JPH0414248A - Independent cooling chamber of multichip unit - Google Patents

Abstract

PURPOSE: To cool a chip on a multi-chip unit with a surface, except for the chip to be cooled being minimized by comprising a heat extracting housing, a first chamber, an attaching means wherein the housing is attached to the multi-chip unit for positioning a semiconductor chip on it, and the first coolant which contacts the semiconductor chip in the first chamber. CONSTITUTION: An independent chamber 10 encloses a housing 24, and the housing 24 is fixed to a circuit board 22, on which semiconductor chips 14A-H are attached. A seal 26 for sealing the interface between the housing 24 and the circuit board 22 is provided, and with it, the first liquid-tight chamber 40 is provided in the housing 24. The semiconductor chips 14A-H provided on the circuit board 22 are assigned in the first chamber 40 determined by the housing 24. The first coolant, fluid or gas, is introduced in the first chamber 40. During operation of the semiconductor chips 14A-H, heat is transferred from the surface of semiconductor chips 14A-H to the first coolant.

Description

DETAILED DESCRIPTION OF THE INVENTION The apparatus of the present invention relates to a new and improved system for cooling elements of a multi-element device and a new and improved method for cooling such elements, and In particular, it relates to a new and improved independent cooling chamber for cooling multi-chip units and a method for cooling single conductor chips in multi-chip units.

Modern high-performance integrated circuit chips not only have large semiconductor transistors and switches, but also operate at higher speeds than we have experienced in the past. in some cases,
Such a chip must produce hundreds of galos per second. By doing meaningfully more work in a shorter amount of time, each semiconductor chip requires more operating power. The higher the operating power, the higher the heat generated, and if the generated heat is not dissipated, the semiconductor chip will fail. Therefore, cooling is an important consideration when designing computer circuits. Without adequate cooling, the clock frequency representing the operating speed of the computer must be reduced. This is the opposite of the goal of designers of high speed computers.

A consideration when using semiconductors and microchips is to make them work well with each other in complex and dense computer environments.

Once this is accomplished, the system speed approaches the individual chip speed very closely. If these speeds were not available, the benefits of high-performance chips would not be realized and would not be developed at all. To obtain sufficient or high performance of a microchip, interrelated signals must reach local or remote destinations with minimal time-phase error. Time-phase error is a function of the time it takes for an electronic signal to travel through a conductor. The longer the conductor, the longer it will take for the signal to reach its destination.

Therefore, if each of several receiving circuits is at a significantly different distance from a common transmitting circuit, the timing of the operation of each of the circuits will be affected.

One way to reduce the distance between chips is to move the chips closer together. However, the design drawback of bringing the chips close together is that they are part of the same multi-chip unit) (MC
U) Although backing more chips on top reduces interconnect links, chips operating in such a crowded environment can quickly overheat, which can ruin the chip without adequate cooling. become. Adequate cooling is necessary at least to remove heat from the rapidly heating chip.

One form of cooling that has been attempted is to provide heat removal devices next to certain semiconductor chips to remove heat from the chips and keep them at operating temperatures. Since the input/output electrical conductors also contact the semiconductor chips, providing a heat removal device next to each chip makes the area in the immediate vicinity of these chips very congested. In a crowded chip environment, heat is generated more rapidly and is difficult to dissipate.

Other types of cooling are bottom cooling and top cooling, which refer to the direction of heat as it exits the heated chip. An example of bottom cooling is a structure in which a semiconductor chip is welded to a molybdenum bottom plate. The bottom plate and its associated conductor layers form a multi-brane or high-density signal carrier. The bottom plate provides cooling by conducting heat away from the chips attached to it. This cooling requires connecting the bottom of the chip directly to the plate.

To make such a contact, the high-density signal carrier and all associated conductor layers must be recessed or open for contact between the chip and the plate. These intrusions pose a design problem. This is because the space occupied by the chip cannot be occupied by conductors in the several layers that are allowed to penetrate inside. As a result, conductors between different plates and layers must be placed around these intrusions, increasing conductor length and reducing chip performance.

