JPS6184850A - Heatconductive cooling module - Google Patents

Abstract

PURPOSE:To prevent thermal power generators from forming electrical connection paths to each other through thermal conduction paths, and to prevent the deterioration of connection pins and connecting members, by a method wherein, regarding the technique for transmitting the heat generated by a semiconductor device to a cooling device, a part located in a thermal conduction path connected to a small power consumption heat generator and carrying out heat-exchange of the housing is provided with an insulating oxide which increases the thermal resistance. CONSTITUTION:The inside of the housing 16 is provided with thermal conductive relay members 20 arranged in opposition to chips 10 and 10a and so engaged as to form thermal conductive interfaces that exchange heat with the housing 16, and these members 20 keep contact with the chips 10 and 10a under the pressure of springs 21. At this time, the housing 16pts. contained in thermal conduction paths connected to the small power chips 10a are coated with Si dioxide films 16d and thus designed so as to increase the thermal resistance of the interfaces between the members 20 and the housing 16. Therefore, the thermal transmittance from the small power chips 10a to the housing 16 is inhibited by the thermal resistance of the Si dioxide films 16d.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to structures and techniques for transferring heat generated by a semiconductor device substrate to a cooling device. Furthermore, in particular, the semiconductor body is maintained at a higher temperature by increasing the thermal resistance of the thermal conduction path associated with the semiconductor body with a lower power consumption, while at the same time increasing the thermal conductivity associated with each of the semiconductor device bodies. The present invention relates to a thermally conductive cooling module device having a specially configured cap or housing so as not to create an electrical conduction path through the circuit.

[Background of the invention]

Conventionally, large-scale electronic computers have been required to have high calculation speeds, so in recent years, a large number of semiconductor devices have been integrated into a limited semi-reactive substrate, thereby maximizing the length of the electrical interconnections between each device. LSI chips have been developed that are shortened to . or,
A circuit board on which an LSI chip is mounted and which electrically interconnects the chip and an external circuit has multi-layered and high-density electrical wiring, and the length of the interconnection wiring is substantially shortened. Furthermore, a method has been developed in which a large number of LSI chips are mounted on a circuit board. In order to maintain the operating parameters of an LSI chip within a predetermined range and to prevent the 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.

One example of auxiliary cooling means that has been proposed is a cooling system that uses both air cooling and liquid cooling. this is,
As shown in US Pat. No. 3,741,292, the module has a heat generating component immersed in a portion surrounded by a low melting point dielectric liquid encapsulated within a capsule. What is the most commonly used liquid for this?

A low boiling point fluorocarbon liquid that boils at relatively low temperatures. In other words, this liquid, which is heat-transferred from the heat-generating component, turns into vapor, moves to the vapor part located above the liquid level, is cooled by internal fins that act as a condenser, and is liquefied again. Repeat the cycle. At this time, the external fins extending outward from the container are air-cooled, and heat dissipation of the heat-generating components is achieved through the process of acting as a heat dissipation body for the heat transferred from the internal fins. However, this type of liquid encapsulation module must be maintained to ensure that the basic process of boiling-condensation is carried out, which requires extremely high purity and contaminant-free coolant liquid. do. Furthermore, this cooling concept cannot be easily applied when cooling a heat-generating component such as an LSI chip. This is because there is an extremely high risk that LSI constituent materials will be corroded by the liquid and impurities or contaminants taken into the liquid, and that failures will occur as a result.

US Pat. No. 3,993,123 discloses a cooling module device in which a heat generating device such as a semiconductor chip is encapsulated with gas. The heat generating device is mounted on an alumina substrate and sealed by this substrate and a cap.
This sealed space is filled with an inert gas, and a thermally conductive member is disposed. The wall of the cap facing the substrate has an elongated aperture extending toward the heat generating device and coaxially with the heat generating device.

An elastic member is disposed at the inner end of the aperture.

A thermally conductive member is disposed within each aperture, and a narrow peripheral gap is formed between the wall of each aperture and its associated thermally conductive member. The elastic member applies a force to the thermally conductive member that presses the thermally conductive member against the heat generating device. The airtight space is filled with an inert gas, which forms a peripheral gap and an interface between the heat generating device and the thermally conductive member. The heat generated by the heat generator is
It reaches the cap via inert gas and thermally conductive material.

