JPH04106965A - Cooling apparatus - Google Patents

Abstract

PURPOSE:To prepare a compact and light-weight cooling apparatus able to endure a temporary overheating by painting the surface of a heat radiating fin spottily with paint containing microcapsules so as to form microcapsule colonies. CONSTITUTION:On the surface of a relatively thin heat radiating fin 11 mounted to a semiconductor element A, microcapsule colonies 12 are installed spottily painted with paint containing cooling liquid microcapsules. This spot colony 12 is painted with paint made of epoxy adhesive or the like as matrix with microcapsules 13 containing coolant 14 having large specific heat such as water or anmonium distributed therein. In the case shortcircuit failure or the like occurs and as a result element A is unusually overheated, coolant contained in capsules 13 immediately expands, runs out breaking through thermally softened shells of capsules, and vaporises taking peripheral heat away. With this, the fin 11 is rapidly cooled and element A is protected from being destroyed. With this, since the volumed of fin 11 is reduced, thereby being able to prepare a compact and light-weight cooling apparatus.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a cooling device that prevents thermal destruction of semiconductor devices, single-circuit devices, electric circuits, etc. due to temporary overheating.

B1 Summary of the Invention The cooling device of the present invention has the following features: 1. When a semiconductor element or the like reaches an abnormal temperature; The shells of microcapsules, cylinders, pressure tanks, tubes in heat pipes, etc. break, or the melting plug melts.
Alternatively, a heat dissipating fin to which a semiconductor element or the like is attached is absorbed by the latent heat generated when the safety valve is opened and the liquid inside is spouted out and vaporized.

It cools heat transfer substrates, pressure tanks, heat absorbing parts of heat pipes, etc. to prevent thermal damage to semiconductor elements and the like.

C1 Conventional technology Conventionally, in order to prevent overheating, semiconductor devices for power conversion such as power transistors and thyristors are equipped with heat sinks with heat dissipation fins made of AI or other materials with high thermal conductivity, or are equipped with heat dissipation fins made of materials such as AI that have high thermal conductivity. Since heat transfer efficiency is extremely low and it takes time to dissipate heat, it is necessary to temporarily store heat inside the fins. Therefore, by increasing the volume of the fins by increasing the wall thickness of the fins, a certain amount of heat capacity can be achieved. I have it.

B1 Problems to be Solved by the Invention By the way, the thickness of the fins of the heat radiator needs to be designed to be sufficient in consideration of the possibility of temporary overheating to a high temperature due to a short circuit or the like. The wall thickness of this fin is unnecessarily thick under normal conditions, so the portion of the heat dissipation fin that should normally be thinner and smaller becomes abnormally large, making the board larger and hindering efforts to make it smaller and lighter. was.

The present invention has been made in view of these problems with conventional heat radiators, and its purpose is to provide a cooling device that is small and lightweight and can cope with temporary overheating. .

E1 Means for Solving Problems In order to achieve the above object, the cooling device of the present invention includes a cooling liquid contained in the surface of a heat dissipation fin to which a semiconductor element or the like is attached, and prevents expansion of the cooling liquid at abnormal temperatures. It is made by applying a paint containing microcapsules that can be broken down in spots to form microcapsule colonies.

For the same purpose, a heat transfer substrate to which a semiconductor element or the like is attached is provided with heat dissipation fins via a large number of short columns, and a center portion of the heat dissipation fin is provided with a mouth portion in contact with the heat transfer plate. It may also be configured with a small liquefied gas cylinder sealed with a melting plug that melts due to the abnormal temperature provided.

Alternatively, a pressure tank that houses water and a porous metal piece inside, has a safety valve that operates at abnormal temperatures, and has a semiconductor element, etc. attached to one side, and a heat dissipator that is fixed to the other side of the pressure tank. It can also be composed of fins.

Alternatively, a semiconductor element or the like is attached to one end, a partition with a hole in the center is provided at the other end, a wick is provided on the inner surface between the one end and the partition, and a heat dissipation fin is provided at the other end. an outer pipe having a heat pipe function; an ultra-thin pipe having one end supported by a melting plug that melts at an abnormal temperature on the inner surface of one end of the outer pipe and the other end fixed to the center of the partition; and the outer pipe. A piston and a compression spring provided between the partition and the rear end of the pipe, a refrigerant liquid placed between the partition and the piston in the ultra-thin pipe and the outer pipe, and an outer pipe provided in the outer pipe. It may also consist of a safety valve for releasing abnormal internal pressure.

Regarding F0 effect claim (1), normally the heat of the semiconductor element, etc. is radiated from the portion of the radiation fin where there are no microcolonies. When a semiconductor device or the like overheats abnormally, the cooling liquid in the microcapsule expands, breaks the shell of the microcapsule that has been softened by the heat, and jumps out, absorbing heat from the surrounding area and vaporizing, rapidly cooling the heat dissipation fins and cooling the semiconductor. Protects elements etc. from thermal damage.

