JPH05160589A - Mounting structure for electronic device - Google Patents

Abstract

PURPOSE:To mount in a high density and to form an inexpensive cooling system by placing an air-cooled heat sink on an opposite surface of a multichip module to a large-sized circuit board and disposing an air-cooled heat sink in a space formed between the module and the board. CONSTITUTION:Heat generated from an LSI chip 1 is radiated into the air by a pin fin type air-cooled heat sink 11 provided on a rear surface of a multichip module 3. Here, since a power supply connector 6 is placed along an air flowing direction 10, a space formed of the connector 6, the module 3 and a large-sized printed circuit board 7 is operated as an air flowing duct. The module 3 is simultaneously forcibly air-cooled by fans 12 provided above and below an air flowing air duct 18. Thus, a high density mounting is performed with a cooling system space kept to an extremely low value, and high cooling capacity can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an electronic device which requires high speed and high density mounting of an electronic device system.

[0002]

2. Description of the Related Art FIGS. 6 (a) and 6 (b) are a plan view and a sectional view of an essential part showing a conventional mounting structure, in which 1 is an LSI chip, 2 is TAB (Tape Automated Bonding), and 3 is a plurality. Of the multichip module (electronic circuit module) on which the LSI chip 1 is mounted, 4 is a wiring board of the multichip module 3, 5 is a feeding pin provided on the back surface of the multichip module 3, and 6 is a large-sized multichip module 3. A power feeding connector for connecting power to the printed wiring board, and 7 is a printed wiring board which is an example of a large wiring board, and usually a multilayer wiring board is used. Reference numeral 8 denotes a flexible wiring board which serves as a signal connection path between the adjacent multi-chip modules 3, and is a flexible printed wiring board using polyimide or the like as an insulating layer and copper or the like as a conductor material. Reference numeral 9 is a surface-mounting type flexible wiring board connector for connecting the flexible wiring board 8 and the multichip module 3, 10a and 10b are air flow directions, and 11 is mounted on the surface of the multichip module 3. Each of the pin fin type air-cooled heat sinks is shown. Further, FIG. 7 is a view showing a cross-sectional structure of a conventional mounting structure, 10c is a flow direction of air, 12 is a fan for air-cooling the entire apparatus, and 13 is air to each of the multi-chip modules 3. For supplying air, 14 is an air exhaust duct for cooling the multi-chip modules 3 and then exhausting warmed air to the outside, 15 is the air supply duct 13, the air exhaust duct 14 and the fan 1.
2 shows air ducts for connecting with 2 respectively.

[0003]

This structure shows a conventional structure for cooling a multi-chip module 3 which generates a large amount of heat, and a flexible wiring board 8 and a flexible wiring board 8 are provided between adjacent multi-chip modules 3. The surface of the multichip module 3 is surrounded by the flexible wiring board 8 because the surface mounting type flexible wiring board connector 9 is used to connect the multichip module 3 and the multichip module 3. Therefore, a pin fin type air-cooled heat sink 1 is provided on the surface of the multi-chip module 3.
Even with No. 1, it is possible to adopt a generally used forced forced air cooling configuration (a configuration in which air is laterally passed through the heat sink and the heat sink on the downstream side is also air cooled by the air flow). Instead, a cooling structure such as air jet cooling as shown in FIG. 7 is essential. For this reason,
The air supply duct 13 for supplying fresh air and the air exhaust duct 14 for exhausting warmed air are required, and there is a problem that an extremely large cooling space is required.

In addition, the use of air jet cooling increases pressure loss and requires a large fan. That is, there is a problem that the noise of the entire apparatus is increased and the cost of the entire apparatus is increased (initial cost and operating cost). Further, in order to replace the multi-chip module 3 due to a failure or the like, the air supply duct 13 and the air exhaust duct 14 must be removed from the device and replaced, but at this time, the entire device cannot be cooled. That is, there is a problem in that it is necessary to stop the device when replacing the multichip module 3. Furthermore, it is not possible with the conventional configuration to perform an electrical characteristic test in the operating state of the LSI chip 1 or the wiring mounted on the multi-chip module 3. There is a problem that it is necessary to configure a special cooling system for a test other than that shown in FIG. 7 to carry out the test.

An object of the present invention is to provide a mounting structure of an electronic device having a low-cost cooling system while enabling high-density mounting, and further mounting of the electronic device capable of performing an LSI test in an operating state. To provide the structure.

