JPH0439781B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to structures and techniques for transferring heat generated in a semiconductor device substrate to a cooling device. More specifically, a thermal conductor having a thermally conductive relay member specially formed to increase the thermal resistance of a thermally conductive path associated with a semiconductor body with low power consumption and to maintain said semiconductor body at a higher temperature. The present invention relates to a cooling module device.

[Background of the invention]

Since large-scale electronic computers require high calculation speed, semiconductor devices are developed in which a large number of semiconductor elements are integrated in a limited semiconductor substrate, and the electrical wiring length between each element is shortened as much as possible. That is, large
Scale Integrated Circuits (hereinafter referred to as
(LSI) chips have been developed. Also, that
The circuit board on which the LSI chip is mounted and which electrically interconnects the chip with external circuits is also multi-layered and highly dense, thereby substantially shortening the length of the interconnect wiring. Furthermore, there is a trend for large numbers of LSI chips to be mounted on a circuit board. In order to maintain the operating parameters of the LSI chip within the desired range and to prevent the LSI chip from being destroyed due to overheating, it is necessary to provide auxiliary means to efficiently dissipate the heat generated during operation to the outside. be.

The following has been proposed as an example of an auxiliary cooling means. That is, an airtight container is formed by an alumina substrate and a metal cap member, a large number of semiconductor chips are mounted on the alumina substrate, a forced cooling means using a refrigerant is attached to the outside of the cap member, and the semiconductor chips are A heat transfer means consisting of a cylinder attached to the cap member and a piston pressed against the semiconductor chip is provided between the cap member and the cap member, and an inert gas is provided in the container to help dissipate heat from the semiconductor chip. A semiconductor cooling module device in a filled configuration has been proposed.

This cooling module device has an extremely excellent heat dissipation effect and is suitable for operating heat generating devices such as semiconductor chips at low temperatures.

However, if a heat generating device with low power consumption, i.e., a low calorific value, and a heat generating device with a high power consumption, i.e., a large calorific value, are housed in the same container, or if a module consisting only of a heat generating device with low power consumption When modules consisting only of heat generating devices with high power consumption are installed in parallel, the cooling efficiency for the heat generating devices with low power consumption is too high, so the heat generating devices with low power consumption are effectively cooled too much. . In order for these heat generating devices to operate as intended, they must be maintained above a minimum operating temperature. Also, if it is too cool, it will take a long time for the heat generating device to reach its minimum operating temperature. Such an operating temperature problem is more noticeable in a heat generating device that consumes less power than in a heat generating device that consumes a large amount of power. Furthermore, if the operating temperatures of semiconductor chips arranged in parallel are different, the characteristics of each chip will become non-uniform, and there is a possibility that a module device with desired characteristics cannot be obtained.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved thermal conduction cooling module device that overcomes the above-mentioned problems.

Specifically, the purpose of the present invention is to provide a heat conduction cooling module device that makes the operating temperatures of the heat generating devices substantially equal when the heat generating devices having different calorific values are cooled by the same cooling means. There is a particular thing.

[Summary of the invention]

A feature of the heat generating device of the present invention that achieves the above object is that the thermal resistance of the heat transfer means interposed between the heat generating device with a small amount of heat generation and the cooling means is reduced by the thermal resistance of the heat transfer means interposed between the heat generating device with a large amount of heat generation and the cooling means. The thermal resistance is greater than the thermal resistance of the heat transfer means interposed between the
Means for changing the thermal resistance include changing the material of each member that makes up the heat transfer means, partially changing the shape of each member, and adding a member with high thermal resistance to a part of each member. . The heat generating device referred to herein includes semiconductor chips and non-semiconductor circuit elements. Furthermore, the heat generating device that generates a small amount of heat and the heat generating device that generates a large amount of heat may be housed in the same sealed container or may be housed in different sealed containers.

Other features of the invention will become apparent from the following description of the embodiments.