Top cooling may be used instead of bottom cooling.

Top cooling involves placing a conductive material (mechanical or liquid) in direct contact with the top of one or more heated chip surfaces, thereby carrying heat away from the chip. The advantage of top cooling is that it creates space in the conductive layers of the multichip unit and optimizes the required conductor length.

Top mechanical cooling uses a thermal conductor in mechanical contact with the chip to absorb unwanted heat and transport it toward the cold end of the mechanical thermal conductor. The cold end of the conductor is usually in contact with another heat absorber that absorbs unwanted heat.

There are also liquid top cooling devices that flow a fluid in contact with a heated surface. Heat is transferred to the fluid and the fluid expands. This expansion reduces the density of the fluid, and the now thick liquid rises from the heat source, which in this case is a semiconductor chip. One form of top cooling using liquid uses a large, centrally shared cooling chamber. When using this cooling system, several circuit boards are placed in a large common cooling chamber. In this apparatus, the circuit boards are immersed in a cooling fluid with both sides of each multi-chip unit package board exposed to the cooling fluid.

Centralized liquid cooling systems require expensive and time-consuming maintenance. To maintain or service an individual board, the entire equipment must be shut down and a technician must remove the board from the cooling chamber for service. This service requires technicians to handle coolant. Coolants are often expensive and some are toxic and special care must be taken to avoid spilling during service. It is very difficult to test this cooling device in the field. This is because the chip must be cooled while it is being tested. Testing individual chips or boards while the cooling system is inactive requires special equipment that is not easily available to field maintenance personnel. This need for specialized equipment increases the price of the service as it requires special training of technicians in this all-important top job.

Preferably, there is a separate coolant chamber that is part of each multi-chip unit. Such equipment is more convenient to manufacture and maintain, requires less coolant, and as a result reduces the cost of the total amount of coolant required.

It is an object of the present invention to provide a new and improved device for extracting heat from a multi-chip unit.

Another object of the invention is to provide a new and improved method for cooling semiconductor chips or microchips.

Yet another object of the present invention is to provide a new and improved dual independent cooling chamber for a multi-chip unit for extracting heat from the semiconductor chips of the multi-chip unit.

Yet another object of the present invention is to provide a new and improved method for independently cooling a multichip unit and the semiconductor chips contained therein.

Briefly, the present invention provides a new and improved independent coolant chamber for a multi-chip unit for cooling semiconductor chips, and a new and improved independent coolant chamber for cooling semiconductor chips in a multi-chip unit. It is aimed at methods that The independent chamber of the present invention includes a housing that is secured to a circuit board for mounting a semiconductor chip. A seal is provided to seal the interface between the housing and the circuit board, thereby providing a first fluid-tight chamber within the housing.

A semiconductor chip mounted on the circuit board is disposed within a first chamber defined by the housing. A first coolant, either a fluid or a gas, is introduced into the first chamber. During operation of the semiconductor chip, heat is transferred from the surface of the semiconductor chip to the first coolant. Preferably, a second semiconductor chip may be provided on the housing and in thermal communication with the first chamber. A second coolant is provided in the second chamber, and heat of the first coolant is transferred to the second coolant.

In accordance with the principles of the present invention, each multi-chip unit may be provided with a separate cooling chamber. Providing such a separate cooling chamber provides a portable unit that is easy to maintain and assemble, thereby significantly reducing the cost of the overall device. Due to the large cooling effect of the independent cooling chamber of the present invention, the chip density of the multi-chip unit can be made higher than before. This high chip density also allows combiator designers to take advantage of shorter interconnect lines and improve the time phase relationship between the transmit and receive chip circuits.

Other objects and advantages of the invention, with reference to the drawings:
It will become clear after reading the description below.

While the invention is susceptible to various modifications and variations, specific embodiments thereof are illustrated in the drawings and will be described in detail below. However, it is not intended that the invention be limited to the particular embodiments disclosed below; on the contrary, the invention is intended to cover all modifications, variations, and equivalents falling within the scope of the claims. , I want you to understand that.

