JPH02168658A - Apparatus for cooling electronic device - Google Patents

Abstract

PURPOSE:To improve heat conductivity for realising efficient cooling performance by providing grooves having a function of holding and preventing heat conductive grease interposed between an electronic device and a cooling body in contact therewith from being pressed out of the contact face. CONSTITUTION:A water-cooling jacket 7 is attached to a cooling face 6 of a ceramic package 4 by clamps 8. On a heat exchanging face 9 of the water- cooling jacket 7, there are provided a multiplicity of grooves 10 communicating with the periphery of the heat exchanging face. A high heat conducting grease 11 is interposed between the cooling face 6 of the package 4 and the heat exchanging face 9 of the water-cooling jacket 7. Heat generated by an LSI chip is conducted to the ceramic package 4 by pressing flexible heat-conducting contacts 5 against the rears of microchip carriers 2, then conducted from the heat exchanging face 6 of the package 4 to the heat exchanging face of the water-cooling jacket 7 through the high heat conductive grease 11 and finally fetched by the cooling water. In this manner, the heat conductivity and the cooling performance as well can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic device for cooling an electronic device such as a semiconductor chip, a chip module containing one semiconductor chip, or a multi-chip module containing a large number of semiconductor chips. Regarding the cooling device, a cooling device is described in Japanese Patent Application Laid-Open No. 62-268148.

On the other hand, in the specification of U.S. Patent No. 4,567,505,
As shown in Fig. 1, between the heat transfer surface of the cooling body, which has a large number of so-called reentrant-like micro grooves that have a narrow entrance and widen toward the bottom, and the smooth surface of the semiconductor chip, which is the heating element. A technique has been disclosed in which a liquid that easily wets and spreads on the solid surface, such as silicone oil, is interposed, and the two heat transfer surfaces are brought into close contact with each other by the adsorption force due to the surface tension of the liquid, thereby reducing the contact thermal resistance.

[Problem to be solved by the invention]

The former of the above-mentioned conventional techniques does not take into account the issue of thinning the layer of thermally conductive material interposed between the chip and the cooling body to improve thermal conductivity. There is also no consideration given to the cooling of electronic devices that accommodate chips and are made into multi-chip modules.

Furthermore, in the case of the cooling structure disclosed in U.S. Pat. If the heat transfer surfaces of the two heat transfer surfaces are warped, due to the rigidity of the cooling body or the semiconductor device, the warp cannot be corrected sufficiently by the adsorption force of the liquid, and the thickness of the liquid layer between the two heat transfer surfaces will decrease. It is not possible to keep the temperature constant.

Since deformation is not suppressed by applying external force, the thickness of the liquid layer changes depending on the degree of warpage of the contact surface. Therefore, the contact thermal resistance cannot be kept stable.

Furthermore, when an attempt is made to pull apart the cooling body adsorbed to the semiconductor device, since the groove shape is reentrant, as the cooling body is pulled away, the liquid is drawn toward the entrance of the groove, and the radius of curvature of the concave surface of the liquid becomes smaller. As a result, the pressure of the liquid becomes more and more negative than the ambient pressure, and the adsorption force increases. For this reason, the pulling force increases. If the separation force is reduced, the adsorption force will be weakened and the contact thermal resistance cannot be reduced.6 Conversely, if the adsorption force is increased, the adsorption force will be weakened and the contact thermal resistance will not be reduced.

Damage may occur to the semiconductor device itself or to the electrical contacts of the semiconductor device.

As mentioned above, none of the conventional technologies has been designed to improve cooling performance while keeping the surface pressure on the contact surface low, and to simultaneously satisfy the requirements for ease of separation when separating the cooling element from the object to be cooled. .

An object of the present invention is to obtain a cooling device for an electronic device that can improve thermal conductivity and efficiently cool the electronic device.

Another object of the present invention is to efficiently cool an electronic device that accommodates a large number of semiconductor chips and is made into a multi-chip module.

Still another object of the present invention is to obtain a cooling device for an electronic device in which a thin and uniform thermally conductive fluid is interposed between the electronic device and a cooling body.

Still another object of the present invention is to obtain a cooling device for an electronic device in which thermally conductive grease is thinly and uniformly interposed between the electronic device and the cooling body without applying a large pressure to the electronic device.

Another object of the present invention is to obtain a cooling device for electronic devices that is easy to manufacture, assemble, and disassemble, and has good cooling performance.

Still another object of the present invention is to obtain a cooling device for an electronic device that can improve cooling performance while suppressing the contact surface pressure between the electronic device and the cooling body, and that can easily separate the cooling body from the electronic device. There is a particular thing.

Still another object of the present invention is to cool an electronic device by providing a groove having a function of retaining thermally conductive grease so that the thermally conductive grease interposed in contact between the electronic device and the cooling body does not protrude outside the contact surface. It's about getting the equipment.

