JPH0391948A - Vaporization cooling system integrated circuit device - Google Patents

Abstract

PURPOSE:To simplify the structure of the title device and to prevent the generation of a temperature overshoot by a method wherein the device is provided with an internal space capacity control means, which repeatedly generates the periodical two stable states of enlargement-reduction of an internal space capacity due to a change in the temperature of a liquid coolant. CONSTITUTION:An integrated circuit element 1 is sealed in a lower structure 4 constituting a container with an upper structure 3, which consists of a metal plate having a semispherical recessed part with a flange, along with a refrigeration medium liquid 2, a flange part 3a of the structure 3 is hermetically sealed on the peripheral edge of an opening part of the structure 4 and heat sinks 5 are mounted adjoining the flange part 3a. Moreover, the semispherical recessed part of the structure 3 is inverted and deformed into a projected part corresponding to an increase in an internal pressure and an internal capacity is increased in two stable states. In such a way, when the internal capacity is increased, the internal pressure is reduced, bubbles 6 are generated due to the generation of a boiling point drop, the internal capacity is again reduced from the state of a large capacity to the state of a small capacity and a continuous operation is repeatedly performed. Thereby, the generation of a temperature overshoot is stopped in a single structure.

Description

[Detailed description of the invention]

[Industrial Field of Application 1] The present invention relates to an evaporative cooling integrated circuit device. [Prior Art 1] In a boiling-cooled integrated circuit device, an integrated circuit element, which is a heating element, is generally enclosed together with a refrigerant liquid having a boiling point of about 50° C. in a structure having a condensation space. The cooling operation will be explained below using the boiling heat transfer curve diagram shown in FIG. 7(a). When the integrated circuit element is not in operation, its temperature is room temperature, but when it is in operation, the surface temperature of the integrated circuit element increases due to heat generation. When the integrated circuit element starts to be energized from room temperature, it is cooled only by the convection of the refrigerant liquid until it reaches the boiling point corresponding to the vapor pressure of the refrigerant liquid level. Theoretically, above this boiling point, the amount of heat dissipated should increase due to the generation of bubbles due to boiling, as shown by the dashed line 71 in the same figure, but in reality, as shown by the broken line 72 in the same figure, the amount of heat dissipated should increase. However, a phenomenon (called temperature overshoot) occurs in which bubbles are not generated even when the temperature is low, and cooling efficiency decreases because cooling cannot be performed using the heat of vaporization. Conventionally, as a method for preventing temperature overshoot, a porous layer has been provided on the element wall to promote the generation of bubbles at the start of boiling, as described in JP-A-55-59748, for example. Since the fluorocarbon-based refrigerant liquid as a refrigerant has a small surface tension, the effect of promoting bubble generation may not be sufficient in some cases. In other words, at first the effect is due to the air bubbles adsorbed within the porous material, but as boiling repeats, the effect becomes bubbling and the effect decreases. In addition, as another method, an auxiliary heater for generating bubbles is provided in the refrigerant liquid, and the generated bubbles are applied to the surface of the integrated circuit element, thereby promoting the generation of bubbles from the surface of the element. Issues to be Solved by the Invention The above prior art is not sufficient because the effect of promoting bubble generation does not last long when a porous layer is formed.On the other hand, when an auxiliary heater is used, power loss is Both of these methods were insufficient as a countermeasure against temperature overshoots, as they also complicated the structure. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an improved boiling-cooled integrated circuit device which has a simple structure and is free from temperature overshoot. [Means for Solving the Problems 1] The object of the present invention is to provide a lower structure that accommodates a refrigerant liquid;
an upper structure in which a periphery of an opening of the lower structure is hermetically sealed; and an integrated circuit element immersed in the refrigerant liquid;
Moreover, it is provided with an internal space volume control means for periodically causing two stable states of expansion and contraction in the internal space volume formed by the lower structure and the upper structure, depending on the temperature change of the refrigerant liquid. In addition, the lower structure is made of a material with excellent thermal conductivity, and the integrated circuit element is thermally connected to the lower structure outside the refrigerant liquid system. This is achieved by the constructed boiling-cooled integrated circuit device. Preferably, the internal space volume control means is configured by deforming an upper structure that mechanically deforms in shape in response to pressure fluctuations in the internal space, or by changing the shape of an upper structure in response to temperature changes in the internal space. It is preferable to construct the structure by deforming the shape of an upper structure having a bellows mechanism supported by a shape memory alloy that expands and contracts accordingly. [Operation] When the volume of the internal space changes periodically, repeating between two stable states of expansion and contraction, the internal pressure changes in response to the change in the internal volume. When the internal volume is expanded from small to large at a temperature near the boiling point, the internal pressure decreases. Corresponding to this, the refrigerant R-113 (Freon l) shown in FIG.
As shown in the vapor pressure curve diagram of the species), the boiling point decreases and the generation of bubbles is promoted. Therefore, the relationship between the temperature and the amount of heat radiation is as shown by the solid line 73 in FIG. It has a hysteresis characteristic and can completely prevent the occurrence of temperature overshoot and prevent a decrease in cooling efficiency6.And when the internal temperature decreases and the internal pressure also decreases By changing the internal volume from large to small, it is possible to repeatedly perform a series of operations automatically. Note that it is necessary to change the internal volume within a short period of time; if the internal volume changes slowly, the internal pressure and vapor pressure will be in equilibrium, and no effect of lowering the boiling point can be expected.

