JPS5854506B2 - Hounetu Souchi - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a heating element such as a large-scale integrated circuit device (hereinafter referred to as LSI) mounted on a printed circuit board or a transistor, in which an evaporative liquid is sealed. The present invention relates to a heat radiating device that is thermally bonded to the outer surface of a closed container and transfers heat generated from a heating element to one side of the closed container by utilizing the evaporation and condensation action of an evaporative liquid inside the closed container.

[Background of the invention]

FIG. 1 is a schematic diagram of an example of a conventional heat dissipation device of this type, and FIG. 2 is a cross-sectional view taken along line A-A in FIG.

This is done by applying a porous material 5 (for example, wire mesh, gauze,
Sealed container lined with sintered metal, metal fiber) 4
is attached, and the other end is brought into close contact with the radiation fin 7.

The porous material 5 is impregnated with an evaporable liquid (eg water, alcohol, Freon).

When the closed container 4 receives heat generated from the LSI package 1, the liquid in the porous material 5 in the vicinity evaporates and moves toward the inner wall of the closed container 4 where the radiation fins 7 are attached due to the vapor pressure difference.

This steam releases latent heat of condensation and condenses there, but this heat escapes from the radiation fins 7 to the atmosphere by natural convection or forced convection of air.

On the other hand, the condensed liquid returns to the closed container 4 attached to the LSI package 1 due to the capillary force of the porous material 5, and repeats the same cycle as before.

In this way, by utilizing the evaporation and rapid condensation of the evaporative liquid contained in the sealed container 4, a large amount of heat can be transported from the LSI package by the heat dissipation fins with a small temperature difference.

The cross section of this conventional sealed container 4 is as shown in FIG.
In order to improve thermal contact with the normal plane of the SI package 1, its cross-sectional shape is generally rectangular.

The problem when installing a large number of LSI packages 1 in such a rectangular airtight container 4 is that when soldering the lead wires 2 of the LSI packages 1 to the printed circuit board 6, it is necessary to make sure that all the packages are at the same height. If this is not done, there will be insufficient thermal contact between the sealed container 4 and the LSI package 1, and some of the many LSIs may be destroyed due to poor heat dissipation.

For this reason, grease 3 is applied to the contact surface between the LSI package 1 and the sealed container 4, but this grease also dries out over many years and creates gaps in that area, resulting in an increase in contact thermal resistance. Another disadvantage of this conventional rectangular airtight container 4 is that it cannot be bent freely, so of the LSIs mounted on the printed board 6, those with a large amount of heat dissipation are selected and only those are sealed. The heat radiating fins 7 are attached to the container 4 and dissipate the heat generated from them.
It is not possible to transport and dissipate heat in one step.

If you want to make this possible, use an LSI with a large amount of heat dissipation.
must be arranged in a straight line,
This results in wiring restrictions.

Similarly, it is not easy to selectively take out a plurality of LSIs whose temperature-dependent electrical characteristics are desired to be made the same, and connect them to the closed container 4 to make the temperatures of the LSIs the same.

In the conventional example shown in FIG. 3, an airtight container 4 is provided between the package 1 and the printed circuit board 6, and when the lead wires 2 of the package 1 are soldered to the printed circuit board 6, the package 1 is attached to the outer surface of the airtight container 4. In this case, since the sealed container 4 is made of metal and is an electrical conductor, the sealed container 4
An insulating plate 8 made of 1D mylar, mica, etc. must be inserted between the board 6 and the printed circuit board 6.

In the conventional example shown in FIG. 3, the contact thermal resistance between the package 1 and the closed container 4 can be made small, and variation in the contact thermal resistance from package to package can be relatively reduced.

However, as in the conventional example shown in FIG. 2, the closed container 4 cannot be bent freely, so it is not possible to select only an LSI package with a large amount of heat radiation and attach it to the closed container 4.

Another drawback of the conventional examples of the button in FIG. 2 and the button in FIG.
As shown in the figure, the distance t between adjacent printed circuit boards 6'
The drawback is that it is inevitably long and requires a low packaging density.

[Purpose of the invention]

The purpose of the present invention is to improve the above-mentioned drawbacks, to improve heat dissipation by reducing the contact thermal resistance between a heating element such as an LSI package and a sealed container, and to increase packaging density by shortening the interval between printed circuit boards. It is.

[Features of the invention]

A feature of the present invention is that a part of the mounting member fixed on the heating element is extended laterally, and a sealed container is fixed on the side of the extended part facing the printed circuit board. This is because the distance between the printed circuit boards has been reduced.

[Embodiments of the invention]

An embodiment of the heat dissipation device of the present invention will be described below with reference to FIGS. 4 and 5.

FIG. 4 is a schematic diagram illustrating an example in which the heat dissipation device of the present invention is implemented as heat dissipation for an LSI package, and FIG. 5 is a sectional view taken along line B-B' in FIG. 4.

The sealed container 4, which is lined with a porous material 5 impregnated with an evaporative liquid, is constructed to be strongly bendable, and LSI package mounting members 9 are thermally bonded to multiple locations on its outer surface. A radiation fin 7 is provided on the tip side.

Further, a metal plate 11 with screws 11' is fixed to the outer surface of the LSI package 1.

The LSI package 1 can be attached to the package mounting member 9 with extremely low contact thermal resistance by inserting the screws 11' attached to the metal plate 11 into the holes of the package mounting member 9 and firmly tightening them with the nuts 10. Easy to install.

In such a configuration, the chip 1' in the package 1
The heat generated from the metal plate 1 passes through the package 1 (made of epoxy resin or alumina, for example) and then passes through the metal plate 1.
1 (for example, copper, aluminum) to the package mounting member 9 (for example, copper, aluminum).

This heat is diffused by the package attachment member 9 and then transmitted to the closed container 4, and is transported to the heat radiation fins 7 by the evaporation phenomenon of the evaporative liquid of the closed container 4.

Although it appears that the thermal resistance due to heat conduction from the package attachment member 9 to the closed container 41 is large, experiments have shown that this thermal resistance is relatively small.

In addition, since the sealed container 4 is very thin compared to the conventional examples shown in FIGS. 2 and 3, the heat removal ability of the evaporative liquid in the porous material 5 lined inside the sealed container 4 is very poor. Although it seems that the LSI package 1
The heat generated from the chip 1' inside the chip 1' is only a few watts at most, and even though the heat generation density at the chip 1' is very high, the surface area of the package 1 is several tens of times larger than the chip area, so the amount of heat generated on the package surface is small. The heat flow density is lowered to several tenths of the heat generation density of the chip 1'.

Therefore, the heat flow density when heat is transferred from the mounting member 9 to the closed container 4 is low, and the thermal resistance at that portion is not so large.

This eliminates the need for the surface of the sealed container 4 to come into contact with the entire surface of the package 1, as shown in FIGS. 2 and 3 in the conventional example.

That is, by using the mounting member 9, it is not necessary to stack the thick sealed container 4 on the package 1, so there is no need to increase the distance between the adjacent printed circuit board 6'.
The packaging density can be increased.

Additionally, according to this embodiment, the contact thermal resistance value between the LSI package and the sealed container does not vary greatly from package to package, and the LSI mounted on the printed circuit board
Since it is possible to take out and radiate heat from only those that generate a large amount of heat from the package etc. using the flexible airtight container 4, the whole can be kept at a uniform temperature, and those that generate a large amount of heat transfer heat to those that generate a small amount of heat. It never heats up and gets hot.

In addition, I would like to have uniform electrical characteristics that depend on temperature.
By selecting an SI package or the like and communicating with each other through a sealed container, it is possible to match the electrical characteristics of both packages.

FIG. 6 and FIG. 7 show another example of the method for attaching the attachment member 9 and the package 1.

In the example shown in FIG. 6, the sealed container 4 is attached by welding to the back side of the mounting member 9, that is, the surface facing the printed circuit board 6, in order to further reduce the distance between adjacent printed circuit boards, and the screws 11' are also attached. It is made into a dish shape so that its head does not protrude outside, and it is screwed into the female thread cut into package 1.

However, it is necessary that the female screw thread cut into the package 1 be provided in a part that does not harm the chip 1' and the lead wires connected thereto.

In the example shown in FIG. 7, a magnet 14 is provided on the mounting member 9, and the mounting member 9 is brought into close contact with the metal plate 11 using the magnetic force.

In this case, the metal plate 11 needs to be made of a magnetic material such as iron, but it does not need to be entirely magnetic;
The rest is made of copper and aluminum, which have good thermal conductivity but are non-magnetic.

In the above embodiments, the hermetic container 4 and the mounting member 9 were integrally constructed or joined by welding.
As shown in the figure, the attachment member 9 may be attached to the closed container 4 by sliding it.

That is, the mounting member 9 is provided with a hole at its end, the airtight container 4 is inserted into this hole, and the mounting member 9 is fixed at an appropriate position in the longitudinal direction of the airtight container 4 with screws 11'. do.

FIG. 9 is a schematic diagram showing how the mounting member 9 is moved in the longitudinal direction of the closed container 4.

With this configuration, when attaching the LSI package 1 to the attachment member 9, positioning etc. become easier.

In fact, the sealed container can be used without being bent as long as there is not much variation in the amount of heat generated by the many heating elements on the printed circuit board.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reduce the contact thermal resistance between the heating element and the sealed container, thereby greatly improving heat dissipation, and it is also possible to shorten the interval between printed circuit boards, thereby reducing the packaging density. It can be made larger.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram illustrating an example of a conventional heat dissipation device;
The figure is a sectional view taken along the line A-A' in FIG. 1, FIG. 3 is a sectional view of a main part of another example of a conventional heat radiating device, and FIG. 4 is a plan view illustrating an embodiment of the heat radiating device of the present invention. Figure 5 is B-B of Figure 4.
' The sectional views, FIGS. 6 and 7 are sectional views showing other examples of the method of attaching the mounting member and the heating element in FIGS. 4 and 5,
FIG. 8 is a cross-sectional view showing another example of the method of attaching force between the mounting bracket and the heating element for the heat dissipation device of the present invention, and FIG. 9 is a side view of FIG. 8. DESCRIPTION OF SYMBOLS 1...Package, 4...Airtight container, 6...Printed circuit board, 7...Radiation fin, 9...Mounting member.

Claims (1)

[Claims] 1 The mounting fixed on the heating element mounted on the printed circuit board extends a part of the member laterally, and a closed container containing a heat transfer refrigerant is placed on the side of the extended portion facing the printed circuit board. A heat dissipation device characterized by fixed.