Multichip or semiconductor chips for computers and similar electronic devices are typically mounted on circuit boards or multichip units. This multi-chip unit acts to protect the chips from the ambient environment and heat, and also provides power and signal transmission between other chips within the multi-chip unit and other multi-chip units within a computer or similar electronic device. can meet the requirements of chips for interconnection. Developments in electronic devices, including the design of electronic devices, are moving toward increasing the operating speed of semiconductor chips and increasing the amount of work that the chips can perform. The higher the operating speed, the
Operating power is greater, but as a result, operating heat levels are higher. These high operating heat levels create design problems. To increase the operating speed of chips, designers have increased the chip density of multichip units or circuit boards. However, the combination of large chip densities and high operating heat levels results in overheating of the chips, resulting in failure and eventual destruction.

A solution to the overheating problem is to cool the chip in some way. Cooling the chips installed in a multi-chip unit is difficult because the chips are crowded together.
Also, the cooling device is difficult because it is required not to interfere with the conductor portion of the internal chip. In addition,
There is also a need to minimize cooling equipment costs and maintenance. For these reasons, it is preferred that the cooling system be built-in, that requires minimal coolant, and that allows chip testing to be performed without shutting down the entire cooling system. For example, independent cooling devices that can cool specific groups of chips, such as only the chips in a single multichip unit, can meet these design parameters. By providing an independent cooling system, each multichip unit of a computer or other electronic device can be cooled, maintained, tested, and even individually replaced with other multichip units.

The independent cooling system of the multi-chip unit is designated by the reference numeral 10 in FIGS. 1 and 2. This cooling device 10 is a part of a multi-chip unit 12, and includes semiconductor chips or multi-chips 14AS attached to the multi-chip unit 12.
14BS 14C.

It is independent in the sense that it is specifically designed to cool only 14D, 14E, 14F, 14G and 14M.

The multi-chip unit 12 includes a base plate 16, a power supply surface 1
8, a coolant-impermeable, high-density, multi-sided circuit board that includes a signal plane 20 and a high-density signal carrier 22. The high-density signal carrier 22 includes high-performance chips 14A and 14B.
, 14C, 14D, 14E, 14F, 14G and 14
These chips are affixed to the carrier 22 by tape self-adhesion techniques or similar techniques.

The purpose of the independent cooling system is to cool the chips 14A-H on the multi-chip unit 12 while minimizing the surface area other than the chips being cooled.

This creates a need to prevent cooling device 10 from extending beyond that portion of carrier 22 that supports chip 14 A=H. The cooling device 10 also includes a chip 1
4 A-H needs to be portable so that it can be tested, repaired or replaced. These needs are
It can be filled by a housing 24 mounted on the multi-chip unit 12 in exact alignment with a sealing track 26 formed on the upper surface of the signal carrier 22 near its outer periphery. Seal track 26 includes a seal that seals the interface between the lower edge 28 of housing 24 and the top surface of signal carrier 22.

The lower edge 28 of the housing 24 is formed by the lower ends of the four walls 30, 31, 32 and 34 of the housing 24.

In addition to its four walls 30, 31, 32 and 34, the housing 24 has a top 3 with downwardly projecting fins 38.
It is equipped with 6. Walls 30, 31, 32 and 34 and top 36 form a chamber 40 that is mounted to multichip unit 12 such that housing 24 sealingly engages sealing track 26 at its bottom 82B. In some cases, it becomes liquid-tight or air-tight. Housing 24 is securely attached to multichip unit 12 with fasteners 42.

Fasteners 42 are secured to threaded holes 44 formed in multi-chip unit 12 and attached to independent cooling device 10 in the manner described below.

A requirement for independent cooling system 10 is to avoid interference between flat cables 46 external to multichip unit 12 and internal conductive paths 48 interconnecting chips 14A-H within multichip unit 12. Internal conduction path 4
8 extend downwardly or inwardly from chips 14A-H to signal plane 20 inside multichip unit 12. From the signal plane, a conductive path 48 extends under the seal track 26 to a flat cable 46 through which data can reach other destinations within the multichip unit 12 or outside. can. Data to other chips within multi-chip unit 12 is via other internal conductors 50. The passage of conductor 48 passes under seal track 26 so that housing 24 does not interfere with conductor 48. Since the conductors 50 are internal, the independent cooling device 10 does not interfere with these conductors.