Still another object of the present invention is to tighten an electronic device and a cooling body so that the thermally conductive grease interposed between the electronic device and the cooling body is always thinly, uniformly, and stably interposed between the electronic device and the cooling body. The objective is to obtain a cooling system for electronic devices that can be used.

[Means to solve the problem]

In order to achieve the above object, the present invention has an electronic device, a cooling body for removing heat generated in the electronic device, and an electronic device interposed between a heat transfer surface of the electronic device and a heat transfer surface of the cooling body. a thermally conductive fluid with a high thermal conductivity; a tightening means for tightly contacting the cooling body with the electronic device; and a tightening means formed on a heat transfer surface of the electronic device or the cooling body and communicating with a space around the heat transfer surface. It is equipped with a large number of grooves.

Another feature of the present invention is that the electronic device is cooled by bringing a cooling body into close contact with an external force on the heat dissipation surface of the electronic device, which is coated with a thermally conductive fluid that does not easily wet the solid surface and has high thermal conductivity. Either the electronic device or the cooling body has a smooth heat transfer surface, and the other heat transfer surface has a smooth heat transfer surface and a large number of grooves formed on the smooth heat transfer surface and communicating with the surroundings. The grooved surface has a grooved surface, and the volume of the groove is larger than the volume of the highly thermally conductive fluid applied between adjacent groove pitches.

Still other features of the present invention include a cooling body that is in close contact with a heat dissipation surface of an electronic device via a thermally conductive fluid with high thermal conductivity, and a heat transfer surface of either the electronic device or the cooling body. A thermally conductive fluid interposed in the heat transfer surface, comprising a large number of grooves communicating with the outside of the heat transfer surface, the volume of the grooves being larger than the volume of the thermally conductive fluid interposed in the heat transfer surface. The cooling device for an electronic device is configured such that a space communicating with the outside remains in the groove even when the groove is accommodated in the groove.

Still other features of the present invention include an electronic device to be cooled, a thermally conductive fluid provided on the side of the heat sink of the electronic device, and a thermally conductive fluid provided on the side of the heat sink of the electronic device through the heat conductive fluid. A cooling device for an electronic device includes a cooling body that is closely attached and has a large number of grooves communicating with the outside in the tightly attached portion.

Other features of the present invention include an electronic device that includes a plurality of semiconductor chips housed in a package, a cooling body that removes heat generated in the electronic device, and a cooling body that covers the entire heat transfer surface of the electronic device. A cooling device for an electronic device, comprising: a thermally conductive fluid with high thermal conductivity interposed between the cooling body and the heat transfer surface of the electronic device; and a tightening means for tightly contacting the cooling body with the electronic device.

Still another feature of the present invention is that a ceramic multilayer wiring board on which a large number of LSI chips are mounted is hermetically sealed with a ceramic package, and the heat generated in the LIS chips is transferred to the ceramic package through flexible heat conduction contact. with a multi-chip module configured to communicate through the child.
A water cooling jacket is closely attached to the entire surface of the heat dissipation side of this multi-chip module with a thermally conductive fluid having high thermal conductivity and high viscosity interposed therebetween, and a water cooling jacket through which cooling water flows, and the thermally conductive fluid is arranged in a groove layer. According to another aspect of the present invention, there is provided a cooling apparatus for an electronic device, comprising the water cooling jacket and means for bringing the water cooling jacket into close contact with the multichip module so as to be interposed between the multichip modules.

Still another feature of the present invention is that a ceramic multilayer wiring board on which a large number of LSI chips are mounted is covered with a package cap, and heat generated in the LSI chips is transferred to the package cap via a flexible thermally conductive contact. So that
A cooling device for an electronic device, comprising means for interposing a highly thermally conductive fluid in a thin layer between the contact surfaces of the LSI chip and the flexible thermally conductive contact, and bringing the contact surfaces into close contact with each other. .

Still another feature of the present invention resides in an electronic device cooling device in which a highly thermally conductive fluid is also interposed between the sliding contact surfaces inside the flexible thermally conductive contact.

[Effect]

In a cooling device for an electronic device, it is effective to interpose thermally conductive grease between the electronic device and the cooling body to eliminate an air layer between the two and improve thermal conductivity.

In order to further improve the cooling performance, it is possible to increase the thermal conductivity by mixing fine zinc oxide particles or highly thermally conductive ceramic particles in the thermally conductive grease, and to fasten the electronic device to the cooling body using bolts or other methods. It is best to spread the thermally conductive grease as thinly and uniformly as possible by tightening it with a large amount of pressure, and to prevent any air bubbles from remaining in the thermally conductive grease.

If an attempt is made to reduce the contact thermal resistance by thinning the thermally conductive grease interposed between two smooth heat transfer surfaces, a large surface pressure must be applied between the heat transfer surfaces.

