JPH0617311Y2 - Cooling structure of circuit element in multi-chip package - Google Patents

Description

The present invention relates to a structure for forcibly cooling circuit elements of a multi-chip package used in a high-speed computer called a supercomputer, for example.

Conventional technology To increase the computing speed of a computer,
It is necessary to reduce not only the internal gate delay time in a circuit element such as an LSI, but also the connection wiring delay time. As one means of reducing the latter delay time, it is possible to increase the packaging density of circuit elements. Can be mentioned. However, since the circuit element itself is a heating element, there is a problem that when the density is increased, the temperature rise due to the concentration of the heating element becomes noticeable. Therefore, an effective cooling means is required along with the increase in the density of the circuit element. Will be needed.

"NIKKEI ELECTRONICS", a magazine distributed in Japan for an example of cooling means for high-density mounting of circuit elements (June 17, 1985)
7) is an explanatory view showing an example of a cooling structure for a circuit element 1 such as an LSI in the multi-chip package, in which a circuit board 2 has pins 3 protruding from the lower surface and an upper surface. It has a multilayer structure configured to connect with a large number of contacts (not shown) provided on the circuit board 1, and the circuit element 1 is connected to the upper surface of the circuit board 2 by soldering. A shaft-shaped heat dissipation stud 4 is in contact with the upper surface of the circuit element 1 with a high thermal conductivity thermal compound 5 sandwiched between the heat dissipation stud 4 and a heat conduction block 6 arranged on the upper side of the circuit board 2. It is closely fitted. Further, a water cooling plate 7 is arranged on the upper surface of the heat conduction block 6, and the circuit board 2, the heat conduction block 6 and the water cooling plate 7 are integrally connected. A water passage 8 is formed in the water cooling plate 7, and an inflow port 9a and an outflow port 9b communicating with the water passage 8 are provided. Therefore, the heat generated in the circuit element 1 is transferred to the water flowing through the water passage 8 of the water cooling plate 7 through the thermal compound 5, the heat dissipation stud 4 and the heat conduction block 6, and as a result, the heat of the circuit element 1 is converted into water. It is configured to take and cool. The multi-chip package configured as described above is arranged on the board, and in that state, as shown in FIG. 8, the inflow port 9a and the outflow port 9b are sequentially connected to continuously flow cooling water, All circuit elements 1 are cooled together.

Further, conventionally, a heat pipe is formed inside a heat sink, and the heat pipe is pressed against the circuit element to provide cooling means (IBM Technical Report Vol.25, NO.8) or a stud provided on a heat conduction module. Cooling structure that uses the pin fins on the upper surface of the heat conduction module as a heat pipe while pressing the heat conduction module (IBM Technical Report Vol.27, N
O.11) is known.

Problems to be Solved by the Invention In the cooling structure shown in FIGS. 7 and 8, however, the heat dissipation stud 4 intervenes in the heat transfer from the circuit element 1 to the cooling water. Since heat is transferred to the heat conduction block 6 side by the heat conduction of the circuit element 1, the circuit element 1 does not always have a sufficient cooling effect.
There was a danger that the temperature would rise. In addition, the heat conduction block 6
The same applies to the above, and even if a material having a high thermal conductivity is used, the amount of heat transport is not necessarily high, in other words, there is a problem that the thermal resistance is large and therefore a sufficient cooling effect cannot be obtained. Further, although the thermal compound 5 is interposed between the heat dissipation stud 4 and the circuit element 1, it has a thermal resistance itself, and a gap is generated between the heat dissipation stud 4 and the circuit element 1 due to thermal expansion and contraction. There was a problem that it further hindered heat transfer.

