JPS5841778B2 - Cold plate for large-scale semiconductor equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a large-scale semiconductor device, and more particularly, to a cold plate for a large-scale semiconductor device that facilitates heat dissipation of the semiconductor device.

Regarding large-scale semiconductor devices using large-scale integrated circuits (LSI), the problem is how to dissipate and cool a large amount of heat generated within a relatively small volume.

Conventionally, there are forced air cooling methods and liquid cooling methods as methods for cooling such large-scale semiconductor devices.

In forced air cooling, the cooling effect is determined by the air temperature, flow rate, and the size of the heat radiation area of the object to be cooled. Therefore, devices equipped with highly integrated LSIs, etc. require a large heat radiation area. Since a large external heatsink and a blower with a large air volume are required, it is necessary to use a heat dissipation device that is disproportionately large compared to the size of the electronic circuit, and furthermore, the operation of this large blower requires This has disadvantages in that the generated noise harms the environment and the vibration reduces the reliability of electronic circuit devices.

In addition, with forced air cooling, temperature gradients occur within the device depending on the arrangement of circuit components and the direction of air flow, so careful attention must be paid to the layout of components in order to eliminate the negative effects of this temperature gradient. It also has the drawback that it is difficult to design.

On the other hand, liquid cooling systems can be broadly classified into cold plate systems and refrigerant immersion cooling systems, both of which have superior cooling effects compared to forced air cooling systems.

However, with the cold plate method, it is extremely difficult to bond the cold plate to circuit components such as LSI, and once the cold plate is attached to the circuit component, it is difficult to easily remove the cold plate. Therefore, it has the disadvantage that it is difficult to replace parts in the event of failure.

Also, recently, ceramic wiring boards are increasingly being used instead of resin printed wiring boards.
In such cases, it has become possible to join a cold plate through a ceramic/mink wiring board by taking advantage of the good thermal conductivity of the ceramic wiring board.

Therefore, when cooling is performed by using a ceramic wiring board and attaching a cold plate to the ceramic wiring board, it is relatively easy to replace and repair parts, but the joint surface of the cold plate is not connected to the ceramic wiring board. This is disadvantageous in high-density packaging, and it is not always easy to removably connect the cold plate and the ceramic wiring board.

In the immersion cooling method, the circuit equipment is sealed inside the coolant container, so it is not possible to directly inspect each circuit component.
Therefore, it is not easy to adjust and maintain the equipment, and
Since the cooling container itself is required to have a very high degree of reliability, the cost is high and the entire device is extremely large.

For this reason, conventionally, a plurality of electronic elements each having one side connected and fixed to wiring on a circuit board and a stud on the other side, and a plurality of recesses for accommodating the studs of the electronic elements are provided. In addition, a heat sink is provided with a flow path through which fluid can flow, the stud is inserted into the recess, and a low melting point material with good thermal conductivity is filled in the recess and solidified to dissipate the heat of the electronic element. A device has been disclosed in which heat is dissipated through a stud or a low-melting point material (Japanese Patent Publication No. 47-1
0184).

However, in this disclosed device, since the studs are placed in the recesses and fixed by a low-melting point material, it is not always easy to attach and remove the circuit board and the heat shield, and the studs are installed in the recesses. However, if the button is exposed to some thermal strain on the circuit board side, it has the disadvantage that mechanical strain forces will be applied to the stud and the electronic components to which the stud is attached.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to be able to be attached to and detached from the cooling device part, and to reduce the mechanical movement applied to the circuit element side even when the device is installed in the cooling device part. It is an object of the present invention to provide a cold plate for a large-scale semiconductor device that has a large margin for processing.

In order to achieve the above object, the present invention provides an upper part for accommodating a heat dissipation stud, which is formed at a location corresponding to a heat dissipation stud attached to a semiconductor component mounted on a circuit unit, and is filled with a high boiling point refrigerant. A cold plate for a large-scale semiconductor device is provided, which is characterized by having an open recess.

The present invention will be explained in detail below with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of a cold plate for a large-scale semiconductor device according to the present invention.

The large-scale semiconductor device 1 includes a large number of large-scale integrated circuit elements 2a.
A circuit unit 3 on which m2b-... is mounted, and a cold plate 4 for cooling this circuit unit 3.
The circuit unit 3 and the cold plate 4 are assembled by being screwed together via spacers 5 and 6.

As shown in FIG. 2, the circuit unit 3 includes a large number of large-scale integrated circuit elements 2a, 2b,
2c... are arranged in a line within the mounting unit area surrounded by dotted lines, and FIGS. 3 and 4 show details of the vicinity of the large-scale integrated circuit element 2a in FIG. is shown.

The large-scale integrated circuit element 2a includes a ceramic container 9 for storing an LSI chip 8, and a lid 9 for keeping the LSI chip 8 stored in the ceramic container 9 in an airtight state from the external atmosphere. A lead wire 11 from the LSI chip 8 is connected to an external terminal 12 provided on the container 9.

This external terminal 12 is aligned with the circuit element mounting pattern 13 of the multilayer printed board 7 and soldered to it, thereby fixing the large-scale integrated circuit element 12a to the multilayer printed board 7 and making predetermined wiring connections. It will be done.

A cylindrical heat radiation stud 14a is fixed to the upper surface 9a of the ceramic container 9 for dissipating heat generated by the LSI chip 8 and transferred to the ceramic container 9.

This heat dissipation stud 14a is preferably made of a material with good thermal conductivity, such as molybdenum or copper, and similar heat dissipation studs 14b, . 14c, . . . are similarly fixed.

5 and 6 show the cold plate 4 in detail.

The cold plate 4 is made of a metal material with good thermal conductivity, such as copper or aluminum, and has a meandering passage 15 inside thereof for passing a cooling liquid.

One end opening 15a and the other end opening 15b of the passage 15 are
Each opening 15a, 15b is formed on one end surface of the cold plate 4, and is connected to a cooling liquid circulation device (not shown) through a connecting pipe 16, 17.

Therefore, the coolant circulates within the passage 15 by this coolant circulation device (not shown), and the cold plate 4 is cooled by this coolant.

The cold plate 4 further includes each circuit element 2a, 2b.
, 2c...
.

Recesses 18a, 18b for accommodating 14c, .

18c, . . . are provided at the heat dissipation stud mounting position of the circuit unit 3.

The inner diameters of these recesses 18a, 18b, 18c, - are set to be slightly larger than the outer diameter of each heat dissipation stud.
The local end faces of these recesses 18a, 18b, and 18c each form a void 19 provided near the bottom of the cold plate 4.
is connected to.

One end of this gap 19 communicates with an opening 21 provided in a protrusion 20 protruding from one side of the cold plate 4.

The four corners of the cold plate 4 correspond to a total of four through holes 22 (only some of which are shown in the drawings) provided at the four corners of the circuit unit 3 shown in FIGS. 1 and 2. A threaded pin 23 is implanted into the circuit unit 3 and the cold plate 4 by passing the pin 23 through the through hole together with the spacer 5.6 so that each heat dissipation stud penetrates into the corresponding recess. and can be assembled as shown in FIG.

In this case, as already mentioned, the outer diameter of the heat dissipation stud is
Since it is formed to be slightly larger than the inner diameter of the corresponding recess, even if there is some assembly dimensional error between the cold plate 4 and the circuit unit 3, it does not pose a problem at all, and therefore assembly is extremely easy.

In order to efficiently cool each heat dissipation stud by the cold plate 4, each recess 18a, 18b.

A refrigerant liquid 24 is injected into the refrigerant 18c, .

Each recess 18a, 1ab, 18c, . . . is a void 1
9 and the opening 21, by injecting an appropriate amount of refrigerant liquid 24 from the opening 21, each recess 1 Ba
s 18b, 18c, m can be filled with refrigerant 24.

The upper opening of each recess into which the heat dissipation stud penetrates is not particularly liquid-tightly sealed so that the cold plate 4
must be kept substantially horizontal by an appropriate support member.

In this way, each heat dissipation stud is immersed in the coolant liquid filling the corresponding recess, so that the heat from the LSI chip 8 transferred to the heat dissipation stud via the ceramic container 9 is transferred via the coolant liquid 24. The coolant is radiated to the cold plate 4 which is cooled by the coolant circulating in the passage 15, thereby cooling the circuit unit 3.

Therefore, as can be easily understood from the above description, it is preferable to erect the circuit unit 3 and the cold plate 4 so that each heat dissipation stud is inserted as deep as possible into the corresponding recess, but in this case, the heat dissipation stud Direct contact with the cold plate 4 may cause undesirable mechanical strain to be applied to the circuit unit, so when assembling,
Care must be taken to ensure that the heat dissipation stud does not come into direct contact with the cold plate 4.

As can be seen from the above description, the refrigerant liquid 24 is not used to dissipate heat from the heat dissipation studs using the latent heat of vaporization of the refrigerant liquid 24, but to improve heat conduction between the heat dissipation studs and the cold plate. It is nothing more than a heat conduction medium.

Therefore, in order to prevent the refrigerant liquid 24 from scattering due to evaporation from the upper opening of each recess, the refrigerant liquid 24 has a high boiling point and good thermal conductivity, and is also a liquid that does not corrode the device. It is desirable that the liquid be chemically inert so that it does not.

However, among these conditions for the refrigerant liquid 24, regarding the thermal conductivity condition, the refrigerant liquid 24 will generate natural convection in the direction of Omukai, and the natural convection will carry the heat from the heat dissipation stud to the cold plate. Therefore, even if the thermal conductivity of the refrigerant liquid 24 itself is somewhat low, there is no problem at all.

Therefore, as the refrigerant liquid 24, for example, a fluorocarbon liquid such as Fluorinert FC-43 manufactured by 3M Corporation of the United States can be used.

