Cooling system

Abstract: A cooling system for cooling electronic circuit components (1) mounted on a wiring substrate (2) includes containers (9) placed on the respective components, and nozzles (8) each having a central through-hole (20) and peripheral through-holes (21). The outer bottom surface of each container is in good thermal contact with a corresponding electronic circuit component. Each nozzle is inserted into a corresponding container so that first ends of the central and peripheral through-holes of the nozzle are positioned within the container, while the opposite ends are positioned outside the container. The gap between the inner side wall of each container and the outer side surface of a nozzle inserted into the container is hermetically sealed by a sealing member (4). Liquid coolant is supplied through the central through-hole of each container into the container and then discharged through the peripheral through-holes to a location outside the container.

Description: The invention relates to a cooling system, for example for a package in wnicn electronic circuit components are mounted on a wiring substrate. A prior art cooling system of this type is disclosed in a paper entitled "A Conduction-Cooled Module for High-Performance LSI Devices" by S. Oktay and H. C. Kammerer, published in the IBM J. RES. DEVELOP. Vol. 26, No. 1, pp. 55-66, Jan. 1982. The module disclosed in Figure 1 in the paper comprises a multi-layer ceramic substrate, semiconductor chips mounted on the substrate, a hat covering the substrate, cavities formed in the hat, pistons resting in the cavities, springs pressing the pistons against the chips, helium gas filling a space defined by the substrate and the hat, a cold plate through which water flows, and an interposer inserted between the cold plate and the hat. In the module, heat generated from the chips is conducted to the cold plate through the pistons, the helium gas, the hat and the interposer. The module has a thermal-conduction coefficient of no more than 0.1 to 0.5 W/cm 2 °C because of a small effective area for thermal conduction. As a result, the module has a disadvantage in that its cooling capacity becomes insufficient to cool integrated circuit chips as the chips come to consume more power with increasing circuit densities in the chips. Another prior art cooling system is disclosed in U.S. Patent No. 5,050,037. The system comprises a printed circuit board assembly having a printed circuit board 22, heat generative electronic circuit components 26 mounted on both faces of the board 22, and a pair of liquid-cooling modules 30a and 30b arranged on both sides of the board 22. Each of the modules 30a and 30b is provided with a liquid-cooling plate 32 having coolant supply heads 36 and resilient heat transfer units 40 held by the plate 32 and arranged in compressive contact with the components 26 on both faces of the board 22. Each of the heat transfer units 40 has a hollow resilient member 42 constructed as a bellows which must have an appropriate resiliency sufficient to ensure a stable contact between the unit 40 and the component 26 while absorbing any slight differences in the heights of the components 26. To gain a sufficient resiliency, the resilient member 42 is required to be formed thinly, resulting in a disadvantage in that liquid coolant flowing through the heat transfer unit 40 may leak out since the resilient member 42 is apt to easily develop a hole caused by erosion because of its thinness. A further prior art cooling system is disclosed in EP-A-0374479. This comprises a fluid heat exchanger for mating with an electronic component and supported from a fixed support. A connection between the fixed support and the heat exchanger is initially flexible for adjusting the position of the heat exchanger to accommodate variations in the height or attitude of the electronic component for providing a good thermal interface. Thereafter, the connection changes to a rigid connection to provide good structural support for the heat exchanger which allows the support to withstand vibration or shock without overloading the electronic component. The present invention aims to provide a cooling system free from the disadvantages of the above-mentioned prior art cooling systems. The cooling system of the present invention is described in Claim 1 hereof. Further features are described in dependent Claims 2 to 12. The closest known prior art to the present invention is described in US-A-4,977,444 which discloses a semiconductor cooling apparatus in which cooling blocks are connected to the elements to be cooled and are fed with coolant via flexible cooling paths. Preferred features and advantages of the invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a cross-sectional view of a first embodiment of the invention; Figs. 2A, 2B and 2C show top plan, side and cross-sectional views of a nozzle 8, respectively; Figs. 3A and 3B are side and top plan views of a circular spring 10, respectively; Fig. 4 is a cross-sectional view of a second embodiment of the invention; and Fig. 5 is a cross-sectional view of a third embodiment of the invention. In the drawings, the same reference numerals represent the same structural elements. Description will next be made with respect to a first embodiment of the invention in detail. Referring to Fig. 1, a first embodiment of the invention comprises electronic circuit components 1 such as integrated circuit chips, and a wiring substrate 2 on which the components 1 are mounted. A support frame 5 surrounds the periphery of the substrate 2 to support it. Cover means in the form of a cover frame 12 covers the components 1 and the upper surface of the substrate 2 so as to form a space 12a defined by the upper surface of the substrate 2 and the inner side and bottom surfaces of the frame 12. A plurality of cylindrical cooling containers 9 are arranged in the space 12a in alignment with the respective associated components 1, and nozzles 8 are located within the respective associated containers 9. First and second channels 13 and 14 are formed between the inner and outer surfaces of the frame 12. The outer surface of the frame 12 has a coolant inlet 6 connecting to the first channel 13 and a coolant outlet 7 connecting to the second channel 14, thereby to form coolant routing means. Figs. 2A, 2B and 2C show top plan, side and cross-sectional views of one of the nozzles 8, respectively. The nozzle 8 is made of stainless steel and is cylindrical at its