[Embodiments of the invention]

1 and 2 are cross-sectional views showing an embodiment of the heat conduction cooling module device of the present invention using an LSI chip as a heat generating device.

In the figure, a chip 10 is generally attached to one side of a ceramic multilayer wiring board 12 by minute solder balls 11, and 10a is a low-power chip serving as a heat generating device with low power consumption and low heat generation. be. The substrate 12 has connection pins 14 protruding from the other side. These pins 14 are connected to a wiring board 1 that carries auxiliary circuits, etc.
3, and the heat conduction cooling module device is supported by the wiring board 13. A spacer 15 made of metal or ceramic is placed around the side of the substrate 12 on which the chips 10, 10a are mounted, and a cap or housing 16 is placed on the other side of the spacer 15, and a sealing member 17 such as solder is placed. ,1
It is fixed by 8. These members 12,1
5 and 16 form a closed container 19, the inside of which is filled with a thermally conductive gas 31 such as helium gas. Inside the container of the housing 16,
A piston-shaped protrusion 16a is formed opposite each of the chips 10, 10a. Chip 10,
10a, there is an opening 20 for guiding the protrusion 16a.
A cylindrical heat conductive relay member 20 having a diameter of 1.a is disposed with the protrusion 16a engaged with the opening 20a. A spring 21 is disposed at the bottom of the opening 20a of the heat conduction relay member 20, and the pressure of the spring 21 maintains the contact between the chip 10 and the heat conduction relay member 20. The material of the heat conductive relay member 20 is (1)
Sintered silicon carbide to which at least one of beryllium, beryllium oxide, and boron nitride is added is suitable because it has electrical insulation properties, (2) high wear resistance, and (3) light weight. The heat transferred from each of the heat-conducting relay members 20 is stored in the housing 16, transferred to a heat sink such as a cooling plate 32 provided in series with the housing 16, and further accumulated in the cooling plate 32. Heat is transferred to cooling liquid 42 circulating within cold plate 32 . As can be seen in FIG. 1, the outer surface of the housing 16 and the surface of the cooling plate 32 are formed flat to allow good heat transfer between them. A cooling liquid 42 that gradually removes the heat transferred to the cooling plate 32 is circulated in the space 32a of the cooling plate 32, thereby achieving efficient cooling. A liquid such as water is desirable as a cooling liquid capable of efficient cooling. Therefore, if the chip 10 to be cooled is maintained in a state in which it is not overheated above a pre-designed temperature in the operating state, it is also possible to use an air-cooled heat sink instead of cooling with the cooling plate 32. be. In this case, consideration must naturally be given to keeping the noise problem to a minimum.

The heat generated from the chips 10, 10a, which are heat generating devices, is transmitted to the interface between the chips 10, 10a and the heat conductive relay member 20, the heat conductive relay member 20, the inner wall surface of the opening 20a of the heat conductive relay member 20, and the housing. 1
6, the gap between the surface of the protrusion 16a of the housing 1
6. The heat is transmitted sequentially through the interface between the housing 16 and the cooling plate 32 and the cooling plate 32, and finally to the cooling liquid 42, which is a heat sink. FIG. 3 is a schematic cross-sectional view showing an enlarged portion of the heat conduction relay member 20 used as a heat conduction path related to the low power chip 10a. A silicon dioxide film 20d is coated on the opposing surface portions of at least one of the protrusion 16a and the heat conduction relay member 20, which constitute a heat conduction means between the low power chip 10a and the protrusion 16a of the housing 16, and the interface between these is coated with a silicon dioxide film 20d. The thermal resistance is increased. The silicon dioxide film 20d has a thermal conductivity that is about two orders of magnitude lower than that of thermally conductive sintered silicon carbide. Therefore, due to the thermal resistance of this silicon dioxide film 20d, the low power chip 10a
Heat transfer from the heat conductive relay member 20 to the heat conductive relay member 20 or from the heat conductive relay member 20 to the housing 16 is suppressed. As a result, the low power chip 1
Heat storage at 0a is provided to maintain the chip within its intended operating temperature range. The silicon dioxide film 20d is most suitably formed by a thermal oxidation method. In this case, the silicon dioxide film is formed by heating the silicon carbide sintered body in an atmosphere with a controlled oxygen source, for example, an atmosphere containing water vapor and oxygen gas.
Formed by heating to 1500°C. However, methods other than thermal oxidation, e.g.
A silicon dioxide film can also be formed by a method using a chemical reaction such as the chemical vapor deposition method, a sputtering method, etc., and even if the silicon dioxide film is provided by these methods, the present invention can be applied. It can be a carrier to increase thermal resistance to achieve the purpose of. In addition, silicon dioxide film 20
d is not limited to this in achieving the purpose of the present invention. Namely, germanium, aluminum, titanium, magnesium, lithium,
Oxides of at least one metal such as zirconium, lead, and zinc can also serve as thermal resistance increasing carriers. In this case, in addition to the sputtering method, other methods such as a thick film firing method and a thermal spraying method are used.

