JPH0220048A - Boiling-cooling type semiconductor device - Google Patents

Abstract

PURPOSE:To increase an effective heat transfer area to liquid refrigerant and to accelerate a boiling heat transfer by opening refrigerant passage hole row formed as a gear train in the inner wall face of a hole along the contact face with a semiconductor element in a cooler. CONSTITUTION:A plurality of refrigerant passage holes 34 are opened at the center of a cooler 35 in its thickness direction along the contact face 31 of a semiconductor element. The hole 34 is formed with female threads, and female threadlike gear train 33 are formed on the inner wall face of the hole. When the heat generated at the element is transferred to the cooler 35 through the face 31, a heat transfer occurs by convection to the refrigerant in contact therewith. If the wall face of the cooler 35 is at the saturation temperature or higher of the liquid refrigerant, the refrigerant is surface boiled to generate air bubbles on the wall face, and boiling heat transfer occurs. On the other hand, the temperature of the refrigerant filled in the hole 34 is raised by the heat transfer from the cooler 35 thereby to generate liquid density difference in upper and lower parts in a vessel, so-called a chimney effect is operated to rise the liquid refrigerant in the hole 34.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a boiling cooling type device that removes heat generated from semiconductor elements such as thyristors and diodes to the outside of the system by the boiling/condensing action of a liquid refrigerant. Related to semiconductor devices.

[Conventional technology]

First, the conventional configuration of the boiling-cooled semiconductor device mentioned above is explained in the fourth section.
In Fig. 0, which will be explained with reference to Figs. The combined laminate is held under pressure between left and right end plates 5 with an insulating plate 4 in between. Note that 6 is a stand for fastening the stack, 7 is a disc spring that applies pressing force, and 8 is a terminal plate arranged at both ends of the stack.

On the other hand, as shown in the figure, the stack assembly l is housed in a container IO in a horizontal position immersed in a liquid refrigerant 9 such as chlorofluorocarbon, and together constitutes an evaporative cooling type semiconductor device. . In addition, 11 is an external lead terminal from the container 10 connected to the terminal board 8, and 12 is a radiation fin projecting from the outer peripheral surface of the upper space of the container 1O.

The boiling cooling effect with such a configuration is well known, and the heat generated by energizing the semiconductor element 2 is transferred to the cooling body 3, and from there, the boiling heat is transferred to the liquid refrigerant 9 in contact with the surface of the cooling body 3. On the other hand, the refrigerant vapor generated during this boiling heat transfer process becomes bubbles, which rise in the refrigerant liquid due to their buoyancy and are dissipated into the upper space of the container 10. In addition, the refrigerant vapor 13 filling the upper space of the container 10 transfers condensation heat to the wall surface of the container 10 and condenses, changes to a liquid phase again and refluxes into the liquid, and the heat transferred to the container 10 is It is radiated outside the yarn (into the atmosphere) by the heat radiation fins 11. The heat generated by the semiconductor element 2 is removed to the outside of the system by the transfer of latent heat through the evaporation/condensation cycle of the liquid refrigerant. The boiling heat transfer described above mainly proceeds in the region of nucleate boiling, and the refrigerant undergoes surface boiling on the heat transfer surface of the cooling body 3.

On the other hand, regarding the above-mentioned cooling body 3, in order to increase the heat transfer area in contact with the liquid refrigerant 9 and also promote heat transfer, the inside of the cooling body 3 (the central part in the thickness direction) is To,
One in which a plurality of coolant passage holes 32 are bored in parallel along the contact surface 31 of a semiconductor element has already been implemented. The refrigerant passage hole 32 is oriented vertically when the stack assembly 1 is installed in the container 10, as shown in FIG. As a result, the heat transfer area between the cooling body 3 and the liquid refrigerant 9 increases, and in addition to this, the flow of the refrigerant due to the chimney effect of the refrigerant passage hole 32 is added to increase the heat transfer area between the cooling body 3 and the liquid refrigerant 9. is promoted, and cooling performance can be improved.

[Problem to be solved by the invention]

By the way, the conventional equipment described above generally uses CFCs, which have excellent properties as a refrigerant, but recently the use of CFCs has been internationally regulated. 1. For example, the use of fluorocarbon refrigerants is being considered.

However, the thermal conductivity of fluorocarbon refrigerant is lower than that of fluorocarbons, and the boiling heat transfer coefficient when using fluorocarbon refrigerant is
This is reduced to about 2/3 compared to the case of fluorocarbons. Therefore, in order to obtain the same boiling cooling effect as when using CFCs with the conventional structure, it is necessary to take measures such as increasing the heat transfer area by increasing the size of the cooling body by the reduction in the boiling heat transfer coefficient. As a result, the overall structure of the semiconductor device becomes larger.

The present invention has been made in consideration of the above points, and by improving the refrigerant passage holes drilled in the cooling body, the effective heat transfer area between the cooling body and the refrigerant can be increased with the same shape and size. It is an object of the present invention to provide a boiling-cooled semiconductor device with high cooling performance, which can increase heat transfer and effectively promote boiling heat transfer.

[Means for Solving the Problems] In order to solve the above problems, in the boiling-cooled semiconductor device of the present invention, a cooling body that is stacked together with the semiconductor elements to form a stack assembly is provided with a cooling body that is stacked with the semiconductor elements. A large-sized refrigerant passage is formed by drilling along the abutment surface and with the inner wall surface of the hole serving as the tooth row surface.