It is emitted to a heat sink connected to the same cap.

In the encapsulated cooling module device, copper or aluminum is used as the cap material and the thermally conductive member, and helium, hydrogen, or carbon dioxide is used as the filler gas. These materials have excellent thermal conductivity, and by constructing the heat conduction path from the heat generating device to the heat sink with these materials, efficient heat dissipation is realized.

However, if a heat generating device with low power consumption is included in the same module along with a heat generating device with high power consumption, If only low-power heat generators are included, the cooling efficiency of the module is too high and the low-power heat generators are effectively overcooled. In order to perform various operations, it is undesirable for the heat generating device to be cooled below its minimum operating temperature, and if it is cooled too much, it will take a long time for the heat generating device to reach the operating temperature. Such a problem with operating temperature is more noticeable in heat generating devices with low power consumption than in heat generating devices with high power consumption, and requires countermeasures.

Furthermore, heat generating devices are mounted as densely as possible on the substrate within the sealed capsule. Each heat generating device has a large number of semiconductor elements integrated in a limited semiconductor substrate. In order for each semiconductor element to form an electric circuit,
Individual elements must be electrically isolated as required; therefore, semiconductor elements are generally formed in semiconductor regions, commonly referred to as islands, which are electrically isolated by reverse biasing the pn junction. A second problem arises because the voltage to reverse bias the pn junction is applied to the semiconductor substrate, ie, the heat generating device substrate, which forms a contact interface with the thermally conductive member. It is rare that all of the heat generating devices mounted on a board are made of semiconductor substrates with the same function; in general, two or more types of heat generating devices with different functions are mounted within the same cooling module device. I have to think about it.

In such a case, it is necessary to maintain the reverse bias voltage at two or more levels.6 However, the heat generating devices given different reverse bias voltages are connected to each other by a conductive heat conductive member 9 an elastic member. .

Electrical communication will be made through the cap.

The pre-scheduled reverse bias condition cannot be maintained and 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 connects to the cap and forms a contact interface.
Furthermore, there is a risk of forming an electrical communication network due to vibration contact between the cooling module devices on the printed circuit board that is mounted in high density in the housing. It is undesirable for the cap to be electrically connected to anything other than the conductive path, and in this sense it is desirable to provide the cap with an electrically insulating function.

Furthermore, the cap occupies an extremely large proportion of the weight of the entire cooling module device.
A large number of connection pins protrude vertically from the side of the board opposite to the side on which the heat generating device is mounted, and are fixed with something like gold-tin brazing material. The printed circuit board surface is parallel to the direction of attraction.

Therefore, the entire load of the cooling module device is supported by the pin and the connecting member connected thereto, such as gold-tin brazing material or solder. When a cooling module device is in operation, it is subjected to mechanical vibrations transmitted from a housing in which it is mounted via a printed circuit board. In this case, the third problem is that the excessive load accelerates mechanical deterioration of the connection pins and connection members that support the cooling module device, leading to failures associated with this.

[Purpose of the invention]

It is an object of the present invention to be used in the heat transfer paths of low power heat generating devices to be cooled to increase the thermal resistance of the heat transfer paths to increase the operating temperature of the low power heat generating devices below their minimum operating temperature. The object of the present invention is to provide a heat conduction cooling module Mffi having a housing that maintains a high temperature, and in particular a heat conduction cooling module device having a housing coated with a coating that increases the thermal resistance of the heat conduction path.

Another object of the present invention is to provide an improved heat-conducting path for a heat-generating device including a low-power heat-generating device to be cooled, in which no electrical communication path is formed between the heat-generating devices through the heat-conducting path. An object of the present invention is to provide a heat conduction cooling module device having a housing.

Still another object of the present invention is to provide a lightweight thermal conduction cooling module device that prevents or reduces deterioration of connection pins and connection members.

[Summary of the invention]

The heat conduction cooling module device of the present invention has the following features.

(1) The heat conduction cooling module device of the present invention includes a heat generation device including a low power consumption heat generation device to be cooled, and a heat conduction path that faces each of the heat generation devices. A heat conductive relay member arranged to exchange heat between the housing and the front wall of the housing, and an elastic member that presses the heat conductive relay member against the heat generating device to form a heat conductive interface between the two. A heat conduction cooling module device comprising means, the housing being a sintered body mainly composed of silicon carbide, and a heat exchanger in a portion of the housing in a heat conduction path associated with a low power consumption heat generating device. , is characterized by the provision of an insulating oxide that increases thermal resistance.

(2) In the heat conduction cooling module device of the present invention, the housing is mainly composed of silicon carbide and beryllium.

A sintered body containing at least one of beryllium oxide and boron nitride, which is an insulating oxide that increases thermal resistance and is provided at least in a heat-exchanging part of the housing in a heat conduction path associated with a low power consumption heat generating device. The materials are silicon and germanium.

aluminum, titanium, magnesium, lithium,
It is characterized by being an oxide of at least one metal among zirconium, lead, and zinc.

(3) In the heat conduction cooling module device of the present invention, the housing is mainly composed of silicon carbide and beryllium.

At least one of beryllium oxide, boron nitride, and aluminum, silicon, iron, and titanium.

A sintered body containing at least one element, oxide or carbide of nickel, which is at least a thermal resistor provided in a heat exchanger part of the housing in a heat conduction path associated with a low power consumption heat generating device. The increasing number of insulating oxides
silicon.

It is characterized by being an oxide of at least one metal selected from germanium, aluminum, titanium, magnesium, lithium, zirconium, lead, and zinc.

By the way, since the housing is also used as a heat conduction path associated with a heat generating device that consumes a large amount of power, it is necessary to inherently have high thermal conductivity, as well as be lightweight and have electrical insulation properties. is the most desirable. As a result of comparative studies of heat conduction module devices using various materials that can be used as housings, we found that a sintered body whose main component is silicon carbide;
Specifically, for 100 parts by weight of silicon carbide, the beryllium content (in terms of beryllium oxide) and the boron nitride content are 2
The sintered silicon carbide, which is more than part by weight, has a thermal conductivity of 0.7
caIA/”C・cx・s (room temperature), density 3.2g
/ci, Vickers hardness approximately 4000, bending strength, three-point support) 45kg-f/Sono and electrical resistivity 101a
We focused on the fact that it has a resistance of at least Ω・kuni (at room temperature), which makes it suitable for use as a material for housings.

Housing made of silicon carbide sintered body is made of beryllium,
Beryllium oxide and boron nitride increase the electrical resistance of the sintered silicon carbide grain boundaries, imparting electrical insulation and thermal conductivity to the sintered silicon carbide body. Sintered silicon carbide contains residual silicon, aluminum, iron, titanium, and nickel, or their oxides, carbides, and free carbon, which are contained in the form of impurities in the starting materials. These impurities are small, and aluminum works to reduce the resistivity of silicon carbide sintered bodies, so they are small.
It is desirable that the However, on the other hand, aluminum plays an important role in densifying the sintered silicon carbide, ie, reducing the porosity. The necessity of reducing the porosity has a meaning that cannot be ignored in making the package highly airtight, which will be described later. Therefore,
In such a case, it is desirable to add beryllium, beryllium oxide, or boron nitride in an amount that offsets the resistivity lowered by the presence of aluminum.

In the thermally conductive cooling module device of the present invention, the resistivity required to prevent the formation of electrical communication paths in the thermal conduction path is 1010Ω or more, and the thermal conductivity is at least aluminum (0.53ca12/■. It is desirable that the temperature is equal to or higher than ℃・S). To achieve this, the desired addition amount is 2 parts by weight or more when beryllium is added using beryllium oxide and the addition amount of boron nitride based on 100 parts by weight of silicon carbide, which is the main component.

In particular, the housing forms a space surrounding the heat generating device together with the substrate and other members, and contains a gas such as helium gas that assists heat transfer between the heat conductive relay member and the housing, or the interface between the heat generating device. Since it also serves as a container for sealing, it must be highly airtight.

Helium gas is a gas with a small atomic radius.

This is because it easily dissipates through extremely small gaps and pores. Such an airtightness problem must be solved especially when a ceramic material is used as the housing material, unlike when metal is used. In the case of a heat conduction cooling module, this airtightness is preferably 10-'atm mQ/s or less in terms of the amount of helium gas leakage, but this level of airtightness is given to sintered silicon carbide. In order to achieve this, it is desirable that the relative density of the sintered body be 97% or more.To obtain such a silicon carbide sintered body, silicon carbide powder with a particle size of 2 μm or less is typically mixed with equivalent particles. The mixture is uniformly mixed with additives such as beryllium oxide, beryllium, and boron nitride that provide diameter insulation and thermal conductivity, and this mixture is preformed at a pressure of about 98 MPa, and then heated to a temperature of 205 mA (Ic pressure of 30 mA). M P
Vacuum hot press for about an hour at a (vacuum degree 10-'MP)
a) It is better to do so. At this time, in addition to additives for imparting insulation and thermal conductivity, the sintered silicon carbide contains impurities such as silicon, aluminum, iron, titanium, and nickel contained in the starting raw materials, or individual elements thereof. Contains oxides, carbides and free carbon. These impurities have an effective function to make the silicon carbide crystal grains denser. Therefore, in order to actively impart airtightness to sintered silicon carbide, silicon, aluminum,
Iron, titanium, nickel alone or their oxides,
Addition of carbide is preferred.

C Embodiment of the invention] Next, an embodiment of the invention will be described in more detail with reference to the drawings. FIG. 1 is a perspective view of a gas-filled heat conduction cooling module device having a heat generating device shown as an LSI chip 10 and an auxiliary cooling means for cooling the heat generating device, and FIG. 2 is a perspective view of a heat conduction cooling module device shown in FIG. FIG.

To explain with reference to both figures, the chips 10 are attached to one side of a ceramic multilayer wiring board 12 by minute solder balls 11, and some of these chips 10 contain heat sinks that consume less power and generate less heat. A low power chip 10a is included as a generator. The substrate 12 has a connecting pin 14 projecting from the other side.

These pins 14 are connected to a wiring board 1 that carries auxiliary circuits, etc.
3, the thermal conduction module device is supported. A spacer 15 made of metal or ceramic is provided around the side of the substrate 12 on which the chips 10 and 10a are mounted, and a cap, that is, the housing 1 is provided on the other side of the spacer 15.
6 are arranged in a row and are fixed by sealing members 17 and 18 such as brazing material such as solder. A sealed space 19 is formed by these members, and this part is filled with a thermally conductive gas 31 such as helium gas (see FIG. 2). Inside the housing 16,
A heat conductive relay member 20 is disposed to face the chips 10, 10a and is engaged with the housing 16 so as to form a heat conductive interface for heat exchange. 2) maintains contact with the chip 10.10a. At this time, a portion of the housing 16 included in the heat conduction path related to the low power chip 10a is covered with a silicon dioxide film 16d.
It is designed to increase the thermal resistance at the interface between the heat conductive relay member 20 and the housing 16. The silicon dioxide film 16d has a thermal conductivity that is two fingers lower than that of thermally conductive sintered silicon carbide.

Therefore, heat transfer from the low power chip 10a to the housing 16 is suppressed by the thermal resistance of the silicon dioxide film 16d. As a result, heat is stored in the low power chip 10a, and the chip is maintained within a predetermined operating temperature range. It is appropriate that the silicon dioxide film 16d be formed by a thermal oxidation method. In this case, the silicon dioxide film is
For example, in an atmosphere containing water vapor and oxygen gas, a silicon carbide sintered body with an oxygen source of 31!
It is formed by heating to 0-1500°C. However, methods other than the above thermal oxidation, such as Chemica
A silicon dioxide film can also be formed by a method using a chemical reaction such as the lVapor Deposition method, a sputtering method, etc., and even silicon dioxide films formed by these methods can achieve the object of the present invention. It can be used as a carrier to increase thermal resistance. Further, it is not essential that the silicon dioxide film 16d be silicon dioxide in order to achieve the object of the present invention. Namely, germanium.

aluminum, titanium, magnesium, lithium,
Even oxides of at least one metal such as zirconium, lead, and zinc can serve as carriers for increasing thermal resistance. 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.

FIG. 3 is a schematic cross-sectional view showing an enlarged portion of the housing 16 used as a heat conduction path related to the low power chip 10a. The low power chip 10a.

An aperture 20a is provided at the other end of the heat conductive relay member 20 that forms a heat conductive interface with the heat conductive relay member 20 but is not in contact with the chip 10a, and the aperture 20a faces the chip 10a of the housing 16. It is attached so as to be guided by a protrusion 16a provided in the section. Projection 16 of housing 16
A silicon dioxide film 16d is provided on a. At this time, in the heat conduction path for the low power chip 10a, the thermal resistance is adjusted by the thickness of the silicon dioxide film 16d.

The diameter of the end portion 20b of the thermally conductive relay member 20, which is pressed by the spring 21 toward the chip 10a, is approximately 6 mm.
5 trn, and the total length of the same member is adjusted to 6.0 ffff1. The side wall 20c of the opening 20a of the heat conduction relay member 20 and the side wall 16 of the protrusion 16a of the housing 16
The gap in b is approximately 0.025 wtr.

The diameter of the protrusion 16a is equal to D/2, and its length is 8.
0 Im. Therefore, the opposing length that correlates with the opposing area between the side wall 20c and the side wall 16b is 2.5 rrm. Using these constant parameters, by plotting the total thermal resistance ('C/W) from the chip 10a to the housing 16 against the thickness of the silicon dioxide film 16d (μm), the thermal characteristic curve shown in FIG. is obtained. As shown in the curve, the thermal resistance increases as the thickness increases.

It is disclosed that the heat radiation ability can be controlled by adjusting the thickness of the silicon dioxide film 16d.

Incidentally, it goes without saying that the heat dissipation capacity can also be controlled by adjusting the opposing length. Furthermore, if necessary, a silicon dioxide film can be provided on the heat conductive relay member.

Furthermore, in this embodiment, the sintered silicon carbide used as the housing 16 is given electrical insulation by additives, but oxides of various metals can further provide reliable electrical insulation to the sintered silicon carbide. It is effective in giving. Furthermore, the housing 16, which accounts for a large proportion of the total weight of the heat conduction cooling module device, is lightweight by using silicon carbide sintered body, and it is amazing that deterioration of the connecting portion of the connecting pin 14 can be reduced or prevented. It is.

FIG. 5 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 substrate 12 together with other chips 1o, and an opening 16g is provided in the inner wall of the housing 16 facing these chips 10.10a.
A substantially columnar heat conductive relay member 20 is placed in the opening 16g, and a spring 21 applies a force to press the heat conductive relay member 2o against the chip 10.10a. On this occasion.

Silicon dioxide@16d is provided on the surface of the opening 16g 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 10a is maintained within the intended operating temperature range. In addition, in the case of this embodiment, the thermally conductive relay member 2
0 has a structure in which the housing 16 is guided through the opening 16g of the housing 16, which increases the weight of the housing 16 compared to the structure shown in FIG. Of course, this can be implemented to the extent that this problem can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is a sectional view taken along arrows -■ in FIG. 1, FIG. 3 is a sectional view of the housing of the present invention, and FIG. 4 is a thermal Characteristic curve diagram, FIG. 5 is a sectional view of another embodiment of the present invention 616...Housing, 1
6d...Silicon dioxide film.

Claims (1)

[Claims] 1. A heat generating device with low power consumption to be cooled, a housing included in a heat conduction path so as to face each of the heat generating devices, and a surface wall of the housing. A heat conductive cooling module device including a heat conductive relay member arranged to exchange heat between the heat conductive relay member and an elastic means for press-contacting the heat conductive relay member to the heat generating device to form a heat conductive interface, The housing is a sintered body containing silicon carbide as a main component, and an insulating oxide that increases thermal resistance is applied to a portion of the housing that performs heat exchange in a heat conduction path related to the low power consumption heat generating device. A heat conduction cooling module device characterized in that: 2. In claim 1, the housing is a sintered body mainly composed of silicon carbide and containing at least one of beryllium, beryllium oxide, and boron nitride, and the housing is a sintered body containing at least one of beryllium, beryllium oxide, and boron nitride, and the housing is a sintered body containing at least one of beryllium, beryllium oxide, and boron nitride, and The insulating oxide that increases thermal resistance provided in the heat exchange portion of the housing in the conduction path is made of at least one metal selected from silicon, germanium, aluminum, titanium, magnesium, lithium, zirconium, lead, and zinc. A thermal conduction cooling module device characterized in that it is an oxide. 3. In claim 2, the housing is mainly composed of silicon carbide, and at least one of beryllium, beryllium oxide, and boron nitride, and a single substance or oxide or carbide of aluminum, silicon, iron, titanium, or nickel. A heat conduction cooling module device characterized by being a sintered body containing.