[0006]

An electronic device mounting apparatus according to the present invention mounts at least two multichip modules each having an LSI chip mounted on a large wiring board, and at least high speed between adjacent multichip modules. A system signal (a signal having a bit rate of several tens Mb / s or more) line is connected directly to a flexible wiring board connector via a flexible wiring board, not via a large wiring board. An air-cooled heat sink is mounted on the surface facing the large-sized wiring board, and the air-cooled heat sink is arranged in the space formed between the multi-chip module and the large-sized wiring board.

Further, low-speed signal lines (signals having a bit rate of several Mb / s or more) input to and output from the multi-chip module and connectors for connecting the power supply line and the large wiring board are vertically aligned, and An air-cooling duct-like space is formed by forming connector connection areas on two opposing sides in the multi-chip module surface, and a multi-chip is formed in the space formed by the connector, the multi-chip module, and the large wiring board. A heat sink for heat dissipation of the module is arranged.

Further, a heat pipe type heat sink composed of one or more heat pipes is brought into contact with the surface of the multi-chip module facing the large-sized wiring board, and is formed between the multi-chip module and the large-sized wiring board. A heat pipe type heat sink is arranged in the space.

Further, a liquid cooling heat sink composed of one or more pipe lines is arranged in the space.

[0010]

In the present invention, since the air-cooled heat sink is arranged in the space formed between the multi-chip module and the large wiring board, high density mounting is possible.

Further, since the connectors are vertically aligned and the connector connecting regions are formed in the air-cooling ducts on the two opposing sides in the plane of the multichip module, the cooling effect can be improved.

Further, since the heat pipe type heat sink and the liquid heat sink are used, the space can be effectively used,
High-density mounting is possible.

[0013]

1 (a) and 1 (b) are a plan view and a sectional view of a main part showing a first embodiment according to the present invention.
1 is the same as that shown in FIG. However, the pin fin type air-cooled heat sink 11 is mounted on the back surface of the multi-chip module 3. 2 is a top view of the entire electronic device showing the first embodiment of the present invention, in which 12 is a fan for air cooling the entire device, 15 is an air duct, and 16 is a large number of the fans 12 described above. A fan unit, 17 is the multi-chip module 3
Respectively, the sealing rings for sealing the are shown. Further, FIG. 3 is a view showing a cross section taken along the line AA ′ of FIG.
Reference numeral 18 represents an air duct.

In this structure, the LSI chip 1 is mounted face up on the multi-chip module 3,
Multi-chip module 3 on the periphery of the chip 1 mounting surface
This is a structure in which a surface-mounting type flexible wiring board connector 9 serving as a signal connection path is provided, and further, power supply pins 5 are provided on two opposite sides on the back surface side of the multichip module 3. The heat generated in the LSI chip 1 is the pin-fin type air-cooled heat sink 1 provided on the back surface of the multi-chip module 3.
1 radiates heat to the air. Here, the power supply connector 6
Is mounted along the air flow direction 10b, the space formed by the power supply connector 6, the multichip module 3, and the large-sized printed wiring board 7 acts as an air flow duct. The multi-chip modules 3 are collectively and forcibly cooled by the fans 12 provided above and below the air duct 18 for air flow. For this reason, high-density mounting can be performed while keeping the cooling system space extremely low, and high cooling capacity can be realized. Further, since the power feeding connector 6 only feeds power, it is easy to reduce the inductance by increasing the pin diameter even if the height of the connector is slightly increased, and the air duct 18 is configured while satisfying the electrical characteristics. Is easy. Further, it is not necessary to provide a cooling space on the side of the LSI chip 1 mounted on the multichip module 3. Therefore, the LSI chip 1 mounted on the multi-chip module 3 in the actual operating state can be accessed without removing the cooling system. Therefore, the test adjustment work at the time of assembly can be easily realized.

FIG. 4 shows a second embodiment of the present invention, and is a top view of the mounting structure of the present invention, as in FIG. In addition, in order to show the mounting state of the LSI chip 1, the state in which the sealing cap is removed is shown. Here, the same reference numerals as those in FIG. 2 indicate the same parts, 19 is a heat pipe type cold plate, 20 is a heat pipe constituting the heat pipe type cold plate 19,
Reference numerals 21 respectively denote air-cooled heat sinks (air-cooled heat exchangers) provided on the heat pipe type cold plate 19. Further, FIG. 5 is a view showing a BB ′ cross section of FIG.

