JPH01204498A - Heat sink for forced cooling - Google Patents

Abstract

PURPOSE:To improve heat sink characteristic by providing a rectangular flat plate at an angle for generating a turbulent flow behind the plate with respect to a direction of feeding cooling liquid between adjacent fins. CONSTITUTION:A rectangular flat plate 5 provided between a plurality of fins 3 on a flat metal plate 2 is disposed at a predetermined angle theta with respect to a direction of feeding cooling fluid. When the fluid 4 collides with the plate 5, a boundary layer on the plate 5 is reduced in thickness, a turbulent flow 6 is generated at the rear of the plate 5, and Raynolds number is increased. Accordingly, the heat sink amount of the heat sink can be increased. When an angle theta of the plate 5 with respect to a direction of feeding cooling fluid is altered, the magnitude of the flow 6 is varied. Therefore, the heat sink amount of the heat sink can be maximized by regulating the angle theta of the plate 5 with respect to a direction of feeding the fluid. Thus, heat sink characteristic can be improved.

Description

[Detailed description of the invention] 〔overview〕 Regarding forced cooling heat sinks.

The purpose is to increase the amount of heat transfer and improve the heat dissipation characteristics of the heat sink.

In a forced cooling heat sink that has multiple fins installed parallel to each other on a flat metal plate, turbulence occurs between each adjacent fin in the direction in which the cooling fluid flows. It is constructed so that five rectangular flat plates are provided at an angle.

[Industrial application field]

The present invention relates to a heat sink for forced cooling.

Generally, semiconductor devices have a maximum allowable temperature from the viewpoint of characteristics or reliability (in the case of St).

Maximum allowable bonding temperature is 75-200°C). Furthermore, from the standpoint of noise margin, there is a permissible range for temperature differences within a semiconductor device or between semiconductor devices.

It is necessary to cool the semiconductor devices so that each semiconductor device operates stably below these allowable values.

Cooling of semiconductor devices can be roughly divided into natural cooling.

There are three types of cooling: forced cooling and evaporative cooling, but forced cooling is the most widely used because of the abundance of refrigerants, economy, and reliability.

The present invention relates to a heat sink used for this forced cooling.

[Conventional technology]

FIG. 3 is a diagram showing a conventional example.

In FIG. 3, 31 is a substrate, 32 is a metal flat plate, 3
3 is a fin, and 34 is a cooling fluid.

Various devices such as transistors and LSIs are mounted on the substrate 31.

The metal flat plate 32 is made of a metal with good thermal conductivity, such as AI or Cu, and is fixed to the surface of the substrate 31.

The fins 33 are made of a metal with good thermal conductivity, such as AI or Cu, and have a rectangular shape, and a plurality of fins 33 are arranged in parallel to each other on the flat metal plate 32 .

The cooling fluid 34 consists of air, water, and other coolants.

The operation of the conventional example shown in FIG. 3 will be explained below.

Heat generated from various devices such as transistors and LSIs mounted on the substrate 31 is first transmitted through the substrate 31 to a metal flat plate 32 fixed to the surface of the substrate 31.

The heat transferred to the metal flat plate 32 is transferred to the metal flat plate 32.
This is transmitted to the fins 33 planted on top of the fins 33.

On the other hand, a cooling fluid 34 made of air, water, or other coolant is forced to flow through the plurality of fins 33 parallel to the rectangular surfaces of each fin 33 .

The heat transferred to the fins 33 is transferred to this cooling fluid 34. Thereby, heat generated from various devices such as transistors and LSIs mounted on the substrate 31 is dissipated.

[Problem to be solved by the invention]

-C, the amount of heat transferred from the heat sink to the cooling fluid is proportional to the temperature difference between the heat sink and the cooling fluid and the surface area of the heat sink.

To keep various devices mounted on the board, such as transistors and LSIs, below a certain temperature.

Since it is not possible to increase the temperature difference between the heat sink and the cooling fluid, in order to increase the amount of heat dissipated by the heat sink, it is necessary to make the heat sink itself larger and increase the area of the fins, or to increase the flow rate of the cooling fluid. There is.