On the other hand, among the above cooling structures using heat pipes, in the cooling structure in which the heat pipe is formed inside the heat sink,
One end of the heat pipe has a bellows structure, and the bellows portion presses against the circuit element, and therefore the adhesion to the circuit element may be good, but the heat pipe is in a vacuum state in a non-operating state, On the contrary, since it is in a high pressure state in the operating state, it is difficult to make the bellows portion act as expected, and it is difficult to manufacture the bellows portion, which is not practical. Further, in the cooling structure using the pin fins as a heat pipe, since the axial studs and the heat conduction block are interposed in the heat transfer path from the circuit element to the pin fins, there is a case where a sufficient cooling effect cannot be obtained as in the above-mentioned example. There was a problem that arises.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a cooling structure capable of efficiently cooling circuit elements in a multi-chip package and having a simple structure.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention installs a plurality of circuit elements on the upper surface of a circuit board having a large number of pins on the lower surface and dissipates heat on the upper surface of the circuit element. In a multi-chip package in which a stud is brought into contact with the radiating stud and the radiating stud is closely fitted to the heat conducting block is disposed on the upper surface side of the circuit board, and cooling means is provided on the upper surface of the heat conducting block. A heat pipe in which a working fluid for transporting heat as latent heat is enclosed in a sealed tube, and the heat pipe is pressed against the circuit element by an elastic body.

In the multi-chip package targeted by the present invention, the working fluid inside the heat pipe evaporates due to the heat generated in the circuit element, but the heat conduction block in which the heat pipe is closely fitted is provided on the upper surface side. Since it is cooled by the cooling means, the working fluid vapor flows to the side of the heat conduction block having a low temperature, and then radiates heat and condenses. Such heat transfer is performed by transferring heat as latent heat of the working fluid in the heat pipe, so that heat can be efficiently given from the circuit element to the cooling means side, and as a result, the circuit element can be efficiently cooled. To be done. Further, in this invention, since the heat pipe that constitutes the heat dissipation stud is pressed against the circuit element by the elastic body and is in close contact with the circuit element, the heat transfer between the two is good, and furthermore, the thermal expansion and contraction cause the heat pipe between the two. There is no risk of gaps in the circuit elements and the circuit elements are always well cooled.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

In the example shown in FIG. 1, a heat pipe 10 is used as a heat radiating stud for directly removing heat from the circuit element 1 by improving the cooling structure of the conventional multi-chip package shown in FIG. It is closely attached to the element 1. That is, the heat pipe 10 is one in which a condensable fluid such as water or alcohol is sealed as a working fluid after the inside of a hollow shaft-shaped hermetic container is evacuated, or a porous structure such as a wire mesh that causes a capillary pressure. A wick is provided inside as needed, and the heat pipe 10 is movable inside a through hole 12 formed from a lower surface to an upper surface in a portion of the heat conduction block 6 corresponding to the circuit element 1. Are closely fitted to each other. The through hole 12 is closed by a water cooling plate 7 attached to the upper surface of the heat conduction block 6, and the heat pipe 10 is interposed between the heat pipe 10 and the water cooling plate 7 in the through hole 12 and the circuit element 1 is formed. A spring 11 that presses to the side is arranged.

Other configurations are the same as those of the conventional multi-chip package shown in FIG. 7, and are arranged and mounted on a board (not shown) and connected to the water passage 8 in the water cooling plate 7 by connecting the inflow port and the outflow port. Then, it is cooled by flowing cooling water.

According to the above cooling structure, the heat generated by the circuit element 1 is transferred to the heat pipe 10 and the working fluid enclosed therein evaporates, but the portion of the heat pipe 10 that is in contact with the heat conduction block 6 Since the temperature of the heat pipe 10 is low, the working fluid vapor flows upward in the drawing, and
The heat is dissipated and condensed on the peripheral wall portion of the heat transfer section 6, and the heat is transmitted to the heat conduction block 6. A water cooling plate 7 is provided on the upper surface of the heat conduction block 6.
Since it is mounted and cooled, the heat applied to the heat conduction block 6 is transmitted to the outside by the cooling water flowing through the water cooling plate 7 and flowing in the water passage 8. That is, the heat generated in the circuit element 1 is given to the cooling water through the heat pipe 10, the heat conduction block 6 and the water cooling plate 7, and as a result, the circuit element 1 is cooled. In that case, the heat transfer from the circuit element 1 to the heat conduction block 6 is performed by the heat transfer of the working fluid in the heat pipe 10 as its latent heat. Taken to block 6. Further, the heat pipe 10 is pushed by the spring 11 and is in close contact with the circuit element 1, and even if thermal expansion or contraction occurs, the elastic pipe of the spring 11 maintains the close contact state, so that the circuit element 1 and the heat pipe 10 are maintained. Good heat transfer between 10 and 10 is always achieved. Therefore, in the above cooling structure, the heat transfer efficiency from the circuit element 1 to the heat conduction block 6 becomes extremely good, so that the circuit element 1 is efficiently cooled and its temperature rise is surely prevented.