Regarding claim (2), under normal conditions, heat from the semiconductor element, etc. is radiated by the heat radiating fins through the heat exchanger plate and the short pillars. When a semiconductor element or the like overheats abnormally, the melting plug that is in contact with the heat exchanger plate melts, and the liquefied gas in the cylinder vaporizes and blows out, dissipating to the outside.

At this point, heat is rapidly removed from the heat exchanger plate and the short plates, so semiconductor elements and the like are protected from thermal damage.

Regarding claim (3), during normal times, heat from the semiconductor elements, etc. is radiated by the heat radiation fins via the tank. When a semiconductor device or the like overheats abnormally, the water in the tank boils and the internal pressure rises rapidly, and the safety valve opens to release water vapor, lowering the internal pressure and water temperature. Therefore, thermal damage to semiconductor elements and the like is prevented.

Regarding claim (4), under normal conditions, heat from the semiconductor element, etc. is transmitted to the heat radiation fins by the outer pipe having a wick inside that functions as a heat pipe, and is radiated from the fins. When a semiconductor element or the like heats up abnormally, the refrigerant liquid pressurized by the compression spring is ejected from the ultra-thin pipe via the piston, vaporizes when it hits the high temperature surface on the endothermic side, and rapidly cools the endothermic side. . Therefore, thermal damage to semiconductor elements and the like is prevented. When the internal pressure of the outer pipe increases due to vaporization of the liquid, a safety valve is activated and the internal pressure is maintained safely.

G. Example Embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 In FIG. 1, A is a semiconductor element, and 10 is a cooling device. Reference numeral 11 indicates a relatively thin heat dissipation fin attached to a semiconductor element, and reference numeral 12 indicates a microcapsule colony in which the surface of the fin 11 is coated with a paint containing a cooling liquid in spots. This microcapsule colony 12, as shown in FIG.
As shown in FIG. 3, microcapsules 13 containing a cooling liquid 14 having a high specific heat such as water or ammonia are dispersed and applied in a paint having a matrix 15 of an adhesive such as epoxy.

The materials for the microcapsules 13 include inorganic materials such as glass, silica, shirasu, alumina 2, and Zirunia, and organic materials such as carbon, phenol, vinylidene chloride, and acrylonitrile, and the particle size used is approximately 5 to 30 μm. do. Epoxy, which is relatively resistant to heat, is suitable for the matrix 15.

Normally, the heat generated by the semiconductor element A is radiated through the heat radiation fins 11, as shown in FIG. 4(a).

For this reason, the size of the microcapsule colony 12 is made small to the extent that it does not interfere with heat dissipation during normal operation, and the intervals between the spots are made wide as shown in the first figure.

If a short-circuit accident or the like occurs and the semiconductor element A becomes abnormally overheated, 1. As shown in FIG. 4(b), the cooling liquid inside the microcapsules 13 immediately expands, breaks the shell of the microcapsules 13 that has been softened by heat, and jumps out, absorbing the surrounding heat and vaporizing. 11 is rapidly cooled and the semiconductor element A is protected from being destroyed by heat.

By appropriately adjusting the thermal strength of the microcapsules 13 and the coefficient of thermal expansion of the cooling liquid, the temperature setting value during rapid cooling can be determined.

Embodiment 2 In FIG. 5, A is a semiconductor element, and 20 is a cooling device. 21 is a heat exchanger plate made of AA', Cu, etc. to which the semiconductor element is attached, and 22 is a short column connecting the heat exchanger plate 21 and the radiation fins. , 25 are N2. Co2
．． This is a small liquefied gas cylinder containing liquefied gas 27 such as A.

Liquefied gas cylinder 25, as shown in FIG.
It is closed with a melting plug 26 made of thermoplastic resin, and a male thread 29 at the mouth is screwed into a female thread 28 (Fig. 7) provided in the center of the heat radiation vent 23, and the melting plug 26 is closed. Heat exchanger plate 2
1.

Normally, heat generated by the semiconductor element A is radiated through the heat radiation fins 23. The melt plug 25 of the gas cylinder is formulated so that it does not melt at this temperature, but melts at a temperature on the verge of destroying the semiconductor element.

When a short circuit accident occurs and the semiconductor element A becomes abnormally heated and reaches a temperature on the verge of destroying the semiconductor element, the melting plug 26 melts.
At the next moment, the compressed liquefied gas in the small liquefied gas cylinder 25 vaporizes and blows out, passing between the short columns 23 and dissipating to the outside.

At this time, the gas rapidly removes heat from the heat exchanger plate 22 and the short columns 23, so that the semiconductor element A can be prevented from being thermally destroyed due to temporary abnormal heating.