In the heat conduction cooling module device of the above embodiment, the thermal resistance of the heat conduction means between the housing and the low power chip 10a is also adjusted by the thickness of the silicon dioxide film 20d. The diameter D of the end portion 20b of the heat conductive relay member 20, which is pressed by the spring 21 toward the chip 10a, is adjusted to approximately 6.5 mm, and the overall length of the member 20 is adjusted to 6.0 mm. The side wall 20c of the opening 20a of the heat conduction relay member 20 and the side wall 16b of the protrusion 16a of the housing 16
The gap is approximately 0.025mm. The diameter of the protrusion 16a is equal to D/2, and the length is 8.0 mm.
Therefore, the opposing length L, which correlates with the opposing area between the side wall 20c and the side wall 16b, is 2.5 mm. Using these constant parameters, the thermal characteristic curve shown in FIG. 4 is obtained by plotting the total thermal resistance (°C/W) from the chip 10a to the housing 16 against the thickness (μm) of the silicon dioxide film 20d. is obtained. As shown in the curve, the thermal resistance increases as the thickness increases, and the silicon dioxide film 20
It is understood that by adjusting the thickness of d, the heat dissipation capability of the heat conduction path of the low power chip 10a can be controlled. Further, the heat dissipation capacity of the heat conduction path can also be adjusted by providing a silicon dioxide film 20d on a part of the heat conduction relay member 20. FIG. 5 is an enlarged sectional view of the heat conductive relay member 20 in which a silicon dioxide film 20d is selectively provided at a portion forming a heat conductive interface with the chip 10a of the heat conductive relay member 20. With this structure, the total thermal resistance from the chip 10a to the housing 16 can be adjusted to about 1/3 of that in the case where the silicon dioxide film 20d is provided on the entire surface of the heat conductive relay member 20. Furthermore, the heat dissipation ability of the heat conduction path can also be changed by adjusting the film quality of the silicon dioxide film 20d, such as density and porosity.