【Example】

Hereinafter, one embodiment of the present invention will be described in detail using the drawings. Example■. FIG. 1(a) is a sectional view of the boiling-cooled integrated circuit device showing a state in which the internal space volume V is reduced, and the integrated circuit element l
The refrigerant liquid 2 is enclosed in an upper structure 3 made of a metal plate having a hemispherical recess with a flange, and a lower structure 4 forming a container. The flange 3a of the upper structure 3 is hermetically sealed around the opening of the lower structure 4, and the radiator 5 is attached adjacent thereto. On the other hand, FIG. 1(b) shows a state in which the hemispherical concave portion of the upper structure 3 is reversely deformed into a convex portion in response to an increase in internal pressure, and the internal volume increases in a two-stable state. As the internal volume increases, the internal pressure decreases and the boiling point drops, resulting in bubbles 6. Furthermore, when the internal temperature and internal pressure decrease, the internal volume changes from a large state to a small state by the reverse operation, and a series of operations can be performed repeatedly. The upper structure 3 made of a metal plate having a hemispherical concave portion with a flange can be easily obtained by pressing or shaping an elastic metal plate. The lower structure 4 is made of an insulating material such as ceramics or a metal such as stainless steel.In the case of ceramics, it can be used as a wiring board to which the integrated circuit element 1 is attached due to its good insulation properties. It has the advantage that the structure can be simplified because it can be manufactured in various ways. Also,
If it is made of metal such as stainless steel, it can be easily manufactured by press molding. Furthermore, the shape of the opening of the lower structure 4 is preferably circular so that the upper structure 3 can be easily attached. Example 2. FIG. 2(a) is a cross-sectional view of a boiling-cooled integrated circuit device according to another embodiment of the present invention, showing a state in which the internal space volume (2) is reduced. It is enclosed in a structure consisting of an upper structure 7 having a plate welded bellows structure and a lower structure 4 constituting a container. As shown in the figure, one end of the bellows part of the upper structure 7 is hermetically sealed around the circular opening of the lower structure 4, and there is a space between the flat plate part of the upper structure 7 and the integrated circuit element 1 in an extended state. A shape memory alloy 8 in the form of a coil spring with shape memory is attached thereto, and when the temperature of the integrated circuit element 1 rises, this heat is transferred to the shape memory alloy and the shape memory alloy 8 expands. In addition, shape memory alloy 8
For example, a well-known material such as a Ni-Ti alloy can be used. On the other hand, FIG. 2(b) shows a state in which the shape memory alloy 8 and the upper structure 7 are deformed in response to the temperature rise of the integrated circuit cord 1, and the internal volume increases in two stable states. As the internal volume increases, the internal pressure decreases and the boiling point drops, resulting in bubbles 6. Furthermore, when the internal temperature and internal pressure decrease, the internal volume changes from large to small due to the reverse operation, and the series of operations can be repeated. Note that, as the upper structure 7 having the metal plate welded bellows structure, a welded bellows having a small spring constant and a large volume change rate was used. This type of welded bellows is a well-known type in which a metal plate is punched out into a disk shape and the inside and outside of the bellows are alternately welded, and is characterized by large displacement with a small force. Therefore, the shape change operation of the upper structure 7 due to the deformation of the shape memory alloy 8 is ensured. Furthermore, the material of the welded bellows is desirably a beryllium copper alloy or the like, since it is easily soldered to the lower structure 4 because it is not susceptible to attack by fluorine-based refrigerant liquid. In this embodiment, as in the case of the first embodiment, the internal volume rapidly changes in response to the temperature rise of the integrated circuit element 1, and the generation of bubbles is promoted, so that the occurrence of temperature overshoot is sufficiently prevented. We were able to. Example 3. FIG. 3(a) shows a cross-sectional view of an evaporative cooling integrated circuit device according to another embodiment of the present invention in which the internal space volume V is reduced.6The basic configuration is This embodiment is similar to the second embodiment, except that the integrated circuit element 1 is mounted on the outer wall of the lower structure 4. In this case, the integrated circuit element 1 is fixed to the outer wall of the lower structure 4 made of a material with good thermal conductivity, such as a metal such as aluminum, or a ceramic such as alumina or aluminum nitride, by, for example, soldering or brazing, Form a heat sink structure. On the other hand, FIG. 3(b) shows a state in which the shape memory alloy 8 and the upper structure 7 are deformed in response to the temperature rise of the integrated circuit element 1, and the internal volume increases in two stable states. The operation and effect are the same as those of the second embodiment, but the unique effect of this embodiment is that the shape memory alloy 8 does not come into contact with the integrated circuit element 1, so that no physical stress is applied to the integrated circuit element 1. It has the advantage of not costing anything. Example 4. FIG. 4(a) is a sectional view of an evaporative cooling integrated circuit device according to still another embodiment of the present invention, showing a state in which the internal space volume V is reduced. The basic structure is the same as that of the first embodiment, except that the upper structure 3 is made of bimetal 9. On the other hand, FIG. 4(b) shows that in response to an increase in internal pressure due to a rise in temperature of integrated circuit element l and a rise in temperature of refrigerant vapor,
This figure shows a state in which the upper structure 3 made of bimetal 9 is deformed and its internal volume increases in two stable states. The operation and effect are the same as those of the first embodiment, but the unique effect of this embodiment is that the upper structure 3 made of bimetal 9 prevents both an increase in internal pressure and a rise in the temperature of refrigerant vapor. This has the advantage of making the operation more reliable. Note that the hemispherical bimetal 9 that is the upper structure can be easily manufactured by press molding in the same manner as in the first embodiment. And in this case as well, the lower structure 4
The opening has a circular structure to facilitate attachment of the upper structure. Example 5. This embodiment shows an example in which an evaporative cooling type integrated circuit device is mounted on a printed wiring board, and will be described below with reference to FIG. 5. In the boiling-cooled integrated circuit devices of any of the above embodiments, when the integrated circuit element is operated, the upper structure expands and contracts, causing the internal volume of the device to repeat a cycle of increase and decrease. It is necessary to consider FIG. 5 shows the evaporative cooling type integrated circuit device 1 according to the embodiments 2 and 3.
0 is mounted on a printed circuit wiring board ll. To ensure boiling operation during cooling,
It is desirable to mount the welded bellows on the upper side as shown in the figure, and for this reason, the printed circuit wiring board 11
are generally arranged horizontally. FIG. 6 shows an example in which a plurality of printed circuit wiring boards 11 mounted in this manner are housed in a rack 14. During operation, the evaporative cooling type integrated circuit device 10 mounted on the printed circuit wiring board 11 has a space between it and the upper printed circuit wiring board 11, taking into consideration the state of the evaporative cooling type integrated circuit device l3 whose volume has increased. By providing the empty space 12, contact can be prevented.