The melted pieces of the melt plug 26 are blown away by the pressure at this time. The short columns 22 create an active flow in the gas flow and efficiently exchange heat, so the thinner the column 22, the more effective the surface paddle becomes. After the small liquefied gas cylinder 25 has been activated, it can be returned to its original state by removing it like a cartridge and replacing it.

Embodiment 3 In FIG. 9, A is a semiconductor element, and 30 is a cooling device. 3I is Fl, C, A with good thermal conductivity, with a semiconductor element attached to one side and a radiation fin 32 provided on the other side.
This is a pressure tank consisting of I, etc.

The pressure tank 31 is equipped with a safety valve 33 and a water injection tap 34, and as shown in FIG.
A ball valve 35 made of silicone rubber or the like that closes the opening of 2.
The tank 31 has a pressure regulating spring 36 that presses the ball valve against the mouth and a steam vent hole 37 for releasing steam that comes out when the ball valve 35 is opened. A fine porous metal piece 38 is inserted between which water 39 is filled.

The heat generated by the semiconductor element A during normal operation is radiated from the heat radiation fins 32 through the cylinder 31. However, water with a large specific heat3
Since the fins are placed inside the tank 31, they only need to be smaller than normal fins. The heat emitted from the semiconductor element A is once stored in the heat capacity of water and gradually radiated to the outside air through the heat radiation fins 32. Therefore, the internal pressure of the tank 31 increases to a certain degree, but the internal pressure at this point is set so that the safety valve 33 does not open.

When a short circuit accident occurs and the semiconductor element A becomes abnormally heated, the water in the tank 31 boils, vaporizes (absorbs heat due to the latent heat of vaporization), increases the pressure inside the tank (raises the boiling point of water), and opens the safety valve to release water vapor. Heat is absorbed and released by repeating the following steps: pressure drop in the tank - water boiling point drop - vaporization (water temperature drop) - vaporization (heat absorption) -> pressure rise in the tank - safety valve open - water vapor release. This cycle can protect the semiconductor element from thermal damage. When the water gets low, you can add more water through the inlet 34.

Embodiment 4 In FIG. 11, A is a semiconductor element, and 40 is a cooling device. 41 denotes C, S with the semiconductor element A attached to the front end.
An outer pipe made of US, AI, etc., 42 a radiation fin provided near the rear end of the pipe 41, 43 a wick made of gilt copper, porous metal, vertical grooves, etc. provided inside the pipe 41;
44 is an ultra-thin pipe whose one end is temporarily supported by a melt plug 45 made of solder, thermoplastic resin, etc. on the endothermic side, and whose other end is fixed to a partition 46 having a hole formed integrally with the pipe 41; A piston 48 provided on the rear side of the partition 46
50 is a compression spring that urges the piston 47 forward; 49 is water contained in the partition 46, the piston 46, and the ultrathin pipe 44;
51 is the air hole provided at the rear end of the pipe 41, and 51 is the air hole provided at the rear end of the pipe 41.
This is a safety valve installed in the

The part of the pipe 41 containing the wick 43 contains a small amount of refrigerant liquid of the same type as the above-mentioned refrigerant liquid, and the pipe 41
The refrigerant liquid and the wick 43 function as a heat pipe.

Therefore, under normal conditions, the heat generated by the semiconductor element A is transferred by the action of the heat pipe and is radiated through the heat radiation fins 42. However, the melt plug 45 has a composition that does not melt at this normal endothermic side temperature.

When a short circuit accident occurs and the semiconductor element A is abnormally heated, the melting plug 45 melts, and the refrigerant liquid 49 under pressure by the compression spring 48 blows out through the thin pipe 44 and hits the high temperature surface on the heat absorption side, causing the refrigerant to melt. The cooling effect and vaporization of the liquid rapidly cools the high-temperature surface on the endothermic side. The internal pressure of the pipe 41, which has increased due to the vaporization of the refrigerant liquid, is released by the operation of the safety valve 51.

H1 Effects of the Invention Since the present invention is configured as described above, it produces the following effects.

■In the cooling device of claim (1), the heat generated when the semiconductor element, etc. is overheated is dissipated by vaporizing the coolant inside the microcapsules, so the temperature of the heat dissipation fins decreases rapidly. Destruction can be prevented. In addition, there is no need to temporarily store heat inside the radiation fins, and the heat capacity of the fins can be made smaller than conventional ones.
The overall volume of the heat sink is reduced, making it smaller and lighter.

(2) In the cooling device of claim (2), the heat generated when the semiconductor element or the like is overheated is rapidly cooled by absorption of heat when the liquefied gas vaporizes, so that thermal damage to the semiconductor element can be prevented. In addition, there is no need to temporarily store heat inside the radiation fins, and the heat capacity of the radiation fins can be made smaller than that of conventional heat sinks, so the overall volume of the heat sink is reduced, making it possible to make it smaller and lighter.