Further, in the heat conduction cooling module device of this embodiment, the chips 10 and 10a as heat generating devices are mounted as densely as possible. Each heat generating device 10, 10a has a large number of semiconductor elements integrated in a limited semiconductor substrate. In order for each semiconductor element to form an electric circuit, the individual elements must be electrically insulated as necessary. Therefore, semiconductor devices are generally formed in semiconductor regions, commonly called islands, that are electrically isolated by reverse biasing pn junctions.
In this case, a voltage for reverse biasing the pn junction is applied to the heat generating device 10, 10a which forms a contact interface with the semiconductor substrate, ie the thermally conductive member. It is rare that all of the heat generating devices 10, 10a mounted on the substrate 12 are made of semiconductor substrates having the same function, and generally two or more types of heat generating devices 10, 10a with different functions are integrated into the same cooling module. It must be considered that it is implemented within the device. In such cases, it is necessary to maintain the reverse bias voltage at a level of 2 or more. By the way, heat generating devices 10, 1 given different reverse bias voltages
When a conductive heat conduction relay member, a spring 1 as an elastic member, and a housing 16 as a cap are used, the terminals 0a are electrically connected to each other through these, and the planned reverse bias condition cannot be maintained. First, the circuit function of the entire cooling module device is impaired. Further, if the reverse bias conditions of all the heat generating devices mounted in the cooling module device are exactly the same, the above-mentioned problem is solved. However, the cooling module devices are electrically connected to each other through impurities and contaminants in the heat sink or refrigerant that form a contact interface connected to the cap, and furthermore, the cooling There is a risk of forming an electrical network due to vibrating contact between modular devices. Therefore, it is undesirable for heat generating devices mounted on a board to be electrically connected to each other other than through a pre-planned conductive path. It is desirable to provide an insulation function. In this embodiment, the sintered silicon carbide used as the heat-conducting relay member 20 is given electrical insulation properties by additives, but oxides of various metals provide even more reliable electrical insulation properties to the sintered silicon carbide. Furthermore, even when the sintered silicon carbide is not provided with insulation properties by additives, oxides of various metals are effective in imparting new insulation properties to the silicon carbide sintered body.

In this embodiment, the heat conduction relay member 20 is provided with chips 10, 10a or a small amount of solder in order to reduce the load on the member 20 itself, and to prevent the heat conduction cooling module from being exposed to chips 10, 10a or a small amount of solder when excessive inertia is applied to the heat conduction cooling module device. Adverse effects on the ball 11, such as chipping,
In order to avoid cracking, crushing, etc. as much as possible, an opening 20a is provided in the thermally engaged portion with the housing 16 to reduce the load. however,
Sintered silicon carbide itself has a low density of 3.2 g/cm ³ and can be used as a heat conductive relay member with a small load. Therefore, as long as the above-mentioned adverse effects are not exerted, even in the case of a structure in which an opening is provided in the housing and a substantially columnar heat-conducting relay member is placed in the opening, thermal resistance is increased at the heat-conducting interface. The coated columnar member can be used as a heat conductive relay member for low power chips.

Further, in the heat conduction cooling module device of the present invention, there is no problem in that the housing 16 also serves as a heat sink that directly contacts the cooling medium outside the enclosed module device. That is, it is also possible for the housing 16 to be directly cooled by water or air as a cooling medium.

In the heat conduction cooling module device of the present invention, the material of the spacer 15 should be selected with priority given to the fact that the coefficient of thermal expansion matches or is similar to that of the substrate 12 and the housing 16, rather than from the viewpoint of thermal conductivity. It is. For example, when the material of the substrate 12 is alumina ceramic or mullite ceramic, the spacer 15 is made of alumina ceramic, mullite ceramic, silicon carbide sintered body, Kovar, 58Fe-42Ni,
Materials such as tungsten carbide can be selected. The reason for prioritizing the thermal expansion coefficient is that it is necessary to avoid fatigue failure of the sealing member that occurs when thermal cycles are applied due to the difference in thermal expansion coefficient between the substrate 12 or the housing 16. . Furthermore, in order to avoid similar fatigue failure, the material of the housing 16 is most preferably selected from the viewpoint of having a similar coefficient of thermal expansion to that of the spacer 15 and from the viewpoint of having excellent thermal conductivity. For this reason, a silicon carbide sintered body containing the above-mentioned additives is preferably selected as the housing 16. but,
When the cooling by the heat sink is efficient and there is little temperature change at the part sealed with the spacer 15,
That is, as long as fatigue failure of the sealing member 18 is prevented, metals such as copper and aluminum having good thermal conductivity may be used as the material for the housing 16.

