JPH0442931Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Summary] As a method for efficiently cooling semiconductor chips arranged and mounted on a circuit board using the heat of vaporization of a refrigerant, the circuit board is placed on the side surface and a condensing section is formed. The structure includes a coolant reservoir on the top, a starting heater and a refrigerant reservoir on the bottom, and the refrigerant is put in the bottom, decompressed, and sealed.

[Industrial application field]

The present invention relates to a cooling structure for semiconductor devices that efficiently cools semiconductor devices using heat of vaporization.

2. Description of the Related Art As a method for improving the processing performance of information processing devices, semiconductor devices that are composed of a large number of semiconductor elements are being made smaller in size and the number of elements is increased.

That is, the electrode dimensions and conductor pattern widths that form unit elements have been extremely reduced, while the number of elements has increased, and LSI and VLSI have been put into practical use.

In addition, the mounting method on wiring boards has been improved. Previously, each semiconductor chip was housed in a hermetically sealed package and attached to the printed wiring board, but the future format will be based on advances in packaging technology. As a result, a method has been adopted in which multiple LSI chips are mounted on a circuit board made of ceramic or the like to create an LSI module, which is then mounted on a wiring board as a replacement unit.

As unit elements become smaller and more dense, the amount of heat generated by semiconductor devices also increases, making it impossible to maintain the element temperature within the maximum operating temperature range using conventional air cooling methods. .

In other words, up until now, the maximum amount of heat generated by an LSI chip was about 4 watts, but in VLSI, the amount of heat generated is about 10 watts.
It is about to reach the level of Watsuto.

In view of the above, liquid cooling has become necessary as a cooling method for semiconductor devices in place of conventional air cooling and forced air cooling.

[Conventional technology]

The inventor is already applying for several utility models for liquid cooling methods for semiconductor devices in which many LSIs are mounted on a multilayer circuit board.

For example, Utility Application No. 59-016496 (filed on February 8, 1959),
Utility Application 1983-019428 (filed on 2/14/1959), Utility Application 1987-
099389 (filed on June 29, 1959)
Application), Utility Model Application No. 59-157527 (filed on October 18, 1987), etc. The gist of these applications is to provide circuit boards equipped with semiconductor chips that are non-corrosive, non-dissociable, and whose boiling point is the maximum operating temperature of the chips85. Refrigerants below °C, such as Freon (C ₂ Cl ₃ F ₃ boiling point 49 °C) and various fluorocarbons such as C ₅ F ₁₂ (boiling point 30 °C), C ₆ F ₁₄ (boiling point 56 °C)
The circuit board can be sealed by immersing it in a liquid such as ℃), and the circuit board can be connected to an external circuit through a connector provided inside the container, or alternatively, the circuit board can be used as a side wall of the sealed container and the connector can be connected to the lead pins brought out from the back side. Inserting it and making circuit connections.

The refrigerant that boils and evaporates from the semiconductor chip during operation is cooled by a heat exchanger (condenser) provided in the liquid and in the cavity at the top of the container, and is returned to liquid refrigerant.

Here, the characteristics of each application are how to prevent the LSI chip from being covered and insulated by the gaseous refrigerant that boils from the LSI chip that generates heat, and how to quickly liquefy the gaseous refrigerant. I'm suffering from a crab.

As described above, all conventional cooling structures employ a structure in which semiconductor chips are cooled by immersing them in a refrigerant. However, although this type of liquid cooling structure has no problem when the heat output of the semiconductor chip is around a few watts like in the past, when it is as large as around 10 watts, violent boiling occurs and the surface of the chip is exposed to vaporized gas. It is covered by and is cut off from the refrigerant, creating an adiabatic state.
There is a risk of abnormal temperature rise.

Therefore, there is a need for a cooling structure that can be used even with semiconductor chips that consume a large amount of power.

[Problem that the invention attempts to solve]

As mentioned above, a method in which a circuit board equipped with a semiconductor chip that consumes a large amount of power is immersed in a refrigerant and cooled by the heat of vaporization of the refrigerant that comes into contact with the semiconductor chip is a method in which the surface is covered with boiling and vaporized gas and is insulated. There is a need for a cooling method that does not cause this phenomenon.

[Means for solving problems]

The above-mentioned problem is solved by forming a matrix of recesses for mounting semiconductor chips.The side surface has a circuit board with a semiconductor chip inserted into each recess, and the upper surface has a condenser and a condensate reservoir. a bottom portion including a starting heater and a refrigerant reservoir;
This problem can be solved by a semiconductor device cooling structure in which a sealed container is formed, and after the inside of the container is evacuated, a refrigerant is sealed.