In particular, as the heat transfer surface becomes larger, the distance over which excess thermally conductive grease is forced to flow and be expelled from the heat transfer surface becomes longer, and therefore even greater surface pressure is required. Highly thermally conductive grease is a fluid that has very high viscosity coefficients and is difficult to wet solid surfaces because it is mixed with high thermally conductive microparticles at a high density to increase thermal conductivity. Therefore, a large surface pressure must be applied to ensure that no air bubbles remain within the highly thermally conductive grease and to thin it uniformly. Therefore, in the case of electronic devices such as semiconductor chips made of silicon crystal or semiconductor packages made of alumina AQ, O, aluminum nitride AQN, or high thermal conductivity SiC, these materials are less expensive than metals. Since the strength is extremely low and the strength of the electrical connections is also low, applying large surface pressure may damage the electronic device. Furthermore, if a threaded portion is provided in a semiconductor package and the cooling body is tightened with bolts, a large force is generated locally around the thread, which may destroy the electronic device.

On the other hand, if the electronic device fails after the electronic device is attached to the cooling body, it is necessary to separate the cooling body from the electronic device. In this case, the thermally conductive grease cannot be easily separated even if two objects that are tightly adhered to each other are separated.

If you try to pull the cooling body away from the electronic device with strong force,
The electronic device itself or its mounting may damage the supporting parts or electrical connections. Therefore, in order to prevent damage, the thermally conductive grease layer cannot be made thinner, and the size of the heat transfer surface must also be increased. I can't.

Furthermore, if electronic devices or cooling bodies are simply coated with thermally conductive grease and pressed into contact with each other, excess thermally conductive grease will ooze out from between the contact surfaces. Therefore, in order to prevent the thermally conductive grease from spilling out, it is necessary to improve the accuracy of the warping of the mutually contacting surfaces, and to strictly control the contact surface pressure, application amount, etc.

Therefore, in the present invention, a highly thermally conductive fluid that does not easily wet the solid surface is applied to the smooth heat transfer surface of either the electronic device or the cooling body, and the other heat transfer surface is connected to the surroundings of the heat transfer surface. A large number of communicating grooves are provided, and the grooves are sized to leave a space that can communicate with the outside even if the highly thermally conductive fluid applied between adjacent grooves is forced into the grooves.

In this manner, by providing a large number of grooves on the heat transfer surface of either the electronic device or the cooling body, the width of the heat transfer surface that comes into contact with the highly thermally conductive fluid is divided into small pieces. When a heat transfer surface with a groove gap of Ω is closely pressed against a heat transfer surface with a highly thermally conductive fluid coated with an initial coating thickness of δ, the internal pressure of the highly thermally conductive fluid increases and the fluid flows toward the grooves. Begin to. On this occasion,
Since a shearing force τ acts on the fluid contact surface, the surface pressure W on the heat transfer surface that causes the fluid to flow is given by the following equation.

W〉τV・−・・・・(1) δ Therefore, from the above equation, the smaller the groove gap Q, the more the surface pressure W
becomes smaller. The grooves are large enough to leave a space that can communicate with the outside even if the highly thermally conductive fluid applied between adjacent grooves is forced into the grooves, so the dividing effect of the grooves is impaired. Never. Further, as the fluid is forced out toward the groove, air bubbles mixed in the fluid layer are also simultaneously pushed out and discharged to the outside through the groove. Due to the above-described effects, a thin layer of highly thermally conductive fluid can be interposed with a small surface pressure, and the thermal contact resistance between the electronic device and the cooling body can be kept small and stable.

Furthermore, since the size of the groove is larger than the amount of coating, even if the fluid applied to the contact surface is forced out toward the groove, the fluid does not easily wet the solid surface and spread. Therefore, the flow is stopped at the groove position and is prevented from protruding outside the groove position.

Next, when trying to separate the electronic device and the cooling body,
The highly thermally conductive fluid is sucked out from within the groove.

In general, thermally conductive fluids such as highly thermally conductive grease or highly thermally conductive adhesives do not easily wet and spread on solid surfaces, so the contact angle is greater than 90'', and the gas-liquid interface of the fluid displaced into the groove. has a convex surface shape.The pressure P1 of the fluid in the groove forming the convex interface is higher than the surrounding air pressure P8 by (σ/r).Here, σ is the surface tension of the fluid, r is the radius of curvature of the convex interface.Thus, since the pressure of the fluid in the groove is higher than the ambient pressure, when you start bowing the heat transfer surfaces away from each other, the fluid in the groove will move from inside the groove to between the contact planes. At this time, the gas-liquid interface of the highly thermally conductive fluid begins to deform, and air enters the fluid layer.

- When the carrier air enters, the liquid layer is easily disrupted due to the narrow width of the fluid layer between adjacent grooves. The more grooves are formed, the longer the length of the fluid interface in contact with the groove surface, the so-called wetted edge length. Therefore, the number of places where the fluid interface breaks is probabilistically increased. Furthermore, since the area in which the grooved heat transfer surfaces come into close contact becomes smaller, the separation force also becomes smaller.

As described above, a cooling body can be attached to an electronic device with a small load that does not damage the electronic device or the connecting portion of the electronic device, and a stable and low contact thermal resistance can always be ensured. Furthermore, when they are separated from each other, they can be pulled apart with a small force, making assembly, disassembly, and maintenance easier.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the overall structure of a multi-chip module to which the present invention is applied. Multi-chip module 1 is an LSI
It is made by hermetically sealing a ceramic multilayer wiring board 3 on which a large number of microchip carriers 2 with built-in chips are mounted with a ceramic package 4. L.S.
The heat generated from the I-chip is transferred to the microchip carrier 2.
The heat is transferred to the ceramic package 4 by pressing the flexible heat conductive contact 5 against the back surface of the ceramic package 4. As shown in FIG. 2, a specific example of the flexible thermally conductive contact 5 includes a large number of flat fins 30 provided on the inner surface of the package 4, a plurality of flat fins 30 provided on the microchip carrier 2, and the fins 3o and It is composed of a thermal conductor 33 having fins 32 that engage with each other with a small gap 31, and a spring 34 for pressing the thermal conductor 33 against the microchip carrier 2. The microchip carrier 2 is face-down bonded onto a wiring board 3 made up of a large number of conductor layers and insulating layers via minute solder balls 35, and is electrically connected to a large number of pins 36 on the back side of the wiring board 3. There is.

On the other hand, the cooling surface 6 of the ceramic package 4 has a water-cooling jacket (cooling body) 7 in which low-temperature cooling water flows.
However, it is fastened by a metal fitting 8. The heat transfer surface 9 of the water cooling jacket 7 is provided with a large number of grooves 10 communicating with the periphery of the heat transfer surface, as also shown in FIG. Highly thermally conductive grease 11 is interposed between the cooling surface 6 of the package 4 and the heat transfer surface 9 of the water cooling jacket 7.

A sealed space 37 surrounded by the wiring board 3 and the package 4 is filled with Helius gas. Heat generated in the LSI chip is transferred to a thermal conductor 33 in contact with the chip, and is transferred from the fins 32 of the thermal conductor 33 to the fins 30 of the package 4 via the helium gas layer in the minute gap 31. The heat transferred to the package 4 is removed from the heat transfer surface 6 of the package 4.

Next, highly thermally conductive grease 11 was uniformly applied to the heat transfer surface 6 of the package 4 of the multichip module 1, and the heat transfer surface 9 of the water cooling jacket 7, in which a large number of grooves 10 were formed, was simply brought into close contact. The state is shown in FIG. 4(a), the state after pressurizing each other is shown in FIG. 4(b), and the state in the middle of separating the water cooling jacket 7 from the package 4 is shown in FIG. 4(C).
Shown below. In FIG. 4(a), the heat transfer surface of the water-cooled salmon door is in contact with the surface of the highly thermally conductive grease 11 applied on the heat transfer surface of the package 4, except for the grooves 10. It is in a state of being. When the water-cooling jacket 7 is tightened against the package 4 from the state shown in FIG. 4(a) and begins to be pressed using the metal fitting 8, the heat transfer gap between the grooves 10 is high as shown in FIG. 4(b). The grease 11 bites into the inside of the grease 11.
protrudes into the groove 10 and forms a convex gas-liquid interface 12.

Since the highly thermally conductive grease 11 is a liquid that does not easily spread, the gas-liquid interface of the grease has a convex shape. At this time, the width between adjacent grooves 10 is sufficiently narrow, and the grease 11 protruding into the grooves 10 does not completely fill the inside of the grooves 10, leaving a space 13 at the bottom of the groove 10 that communicates with the outside. If there is, the pressing force of the water cooling jacket 7 is small,
The highly thermally conductive grease 11 interposed between the water cooling jacket 7 and the package 4 is a very thin layer. Note that when the heat transfer surface 9 of the water cooling jacket 7 comes into contact with the grease 11,
Even if air bubbles are mixed into the grease 11 or the wetting with the heat transfer surface 9 is poor, as the grease 11 moves toward the groove, the wetting becomes better and the air bubbles are also released from the groove 11 to the outside. Ru. As a result, water cooling jacket 7 and package 4
The contact thermal resistance between them can be kept small and stable.

