JPH0669385A - Heat sink - Google Patents

Abstract

PURPOSE:To get the most efficient cooling effect by putting the convection input face areal share and the convection output face areal share in the optimum relation with limited space. CONSTITUTION:In a heat sink equipped with a heat radiating plate 14 and a plurality of heat radiating pins 10, heat radiation effect (F) is sought with number 1F=(SoXS)/(SiXRp) from convection input face areal share (Si), convection output face areal share (So), the total (S) of the surface areas of heat radiation pins, and the heat resistance (Rp) of all heat radiation pins, whereby the number, the sizes, and the shapes of the heat radiation pins 10 are decided. Moreover, for the heat radiation pin 10, a heat pipe will do, and the heat radiation fin provided at the heat radiation pin 10 may be provided at the position lower than the top of the heat radiation pin 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink for radiating heat from an electronic element used in an integrated circuit or the like.

[0002]

2. Description of the Related Art In recent years, integrated circuits for electronic devices such as computers have been required to have high-speed response and high integration in order to process an increasingly large amount of information. Along with this, the power consumption density of the integrated circuit has increased, and the technology for radiating heat of the circuit components during mounting has become extremely important. As the heat dissipation technology, for example, there is a method in which a heat sink is provided in a circuit component element and convection (wind) is applied to the heat sink.

As is well known, as an example of a conventional heat sink, as shown in FIGS. 11 and 12, a plurality of heat dissipation pins 10 made of a metal material are attached to a heat dissipation plate 14 made of a metal material such as aluminum. There is something.

FIG. 12 is a view of the AA cross section of FIG. 11 as seen in the direction of the arrow. The convection is applied (input) from the upper portion of FIG.
Is coming out along the upper surface of (output).

In FIG. 11, an upper surface of an object to be cooled (not shown, for example, a multi-chip module) is arranged below the heat radiating plate 14, and heat generated from the heat radiating plate 10 is radiated through the bottom surface of the heat radiating plate 10. And are radiated by these.

Further, the heat dissipation plate 14 is provided with a mounting hole 25 for mounting the heat sink on the object to be cooled.

A conventional heat sink 10 as shown in FIG.
In order to improve the heat radiation ability without changing the dimensions a, b, c, and h under forced convection, it is generally known to increase the surface area of the heat radiation pin 10 or reduce the heat radiation resistance of the heat radiation pin 10. There is.

Specifically, "to increase the surface area of the heat dissipation pin 10" means, for example, a heat dissipation fin made of a metal material such as aluminum for all the heat dissipation pins 10 installed as shown in FIG. 12), or as shown in FIG. 7, the number of fins 12 is not provided on the heat dissipation pin 10 to increase the number, and “to reduce the heat dissipation resistance of the heat dissipation pin” means, for example, As shown in FIG. 9, the fins 12 are not provided on the heat dissipation pin 10 to increase the cross-sectional area of the heat dissipation pin 10.

Further, for example, if fins 12 are provided on the radiation pin 10 as shown in FIG. 5, a large radiation area can be obtained without limiting the convection direction.

6 and 8 and 10 are views of the heat sink of FIGS. 5 and 7 and 9 as seen in the direction of the arrow along the line AA, and convection is similar to that of FIG.
Is input to the heat dissipation pin 10 from above and is output along the upper surface of the heat dissipation plate 14.

[0011]

When mounting a heat sink on an integrated circuit for an electronic device such as a computer, this mounting space has, for example, dimensions a and b shown in FIG.
Since it is fixed at c and h, it cannot be expected to secure more space.

[0012] Therefore, the fins are provided on all of the radiation pins 10 described above.
When 12 is provided and when this cross-sectional area is made larger than necessary without providing the fins 12 to the heat dissipation pin 10, the heat dissipation area increases, but the number of the heat dissipation pins 10 is limited in the limited area of the heat dissipation plate 14. As a result, the thermal resistance may be increased as a result.

Further, a fin 12 is provided or a heat radiation pin
Occupancy of the convection input surface area (ratio of the area of the cooling part 10 to the area of the heat dissipation plate 14 where the convection collides) may increase due to the increase in size of 10 itself, and thus convection cannot be effectively used.

In other words, when the fins 12 or the heat radiating pins 10 are unnecessarily dense in the limited heat radiating plate 14 area, "air ventilation" is deteriorated and the heat radiating ability of the heat sink is reduced.