[Effect]

The present invention applies the concept of heat pipes to the cooling structure of semiconductor devices.

FIG. 2 is a principle diagram showing the structure of a heat pipe. It is made of a metal with excellent thermal conductivity such as copper (Cu), and has both ends sealed, evacuated, and a small amount of refrigerant sealed inside.

When one end is heated and the other end is cooled, the cooling part is in a reduced pressure state due to the liquefaction of the refrigerant molecules, so the refrigerant molecules 1 that have been vaporized in the heating part are sucked into the cooling part and liquefied. The refrigerant molecules 2 that have been removed flow and circulate in the original direction, thereby performing cooling.

Here, the cooling efficiency of the heat pipe is The larger the temperature difference between the heating section and the cooling section, the The lower the boiling point of the refrigerant molecules, Remarkable.

Therefore, in the cooling structure according to the present invention, a circuit board equipped with a large number of semiconductor chips is installed in the central part corresponding to the metal tube of the heat pipe, a refrigerant reservoir and a starting heater are installed at the bottom, and a condenser is installed at the top. By circulating the refrigerant, the refrigerant is liquefied in the upper part, and then flowed down onto the semiconductor chip, vaporized over the semiconductor chip, and then returned to the refrigerant reservoir. By doing so, the surface of the semiconductor chip is covered with air bubbles, resulting in a cooling effect. This prevents a decrease in

〔Example〕

FIG. 1 shows the configuration of a cooling device embodying the present invention, and FIG. 1A is a sectional view of the cooling device, and FIG. 1B is a front view of a circuit board forming a side surface of the cooling device.

In other words, a large number of semiconductor chips (hereinafter abbreviated as
Circuit boards 4 mounted with LSI) 3 were placed facing each other to form both sides of a sealed container.

A condensing section 6 consisting of two cooling pipes 5 and a coolant reservoir 7 are provided in the upper part, and a refrigerant reservoir 9 is provided in the lower part, and a starting heater 8 is provided at the bottom thereof.

Here, the reason why the starting heater 8 is provided at the bottom is that before the LSI is energized, the vapor pressure of the solvent in the container is low, there is no refrigerant in the upper coolant reservoir 7, and the refrigerant flows down from the top. This is because it is not.

Therefore, before applying voltage to the LSI, it is necessary to first energize the starting heater 8 to vaporize the refrigerant, cool it by passing water through the cooling pipe 5, and cause the refrigerant to flow down from the upper coolant reservoir 7.

Note that if the LSI 3 generates heat when energized, the temperature of the circuit board 4 rises, and the refrigerant in the refrigerant reservoir 9 becomes violently vaporized, the heating of the starting heater 8 will be stopped, but the LSI 3 with low power consumption will be used. If so, it is necessary to keep the starting heater 8 energized to keep the flow rate constant.

Note that the LSI 3 needs to be well wetted by the refrigerant flowing down from the refrigerant reservoir 7, and for this reason, the LSI 3 is attached to the circuit board 4 as shown in FIG. 1A.
It is necessary that the recess 10 is fitted into the recess 10 provided in the recess 10, and that the recess 10 does not protrude.

In addition, as shown in FIG.
It is better to have it flow over LSI 3.

In this way, if the refrigerant always flows down over the LSI 3, the LSI 3 will not be covered with air bubbles and become insulated, so that sufficient cooling can be achieved.

[Effect of idea]

As described above, by implementing the present invention, it is possible to put into practical use a cooling structure for a semiconductor device with excellent cooling ability.

[Brief explanation of drawings]

FIG. 1A is a sectional view of a cooling device according to the present invention, FIG. 1B is a front view of a circuit board in the cooling device, and FIG. 2 is a diagram showing the principle of a heat pipe. In the figure, 3 is an LSI, 4 is a circuit board, 5 is a cooling pipe, 6 is a condensing section, 7 is a coolant reservoir, 8 is a starting heater, and 9 is a refrigerant reservoir.

Claims (1)

[Scope of Claim for Utility Model Registration] A side portion having a circuit board 4 with a semiconductor chip 3 fitted into each recess 10 formed by arranging recesses 10 for mounting semiconductor chips in a matrix, and a condensing portion 6. A sealed container is formed by a top portion having a heater 8 for starting and a coolant reservoir 7, and a bottom portion having a starting heater 8 and a refrigerant reservoir 9. After the inside of the container is evacuated, a refrigerant is sealed. A cooling structure for a semiconductor device characterized by: