives the ferrule attached to the tip of the optical fiber. The base from the sleeve 11a to the box portion 12 is composed of a plurality of metal cylindrical members (11b to 11c), and optical adjustment between the sleeve 11a and the EA-DFB device housed in the box portion 12 is performed. Realizes the core function. That is, the light emitted from the EA-DFB device must be collected on the optical fiber held in the center of the ferrule housed in the sleeve 11a. Alignment is performed in the direction parallel to the axis (Z direction) and in the direction perpendicular to the axis (XY direction). After alignment, these metal members are permanently fixed by, for example, YAG welding.

  FIG. 3 is a diagram illustrating an internal state of the transceiver 1 when such an EA-DFB module 10 is mounted on the lower housing 5 of the optical transceiver 1. The transceiver 1 includes an optical receptacle 1a, an EA-DFB module 10, a receiving optical sub-assembly (ROSA) 20, and a circuit board 6 on which an electronic circuit is mounted. An optical connector is inserted into the two spaces 1d and 1e of the receptacle 1a. On the other hand, in the transceiver, the EA-DFB sleeve portion 11a and the ROSA sleeve portion 21a protrude into the spaces 1d and 1e, respectively. Here, it is optically coupled with the ferrule attached to the tip. The lower housing 5 is made of metal in this example, but may be made of resin. In the form shown in FIG. 3, the ROSA 20 in a form not having a box-shaped box part is adopted as the receiving-side ROSA 20. Also for this ROSA 20, when a component such as a Peltier cooler is mounted inside, it is also possible to use a ROSA having a box-shaped outer shape.

  On the circuit board 6, a drive circuit for driving the EA-DFB element or a circuit for processing an electrical signal converted from an optical signal by a light receiving element mounted in the ROSA is mounted. In the example of FIG. 3, these circuits are combined into one IC 6a. At the rear end of the circuit board 6, an electrical connector 6b is formed for transmitting and receiving signals and power to and from the host device on which the transceiver 1 is mounted.

  The EA-DFB module 10 and the ROSA 20 are mounted on the receptacle, and at the same time, their sleeves (11a, 21a) are sandwiched between the latch members 5a, so that their positions are determined with respect to the lower housing 5. Here, FIG. 2B shows a plan view of the EA-DFB module. The EA-DFB module 10 is fixed to the lower housing by a latch member 5a at the middle 11c of the sleeve portion 11. On the other hand, among the side surfaces of the box portion 12, the FPC board extends from the front surface 12a to the sleeve portion 11, the rear 12c, and the one side surface 12g, so that these surfaces 12a, 12c, and 12g are heated by other members. Heat can not be achieved by contact. In order to efficiently dissipate the heat generated inside the box portion 12, the remaining one side surface 12h or the upper and lower surfaces (12b) must be used.

  In order to efficiently dissipate heat, these side surfaces 12h and upper and lower surfaces need to be brought into close contact with the inner surface of the casing of the transceiver 1, for example. On the other hand, the middle 11 c of the sleeve portion 11 is also fixed to the lower housing 5. That is, when mounting this type of EA-DFB module 10 on the optical transceiver 1, both the sleeve 11 and the box portion 12 must be fixed to the housing. There is no problem if the mechanical dimensional accuracy of the module 10 or the mechanical dimensional accuracy for mounting the module of the lower housing 5 is sufficiently secured, but the sleeve portion 11 is not between the optical fiber and the element. When the optical coupling is adjusted to the target, a gap is often generated between the box portion 12 and the inner surface of the housing. In order to fill this gap, when the box portion 12 is strongly pressed against the casing, not only the optical coupling efficiency is impaired, but also a large mechanical strain is induced in the attachment portion of the sleeve portion 11 to the box portion 12. As a result, the reliability of the module 10 was impaired.

  4 (a) and 4 (b) show the appearance of the auxiliary member 50 for heat dissipation and fixing according to the present invention in a state of being attached to the EA-DFB module 10. FIG. The form of only the auxiliary member 50 is shown in FIG. The auxiliary member 50 is a metal member having good heat conduction characteristics, and is made of, for example, Al. The cross section of the module 10 has a U-shaped cross section so as to surround the three open faces, 12h, 12b and the bottom face of the box portion. Thermal conduction grease is applied between the upper surface 12b of the box portion 12 and the upper portion 50c of the auxiliary member in contact with the surface to increase the thermal contact efficiency. As described with reference to FIG. 2A, the most heat-generating component in the box portion 12 is the thermoelectric conversion element TEC. The TEC is mounted so as to be in direct contact with the seal lid 12b of the box portion 12. Therefore, by applying heat conduction grease between the upper surface of the module 10 and the side 50c of the auxiliary member and then bringing them into close contact, the heat generated in the module 10 can be efficiently transmitted to the auxiliary member. .