middle portion 17 and opposite end portions 18a and 18b. The outer diameter of the middle portion 17 is larger than those of the end portions 18a and 18b. A tapered portion 19a is formed toward the end portion 18a from the middle portion 17 and a tapered portion 19b is formed toward the end portion 18b from the middle portion 17. The nozzle 8 further has a groove 15 extending around the middle portion 17, a central through-hole 20 penetrating from the end portion 18a to the end portion 18b, and peripheral through-holes 21 penetrating from the tapered portion 19a to the tapered portion 19b (see Fig. 2C). Turning back to Fig. 1, the end portions 18a of the nozzles 8 are inserted in respective associated first holes H 1 extending from the channel 13 to the channel 14 while the middle portions 17 of the nozzles 8 are inserted in respective associated second holes H 2 extending from the channel 14 to the space 12a. Consequently, the tapered portions 19a of the nozzles 8 are positioned within the second channel 14. The nozzles 8 are fixed to the cover frame 12 at these first and second holes by any suitable means such as brazing. Each first hole H 1 and the associated second hole H 2 are arranged in alignment with the associated component 1. The containers 9 made of copper are placed above the associated components 1, and an elastic heat conductive member 3 is interposed between the outer bottom surface of each container 9 and the upper surface of the associated component 1. The inner diameter of each container 9 is slightly larger than the outer diameter of the middle portion 17 of each nozzle 8. An elastic O-ring 4 made of silicone rubber is attached to the groove 15 of each nozzle 8, and the nozzle 8 is inserted into the associated container 9 with the O-ring 4 in compressive contact with the inner side wall of the container 9. As a result, a space 9a is formed by the portions 18b and 19b of the nozzle 8, the O-ring 4, and the side wall and bottom surface of the container 9, and is hermetically sealed by the O-ring 4. Between the inner bottom surface of the frame 12 and the upper edge of each container 9 is a gap in which pressing means (a resilient biassing member) in the form of a circular spring 10 is inserted. As shown in Figs. 3A and 3B, the spring 10 consists of a ring portion 10a and fin portions 10b extending radially outwardly and downwardly from the ring portion 10a. The ring portion 10a is engaged with the upper edge of the container 9, while the tips of the fin portions 10b are in contact with the inner bottom surface of the frame 12 (see Fig. 1). In that state, the container 9 is pressed against the elastic heat conductive member 3 with the elasticity of the fin portions 10b of the spring 10. The frames 5 and 12, which are made of aluminum and stainless steel, respectively, are secured by fixing means such as screws (not shown). Liquid coolant such as water or fluorocarbon is supplied into the channel 13 from the inlet 6. The supplied coolant passes through the central through-holes 20 of the nozzles 8 and impinges on the inner bottom surfaces of the containers 9. Heat conducted from the components 1 to the containers 9 is taken away from the inner bottom surfaces of the containers 9 by the impinging coolant. The coolant heated by the heat subsequently flows through the peripheral through-holes 21 of the nozzles 8 into the channel 14, and is discharged from the outlet 7 (see Fig. 1). Fig. 4 shows a second embodiment of the invention. The construction of the second embodiment is basically the same as that of the first embodiment. In the second embodiment, liquid coolant fed from the coolant inlet 6 flows into only the central through-hole 20 of the first one of the nozzles 8, as compared with the structure in the first embodiment in which the coolant supplied from the inlet 6 flows into the central through-holes 20 of all the nozzles 8, directly. The coolant runs through the central through-hole 20 of the first nozzle into the space 9a of the first nozzle in which heat generated by the associated component 1 is taken away by the coolant. Thereafter, the coolant flows through the peripheral through-holes 21 of the first nozzle into a channel 11 connected to the central through-hole 20 of only the second one of the nozzles 8. In this manner, the coolant fed from the inlet 6 runs from the first nozzle to the last one in sequence or series through the channels 11, each of which links the peripheral through-holes of a previous nozzle to the central through-hole of the next nozzle, and is discharged from the coolant outlet 7. Fig. 5 shows a third embodiment of the invention. The construction of the third embodiment is the same as that of the second embodiment with the exception that the circular springs 10 in the second embodiment are replaced with coil springs 16 and that a flange 9b is formed around the bottom of each container 9. The containers 9 are inserted into the coil springs 16 from first ends of the coil springs 16 until the flanges 9b reach the first ends of the springs 16. The other ends of the coil springs 16 are in contact with the inner bottom surface of the cover frame 12. In that state, the springs 16 are compressed between the flanges 9b and the inner bottom surface of the frame 12, with the elastic heat conductive members 3 in compressive contact with the outer bottom surfaces of the containers 9. In summary, the preferred embodiments relate to a cooling system for cooling electronic circuit components mounted on a wiring substrate including containers placed on the respective components, and nozzles each having a central through-hole and peripheral through-holes. The outer bottom surface of each container is in good thermal contact with a corresponding electronic circuit component. Each nozzle is inserted into a corresponding container so that first ends of the central and peripheral through-holes of the nozzle are positioned within the container, while the opposite ends are positioned outside the container. The gap between the inner side wall of each container and the outer side surface of a nozzle inserted into the container is hermetically sealed by a sealing member. Liquid coolant is supplied through the central through-hole of each container into the container and then discharged through the peripheral through-holes to a location outside the container. It will be understood that the present invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention as defined by the appended claims.

Claims: A cooling system for electronic circuit components (1), said cooling system comprising: a substrate (2) on which said electronic circuit components are mounted; a plurality of containers (9) placed on said electronic circuit components, respectively, each of said containers including a side wall and a base ; a plurality of nozzles (8), each of said nozzles having at least one first through-hole (20) and at least one second through-hole (21) and being inserted into a corresponding one of said containers so that first ends of said first and second through-holes are positioned within said corresponding one of said containers, while second ends of said first and second through-holes are positioned outside said corresponding one of said containers, each of said nozzles including an outer side surface and there being a gap formed between the outer side surface and an inner portion of the side wall of a corresponding one of said containers; sealing members (4) each sealing the gap between the inner portion of the side wall of a corresponding one of said containers and the outer side surface of a corresponding one of said nozzles inserted thereinto; means for biassing (10) said containers toward said electronic circuit components so as to bring outer surfaces of the bases of said containers into thermal contact with said electronic circuit components; and coolant routing means (6, 13, 7, 14 ; 6, 11, 7) for supplying coolant into each of said containers through said first through-hole of a respective said nozzle and discharging said coolant outside each of said containers through said second through-hole of said respective said nozzle. The cooling system as claimed in claim 1, further comprising cover means (12) to which said nozzles are fixed. The cooling system as claimed in claim 2, wherein said coolant routing means is provided in said cover means and includes: a coolant inlet (6); a first channel (13) linking said coolant inlet to said first through-hole (20) of each of said nozzles to supply coolant from said coolant inlet into said containers; a coolant outlet (7); and a second channel (14) linking said coolant outlet to said second through-hole of each of said nozzles to discharge said coolant in said containers from said coolant outlet. The cooling system as claimed in claim 2, wherein said coolant routing means is provided in said cover means and includes: a plurality of channels (11) each of which links said second through-hole of one of said nozzles to said first through-hole of another one of said nozzles following said one of said nozzles; a coolant inlet (6) for supplying coolant into said first through-hole of the first one of said nozzles; and a coolant outlet (7) for discharging coolant flowing out through said second through-hole of the last one of said nozzles. The cooling system as claimed in any of the preceding claims, wherein each of said electronic circuit components comprises a component body and an elastic member (3) of high thermal-conductivity placed on said component body. The cooling system as claimed in any of claims 2 to 4, wherein said containers include upper ends (19A) and wherein said biassing means consists of springs (10) interposed between said cover means and the upper ends of said containers. The cooling system as claimed in claim 6, wherein each of said springs consists of a frame portion (10A) and fin portions (10B) extending radially outwardly and downwardly from said frame portion. The cooling system as claimed in Claim 2 or 4, wherein a flange (9B) is formed around the bottom of each of said containers and perpendicular to the side wall thereof; and said biassing means consists of coil springs (10) each interposed between said cover means and said flange. The cooling system as claimed in any of the the preceding claims, wherein each of said nozzles comprises: a middle portion (11) shaped cylindrically; first and second end portions (18A, 18B) shaped cylindrically, outer diameters of which are smaller than that of said middle portion; a first tapered portion (19A) formed toward said first end portion from said middle portion; and a second tapered portion (19B) formed toward said second end portion from said middle portion. The cooling system as claimed in claim 9, wherein said first through-hole (20) penetrates from said first end portion to said second end portion, and said second through-hole (21) penetrates from said first tapered portion to said second tapered portion. The cooling system as claimed in claim 10, wherein a diameter of each of said containers is slightly larger than an outer diameter of said middle portion of each of said nozzles; each of said nozzles has a groove (15) extending around said middle portion; and each of said sealing members (4) consists of an O-ring and is located in said groove. The cooling system as claimed in any of the preceding claims, wherein said electronic circuit components (1) are integrated circuit chips.

Inventors: AKAMATSU SHINYA, AKAMATSU, SHINYA, AKAMATSU, SHINYA, C/O NEC CORPORATION
Applicants: NIPPON ELECTRIC CO, NEC CORPORATION
Application year: 1993
Main classification: H01L23
IPC codes: H01L23, H05K7