Communication module-cooling structure and communication device

A communication module-cooling structure includes a main body section to be cooled by a cooling mechanism, and a heat sink including a cooling receiving section including partition walls and slit-shaped receiving spaces defined by the partition walls. The receiving spaces of the cooling receiving section receive communication modules, and each of the communication modules includes a substrate mounted with a communication circuit component thereon and first and second sidewalls which sandwich the substrate therebetween in a thickness direction of the substrate. At least one of the first and second sidewalls of each of the communication modules is in surface contact with an inner surface of each of the receiving spaces.

The present application is based on Japanese patent application No. 2012-193380 filed on Sep. 3, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a communication module-cooling structure for use in signal transmission in e.g. high-performance servers, high-speed network devices, and a communication device provided with communication modules and a cooling structure therefor.

2. Description of the Related Art

Conventionally, in order to increase the mounting efficiency of electronic components on a mother board, a communication device in which e.g. a card-like optical communication module (optical module) is arranged perpendicular to a mother board has been known. The communication module of this type is provided with a heat sink to dissipate heat produced by an optical element, a control IC or the like mounted on a substrate thereof, and to suppress a temperature rise (see e.g., JP-A-2011-128378).

The communication module disclosed in JP-A-2011-128378 has a rigid substrate formed with a terminal at its end, and the terminal is electrically connected by mating to a connector socket mounted on the mother board. This rigid substrate is arranged perpendicular to the mother board. A mounting surface of the rigid substrate is mounted with an optical element, a control IC or the like thereon, while a non-mounting surface opposite to the mounting surface is attached with the heat sink. The heat produced by the optical element, control IC or the like thermally conducts via the rigid substrate to the heat sink and will be dissipated from fins formed on the heat sink.

Refer to JP-A-2011-128378, for example.

SUMMARY OF THE INVENTION

Now, in accordance with the enhancement in performance of servers, network devices, etc. in recent years, further high-density mounting of electronic components is required. Therefore, there may be the need to arrange a plurality of communication modules close to each other, for example. However, when placing the communication modules disclosed in JP-A-2011-128378 close to each other, the heat cannot be dissipated sufficiently due to lowering in airflow to the fins of the heat sink. Further, since the entire heat sink including the fins are interposed between the substrates of the adjacent communication modules, the distance between the substrates cannot be shorter than the thickness of the heat sink. This can interfere with high-density mounting.

Accordingly, an object of the present invention is to provide a communication module-cooling structure and a communication device, capable of efficiently dissipating heat produced from communication modules, even when the communication modules are arranged at high density.

(1) According to a feature of the invention, a communication module-cooling structure comprises:

a main body section to be cooled by a cooling mechanism; and

a heat sink including a cooling receiving section comprising partition walls and slit-shaped receiving spaces defined by the partition walls;

wherein the receiving spaces of the cooling receiving section receive communication modules, each of the communication modules including a substrate mounted with a communication circuit component thereon and first and second sidewalls which sandwich the substrate therebetween in a thickness direction of the substrate,

wherein at least one of the first and second sidewalls of each of the communication modules is in surface contact with an inner surface of each of the receiving spaces.

(i) It is preferable that at least the first sidewall is in surface contact with the inner surface of each of the receiving spaces, wherein temperature rise of the first sidewall is greater than temperature rise of the second side wall.

(ii) The heat sink may include a heat absorbing surface for absorbing heat of a semiconductor IC that is electrically connected to the communication modules.

(iii) The cooling mechanism may include a coolant passage, which faces the main body section of the heat sink, a pump for circulating coolant water to the passage, and a radiator for cooling the coolant water.

(iv) The communication module-cooling structure may further comprise a thermally conductive elastic member interposed between the inner surface of each of the receiving spaces and the second sidewall of the communication modules, wherein temperature rise of the second sidewall is smaller than temperature rise of the first sidewall.

(v) The communication module-cooling structure may further comprise:

a mother board to which the heat sink is fixed; and

connectors to which the communication modules are mated, respectively,

wherein the connectors are mounted on the mother board, and each of the receiving spaces is open in both directions perpendicular to the mother board, and in one direction parallel to the mother board.