Next, when the package 4 breaks down or when the package 4 is to be maintained or inspected, it becomes necessary to separate the water cooling jacket 7 from the package 4. Even in this case, if grooves are provided on the heat transfer surface, separation can be achieved with a small force. In other words, when they are in close contact as shown in Figure 4(b), the gas-liquid interface in the grease groove is convex, so the pressure inside the grease is smaller than the pressure around the grease (σ
/r). Here, σ represents the surface tension of the grease, and r represents the radius of curvature of the convex gas-liquid interface. Therefore, when the water cooling jacket 7 begins to be pulled away from the package 4 by some external force, the grease 11 in the groove begins to easily flow toward the gap between the heat transfer surface 9 and the package 4. Then, as shown in FIG. 4(c), the grease in the groove is sucked out, and the gas-liquid interface of the grease in the groove is formed into a concave shape. Here, since the highly thermally conductive grease is a fluid that does not easily spread, the gas-liquid interface of the sucked out grease does not necessarily form a flat surface, but rather an uneven surface. From this non≠− place, the grease layer 11
If air begins to enter the groove, the grease layer 11 will be easily separated because the groove spacing is narrow. especially,
As the number of grooves 10 increases, the width of the grooves 10 in which they are in close contact with each other becomes smaller, and the number of locations where the wet state becomes uneven increases. Therefore, the water cooling jacket 7 can be easily separated from the package 4 with a small force without damaging the package 4.

In the above embodiment, the grooves were provided on the water-cooling jacket side, but they may also be provided on the package side. Also, the same effect can be obtained by using a high thermal conductive adhesive instead of the high thermal conductive grease.
Effects can be obtained.

FIG. 5 shows an example in which grooves 15 are formed in a grid pattern on the surface of the water cooling jacket 14. The groove 15 may be formed in any pattern as long as the groove 15 always communicates with the outside.

FIG. 6 shows an example in which the groove 16 is configured such that the rows become narrower at the bottom of the groove. In this case, as the highly thermally conductive grease 11 enters into the groove 16, the radius of curvature of the convex gas-liquid interface of the grease that is formed becomes smaller. The internal pressure is higher than that of the grease 11 in the groove 16.

For this reason, it has an automatic adjustment function that prevents grease from entering the groove and pushes out grease uniformly into the groove.

FIG. 7 shows an example in which a large number of grooves 18 are formed in the water cooling jacket 17, which is a spherical heat transfer surface, instead of forming grooves in a flat water cooling jacket.

In this way, even if the heat transfer surfaces of the packages on the opposite side are warped and difficult to adhere to, it is possible to make them adhere well to each other by pressing the periphery of the spherical water cooling jacket 17 with a tightening jig. can.

In order to confirm the pressing effect and the separating effect in the apparatus of the present invention shown in FIG. 1, the following experiment was conducted.

Four types of copper water cooling jackets were combined into a ceramic package with a smooth surface. Water cooling jacket A has a smooth surface with no grooves, water cooling jacket B has a groove width of 1*m,
The groove pitch is 6mm, the number of grooves is 13, and the water cooling jacket C has a groove width of 1mm, a groove pitch of 4m+n, and the number of grooves is 19.

Water cooling jacket D has groove width 0, 5 n+m, groove pitch 1
．． 5mm.

The number of grooves is 51. The size of the water cooling jacket is 1100 mm square, and the groove depth is Q, 5 mm.

The layer of highly thermally conductive grease applied to the package is 20 to 1
The thickness was 00 μm.

Figure 8 shows the data when pressed. Using water-cooled jackets A and B, grease was applied using a mask with a thickness of 50 μm, the tightening load was 50 kg and 100 glare, and the tightening was performed using a gap sensor that measured the thickness of the grease layer after the start. show. As a result, it can be seen that the grease layer of water cooling jacket B with grooves becomes thinner more quickly than that of jacket A.

On the other hand, Table 1 shows the pull-off load when a pull-off experiment was conducted using the above-mentioned water-cooled jacket. The more grooves are provided, the smaller the peeling force is. This trend is not affected by the thickness of the grease layer.

Table 1 An example of a water-cooled jacket that can further facilitate pressing and separation will be described below. That is, a large number of grooves provided on the heat transfer surface of the water cooling jacket are made so that they do not penetrate the outer periphery of the water cooling jacket, and a hole passing through the water cooling jacket is provided approximately in the center of the heat transfer surface, and the grooves are inserted into this hole. It is designed so that all the parts are connected to each other.