Cooling of chips 14A-H is provided by coolant within chamber 40. The coolant may be, for example, air, but in a preferred embodiment is a fluorocarbon. Chips 14A-H are cooled by an extended surface on each chip 14A-H, which in the preferred embodiment is a copper sheet 51 brazed to the backside of each chip 14A-H. Each copper sheath 51 is provided with fins 51A that extend into the coolant within the chamber 40. Heat is transferred from the chips 14A-H to the copper sheet 51 and from the copper sheet 51 to the fins 51A. Cooling then occurs intermittently. In intermittent cooling, the coolant is in a liquid state when the operating temperature of chamber 40 is ambient temperature.

As the temperature of the coolant increases, the operating temperature of the chip increases, causing the coolant to change from a liquid state to a gas state when the temperature exceeds the transition temperature. for example,
As shown in FIG. 2, the temperature of the chips 14A-H increases during operation, and the coolant near the fins 51A on the chips 14G and 14H warms up, touching the surfaces of the fins 51A, the chips 14G, and the chips 14H. The tiny particles in the liquid turn into gas. This liquid-to-gas state change increases the specific heat of the coolant, making it a more efficient heat absorber. During this state change, chips 14G and H are cooled as the coolant absorbs heat.

During the phase change, the bubble 52 connects the fin 51A and the tip 14G,
Made in 14H. Since these bubbles 52 are lighter than the coolant, they move to the top of the chamber 40 and rise until they hit the fins 38. Upon hitting the fins 38, the heat of the bubbles 52 is transferred to the fins 38 and the coolant returns to the liquid phase.

A heat exchanger 54 is mounted on the top surface of the housing 24 to dissipate heat from the fins 38. The heat exchanger 54 may be a separate unit attached to the housing 24 or may be an integral component of the housing 24. In this embodiment, the heat exchanger 54 is shaped similar to a duct and has side surfaces 56 , 58 , a top surface 60 and a bottom surface 62 , and further defines an open end 64 .

The ducts formed by these side surfaces 56, 58, top surface 60 and bottom surface 62 lead directly to a coolant source for coolant flow. Here, the coolant is a coolant such as water or air, and communicates with the heat exchanger 54. Coolant flowing through heat exchanger 54 cools fins 38 and top surface 36 and aids in dissipating heat from the coolant within chamber 40 .

The heat exchanger 54 overhangs the housing 24 slightly. Top surface 60 and bottom surface 62 of heat exchanger 54
A hole 66 is drilled in each corner of the hole 66, and the fastener 42 is passed through the hole 66.

Fastener 4 in hole 44 in multi-chip unit 12
2, the housing 24 and the heat exchanger 54 are integrally attached to the multi-chip unit 12, and the contact surface of the lower edge of the housing 24 is sealed against the seal groove 26 to prevent coolant leakage. There is.

According to the present invention, since the cooling device 10 is independent, the chips 14 A-H are connected to the multi-chip unit 12.
short interconnect leads can be used to provide the best performance for the multi-chip unit 12. The cooling device 10 described above is independent, ie portable, in the sense that the multi-chip unit 12 is not constantly connected to the overall cooling device for the attached computer or electronic equipment. Therefore, this cooling device 10 can be shut down, disassembled, and the chips 14A-H can be tested and replaced without affecting other cooling devices. Providing a portable means of attaching a separate cooling system 10 to the multichip unit 12 minimizes the need for technicians to handle toxic coolant when testing or repairing the multichip unit 12.
This creates a safe working environment.

The foregoing description is merely illustrative of the principles of the invention. Various modifications will readily occur to those skilled in the art, and therefore, the present invention is not limited to the precise construction and operation described herein, but is intended to include all suitable modifications that fall within the scope of the claims. This includes variations of .

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a separate cooling chamber and multichip unit constructed in accordance with the principles of the present invention;
FIG. 2 is a partially cutaway side view of the independent cooling chamber and multi-chip unit of the present invention. 10...Independent cooling device, 12...Multi-chip unit, 14A-H・
... Chip, 22 ... Carrier, 24.
... Housing, 26 ... Seal track, 28 ... Lower edge, 30.31.32.34.
...Wall, 36...Top e, 38...
・Fin, 40...Chamber 42...
- Fastener 44...Threaded hole, 46...
...Flat cable, 48...Internal conduction path,
50...Inner conductor, 51...Copper nut, 51A...Fin, 52...Bubble,
54...Heat exchanger. Procedural amendment (method) % formula % ■, Indication of case 1990 Patent Application No. 1 +496,11 No. 3, Person making the amendment Relationship to the case Applicant 4, Agent 5, Date of amendment order 1990 July 31st

Claims (21)

[Claims] (1) An independent heat extraction device for semiconductor chips in a multi-chip unit, comprising: a heat extraction housing for at least one semiconductor chip of the multi-chip unit; a first chamber in the heat extraction housing; mounting means for mounting the heat extraction housing on a chip unit and positioning the at least one semiconductor chip in at least a portion of the housing; 1. An independent heat extraction device comprising: 1 coolant. (2) The independent heat extraction device according to claim 1, wherein the first coolant is a fluorocarbon. (3) The independent heat extraction device according to claim 1, wherein the first coolant is air. (4) The independent heat extraction device according to claim (1), wherein the heat extraction housing includes a heat exchanger. (5) The heat exchanger includes a second chamber in thermally conductive relationship with the first chamber in the heat extraction housing, and includes a second coolant within the second chamber. ) Independent heat extraction device as described. (6) The independent heat extraction device according to claim 1, further comprising sealing means for sealing an interface between the heat extraction housing and the multi-chip unit when the heat extraction housing is attached to the multi-chip unit. . 7. The independent heat extraction device of claim 1, wherein said attachment means includes an opening in said first chamber having substantially the same shape as said at least one semiconductor chip. (8) a multi-chip unit including at least one semiconductor chip; and an independent cooling chamber for cooling the at least one semiconductor chip, the independent cooling chamber being shaped to at least cover the at least one semiconductor chip; an independent cooling chamber including a housing having a first chamber containing a first coolant; and an interface between the housing of the independent cooling chamber and the multi-chip unit when the housing is attached to the multi-chip unit. and sealing means for sealing. (9) The combination according to claim (8), wherein the first coolant is fluorocarbon. (10) Claim (8) wherein the first coolant is air.
Combinations listed. 11. The combination of claim 9, further comprising a heat exchanger for dissipating heat from the first chamber, the heat exchanger including a second chamber containing a second coolant. . (12) The combination according to claim (11), wherein the second coolant is fluorocarbon. (13) Claim (11) wherein the second coolant is air.
9) Combination as described. (14) The combination according to claim (8), wherein the sealing means includes a sealing element attached to the multi-chip unit and surrounding the at least one semiconductor chip. 15. The combination of claim 8, wherein the at least one semiconductor chip includes an extended surface at least partially within the independent cooling chamber. (16) A method for cooling semiconductor chips in a multi-chip unit, comprising: disposing an open-end housing over at least one semiconductor chip of the multi-chip unit; fixing the open-end housing to the multi-chip unit; A method comprising: defining a first chamber containing one semiconductor chip; and introducing a first coolant into the first chamber into contact with the at least one semiconductor chip. 17. The method of claim 15, including the step of exchanging heat from the first coolant to a second coolant. 18. The method of claim 16, including the step of sealing an interface between the first chamber and the multi-element device. (19) A method for cooling a selected chip of a multi-chip unit, comprising: isolating the selected chip from other chips of the multi-chip unit; and cooling the isolated selected chip with a first coolant. A method characterized by exposing to. 20. The method of claim 19, wherein isolating the selected chip includes securing a housing to the multi-chip unit to accommodate the selected chip within the housing. 21. The method of claim 19, further comprising the step of conducting heat from the first coolant to a second coolant.