[Effect]

In the above configuration, the tooth row formed on the inner wall surface of the refrigerant passage hole is
It is formed as a female thread or the teeth of an internal gear. As a result, if the height of the tooth row is about 11, the heat transfer area of the refrigerant passage hole in contact with the refrigerant increases by about 1.8 times compared to a refrigerant passage hole of the same inner diameter with a flat inner wall surface. Further, the unevenness of the inner wall surface of the hole formed by this tooth row effectively acts as a nucleus for the generation of bubbles of the refrigerant, and the number of bubble generation points increases accordingly. Furthermore, during the boiling heat transfer process, the above-mentioned dentition surface adds a disturbance to the refrigerant flow rising in the refrigerant passage hole due to the chimney effect, resulting in surface boiling and bubbles forming on the heat transfer surface of the cooling body. Cuts better. As a result, boiling heat transfer between the cooling body and the refrigerant is further promoted due to the synergistic effect of the above actions, and the boiling cooling effect is enhanced.

[Embodiment] FIGS. 1 to 3 show the structure of a cooling body according to an embodiment of the present invention, and similarly to FIG. 5, the thickness direction of the cooling body 35 is A plurality of refrigerant passage holes 34 are bored in the center of the refrigerant passage hole 34 .

Note that when the cooling body 35 is assembled into the stack assembly shown in FIG. 4, it is assembled with the coolant passage hole 34 facing in the vertical direction, as in the conventional case. Here, according to the present invention, the refrigerant passage hole 34 described above is a female threaded tapped hole, as clearly shown in FIG. 3, and a female threaded tooth row 33 is formed on the inner wall surface of the hole. Note that the tooth row 33 may be formed as a tooth row of an internal gear instead of a female thread. In either case, the inner wall surface of the refrigerant passage hole 34 becomes an uneven tooth row surface. Here, if the height of the threads as the tooth row 33 in FIG. This is approximately 1.8 times larger than the hole (conventional refrigerant passage hole).

With this configuration, when the heat generated by the semiconductor element is transferred to the cooling body 35 via the contact surface 31 as explained in FIG. Heat transfer occurs between the two by convection.

If the wall surface of the cooling body 35 is equal to or higher than the saturation temperature of the liquid refrigerant, the refrigerant undergoes surface boiling, bubbles are generated on the wall surface, and boiling heat transfer occurs. On the other hand, the temperature of the refrigerant filling the inside of the refrigerant passage hole 34 increases due to heat transfer from the cooling body 35, and this causes a difference in liquid density between the upper and lower parts of the container, causing a so-called chimney effect, and the liquid refrigerant becomes the refrigerant. The fluid flows upward through the passage hole 34.

By the way, according to the present invention, since the tooth row 33 is formed on the inner wall surface of the refrigerant passage hole 34 as described above, the effective heat transfer area with the refrigerant increases, and the uneven surface due to the tooth row 33 increases. acts effectively as a nucleus for bubble generation, and the number of bubble generation points increases significantly. In addition, the tooth row 33 gives a disturbance effect to the refrigerant flow rising inside the hole due to the chimney effect of the refrigerant passage hole 34, so that the air bubbles generated by surface boiling do not stagnate on the wall surface but immediately peel off. This results in better cutting, and the synergistic effect of these effects promotes boiling heat transfer.

As a result, the boiling cooling efficiency in the boiling cooling system is improved, and the size of the cooling body 35 itself can be reduced, or equivalent cooling performance can be ensured even when the refrigerant is changed from fluorocarbon to a fluorocarbon refrigerant. Further, even if an overload is applied to the semiconductor device, the thermal resistance between the cooling body 35 and the liquid refrigerant is maintained in a low state, so that the overload tolerance is increased accordingly. In this regard, the results of a comparative experiment with a conventional device conducted by the inventor have confirmed that the thermal resistance is reduced by almost half.

Although the illustrated embodiment shows an example in which the refrigerant passage holes 34 are drilled in a horizontal row for the - number of cooling bodies 35, the large-sized refrigerant passages may be arranged in two or more rows to provide a hole for each person. By forming a tooth row on the inner wall surface of the cooling member, the cooling performance can be further improved.

(Effects of the Invention) Since the evaporative cooling type semiconductor device of the present invention is configured as described above, it exhibits the following effects.

That is, a row of refrigerant passage holes are bored inside the cooling body that is stacked together with the semiconductor element to form a stack assembly, along the contact surface with the semiconductor element, and with the inner wall surface of the hole serving as the toothed surface. With this configuration, it is possible to increase the effective heat transfer area with the liquid refrigerant and promote boiling heat transfer compared to the conventional configuration. As a result, it is possible to obtain a small-sized boiling-cooled semiconductor device with high boiling-cooling efficiency, which can also be used with a fluorocarbon refrigerant having a lower thermal conductivity than fluorocarbon.

[Brief explanation of the drawing]

1 is a sectional view of a cooling body incorporated in a stack assembly according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is an enlarged sectional view of the refrigerant passage hole in FIG. Figure 4 shows the overall configuration of the evaporative cooling type semiconductor device, and Figure 5 is a perspective view of a conventional cooling body. Contact surface of semiconductor element, 32,347 refrigerant passage hole, 33: tooth row, 9: liquid refrigerant, 10: container, 12:
Figure 2 Figure 3 33 Figure 4? ! Figure 5

Claims (1)

[Claims] (1) A stack assembly formed by alternately stacking semiconductor elements and flat cooling bodies is immersed in a liquid refrigerant and housed in a container, and the heat generated by the semiconductor elements is transferred to the refrigerant through the cooling body. In a boiling-cooled semiconductor device in which heat is generated and heat is removed by condensing refrigerant vapor onto a heat dissipation surface to the outside of the system, inside the cooling body, along the contact surface with the semiconductor element, An evaporative cooling type semiconductor device characterized in that a refrigerant passage hole row is bored with the inner wall surface of the hole serving as a tooth row surface.