(vi) The semiconductor IC may comprise a plate shaped semiconductor package substrate and an IC chip mounted on the semiconductor package substrate, and

the semiconductor package substrate is mounted with connectors to which the communication modules are mated.

(vii) The communication circuit component may include an optical element which is optically coupled to an optical fiber, and a semiconductor circuit element which is electrically connected to the optical element, and at least the first sidewall of each of the communication modules is in surface contact with an inner surface of the cooling receiving section, where temperature rise of the first sidewall is greater due to heat produced by the semiconductor circuit element and the optical element than temperature rise of the second side wall.

(2) According to another embodiment of the invention, a communication device comprises:

a main body section cooled by a cooling mechanism;

a heat sink including a cooling receiving section comprising partition walls and slit-shaped receiving spaces defined by the partition walls;

a substrate mounted with a communication circuit component thereon; and

communication modules, each of which includes first and second sidewalls which sandwich the substrate therebetween in a thickness direction of the substrate,

wherein the communication modules are received in the receiving spaces of the cooling receiving section of the heat sink, and at least one of the first and second sidewalls is in surface contact with an inner surface of each of the receiving spaces.

Points of the Invention

With the communication module-cooling structure and the communication device according to the present invention, it is possible to mount the communication modules on a substrate at high density, and more efficiently dissipate heat produced from the communication modules.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiment

FIG. 1is an exploded perspective view showing a configuration example of an optical communication device1as a communication device in an embodiment of the present invention.

The optical communication device1is configured as including a plurality (sixteen in this embodiment) of optical modules2as communication modules, a processor7as a semiconductor IC that is electrically connected to the optical modules2, a mother board4mounted with the processor7and the optical modules2, and a heat sink6for cooling the optical modules2. A plurality of optical fiber cables5are connected to the plurality of optical modules2, respectively. In the peripheral portion of the optical modules2, the plurality of the optical fibers5aextend in a direction parallel to the mother board4.

The mother board4is, e.g., a glass epoxy substrate with a wiring pattern formed by pasting a plurality of copper foils to a plate shape substrate formed by thermosetting epoxy resin-impregnated glass fibers and etching these copper foils. The mother board4is mounted with electronic components such as a CPU (Central Processing Unit) (not shown), a memory element (not shown), etc. in addition to the processor7and the optical modules2. By optical communication using the optical fibers5amounted to the optical modules2as a transmission medium, a signal is transmitted or received between it and another electronic circuit board or an electronic device.

In this embodiment, a mounting surface4aof the mother board4is mounted with a plurality (sixteen in this embodiment) of female connectors3mated with the optical modules2and a socket8which holds the processor7. The socket8is formed with a recessed portion80mated with the processor7. In the recessed portion80, a plurality of electrodes81are arranged in a grid pattern, and are electrically connected to a plurality of electrodes (not shown) formed on a bottom surface of the processor7. The mother board4and the socket8are electrically connected together via a plurality of electrodes40that are mounted on the mounting surface4aof the mother board4.

The sixteen female connectors3constitute one pair of connector groups3aon the mounting surface4aof the mother board4. Each connector group3ais constituted from eight aligned female connectors3. One connector group3ais located opposite the other connector group3a. The sixteen optical modules2correspond to the one pair of the connector groups3a, and are constituted from one pair of the eight optical modules2. The one pair of the eight optical modules2are arranged parallel to the mounting surface4aof the mother board4in accordance with the arrangement of the one pair of the connector groups3a. The processor7and the socket8are arranged between the one connector group3aand the other connector group3a.

The heat sink6integrally (e.g. as one piece) includes one pair of cooling receiving sections61, each of which is formed with a plurality of slit-shaped receiving spaces610(to be described later) to receive the plurality of optical modules2, and a plate shaped main body section60to interlock the pair of the cooling receiving sections61. An upper surface (surface opposite to the mother board4) of the main body section60is provided with a passage section62which constitutes a passage of the coolant water for cooling the heat sink6.

To the passage section62are connected a first hose620for discharging the coolant water from the passage section62, and a second hose621for feeding the coolant water into the passage section62. The heat sink6is fixed to the mother board4by four bolts (not shown) which penetrates a mounting hole64formed in an upper surface of both the cooling receiving sections61, and four mounting holes4bformed at both ends of the connector groups3aof the mother board4, and nuts which are screwed onto these bolts, respectively. When the heat sink6is fixed, the processor7and the socket8and the female connector3are sandwiched between the heat sink6and the mother board4.

FIG. 2is a perspective view of the optical module2, and the female connector3.

The optical modules2includes a module case20including a first sidewall201and a second sidewall202as one pair of sidewalls which sandwich the substrate therebetween in a thickness direction of the substrate mounted with a later described communication circuit component thereon. A bottom surface205of a module case20that faces the mounting surface4aof the mother board4is provided with a male connector21that is mated to the female connector3. The male connector21is formed with a plurality of male terminals21ain an extending direction of the optical fiber cable5.

Further, the module case20includes a third sidewall203that is provided in a normal direction to the mounting surface4aof the mother board4and between one end of the first sidewall201and one end of the second sidewall202, and a fourth sidewall204that is provided opposite the third sidewall203and between the other end of the first sidewall201and the other end of the second sidewall202. The third sidewall203and the fourth sidewall204are formed with one pair of protruding portions22(only one protruding portion22shown inFIG. 2) which are mated to the one pair of the mounting holes31arespectively formed in the female connector3. Further, the third sidewall203is attached with a rubber boot50of the optical fiber cable5.

The module case20is e.g. 23 mm in entire length along the extending direction of the optical fiber cable5, and is e.g. 3.6 mm in the thickness direction dimension orthogonal to the extending direction. The height direction (direction perpendicular to the mother board4) dimension of the optical modules2is e.g., 24 mm.

The female connector3includes a connector case30formed with a receiving space300for receiving the plurality of the female terminals32which are electrically connected to the plurality of the male terminals21aand an extending portion31which extends in the mating direction of the female connector3and the male connector21from the connector case30. The extending portion31is in contact with the third sidewall203and the fourth sidewall204of the module case20. The extending portion31is formed with a rectangular mounting hole31awhich engages the protruding portion22formed on the third sidewall203and the fourth sidewall204. A bottom surface opposite the mounting surface4aof the mother board4of the connector case30is formed with a plurality of terminals33which are formed in the extending direction of the optical fiber cable5. The plurality of the terminals33are connected by soldering to the mounting surface4aof the mother board4.

FIG. 3is a cross sectional view taken along line B-B inFIG. 2showing the optical modules2.

The optical module2comprises a first substrate27, one pair of optical element arrays26with a plurality of optical elements arranged therein, one pair of semiconductor circuit elements25which are electrically connected to the one pair of the optical element arrays26, a lens array24for optically coupling the optical fiber5aand the element arrays26and a second substrate28which is sandwiched between the first substrate27and the lens array24, all of which are received in the module case20. The first substrate27is disposed on the side of the first sidewall201in the module case20, and the lens array24is disposed on the side of the second sidewall202in the module case20. The mounting surface27aof the substrate27is mounted with the one pair of the optical element arrays26, and the one pair of the first semiconductor circuit elements25. The one pair of the semiconductor circuit elements25are disposed to locate the one pair of the optical element arrays26therebetween. The optical fiber5ais located on the sidewall202side with respect to the second lens array24and is pressed against the lens array24by a pressing member29.

The optical element is an element that converts electrical energy to light, or converts light to electrical energy. As the former light-emitting element, there are listed e.g. a laser diode, a VCSEL (Vertical Cavity Surface Emitting LASER), and the like. Further, as the latter light receiving element, there are listed a photodiode and the like. The optical elements are configured to emit or receive light to or in the lens array24.