However, increasing the size of the heat sink itself is
This is difficult because the size of the semiconductor device increases, and increasing the flow rate of cooling fluid requires either increasing the size of the cooling fan or increasing its power, which is also difficult to achieve. It is.

Therefore, with conventional heat sinks, there has been a problem in that it is difficult to increase the amount of heat dissipation.

An object of the present invention is to provide a forced cooling heat sink that has the same shape and the same material as a conventional heat sink, has the same flow rate of cooling fluid as a conventional heat sink, and can dissipate more heat than a conventional heat sink. shall be.

[Means to solve the problem]

The present invention provides a forced cooling heat sink having a plurality of fins installed in parallel to each other on a flat metal plate,
By configuring a rectangular flat plate between adjacent fins at an angle that generates turbulence behind the cooling fluid flow direction, the amount of heat transfer is increased and the heat dissipation characteristics of the heat sink are improved. It is intended to improve

FIG. 1 is a configuration diagram of one embodiment of the present invention.

A means for solving one problem will be explained using FIG.

In FIG. 1, 1 is a substrate, and 2 is a metal flat plate.

3 is a fin, 4 is a cooling fluid, and 5 is a rectangular flat plate.

Various devices such as transistors and LSIs are mounted on the substrate l.

The metal flat plate 2 is made of a metal with good thermal conductivity, such as Al or Cu, and is fixed to the surface of the substrate 1.

The fins 3 are made of a metal with good thermal conductivity, such as At or Cu, and have a rectangular shape, and a plurality of fins are planted parallel to each other on the flat metal plate 2.

The cooling fluid 4 consists of air, water, and other coolants.

The rectangular flat plate 5 is attached between the two individual fins 3 at an angle relative to the direction in which the cooling fluid flows so as to generate turbulent flow behind it. What is the material?

^1. A metal with good thermal conductivity such as Cu is desirable.

[Effect]

Generally, the heat i transferred from the heat sink to the cooling fluid
H can be expressed by a linear equation. Namely.

H=Q・ΔT・S・α (11 here.

Q: Heat transfer coefficient ΔT: Temperature difference between the heat sink and the cooling fluid S: Surface area of the heat sink α: Constant.

(In Equation 11, S and α are values determined by the shape and material of the heat sink, so when considering a heat sink that has the same shape and is made of the same material as a conventional heat sink,
The values of S and α cannot be changed.

Also, since the device must be operated below a certain temperature, the temperature difference ΔT between the heat sink and the cooling fluid is
The value cannot be changed either.

Therefore, in order to increase the heat iH transferred from the heat sink to the cooling fluid, the value of the heat transfer coefficient Q must be increased.

The heat transfer coefficient Q is expressed by a linear equation in a fluid.

Namely.

γ Q-β・(R,) (21 where.

β, x constant Ro: Reynolds number It is.

In equation (2), the Reynolds number R is a value representing the degree of turbulence in the fluid, and increases as the turbulence increases. Therefore, it can be seen that in order to increase the heat transfer coefficient Q, it is sufficient to cause turbulence in the fluid.

From the above, the same shape as the conventional P1-sink,
The heat sink is made of the same material and the flow rate of the cooling fluid is the same as conventional ones.In order to make the heat dissipation characteristics of a forced cooling heat sink larger than that of conventional ones, it is necessary to create turbulence in the cooling fluid. I understand that.

The present invention has been made based on one or more findings.

FIG. 2 is an explanatory diagram of the operation of the present invention.

Hereinafter, the present invention will be described in detail with reference to FIG.

The forced cooling heat sink of the present invention includes a metal flat plate 2
A rectangular flat plate 5 is provided between a plurality of fins 3 that are set up parallel to each other.

This rectangular flat plate 5 forms a certain angle θ with respect to the direction in which the cooling fluid flows.

When the cooling fluid 4 collides with the rectangular flat plate 5, the boundary layer on the rectangular flat plate 5 becomes thin, and a turbulent flow 6 is generated behind the rectangular flat plate 5. This increases the above-mentioned Reynolds number R, so that the amount of heat dissipated from the forced cooling heat sink can be increased.

By changing the angle θ that the rectangular flat plate 5 makes with respect to the direction in which the cooling fluid flows, the magnitude of the turbulent flow 6 changes. Therefore, the heat dissipation characteristics of the forced cooling heat sink can be maximized by adjusting the angle θ that the rectangular flat plate 5 makes with respect to the direction in which the cooling fluid flows.

〔Example〕

FIG. 1 is a block diagram of one embodiment of the present invention.

In Fig. 1, ■ is a substrate, and 2 is a flat metal plate.

3 is a fin, 4 is a cooling fluid, and 5 is a rectangular flat plate.

Various devices such as transistors and LSIs are mounted on the substrate 1.

The metal flat plate 2 is made of a metal with good thermal conductivity, such as aluminum or Cu, and is fixed to the surface of the substrate 1.

The fins 3 are made of a metal with good thermal conductivity, such as AI or Cu, and have a rectangular shape, and a plurality of fins are planted parallel to each other on the flat metal plate 2.

The cooling fluid 4 consists of air, water, and other coolants.

A rectangular flat plate 5 is mounted between two individual fins 3 at an angle such that turbulence is generated in the cooling fluid 4. The material is preferably a metal with good heat conduction, such as AI or Cu.

Seven examples will be described below.

The rectangular flat plate 5 is A! , is a single plate made of a metal with good thermal conductivity such as Cu, and is provided through a through hole formed in the fin 3.

This rectangular flat plate 5 forms a certain angle with respect to the direction in which the cooling fluid 4 flows.

When the cooling fluid 4 collides with the rectangular flat plate 5, the boundary layer on the rectangular flat plate 5 becomes thinner, and turbulent flow occurs behind the rectangular flat plate 5. This increases the above-mentioned Reynolds number, so that the amount of heat dissipated by the forced cooling heat sink of this embodiment can be increased.

By changing the angle that the rectangular flat plate 5 makes with respect to the direction in which the cooling fluid 4 flows, the magnitude of the turbulence changes.

Therefore, the heat dissipation characteristics of the two forced cooling heat sinks can be maximized by adjusting the angle that the rectangular flat plate 5 makes with respect to the direction in which the cooling fluid 4 flows.

According to experimental results, when the angle between the rectangular flat plate 5 and the direction in which the cooling fluid 4 flows is 20 to 45 degrees, the heat radiation amount of the forced cooling heat sink of this embodiment is maximized.

In this embodiment, only one rectangular flat plate 5 is provided, but
A plurality of sheets may be provided.

In addition, in the case of the embodiment in which only one rectangular flat plate 5 is provided, a through hole is formed in the fin 3 and the fins 3 are inserted through the through hole, but the rectangular flat plate 5 is individually inserted without forming a through hole in the fin 3. It may be divided into two parts and adhered to the fins 3.

〔Effect of the invention〕

In the present invention, a rectangular flat plate is provided at an angle such that turbulent flow occurs behind the direction in which cooling fluid flows between a plurality of fins installed in parallel on a flat metal plate. Therefore, turbulence occurs in the cooling fluid flowing between the fins, which increases the amount of heat transfer and improves the heat dissipation characteristics of the forced cooling heat sink.

According to the forced cooling heat sink of the present invention, the heat dissipation characteristics are improved by about 30% compared to a conventional heat sink having the same shape, the same material, and the same cooling fluid flow rate.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the present invention, and FIG. 3 is a diagram showing a conventional example. In Figure 1, 1: Substrate 2: Metal flat plate 3: Fin 4: Cooling fluid 5: Rectangular flat plate

Claims (1)

[Claims] In a forced cooling heat sink having a plurality of fins (3) installed in parallel to each other on a flat metal plate (2), a cooling fluid is provided between each adjacent fin (3). (4) A heat sink for forced cooling, characterized in that a rectangular flat plate (5) is provided at an angle that generates turbulence behind the rectangular flat plate (5) with respect to the direction in which the heat sink flows.