【Effect of the invention】

As described in detail above, according to the present invention, since the occurrence of temperature overshoot can be prevented with a simple structure, a decrease in cooling efficiency can be prevented and a high cooling effect can be maintained at all times.

[Brief explanation of drawings]

1, 2, 3, and 4 are cross-sectional views of a boiling-cooled integrated circuit device each showing an embodiment of the present invention, and FIG. 5 similarly showing an embodiment of the present invention. A perspective view showing a state in which an evaporative cooling type integrated circuit device is mounted on a blind wiring circuit board, FIG. 6 is a front view of a state in which a plurality of integrated circuit devices are housed in a rack, and FIG. 7 is an illustration of the evaporative cooling operation. A boiling heat transfer curve diagram, and FIG. 8 is a vapor pressure curve diagram of refrigerant R-113 showing an example of a decrease in boiling point temperature. In the figure, 1... integrated circuit element 3... upper structure 5... radiator 7... welded bellows upper structure 8... shape memory alloy coil spring 2... refrigerant liquid 4...・Lower structure 6...Bubble 9...Bimetal upper structure 10...Boiling cooling type integrated circuit device 11...Printed wiring circuit board 12...Empty space

Claims (1)

[Scope of Claims] 1. A lower structure housing a refrigerant liquid, an upper structure hermetically sealing the periphery of an opening of the lower structure, and an integrated circuit element immersed in the refrigerant liquid. , and the volume of the internal space formed by the lower structure and the upper structure is periodically expanded and contracted by the temperature change of the refrigerant liquid.
An evaporative cooling type integrated circuit device comprising internal space volume control means for repeatedly producing a stable state. 2. A lower structure that accommodates a refrigerant, an upper structure that hermetically seals the periphery of an opening of the lower structure, and an integrated circuit element that is at least thermally connected to the lower structure;
Further, the boiling device is provided with an internal space volume control means for repeatedly causing two stable states of expansion and contraction in the internal space volume formed by the lower structure and the upper structure, depending on temperature changes of the refrigerant. Cooled integrated circuit device. 3. The evaporative cooling integrated circuit device according to claim 1 or 2, wherein the internal space volume control means is configured by deforming an upper structure mechanically deforming the shape in response to pressure fluctuations within the internal space. . 4. The internal space volume control means is configured by deforming an upper structure having a bellows mechanism supported by a shape memory alloy that expands and contracts in response to temperature changes in the internal space. boiling cooled integrated circuit device.