FIG. 2 is a schematic cross-sectional view showing a second embodiment of the present invention, and the example shown here is configured so as to transfer heat between the heat conduction block 6 and the water cooling plate 7 more efficiently. Is. That is, the second heat pipe 13 is inserted into and closely fitted to the heat conduction block 6 from the upper surface side, and the projecting end of the second heat pipe 13 from the heat conduction block 6 is the water cooling plate 7. The second heat pipe 13 connects the heat conduction block 6 and the water cooling plate 7 in a heat transferable state.

Therefore, in the cooling structure shown in FIG. 2, heat is transported from the heat conduction block 6 to the water cooling plate 7 via the heat pipe 13 having an extremely high thermal conductivity, and eventually the heat conduction from the circuit element 1 is conducted. Since the heat pipes 10 and 13 mediate both the transfer of heat to the block 6 and the transfer of heat from the heat transfer block 6 to the water cooling plate 7, the circuit element 1 is cooled very efficiently. Will be possible.

FIGS. 3 and 4 show a third embodiment of the present invention, and the example shown here is different from each of the above-described embodiments.
It has an air-cooled structure. That is, the heat pipe 10 that constitutes the heat dissipation stud is movably and closely fitted into the bottomed cylindrical hole 14 formed in the heat conduction block 6, and the heat pipe 10 is provided above the heat pipe 10. Spring 1 for pressing the circuit element toward the circuit element 1
1 is arranged. An air cooling plate 15 is attached in close contact with the upper surface of the heat conduction block 6. The air-cooling plate 15 has a plate-shaped body made of a material having a high thermal conductivity and is fitted with one end of a plurality of heat pipes 16 in close contact with each other, and the heat radiation fins 17 are attached to the protruding ends of the heat pipes 16. This air-cooled plate 1
5 is a heat dissipation block 6 like the water cooling plate 7 described above.
It is also fastened so as to be integrated with the circuit board 2.

Therefore, the heat generated in the circuit element 1 is transferred to the heat conduction block 6 via the heat pipe 10, and the heat transferred from the heat conduction block 6 to the air cooling plate 15 is transferred to the outside air or low temperature via the heat pipe 16. Transmitted to the air. That is, the heat of the circuit element 1 is the air cooling plate 1
The circuit element 1 is substantially air-cooled because it is carried to the No. 5 and is discharged to the outside air or low temperature air through the heat pipe 16 from there. In that case, the heat pipe 10 mediates transfer of heat from the circuit element 1 to the heat conduction block 6,
Further, since the heat transfer from the heat conduction block 6 to the outside air is mediated by the heat pipe 16 attached to the air cooling plate 15, the heat is positively and largely transferred, and therefore the circuit element 1 can be efficiently air cooled. it can.

When the circuit element 1 is air-cooled, a heat sink can be used, an example of which is shown in FIGS. 5 and 6.

That is, in FIG. 5, the heat pipe 17 inserted into the heat conduction block 6 has a tip end (lower end) contacting the circuit element 1 and a rear end (upper end) having a hollow cylindrical shape with a bottom. A connecting portion 18 having a screw formed on the inner peripheral surface is provided. Further, a heat sink 20 having heat radiation fins 19 is attached to the upper surface of the heat conduction block 6 in a close contact state, and an insertion hole 21 is formed in a portion of the heat sink 20 on the same axis as the heat pipe 17. Another heat pipe 22 is movably and closely fitted to the heat pipe 22, and a spring 23 for pressing the heat pipe 22 downward is disposed between the heat pipe 22 and the bottom surface of the insertion hole 21. There is. This heat pipe 2
2 is projected to the heat conduction block 6 side, a screw is formed on the outer periphery of the protruding end, and the screw is screwed into the connecting portion 18 to be connected to the heat pipe 17.

Therefore, the heat generated in the circuit element 1 is, on the other hand, transferred to the heat conduction block 6 via the heat pipe 17, then transferred from the heat conduction block 6 to the heat sink 20 and radiated to the outside air from the fin 19. On the other hand, after being directly transmitted to the heat sink 20 via the heat pipes 17 and 22, the fins 19 radiate heat to the outside air. Even in such a heat radiation process, heat transfer is performed by the heat pipes 17, 2
Since the heat pipe 17 is always brought into close contact with the circuit element 1 by the spring 23, the heat transfer from the circuit element 1 can be smoothed and efficient cooling can be performed.

In addition, the example shown in FIG. 6 uses one heat pipe 24 in contrast to the two heat pipes 17 and 22 used in the example shown in FIG. That is, the heat pipe 24 is inserted into the heat conduction block 6 on the one hand, and is closely fitted to the insertion hole 21 of the heat sink 20 on the other hand, and the heat pipe 24 is inserted in the insertion hole 21 toward the circuit element 1 side. A pressing spring 23 is arranged.

With such a configuration, the heat pipe 24 directly conveys heat from the circuit element 1 to the heat sink 20, and during that, heat transfer between the heat pipes as in the example shown in FIG. Therefore, the circuit element 1 can be cooled more efficiently as compared with the configuration shown in FIG.

Effects of the Invention As is apparent from the above description, according to the cooling structure of the present invention, the heat pipe is pressed against the circuit element by the spring to be in close contact therewith, and the heat is taken from the circuit element through the heat pipe to cool the circuit element. It becomes possible to quickly and largely transfer heat from the circuit element to the cooling means, and as a result, the circuit element can be efficiently cooled and its temperature rise can be reliably prevented. Since the heat pipe as a heat dissipation stud is pressed against the circuit element by an elastic body such as a spring, even if thermal expansion or contraction occurs, the heat pipe moves accordingly, so that the heat pipe for the circuit element does not move. In addition to being able to maintain a good close contact state at all times, it is possible to prevent excessive stress from occurring.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention, FIG. 2 is a schematic sectional view showing a second embodiment, FIG. 3 is a schematic sectional view showing a third embodiment, and FIG. The IV-IV line arrow view, FIG. 5 is a schematic sectional view showing a fourth embodiment of the present invention.
FIG. 7 is a schematic sectional view showing a fifth embodiment, FIG. 7 is an explanatory view of a conventional cooling structure for a multi-chip package, and FIG. 8 is an explanatory view of the arrangement state thereof. 1 ... Circuit element, 2 ... Circuit board, 3 ... Pin, 6 ...
Heat conduction block, 7 ... Water cooling plate, 10, 13, 1
6, 17, 22, 24 ... Heat pipes 11, 23 ...
…spring.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryuichi Okiayu 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) Reference JP-A-59-115548 (JP, A)

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A plurality of circuit elements are installed on the upper surface of a circuit board having a large number of pins on the lower surface, and a heat radiating stud is brought into contact with the upper surface of the circuit element, and the heat radiating stud is closely fitted to the heat. In a multi-chip package in which a conductive block is arranged on the upper surface side of the circuit board and a cooling means is provided on the upper surface of the heat conductive block, the heat dissipation stud encloses a working fluid for transporting heat as latent heat in a sealed tube. A cooling structure for a circuit element in a multi-chip package, which is a heat pipe, and the heat pipe is pressed against the circuit element by an elastic body.