When the optical element is an element for converting electric energy to light, the semiconductor circuit element25is a driver IC for driving the optical elements based on an electric signal inputted from the mother board4side. Further, when the optical element is an element that converts light which the optical elements receive into electric energy, the semiconductor circuit element25is a preamplifier IC that amplifies an electrical signal input from the optical elements and outputs it to the side of the mother board4.

Incidentally, in this embodiment, one optical element array26is a light emitting element, while the other optical element array26is a light-receiving element. Therefore, for the semiconductor circuit elements25, one semiconductor circuit element25is a driver IC, while the other semiconductor circuit element25is a preamplifier IC.

The lens array24is formed with a plurality of lenses240in correspondence to the plurality of the optical elements at positions opposite to the optical element arrays26. The light (optical axis L) emitted from the optical elements of the optical element arrays26is collimated by the lenses240, reflected at a mirror surface24aof the lens array24, and received in a core of the optical fiber5a. Further, the light (optical axis L) emitted from the core of the optical fiber5ais reflected at the mirror surface24a, collimated by the lenses240, and received in the optical elements.

Each of optical element arrays26and the semiconductor circuit elements25is a heating element that emits heat by operation thereof. This heat is dissipated primarily from the second sidewall202and the first sidewall201of the module case20. In comparison with the second sidewall202, the first sidewall201is short in distance from the semiconductor circuit elements25and the optical element arrays26. Therefore, the temperature rise of the first sidewall201due to heat produced by the semiconductor circuit elements25and the optical element arrays26is greater than the temperature raise of the second sidewall202.

The optical modules2are cooled by a cooling structure using the heat sink6. Then, the cooling structure for cooling the optical module2will be explained in more detail.

FIGS. 4A and 4Bare a perspective view and a partial side view showing a portion of the heat sink6.

In this embodiment, a cooling receiving section61of the heat sink6is formed with eight slit-shaped receiving spaces610in which the eight optical modules2corresponding to the connector group3aare received, respectively. The cooling receiving section61has a plurality (seven) of partition walls611that separate (i.e. define) the adjacent receiving spaces610. The partition walls611are formed parallel to each other between the eight receiving spaces610. That is, the plurality of the receiving spaces610are formed between the plurality of the partition walls611. The receiving spaces610are open in one direction parallel to the mother board4and in both directions perpendicular to the mother board4.

The optical fibers5aextend outwardly from an opening610cof the receiving spaces610which is formed on the opposite side to the main body section60of the heat sink6. The third sidewall203of the optical modules2is provided with a fiber mounting portion23which engages the rubber boot50of the optical fiber5a.

As shown inFIG. 4B, the first sidewall201of the optical modules2is in surface contact with one inner surface of one pair of mutually opposing inner surfaces of the receiving spaces610. In the following description, it is assumed that the one pair of the inner surfaces, the inner surface in surface contact with the first sidewall201is a first inner surface610aand the other inner surface facing parallel to the first inner surface610ais a second inner surface610b. Between the second inner surface610band the second sidewall202of the optical modules2, a thermally conductive elastic member9is interposed. By the biasing force of the elastic member9, the first sidewall201of the optical modules2is pressed against the first inner surface610aof the receiving spaces610.

FIG. 5is a cross sectional view taken along line A-A inFIG. 1.

When the heat sink6is attached to the mother board4, the receiving spaces600are formed between the mounting surface4aof the mother board4and the main body section60of the heat sink6. The socket8and the processor7are received in the receiving spaces600. Between the processor7and the main body section60, a gap is formed and a heat grease7bto fill the gap is interposed. The heat grease7bis in close contact with the inner surface600aas a heat absorbing surface of the receiving spaces600and an upper surface7aof the processor7.

Then, the procedure for attaching and detaching the optical module2to and from the female connector3will be explained.

In the case of mounting the optical module2to the female connector3, the optical module2mounted with the elastic member9is inserted into the receiving space610from a direction perpendicular to the mother board4, and is mated into the female connector3. When taking the optical module2out from the receiving space610, after detaching the projecting portion22of the optical module2from the mounting hole31aof the female connector3, the optical module2is drawn out from the receiving space610in a direction perpendicular to the mother board4. In other words, the optical module2is attached and detached in both arrow C directions inFIG. 5.

Between the surfaces facing each other of the passage section62and the main body section60of the heat sink6is formed a first passage62awhich is a space which constitutes a passage in which coolant water is circulated. The coolant water flows into the passage section62from the second hose621(shown inFIG. 1), flows through a first passage62afacing the passage section62and the main body section60, and is discharged to the outside of the passage section62from the first hose620. The first hose620and the second hose621are attached to the upper surface of the passage section62with a nut622. The cooling water discharged from the first hose620flows through the second passage12, which will be described later in the outside of the heat sink6and flows from the second hose621again into the passage section62.

In the process of coolant water flowing through the first passage62a, the main body section60is cooled by the coolant water. That is, the heat produced in the heat source (semiconductor circuit elements25and the optical element arrays26) of the optical module2is transferred mainly to the first sidewall201of the module case20, and further is transferred from the first sidewall201to the partition walls611of the cooling receiving section61through the first inner surface610aof the receiving space610. Further, another part of the heat produced by the heat source of the optical module2is transferred to the second sidewall202of the module case20, and further is transferred from the second inner surface610bof the receiving space610via the elastic member9to the partition walls611of the cooling receiving section61. The heat transferred to the cooling receiving section61is transferred to the main body section60, and is dissipated into the coolant water from the main body section60.

The heat produced by the processor7is transferred to the heat grease7bfrom the upper surface7aof the processor7. Then, the heat is transferred from the heat grease7bto the main body section60of the heat sink6through the inner surface600aof the receiving space600, and is dissipated to the coolant water from the main body section60.

FIG. 6is a schematic diagram showing an exemplary configuration of a cooling mechanism for cooling the main body section60of the heat sink6.

The cooling mechanism in this embodiment is configured to have a second passage12in the outside of the heat sink6and the first passage62afacing the main body section60of the heat sink6, a pump10for circulating the coolant water to the first and second passages62a,12, and a radiator11for cooling the coolant water.

The coolant water warmed by absorbing the heat from the processor7and the optical module2is sucked up by the pump10provided in the second passage12, and is discharged to the second passage12from the first hose620. The coolant water warmed is then cooled by the radiator11provided in the second passage12. The cooling water cooled flows into the passage section62from the second hose621through the second passage12. The cooling water flowing inside the passage section62flows like two-dot chain line inFIG. 6in the first passage62a. Thus, the coolant water is circulated through the first passage62aand the second passage12, and cools the heat sink6.

Effects of the Embodiment

According to the embodiment which has been described above, it is possible to provide the following effects.

(1) The heat sink6includes the cooling receiving section61formed with the slit-shaped receiving spaces610provided between the partition walls611. The heat produced by the optical modules2received in the receiving spaces610is transferred to the main body section60of the heat sink6from the partition walls611, and is dissipated to the coolant water from the main body section60. Thus, the heat dissipation from the optical modules2can be achieved by a single heat sink6, so that it is not necessary to provide a heat dissipating portion such as fin for each of the optical modules2. Although the plate shaped partition wall611is interposed between the adjacent optical modules2, the thickness of the partition wall611is sufficient if the heat generated by the optical modules2can be transferred to the main body section60. It is therefore possible to arrange the optical modules2at a higher density compared with a configuration in which the heat dissipating means is provided for each of the optical modules2.

(2) By directly cooling by contacting with the first inner surface610aof the receiving space610the first sidewalls201whose temperature rise due to heat produced by the optical modules2is high, the cooling efficiency is improved in comparison with e.g. the case of contacting only the second sidewall202with the inner surface (second inner surface610b) of the receiving spaces610.

(3) Since the optical modules2are in contact with only the first inner surface610and the second inner surface610bin the receiving space610of the heat sink6. Therefore, it is possible to attach and detach the individual optical modules2without removing the heat sink6from the mother board4.

(4) Because the receiving spaces610of the heat sink6are open in one direction parallel to the mother board4and in both directions perpendicular to the mother board4, the attaching and detaching the optical modules2to and from the receiving spaces610is facilitated. It is also possible to mount the optical fibers5ato either surface of the third sidewall203or the upper surface of the module case20.

(5) The heat sink6is in contact with the processor7. By doing so, it is possible to cool the heat emanating from the processor7as well as the heat emanating from the optical modules2. Since the heat generated by the optical modules2and the heat generated by the processor7are dissipated from a single common heat sink6, the mounting positions of the optical modules2and the mounting position of the processor7become closer to each other, so that an electric wiring between the optical modules2and the processor7can be shortened. Accordingly, it is possible to suppress deterioration in signal transmission between the optical modules2and the processor7.

(6) The heat sink6is cooled by the cooling mechanism by circulating coolant water. Therefore, it is possible to increase the cooling capability as compared with the case of cooling the heat sink by natural cooling or air cooling.

(7) The thermally conductive elastic member9is interposed between the second inner surface610bof the receiving space610of the heat sink6and the second sidewall202of the optical module2. Thus, the contact area increases by the first sidewall201whose temperature increase due to heat production is large being pressed against the first inner surface610aof each of the receiving spaces610. Further, the heat is transferred from the second side wall202to the partition wall611via the elastic member9. Therefore, the optical module2cooling power of the heat sink6is further improved.

Incidentally, the optical communication device1in the embodiment is also possible to implement by modifying, for example, as follows.

FIG. 7is a schematic view showing a cross section of an optical communication device in modification 1 in a cross section corresponding to the A-A cross section inFIG. 1. In the drawings, common reference numerals are given for members having the same functions as those in the embodiment described earlier, and the duplicate description thereof will be omitted.

In the optical modules2A in this modification, the rubber boot50of the optical fiber cable5is provided on an upper surface (opposite surface to the bottom surface205) of the optical modules2A. Thus, the optical fiber cable5extends in a direction perpendicular to the mother board4. The processor7A which is electrically connected to the optical modules2A is constituted from an IC chip70A and a package71A as a semiconductor package substrate on which the IC chip70A is mounted. The package71A is mounted with, in addition to the IC chip70A, the female connector3, which is mated with the male connector21formed in the optical modules2A.

This modification 1 has the following effects in addition to the effects (1) to (7) described in the embodiment.

By the female connector3being mounted on the package71A of the processor7A, the wiring of the optical modules2A and the processor7A is not required to pass through the mother board4and the socket8A. Therefore, it is possible to shorten the connection distance between the processor7A and the optical modules2A, and suppress degradation in signal transmission.

FIG. 8is a diagram showing a portion of a cooling receiving section61A of a heat sink6A in modification 2.

In the cooling receiving section61A of the heat sink6A, a plurality of slit shape receiving spaces610in which the optical modules2are received, and a plurality of partition walls611A which separate the adjacent receiving spaces610are formed radially. That is, the plurality of the partition walls611A are not parallel to each other, but are formed in a shape of a fan.

This modification 2 also has the similar effects to the effects (1) to (7) described in the embodiment.

Although the embodiment of the present invention has been described above, the embodiment described above is not intended to limit the invention in the appended claims. It should also be noted that not all the combinations of the features described in the above embodiment are essential to the means for solving the problems of the invention.

For example, although in the above-described embodiment it has been described that the communication module is the optical modules2,2A which perform optical communication via the optical fiber cable5, the present invention is not limited thereto, but may also be applied to a communication module which perform communication through differential signal lines, e.g.

Further, the number of the optical modules2,2A which are received in the receiving spaces610may be not one, but two. In this case, it is preferable to interpose an elastic member9between the two optical modules2,2A.

Further, the cooling mechanism may use not coolant water, but air cooling. That is, the configuration of the cooling mechanism itself is not particularly limited.

Further, the passage section62may be attached to the upper side of the cooling receiving section61of the heat sink6.

There is no limit on the number of the optical modules2.