  On the other hand, an elastic member 60 is interposed between the bottom surface of the box portion and one side 50a of the auxiliary member. Due to the presence of the elastic member 60, the box portion is pressed against the upper surface 50 c of the auxiliary member 50. Since thermally conductive grease is applied between the upper surface 50c and the module 10, a thermally efficient coupling is realized between them. The relative position in the horizontal (horizontal) direction between the module 10 and the auxiliary member 50 is not limited in any way. That is, a gap may be formed between the side surface 50 b of the auxiliary member 50 having a U-shaped cross section and the side surface 12 h of the module 10.

  FIG. 4C shows a state in which the module 10 with the auxiliary member 50 is viewed from the opposite side to FIG. 4A. The outer surface 50b of the auxiliary member 50 has a pair of convex portions 50d in a substantially central vertical direction, and a screw hole 50e is formed between the pair of convex portions 50d. The functions of these convex portions 50d and screw holes 50e will be described later.

  5A to 5C show an example of the elastic member 60. FIG. In this example, a shape in which a plurality of punch holes are formed in a thin metal plate and the latch pawls 60a are left inside the plurality of holes is shown. Each claw 60a is lightly bent downward, and when the elastic member 60 is inserted between the auxiliary member 50 and the module 10 by the claw, an elastic force is generated to push the module 10 upward. The sum of the amount of bending of the claw 60a, the thickness of the elastic member 60, and the total height of the box portion 12 of the module 10 is larger than the distance between the upper and lower pieces of the auxiliary member 50, 50a, 50c, The total height of the box portion 12 must be smaller than the distance between the upper and lower pieces 50a and 50c of the auxiliary member 50. Furthermore, not only between the box part 12 and the upper piece 50c of the auxiliary member 50, but also between the lower piece 50a and the side where the elastic member 60 is inserted, heat conductive grease is applied. Thus, the heat dissipation characteristics from the module 10 can be further improved.

  6A to 6D are a side view (a), a front view (b), and two overhead views (c) and (d) of the auxiliary member 50. FIG. As already described, the auxiliary member 60 is made of a metal having good thermal conductivity, such as Al, and is a member having a U-shaped cross section with the front end and the rear end open. As described above, the upper piece 50c is coated with the thermal conductive grease and is in close contact with the module 10, while the lower piece 50a is connected to the elastic member 60 or the elastic member 60 and the thermal conductive grease through the module. 10 is in contact. On the outer side of the side piece 50b of the member 50, a rib-like projection 50d extending vertically is formed at a substantially central portion with a screw hole 50e therebetween. A screw for attaching the auxiliary member 50 to the upper housing 4 of the transceiver 1 is inserted into the screw hole 50e. Further, the protrusion 50 d engages with a groove formed on the inner surface of the upper housing 4.

  FIGS. 7A and 7B are overhead views of the transceiver 1 on which the EA-DFB module 10 described above is mounted (FIG. 7A), and a side view (FIG. b)). The EA-DFB module 10 is mounted on the mounting portion 4 a of the upper housing 4. A flange portion 4d for mounting the sleeve 11a is also formed in front of the mounting portion 4a. A groove 4c is formed in the inner surface of the side wall of the upper housing 4 in the vertical direction, and a screw hole 4b penetrating to the outer surface of the upper housing 4 is formed in the middle of the groove 4c. In the module 10 with the auxiliary member 50, the protrusion 50d extending in the vertical direction formed on the outer surface of the auxiliary member 50 engages with the groove 4c formed on the inner surface of the side wall, and the screw hole 50e is connected to the screw hole 4b. Match. A relative position of the auxiliary member 50 relative to the upper housing 4 is determined by allowing a screw to pass through the screw hole from the outside of the upper housing 4 and bringing the auxiliary member 50 into close contact with the inner surface of the side wall.

  As described above, in the optical transceiver 1 according to the present invention, the sleeve 11a of the module 10 is also rigidly fixed to the upper housing 4. Since 12 is not fixed to the rigid, it can be arbitrarily adjusted. Further, in the vertical direction, the screw holes formed in the transceiver side wall for fixing the auxiliary member are formed in a vertically long shape. Therefore, it is possible to absorb the vertical shift by adjusting the screw position. That is, even if the sleeve 11 a is rigidly fixed to the upper housing 4, mechanical distortion does not occur in the sleeve portion 11 or the box portion 12.

  That is, even if the sleeve 11 a is rigidly fixed to the upper housing 4, mechanical distortion does not occur in the sleeve portion 11 or the box portion 12. Further, the seal lid 12b of the box portion 12 of the module 10 and the upper piece 50c of the auxiliary member are in close contact with the elastic member 60 through the heat conduction grease between them due to the pressing force. Further, the side piece 50b of the auxiliary member and the side wall of the upper housing 4 are closely contacted and fixed by screws. Accordingly, the box portion 12 of the module 10 and the upper housing 4 are in close thermal contact with each other, and the heat generated inside the box portion 12 is efficiently transmitted to the housing side wall via the auxiliary member 50. can do.

  FIGS. 8A to 8C correspond to an overhead view, a plan view, and a front view, respectively, showing the state of contact between the module 10 and the upper housing 4. In each figure, the EA-DFB module 10 is shown in cross section.

  The module 10 is placed on the upper housing 4 with the base of the sleeve portion 11 (the location closest to the block portion 12) placed on the flange 4 d formed on the upper housing 4. The middle portion 11c of the sleeve portion 11 is fixed to the housing at the same time as its position is determined by the latch member. Only the auxiliary member 50 is fixed to the housing 4, and there is no positional restriction relationship between the auxiliary member 50 and the module 10. There is a gap between the side surface 12h of the box portion 12 and the side piece 50b of the auxiliary member 50. On the other hand, the upper piece 50c of the auxiliary member 50 and the module 10 On the other surface, only the piece 50a of the auxiliary member 50 is in contact with the elastic member 60 interposed therebetween.

  The position of the box portion 12 in the left-right direction (horizontal direction) can be arbitrarily adjusted in accordance with the fixing of the auxiliary member 50 to the housing 4 with the screw 4e or the fixing of the auxiliary member 50 to the housing 4 with the sleeve portion 11. Further, the screw hole 4b provided in the side wall of the housing 4 has a large clearance with respect to the inner diameter, particularly the vertical inner diameter, with respect to the outer diameter of the screw 4e. Therefore, the auxiliary member 50 is not restricted to move in the vertical direction by this clearance, and can move itself (box portion) in the vertical direction in accordance with the fixing of the sleeve portion 11. This is a problem in fixing the conventional module, and mechanical strain induced to the connection portion between the sleeve portion 11 and the box portion 12 can be avoided when the box portion 12 is fixed.

FIG. 1 is a bird's-eye view of the entire optical transceiver according to the present invention. FIG. 2A is an overhead view of the optical module according to the present invention, and FIG. 2B is a plan view of the module. FIG. 3 is an overhead view showing a state in which the TOSA, the ROSA, and the circuit board are fixed to the lower housing of the optical transceiver according to the present invention. 4A is a perspective view showing a state where the optical module according to the present invention is mounted on an auxiliary member, FIG. 4B is a side view thereof, and FIG. 4C is a perspective view seen from the other side. Show. FIGS. 5A to 5C are views showing an elastic member according to the present invention. 6 (a) to 6 (d) are diagrams showing an auxiliary member according to the present invention. FIG. 7A is a perspective view showing an upper housing on which the optical module according to the present invention is mounted, and FIG. 7B is a side view thereof. 8A is a perspective view showing a state of the upper housing on which the optical module according to the present invention is mounted, FIG. 8B is a plan view thereof, and FIG. 8C is a front view thereof.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical transceiver 2 Grip 4 Upper housing 5 Lower housing 6 Circuit board 10 Optical module 11 Sleeve part 12 Box part 50 Auxiliary member 60 Elastic member

Claims (1)

In the optical transceiver mounting the optical module having a sleeve portion and the box portion on the housing,
The sleeve portion is mechanically fixed to the housing, the box portion is indirectly fixed to the housing via an auxiliary member,
The auxiliary member is positioned and fixed at a predetermined position by adjusting means whose relative position can be adjusted in a direction perpendicular to the main surface of the housing, and the auxiliary member includes a first surface parallel to the main surface, and the first surface. A second surface facing the first surface in parallel, the box portion including a heat radiating surface in contact with the first surface, a pressing surface parallel to the opposite side of the heat radiating surface, the second surface A metal elastic member is disposed between the pressing surface and the metal elastic member urges the pressing surface in a direction in which the heat dissipation surface is pressed against the first surface, and the box portion The optical transceiver is held relative to the auxiliary member in two directions parallel to the main surface .

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