In this embodiment, as in the first embodiment, the LSI chip 1 is mounted face up on the multi-chip module 3 and the signal connection between the multi-chip modules 3 is carried out in the peripheral portion within the mounting surface of the LSI chip 1. This is a structure in which a flexible wiring board connector 9 serving as a path is provided, and further, power supply pins 5 are provided on two opposite sides on the back surface side of the multichip module 3. The heat generated in the LSI chip 1 is transferred to the upper portion of the printed wiring board 7 by the heat pipe type cold plate 19 provided on the back surface of the multi-chip module 3, and the flow direction 1 of the air flowing through the air-cooled heat sink 21 is 1.
Heat is exhausted to the outside air by zero. Here, since the heat pipe 20 can be regarded as a superheat conductor, its outer dimensions can be made smaller than that of the pin fin type air-cooled heat sink 11 as shown in the first embodiment, and therefore, the power supply connector. 6, there is an advantage that the space constituted by the multi-chip module 3 and the large printed wiring board 7 can be further downsized. Further, instead of the heat pipe type cold plate 19, if a liquid cooling cold plate made of a heat conductive member provided with a tube through which a liquid refrigerant can flow is used,
Needless to say, the device can be made compact and a high cooling capacity can be realized.

[0017]

As described above, the present invention provides an LSI
Two or more multi-chip modules each having a chip mounted thereon are mounted on a large wiring board, and at least high-speed system signal lines between adjacent multi-chip modules are flexible, not via a large wiring board, but via a flexible wiring board. In an electronic device directly connected by a wiring board connector, an air-cooled heat sink is mounted on the surface of the multi-chip module facing the large-sized wiring board, and an air-cooled heat sink is placed in the space formed between the multi-chip module and the large-sized wiring board Since the arrangement is provided, there is an advantage that a low-cost cooling system can be configured while enabling high-density mounting. Furthermore, the LSI mounted on the multi-chip module can be accessed in the actual operating state. At this time, it is not necessary to remove the cooling system. Therefore, there is an advantage that the test adjustment work at the time of assembly can be easily realized.

[Brief description of drawings]

FIG. 1 is a top view and a cross-sectional view showing a first embodiment according to the present invention.

FIG. 2 is a front view showing a first embodiment according to the present invention.

FIG. 3 is a sectional view of a cooling system showing a first embodiment according to the present invention.

FIG. 4 is an upper side view showing a third embodiment according to the present invention.

FIG. 5 is a sectional view of a cooling system showing a second embodiment according to the present invention.

6A and 6B are an upper die view and a cross-sectional view showing a mounting structure of a conventional electronic device.

FIG. 7 is a cross-sectional view showing a cooling system configuration of a conventional electronic device.

[Explanation of symbols]

 1 LSI Chip 2 TBA 3 Multi-Chip Module 4 Wiring Board 5 Power Supply Pin 6 Power Supply Connector 7 Printed Wiring Board 8 Flexible Wiring Board 9 Flexible Wiring Board Connector 10a Air Flow Direction 10b Air Flow Direction 10c Air Flow Direction 11 Air Cooled Heat Sink 12 Fan 13 Air Supply Duct 14 Air Exhaust Duct 15 Air Duct 16 Fan Unit 17 Sealing Ring 18 Air Duct 19 Heat Pipe Cold Plate 20 Heat Pipe 21 Air Cooled Heat Sink

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 7/20 G 8509-4E

Claims (4)

[Claims] 1. A multi-chip module including two or more LSI chips mounted on a large wiring board, wherein at least high-speed system signal lines between adjacent multi-chip modules do not pass through the large wiring board, In an electronic device directly connected by a flexible wiring board connector via a flexible wiring board, an air-cooling heat sink is mounted on the surface of the multichip module facing the large wiring board, and the multichip module and the large wiring board are connected together. An electronic device mounting structure, wherein the air-cooled heat sink is arranged in a space defined therebetween. 2. A connector for connecting a low-speed system signal line and a power supply line input / output to / from a multi-chip module and the large-sized wiring board are vertically aligned, and on two opposing sides in the plane of the multi-chip module. An air-cooled duct-like space is formed by forming a connector connection region, and further in the space formed by the connector, the multichip module, and the large wiring board,
The mounting structure for an electronic device according to claim 1, wherein a heat sink for heat dissipation of the multi-chip module is arranged. 3. A heat pipe type heat sink composed of one or more heat pipes is brought into contact with the surface of the multi-chip module facing the large-sized wiring board, and is arranged between the multi-chip module and the large-sized wiring board. The mounting structure for an electronic device according to claim 1, wherein the heat pipe type heat sink is arranged in a space. 4. A liquid-cooled heat sink composed of one or more conduits is brought into contact with the surface of the multi-chip module facing the large-sized wiring board, and is formed between the multi-chip module and the large-sized wiring board. The mounting structure for an electronic device according to claim 1, wherein the liquid cooling heat sink is arranged in a space.