■In addition, maintenance is easy because the small liquefied gas cylinder can be replaced as a cartridge type.

■In the cooling device according to claim (3), since water with a large heat capacity is contained inside the tank, a radiating fin with a much smaller volume than the conventional radiating fan 1' is sufficient, making the radiating fin smaller and lighter. can.

■Also, since a porous metal with high thermal conductivity is inserted inside the tank, the heat stored in the water can be quickly transferred to the heat dissipation fins.

Furthermore, when the water inside the tank boils due to overheating of semiconductor devices, etc., the pressure valve operates to release the water vapor, and at the same time, the water temperature decreases due to the pressure drop, which prevents thermal damage to the semiconductor devices.

(2) In the cooling device of claim (4), since the heat generated when the semiconductor element or the like is overheated is rapidly cooled by injecting the refrigerant liquid, the cooling effect during overheating is greater than that using a conventional heat pipe.

[Brief explanation of drawings]

Figures 1 to 4 relate to Example 1 of the present invention; Figure 1 is a perspective view of a cooling device, Figure 2 is a cross-sectional view of a microcapsule, and Figure 3 is an enlarged front partial view of a microcapsule colony. , FIGS. 4(a) and 4(b) are explanatory diagrams of normal heat dissipation and overheating time thermal states. 5 to 8 relate to the second embodiment, in which FIG. 5 is a side sectional view of the cooling device, FIG. 6 is a sectional view taken along line V-V in FIG.
The figure is a side view of the cylinder. Figures 9 and 10 relate to Example 3, with Figure 9 being a perspective view of the cooling device and Figure 10 being a perspective view of the cooling device.
The figure is a sectional view of the same side. FIG. 11 is a side sectional view of a heat radiator related to Example 4. A-...Semiconductor element, 10, 20, 30.40-i cooling device, 11, 23, 32.42...Radiating fin, 12.
... Mer 1' black capsule colony, 13 ... Microcapsule, 14 ... Coolant, 15 ... 7 tricks, 21 ... Heat exchanger plate, 22 ... Short column, 25 ... Liquefied gas cylinder , 26.45... Melting frame, 27... Liquefied gas, 28... Female thread, 29... Male thread, 31... Pressure tank, 33.51... Safety valve, 35... Pall valve, 36...Pressure adjustment spring, 37...Steam vent hole, 38...
...Porous metal, 39...Water, 41...Outer pipe, 43...Wick, 44...Extra-fine pipe, 4
6... Partition, 47... Piston, 48... Compression spring, 49... Refrigerant liquid, 5o... Air hole. Figure 1 (Tamitsu Takumi) 1) A-----Ichikan Shiban Sokan 10----Ichijo Sokukenho 11----Ichishu Pef, Alun 12----I de 1 Colony 23 --- Release* A Aso 29 --- Ichitsuji 11 --- One door muff 1 n 12 ------ Fu Al DD, Ru] Ronnie 13--
--1 Ward Iku [l Kabukol 14-----Kitsubo 15--1 Tato 1 Piece Nox (a) A-kun 1 also Kesu Roku N Figure 3 Figure 4 (b) L Chiku Mutsu Roku Naturally

Claims (4)

[Claims] (1) On the surface of the heat dissipation fin to which semiconductor elements etc. are attached,
A cooling device characterized in that a paint containing microcapsules containing a coolant and broken by expansion of the coolant at abnormal temperatures is applied in spots so as to form microcapsule colonies. (2) A heat transfer substrate to which a semiconductor element or the like is attached, which is provided with heat dissipation fins via a large number of short columns, and a heat transfer substrate that is attached to the center of the heat dissipation fin so that the mouth part is in contact with the heat transfer plate. A cooling device comprising a small liquefied gas cylinder sealed with a melting plug that melts due to abnormal temperatures. (3) A pressure tank that contains water and a porous metal piece and is equipped with a safety valve that operates at abnormal temperatures, and a semiconductor element, etc. is attached to one side of the pressure tank, and a pressure tank that is fixed to the other side of the pressure tank A cooling device characterized by consisting of heat dissipation fins. (4) A semiconductor element, etc. is attached to one end, a partition with a hole in the center is provided on the other end, a wick is provided on the inner surface between the one end and the partition, and a heat dissipation fin is provided on the other end. an outer pipe having a heat pipe function, one end of which is supported by a melting plug that melts at an abnormal temperature on the inner surface of one end of the outer pipe, and the other end of which is fixed to the center of the partition; a piston and a compression spring provided between the partition and the rear end of the pipe; a refrigerant liquid placed between the partition and the piston in the ultra-thin pipe and the outer pipe; and an outer pipe provided in the outer pipe. A radiator with a thermal heater characterized by comprising a safety valve for releasing abnormal internal pressure.