FIG. 6 is a schematic sectional view showing an enlarged heat conduction path of a heat conduction cooling module device disclosing another embodiment of the present invention. The low power chip 10a is mounted on a board 12 together with other chips 10, and a housing 16 facing these chips 10, 10a is mounted.
An aperture 16g is provided in the inner wall of the chip, a substantially columnar heat conduction relay member 20 is placed in the aperture 16g, and a force is applied by a spring 21 to press the heat conduction relay member 20 against the chips 10, 10a. ing. On this occasion,
A silicon dioxide film 20d is provided on the surface of the heat conduction relay member 20 in the heat conduction path of the low power chip 10a, and is designed to adjust the thermal resistance in the heat conduction path. As a result, the low power chip 10
a is maintained within the intended operating temperature range. still,
In the case of this embodiment, since the heat conductive relay member 20 has a structure in which it is guided through the opening 16g of the housing 16, the housing 16 is
6 with an increase in weight. Even in this case, it goes without saying that the present invention can be implemented as long as the problem of the connection part related to the connection pin 14 can be avoided.

Although typical embodiments of the present invention have been described above, the present invention is not limited to these and can be modified in various ways. For example, in FIGS. 3 and 6, instead of the silicon dioxide film, a predetermined number of recesses may be provided on the opposing surfaces of the heat conductive relay member and the housing, and in FIGS. It is also an effective method for realizing the present invention that the heat conductive relay member is made of a metal material and its surface is coated with a silicon dioxide film.

〔Effect of the invention〕

According to the present invention, there is an effect that the operating temperature can be made substantially uniform regardless of the amount of heat generated by the heat generating device. Therefore, by changing the heat transfer means, a large number of heat generating devices with different calorific values can be cooled by the same cooling means, and the configuration of the device can be simplified.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the heat conduction cooling module device of the present invention, and FIG.
A schematic cross-sectional view along line A', Figure 3 is a partially enlarged view of Figure 2, Figure 4 is a relationship between the thickness of silicon dioxide film and thermal resistance, and Figure 5 is a diagram of other thermally conductive relay members. A sectional view showing an embodiment, and FIG. 6 is a sectional view showing still another embodiment. 10...LSI chip (for high power consumption), 10a
... LSI chip (for low power consumption), 12 ... board,
16...Housing, 16a...Protrusion, 20...
...Heat conductive relay member, 20d...Silicon dioxide film.

Claims (1)

[Scope of Claims] 1 Heat generating devices with different calorific values, an airtight container housing the heat generating devices, a cooling means disposed outside the airtight container to cool the heat generating devices, and a combination of the heat generating devices and the cooling means. and a heat transfer means that thermally connects the heat generating device with a large calorific value and the cooling means, the thermal resistance of the heat transfer means disposed between the heat generating device with a small calorific value and the cooling means is A thermal conductive cooling module device, characterized in that the device is larger than that of the heat transfer means disposed between the device. 2. The heat conduction cooling module device according to claim 1, wherein the heat transfer means includes a cylinder section provided between the heat generating device and the container, and a piston section guided by the cylinder section. . 3. The heat conduction cooling module device according to claim 2, wherein the heat transfer means on the side with larger thermal resistance has an insulating film at the portions of the cylinder portion and the piston portion that serve as heat transfer passages. 4. In claim 2 or 3, the cylinder part and the piston part are formed of a sintered body containing silicon carbide as a main component and adding at least one of beryllium, beryllium oxide, and boron nitride thereto. A heat conduction cooling module device characterized by: 5 In claim 4 or 5, the insulating film is made of silicon, germanium, aluminum, titanium, magnesium, lithium,
1. A heat conduction cooling module device characterized in that it is an oxide of at least one of zirconium, lead, and zinc. 6. A heat conduction cooling module device according to claim 1, 2, 3, 4, or 5, wherein the heat generating device is a semiconductor chip.