According to these authorities, each electronic element on the circuit unit is cooled by bringing the heat dissipation stud provided on each circuit element into contact with the cold plate via the refrigerant liquid injected into the recess of the cold plate. Extremely good cooling can be performed by the cold plate without mechanical connection to the cold plate, and therefore, the assembly dimensional error between the cold plate and the circuit unit is extremely small, so a reduction in manufacturing costs can be expected. can.

Further, since the cold plate and the circuit unit are assembled by screwing, it is extremely easy to attach and detach the circuit unit and the cold, and parts can be easily replaced, repaired, and inspected.

Another advantage is that since the other side of the circuit unit is completely open, the circuit unit can be inspected extremely easily by providing inspection terminals on the other side via through holes. At the same time, for example, as shown in FIG.
a, 25b, 25c, . . . are mounted, and these electronic elements 25a, 25b.

As for 25c, it is also possible to perform cooling by natural convection or forced air cooling using a very small amount of air.

FIG. 8 shows another embodiment of the device of the present invention, which further enhances the cooling effect.

This large-scale semiconductor device 1' includes ribbon-shaped thermally conductive spring members 26a, 2 made of a material such as phosphor bronze, which are in spring contact with the heat dissipating stud 14a within the recess 18a.
6b is provided so as to be lightly pressed against the surface of the heat radiation stud 14a inserted into the recess 18a.

By providing the thermally conductive spring members 26a, 26b in this manner, heat from the heat dissipation stud 14a is transmitted to the cold plate 4' via the refrigerant liquid 24, and the heat is transferred to the cold plate 4' via the spring members 26a, 26b. 4', a significant cooling effect can be achieved through the synergistic effect of both.

FIG. 9 shows experimental results confirming the cooling effect of the apparatus of the present invention.

In this experiment, the heat dissipation resistance AI:'C/W:] was measured when the diameter of the heat dissipation stud was fixed at 5[deg.] and the diameter of the hole into which the heat dissipation stud was inserted was varied.

In the figure, the straight line A indicates the case where Fluoriner FC-48 was used as the refrigerant liquid and no thermally conductive spring member was used, and the straight line A indicates the case where Fluoriner) FC-48 was used as the refrigerant and a thermally conductive spring member was used. In this case, straight line C is the characteristic when water is used as the refrigerant liquid and no thermally conductive spring member is used, and straight line 2 is the characteristic when water is used and a thermally conductive spring member is used.

In the embodiment shown in FIG. 8, the thermally conductive spring member is provided on the cold plate side, but it goes without saying that it may be provided on the heat radiation stud.

According to the present invention, as described above, the cooling device portion can be attached and removed from the circuit unit extremely easily, and the circuit unit portion can be inspected, repaired, and adjusted extremely easily. It does not require low dimensional accuracy, is extremely easy to manufacture and assemble, and has an extremely excellent cooling effect that does not cause any mechanical distortion to the electronic elements of the circuit even if the circuit unit is thermally deformed. A cold plate for large-scale semiconductor devices can be provided.

[Brief explanation of the drawing]

1 is a partially cutaway side view showing the assembled state of a cold plate for a large-scale semiconductor device as an embodiment of the present invention; FIG. 2 is a schematic partial plan view of the circuit unit shown in FIG. 1; Figure 3 is a partially enlarged plan view showing the mounting state of electronic elements that are buttoned to the circuit unit in Figure 2, Figure 4 is the x-x' drawing in Figure 3, and Figure 5 is the cold plate in Figure 1. 6 is a partially sectional side view of the cold plate shown in FIG. 5, FIG. 7 is a side view showing a modification of the cold plate shown in FIG. 1, and FIG. 8 is another embodiment of the present invention. A partial cross-sectional view showing the main parts of a cold plate for a large-scale semiconductor device,
FIG. 9 is a graph showing actual measured values of heat dissipation resistance. 1.1'...Large-scale semiconductor device, 2a, 2b. 2c...Large scale integrated circuit element, 3...Circuit unit, 4---r-rudo plate, 14a, 14b, 14c
... Heat dissipation stud, 18a, 18b, 18c... Recess, 24... Refrigerant liquid, 26a, 26b... Heat conductive spring member.

Claims (1)

[Scope of Claims] 1. The circuit unit is provided with an upper open recess for accommodating the heat dissipation stud, which is formed at a location corresponding to the heat dissipation stud attached to the semiconductor component mounted on the circuit unit, and filled with a high boiling point refrigerant. Cold plate for large-scale semiconductor equipment. 2. The cold plate for a large-scale semiconductor device according to claim 1, wherein a thermally conductive spring member is provided in the recess, the thermally conductive spring member being in contact with the stud accommodated in the recess with spring properties. . 3. The cold plate for a large-scale semiconductor device according to claim 1, wherein the stud is provided with a thermally conductive spring member that contacts the inner wall surface of the recess with spring properties.