Further, instead of providing the fins 12, the heat dissipation pin 10
Although the heat radiation area increases when the number of the heat radiation pins is increased, it is inevitable that the individual cross-sectional area of the heat radiation pin 10 must be reduced. Even if the number of the heat radiation pins 10 can be increased in place of reducing the cross-sectional area due to the reduced function, the heat radiation effect corresponding to this cannot be obtained.

Further, since the fins 12 are not provided, the convection output surface area occupation ratio (ratio of the area of the cooling part 10 to the area of the heat dissipation plate 14 through which convection escapes) does not become a very large value, and convection cannot be used effectively. .

[0017]

In order to solve the above-mentioned problems, in the present invention, the radiation pins attached to the radiation plate are provided with the convection input surface area occupancy rate and the convection output surface area occupancy rate, the total surface area of the front radiating pin, and the front surface. Calculate the optimal size and number of heat sink mounting space from the thermal resistance of the heat dissipation pin.

When the fins are provided on the heat radiating pin, the fin shape may be well ventilated in consideration of the convection input surface area occupation ratio and may be provided at a position lower than the tip of the heat radiating pin. Further, it is conceivable to use a heat pipe described later as the heat dissipation pin.

[0019]

With the above means, the convection input surface area occupation rate and the convection output surface area occupation rate have an optimum relationship, and a heat sink with which an efficient cooling effect can be obtained can be obtained.

Further, the heat radiating pin 10 is a heat pipe which will be described later, and the fin provided on the heat radiating pin 10 is formed in a shape that is well ventilated in consideration of the convection input surface area occupation ratio. If it is provided, the convection input surface area occupation rate can be further reduced, and the heat sink can obtain an efficient cooling effect.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention, and FIG. 2 shows a view of the heat sink of FIG.
In FIGS. 1 and 2, a heat dissipation pin 10 is fixed to a heat dissipation plate 14 made of a metal material such as aluminum, and the heat dissipation pin 10 is provided with fins having a well-ventilated shape in consideration of a convection input surface area occupation ratio. It includes some pins (hereinafter referred to as "radiating pins with fins 11").

Further, in the present invention, the convection is inputted from the upper part of FIG.
Is output along the upper surface of.

In the heat sink of this embodiment, a radiation pin 10 having a diameter of 3 mm is attached to a 4-inch square heat dissipation plate 14, and the upper surface of a multi-chip module (not shown) is closely attached to the lower part of the heat dissipation plate 14. .

Further, the heat dissipation plate 14 is provided with a heat dissipation plate mounting hole 25 for mounting the heat sink to the multi-chip module. Since the heat dissipation plate mounting holes 25 are conventionally arranged at the four corners of the heat dissipation plate 14, only a part of the periphery of the heat dissipation plate mounting hole 25 is covered with the heat dissipation pin 10, but in the present invention, the heat dissipation plate mounting hole 25 is used. Is arranged at a position where the entire circumference is covered with the heat dissipation pin 10 or the finned heat dissipation pin 11.

In the above embodiment, in order to improve the heat dissipation effect, the heat dissipation pin 10 is a heat pipe described later, which makes the present invention more effective than the usual heat dissipation pin.

The heat pipe is a medium in which a gas layer and a liquid layer called a working fluid, which are likely to change alternately, are enclosed in a sealed container, and the heat is transported by a flow by mediating the latent heat of the phase change. Yes, a large amount of heat can be transported with a small temperature difference.

The most efficient cooling effect can be obtained by determining the size and number of the radiation pins 10 attached to the radiation plate 14 and the number of finned radiation pins 11 by the following means.

The above means means that the convection input surface area occupancy is "Si", the convection output surface area occupancy is "So", and the total surface area of all the radiation pins (in case of the finned radiation pin 11, the surface area of this fin). Is defined as “S” and the thermal resistances of all the radiation pins are defined as “Rp”.

## EQU1 ## F = (So × S) / (Si × Rp) Here, "Si" and "So" are the following two, respectively.
And can be obtained by the equation 3.

## EQU2 ## Si = (ip × N1 + if × N2) / (a ×
b) Here, “ip” is the upper surface area of the heat dissipation pin 10 shown in FIG.
“If” is the top surface area of the finned heat dissipation pin 11, “N1”
Is the number of radiating pins 10 without fins, and “N2” is the number of radiating pins 11 with fins.

## EQU3 ## So = (op × n1 + of × n2) / (b ×
h) Here, “op” is the cross-sectional area of the side surface of the heat dissipation pin 10 shown in FIG. 3, “of” is the cross-sectional area of the side surface of the finned heat dissipation pin 11, and “n1” is the side surface of the heat sink as shown in FIG. Seen from the number of heat dissipation pins 10 without a row of fins,
Similarly, "n2" is the number of finned heat radiation pins 11 in one row when the heat sink as shown in FIG. 3 is viewed from the side.

The larger the value of the heat dissipation effect coefficient "F" obtained by the above means is, the more efficiently the heat sink can obtain a cooling effect. Therefore, the size of the heat dissipation pin 10 is set so that this "F" becomes the largest. The number and the number of finned heat radiation pins 11 may be determined.

Further, the optimum ratio of the finned radiating pin 11 and the finless radiating pin 10 can be calculated by the above means.
If the range in which the heat dissipation pin 10 can be arranged on the heat dissipation plate 14 is limited by the mounting holes 25 and the like as described above, the heat dissipation pin 10 cannot necessarily be arranged in the above calculation result, but in this case, the ratio should be as close as possible to the above calculation result. The heat dissipation pin 10 and the finned heat dissipation pin 11 may be determined.

In the above embodiment, the fin of the finned heat radiating pin 11 covers the entire pin, but it may be provided at a position lower than the tip of the pin as shown in FIG. It is formed by transforming the outer shape of 10,
This is a single component fin as described in "Prior Art".
The radiation pin 10 may be covered as 12.

In the above embodiment, the heat pipe is used as the heat radiating pin 10. However, if this is not used, the pin diameters of the heat radiating pin 10 and the fin radiating pin 11 are reduced as shown in FIG. In order to make it easier (to widen the convection input surface), the upper ends of the heat dissipation pin 10 and the finned heat dissipation pin 11 are bent and spread out toward the end face of the heat dissipation plate 14 to reduce or eliminate the finned heat dissipation pin 11
Can be satisfied.

[0033]

EFFECTS OF THE INVENTION In a multi-chip module using the heat sink having the above-mentioned structure and having a heating power of 100 to 150 watts, it is experimentally required to suppress the temperature rise within 20 ° C., and the heat dissipation pin obtained by the above means. The 10 provides the best cooling in a limited heat sink space, while at the same time improving heat sink reliability.

Further, if the heat dissipating pin 10 is a heat pipe and the fins are provided at positions lower than the tips of the pins, a more efficient cooling effect can be obtained.

Further, by disposing the heat dissipation plate mounting hole 25 at a position where the entire circumference is covered with the heat dissipation pins 10, it becomes possible to send convection to a larger number of the heat dissipation pins 10.

[Brief description of drawings]

FIG. 1 is a top view of a heat sink showing an embodiment of the present invention.

FIG. 2 is a side view of the heat sink shown in FIG. 1 as seen in a direction of an arrow in the AA cross section.

FIG. 3 is a side view of the heat sink of the present invention in which the fins are located lower than the tips of the heat dissipation pins.

FIG. 4 is a side view of the heat sink of the present invention in which the upper end portion of the entire heat dissipation pin is bent and widened toward the end surface of the heat dissipation plate.

FIG. 5 is a top view of a heat sink including fins on all of the heat dissipation pins.

6 is a side view of the heat sink shown in FIG. 4 as seen in the direction of the arrow along the AA cross section.

FIG. 7 is a top view of a heat sink in which a radiation pin has a large cross-sectional area.

FIG. 8 is a side view of the heat sink shown in FIG. 6 as seen in the direction of the arrow along the AA cross section.

FIG. 9 is a top view of a heat sink in which the number of heat dissipation pins is increased in the same area as a conventional heat dissipation plate.

FIG. 10 is a side view of the heat sink shown in FIG. 7 as seen in the direction of the arrow along the line AA.

FIG. 11 is a top view of a conventional heat sink.

12 is a side view of the heat sink shown in FIG. 10 as seen in the direction of the arrow along the AA cross section.

[Explanation of symbols]

 In the drawings, the same reference numerals indicate the same or corresponding parts. 10 radiating pin 11 radiating pin with fin 12 radiating fin 14 radiating plate 25 radiating plate mounting hole

Claims (3)

[Claims] 1. A convection input surface area occupation ratio (Si) in a heat sink including a heat dissipation plate and a plurality of heat dissipation pins.
And the convection output surface area occupancy rate (So), the total surface area of all radiating pins (S), and the thermal resistance (Rp) of all radiating pins determine the radiating effect coefficient (F). , A heat sink whose shape is determined. 2. The heat sink according to claim 1, wherein
A heat sink that uses a heat pipe for the radiation pin. 3. The heat sink according to claim 1, wherein the radiation fin is provided at a position lower than the tip of the radiation pin.