A specific example of this is shown in FIGS. 9 and 10. That is, a large number of grooves 21 running vertically and horizontally provided in the upper center of the heat transfer surface 20 of the water cooling jacket 19 are in communication with grooves 22 that run around the outer periphery of the heat transfer surface 2o. A hole 2 that does not penetrate the outer periphery, is provided approximately at the center of the water cooling jacket 19, and penetrates the water cooling jacket 19.
3 and the grooves 21, 22 communicate with each other. In this way, the heat transfer surface 20 provided with a large number of grooves 21 and 22 is brought into close contact with the highly thermally conductive grease, and after they are slightly pressed against each other, the air in the grooves is pumped through the through hole 23 using a vacuum pump or the like. When suction is applied, the water-cooled jacket is easily pressed due to the pressure difference inside and outside the groove. On the other hand, when attempting to separate the water-cooling jacket, by forcing compressed air through the through hole, the inside of the groove is pressurized, and the water-cooling jacket can be easily separated without applying any other external force. At this time, the compressed air acts to separate the water cooling jacket from the package and to separate the grease layer.

11 and 12 also show other examples similar to the examples shown in FIGS. 9 and 10, respectively. In the example shown in FIG. 11, the radial groove 24 is replaced with a concentric groove 25. The example shown in FIG. 12 has a large number of grooves 2 extending radially.
6 was formed.

In the above embodiments, the cooling body is a water-cooled jacket that is cooled by water, but it may be cooled by other means such as air.

FIG. 13 shows another embodiment similar to the embodiment shown in FIG. 1, in which the tightening of the metal fittings in FIG. Leaf spring 82. This plate spring 82 is tightened by the outer frame 81.
Fixing screw 83. It consists of a load support 84 that transmits the load of the leaf spring 82 to the center of the water cooling jacket 7. With this configuration, even if the heat transfer surface 6 of the ceramic pancage 4 is thermally deformed and warped due to the heat generation of the microchip carrier 2 and the cooling of the water cooling jacket 7, the center of the water cooling jacket 7 can be connected to the plate spring. Since a load is always applied by the elastic force of 83, the heat transfer surface 9 of the water cooling jacket 7 can follow the thermal displacement of the heat transfer surface 6. Therefore, the layer of highly thermally conductive grease 11 interposed between each heat transfer surface 69 can always be stably maintained at a constant layer thickness. In addition, thermally conductive grease 11 in FIG.
is interposed only on the heat transfer plane 9 formed between the grooves 10 to prevent the grease 11 from protruding from the outer periphery of the heat transfer surface 9 of the water cooling jacket 7. That is, the outermost groove 10 prevents the grease 11 from running out.

Next, in another embodiment of the present invention shown in FIGS. 14 to 20, grooves are formed on the heat transfer contact surface of the flexible heat transfer contact S shown in FIGS. 1, 2, or 13. This shows the case where it is provided. Components that are the same as or equivalent to those in FIGS. 1 and 2 are designated by the same numbers, and explanations and representations thereof will be omitted.

In FIG. 14, the flexible heat conductive contact 5 has a large number of flat fins 30 provided on the inner surface of the package 4, and fins 32 that engage with each other with a minute gap 31, and a heat conductor 33 and a heat conductor 33. A spring 34 for pressing the heat transfer plane 100 of the conductor 33 against the heat transfer plane 101 of the microchip carrier 2, and a large number of grooves 40 in the heat transfer plane 100 of the r conductor 33 communicating with the surroundings of the heat transfer surface. There is. The grooves 40 are orthogonal to the grooves 41 on the heat transfer plane 100, as shown in FIG. Furthermore, these grooves 40.4
1 is formed inside the heat transfer plane 101 of the microchip carrier 2. The size of 840.41 is larger than the amount of high thermal conductive grease 11 surrounded by the groove and coated between the two heat transfer planes 100 and 101.

With such a configuration, the thermal conductor 33 is always placed in the microchip carrier 2 with the stable grooved high thermal conductive grease 1.
Close contact can be made through one layer, and heat generated by the microchip carrier 2 can be efficiently cooled.

Further, even when the heat conductor 33 is assembled and removed, the minute solder balls 35 are not damaged.

In FIG. 16, two grooves 42 and 43 are formed in the heat transfer plane 100 of the heat conductor 33 in the horizontal and vertical directions. These grooves 42 and 43 are provided slightly inside the outermost periphery of the heat transfer plane 101 of the microchip carrier 2.

Similar to the outermost groove in FIG. 15, the grooves 42 and 43 serve to prevent the intervening thermally conductive grease 11 from protruding outside the contact surface.

FIG. 17 shows another example of the embodiment shown in FIG. 14,
This embodiment differs from the embodiment shown in FIG. 14 in that a highly thermally conductive grease 11 is interposed even in the minute gap 31. According to this embodiment, the microchip carrier 2
The heat generated by the package 4 can be transferred efficiently without being affected by surrounding gas, etc., so the package 4 can be transferred to the wiring board 3.
There is no need for airtight sealing, which simplifies assembly.

In the embodiments shown in FIGS. 14 to 17, the grooves were provided on the thermal conductor 33 side, but they may also be provided on the microchip carrier 2 side. Similar actions and effects can be obtained with adhesives.

Next, still another embodiment will be described with reference to FIGS. 18 to 2o.

A large number of V-shaped grooves 402 are formed on the inner surface of the package 401 and are perpendicular to one drawing.
A heat conductor 501, which is a triangular flexible heat conduction contact, is provided between the groove 402, and the surface of the triangular heat conductor 501 is such that the surface 102 in contact with the microchip carrier 2 is flat; The surface in contact with the plane 4o3 is the cylindrical surface 10
3. Spring 4, which is composed of a flat surface facing the other flat surface 404 of the groove and applies contact pressure to the thermal conductor 5o1.
05 is provided. Further, the cylindrical surface 103 and the plane 102 are provided with orthogonal grooves 406 as shown in FIG.
, 407 are provided. and the contact plane 1 between the groove plane 403 of the groove 402 and the cylindrical surface 103, and the contact plane 1 between the heat transfer plane 101 of the microchip carrier 2 and the thermal conductor 501.
A highly thermally conductive grease 11 is interposed between each of the parts 02 and 02. Note that since one surface of the thermal conductor 501 is the cylindrical surface 103, even if the microchip carrier 2 is mounted on the wiring board 3 in an inclined manner, the cylindrical surface 103 and the V-groove plane 403 slide against each other, so that the The cylindrical surface 1° 3 of the heat conductor 501 can be in linear contact with the V-groove plane 403 .

When the thermally conductive grease 11 is interposed in the above state, a thin grease layer can always be formed due to the action and effect of the grooves described above.

FIG. 20 shows another example of grooves formed on the surface of the heat conductor 501, in which only parallel grooves 408 and 409 are provided on each plane. Other points are the same as in the previous embodiment.

〔Effect of the invention〕

According to the present invention, a cooling body is pressed onto an electronic device such as an LSI chip itself, a microchip carrier containing an LSI chip, or a multichip module containing them by interposing a highly thermally conductive fluid that is difficult to wet and spread. When cooling by applying heat to the electronic device, the cooling body can be brought into close contact with the electronic device with a small force. For this reason,
It is possible to keep the mutual connection thermal resistance low and stable without damaging electronic devices or the connecting parts of electronic devices. On the other hand, when separating the cooling body from the electronic device, it can be separated with a small force, so no damage or deformation will occur.Furthermore, the mechanism for assembly and disassembly is simple, reducing costs and reducing work. Effects such as improved efficiency can also be obtained.

Furthermore, it is possible to prevent the highly thermally conductive fluid from protruding out of the intervening contact surface, and it is also possible to prevent unnecessary attachment of the highly thermally conductive fluid.

2 is a longitudinal sectional view showing an example of the flexible thermally conductive contact shown in FIG. 1. FIG. 3 is a bottom view of the water cooling jacket shown in FIG. Figure 4 (a), Figure 4 (
b) and FIG. 4(c) are longitudinal cross-sectional views showing each state when the water-cooling jacket is brought into close contact with, tightened, and separated from an electronic device using highly thermally conductive grease in the embodiment shown in FIG. 5, 6, and 7 are bottom views showing other examples of water cooling jackets, FIG. 8 is a diagram showing the experimental results of pressing in the embodiment of the present invention, and FIG. ...Outside.

82...Removal spring, 83...Fixing screw, Bottom view showing another example of the jacket, Fig. 13 is a vertical sectional view showing another example of the cooling device for electronic devices, Figs. 14, 17 18 are enlarged sectional views of main parts showing other embodiments of the present invention, FIG. 15 is a perspective view of the lower fin shown in FIG. 14, and FIG. 16 is a perspective view of the lower fin shown in FIG. 14. FIG. 7 is a perspective view showing still another example.

FIG. 19 is a perspective view showing the flexible thermally conductive contact shown in FIG. 18, and FIG. 20 is a perspective view showing still another example of the flexible thermally conductive contact shown in FIG. 19.

DESCRIPTION OF SYMBOLS 1... Module, 2... Microchip carrier, 3... Ceramic multilayer wiring board, 4,401.
...Package, 6...Package cooling surface, 7...
Water cooling jacket, 8... Tightening jig, 9... Water cooling jacket heat transfer surface, 10.15, 16, 18, 21, 22
,24,25°26.40~43,406~409...
・Groove, 11...High thermal conductivity grease, 12...Convex gas-liquid interface, 13...Groove space, 23...Hole, 33,
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Claims (18)

[Claims] 1. an electronic device, a cooling body for removing heat generated in the electronic device, a thermally conductive fluid with high thermal conductivity interposed between a heat transfer surface of the electronic device and a heat transfer surface of the cooling body; An electronic device comprising a pressurizing means for bringing a cooling body into close contact with the electronic device, and a large number of grooves formed on a heat transfer surface of the electronic device or the cooling body and communicating with a space around the heat transfer surface. Cooling system. 2. 2. The cooling device for an electronic device according to claim 1, wherein the thermally conductive fluid is a fluid that does not easily wet the solid surface. 3. 3. The apparatus for cooling an electronic device according to claim 2, wherein the thermally conductive fluid is either grease or a thermally conductive adhesive. 4. 4. The apparatus for cooling an electronic device according to claim 3, wherein the thermally conductive fluid is a highly viscous grease. 5. In claim 1, the volume of the groove is larger than the amount of thermally conductive fluid interposed between the electronic device and the cooling body between each groove, and the thermally conductive fluid between the grooves enters the groove. A cooling device for an electronic device in which a space remains in the groove. 6. The electronic device is cooled by bringing a cooling body into close contact with the heat dissipation surface of the electronic device by applying an external force to the heat dissipation surface of the electronic device coated with a thermally conductive fluid that does not easily wet the solid surface and has high thermal conductivity, and further includes a cooling body that cools the electronic device. One of the heat transfer surfaces is a smooth surface, and the other heat transfer surface is a grooved surface having a smooth heat transfer surface and a number of grooves formed on the smooth heat transfer surface and communicating with the surroundings, and the grooves are A cooling device for an electronic device, characterized in that the volume of the fluid is larger than the volume of the highly thermally conductive fluid applied between adjacent groove pitches. 7. 7. A cooling device for an electronic device according to claim 6, wherein the shape of the groove is gradually narrowed from the surface of the cooling body toward the bottom of the groove. 8. 7. The cooling device for an electronic device according to claim 6, wherein all the grooves are in communication with each other. 9. 9. The electronic device according to claim 8, wherein the cooling body is formed with a hole passing through the cooling body, and the groove is communicated with the hole passing through the cooling body, so that the groove is communicated with the circumference of the cooling body. Device cooling. 10. 7. The cooling device for an electronic device according to claim 6, wherein the electronic device is a multi-chip module composed of a package made of highly thermally conductive ceramic. 11. A cooling body that is in close contact with the heat radiation surface of the electronic device via a thermally conductive fluid with high thermal conductivity, and a large number of cooling bodies formed on the heat transfer surface of either the electronic device or the cooling body and communicating with the outside of the heat transfer surface. a groove, the volume of the groove is larger than the volume of the thermally conductive fluid interposed in the heat transfer surface, and the thermally conductive fluid interposed in the heat transfer surface is accommodated in the groove. A cooling device for an electronic device, characterized in that a space communicating with the outside remains in the groove. 12. 12. The apparatus for cooling an electronic device according to claim 11, wherein the thermally conductive fluid is either grease or a thermally conductive adhesive. 13. An electronic device to be cooled, a thermally conductive fluid provided on the heat radiating side of the electronic device, and a thermally conductive fluid that is closely attached to the heat radiating side of the electronic device via the thermally conductive fluid, and an external A cooling device for an electronic device, comprising a cooling body having a large number of communicating grooves. 14. In claim 13, the volume of the groove is larger than the amount of thermally conductive fluid interposed between the electronic device and the cooling body between each groove, and the thermally conductive fluid between the grooves enters the groove. A cooling device for an electronic device in which a space remains in the groove. 15. An electronic device comprising one or more semiconductor chips housed in a package, a cooling body for removing heat generated by the electronic device, an entire heat transfer surface of the electronic device, and a heat transfer surface of the cooling body. A cooling device for an electronic device, comprising a thermally conductive fluid with high thermal conductivity interposed between the cooling body and a pressurizing means for bringing the cooling body into close contact with the electronic device. 16. A ceramic multilayer wiring board on which a large number of LSI chips are mounted is hermetically sealed in a ceramic package, and the heat generated by the LSI chips is transmitted to the ceramic package via a flexible thermally conductive contact. a water-cooling jacket that is closely attached to the entire surface of the heat dissipation side of the multi-chip module with a thermally conductive fluid having high thermal conductivity and high viscosity interposed therein, and through which cooling water flows; and means for bringing a water cooling jacket into close contact with a multi-chip module in order to interpose a magnetic fluid in the form of a groove layer between the water cooling jacket and the multi-chip module. 17. 17. The apparatus of claim 16, wherein the thermally conductive fluid is grease. 18. A ceramic multilayer wiring board on which a large number of LSI chips are mounted is covered with a package cap made of a highly thermally conductive material, so that the heat generated by the LSI chips is transferred to the package cap via a flexible thermally conductive contact. In the multi-chip module configured as follows, the LI
Means for interposing a highly thermally conductive fluid in a thin layer state on the contact surface of either the flexible heat conductive contactor that is in contact with the heat transfer surface of the S chip or the heat transfer surface of the inner wall of the package to bring it into close contact. A cooling device for an electronic device characterized by comprising: