JPH0650398U - Heat sink - Google Patents

Abstract

(57) [Abstract] [Purpose] It is intended to provide a heat sink that is effective in protecting the other circuits by destroying the heat generating element when the heat generating element heats up abnormally and becomes high temperature. . A heat dissipation plate, to which a heat generating element is attached via an insulating material, is fixed to a printed circuit board, and a safety plate whose shape changes according to a temperature rise of the heat generating element is used as the insulating material and the heat dissipation plate. It is characterized by being provided between.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat dissipation plate having a heat generation element attached and fixed to a printed circuit board, and particularly to a heat dissipation plate for preventing heat generation elements such as transistors and diodes from being used in an abnormally high temperature state. Regarding

[0002]

[Prior art]

 In the conventional heat sink, as shown in FIG. 3, when mounting the heat generating element 2 such as a transistor, a diode or a hybrid IC on the heat sink 1, an insulating material 3 is provided between the heat sink 1 and the heat generating element 2. The heat generating element 2 is fixed to the heat radiating plate 1 by the elastic force of the fastener 4 attached to the heat radiating plate 1. At this time, the heat generating element 2 is in contact with the heat sink 1 via the insulating material 3. Tongues 5 and 5 are formed in a lower portion of the heat sink 1 at right angles to the heat sink 1, and screws 6 and the like are screwed to the tongue 5 through the printed circuit board 7 to attach it to the printed circuit board 7. The heat radiating plate 1 is fixed, and the lead terminals 8 of the heat generating element 2 are soldered to the pattern of the printed circuit board 7 to electrically connect them. Here, for example, the transistors and diodes used in the RCC converter circuit are attached to the heat sink 1 so as to have a large contact area so as to efficiently conduct and radiate heat. Normally, when a transistor is operated, Joule heat is generated at the junction due to power loss (collector loss). This Joule heat raises the temperature of the junction, and when it rises above a certain limit temperature, the characteristics of the transistor change and cannot return to the original characteristics. The maximum limit temperature is said to be about 80 to 90 ° C for germanium transistors and about 150 to 180 ° C for silicon transistors.

[0003]

[Problems to be solved by the device]

 If an abnormality occurs in the heat generating element 2 attached to the heat sink and the heat generating element 2 generates heat, an overheat protection circuit may be added. If not, it may be due to an abnormal high temperature condition. It could be used with the changed characteristics, adversely affecting other circuits, and causing malfunction.

The present invention has been made in view of the above problems of the prior art, and is effective for destroying the heat generating element and protecting other circuits when the heat generating element abnormally generates heat and becomes high in temperature. The purpose is to provide a heat sink.

[0005]

[Means for Solving the Problems]

 The heat dissipation plate according to the present invention is a heat dissipation plate in which a heat generating element is attached via an insulating material and is fixed to a printed board, and a safety plate whose shape changes according to the temperature rise of the heat generating element is provided. It is characterized in that it is provided between the insulating material and the heat sink.

[0006]

[Action]

 According to the heat dissipation plate of the present invention, the heat generating element is attached to the heat dissipation plate with the safety plate interposed as described above. This safety plate is made of, for example, a shape memory alloy, and is formed so as to be transformed into a corrugated plate when the temperature reaches a predetermined temperature of 100 to 200 ° C. Here, when the heat generating element attached to the heat sink rises to a high temperature in an abnormal state where the safety plate is deformed, the safety plate is transformed into a corrugated plate in response to the temperature, and the heat generating element with respect to the heat dissipation plate is The contact area is reduced to reduce the amount of conduction heat transfer. Therefore, the heat-generating element does not conduct its heat to the heat sink, and the temperature rises rapidly and reaches the destruction temperature to destroy it. As a result, other circuits are protected and malfunction of the circuit is prevented. .

[0007]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views for explaining an embodiment of a heat sink according to the present invention. In the present embodiment, parts corresponding to those of the conventional example are designated by the same reference numerals. As shown in FIG. 1, the heat dissipation plate 1 of the present embodiment is configured by providing an insulating material 3 between the heat generating element 2 and a safety plate 9 between the insulating material 3 and the heat dissipation plate 1. ing. Tongues 5 and 5 are formed in a lower portion of the heat dissipation plate 1 at right angles to the plate surface, and a screw 6 or the like is screwed to the tongue 5 through the printed circuit board 7 so that the tongue 5 is attached to the printed circuit board 7. The heat sink 1 is fixed. The heat generating element 2 is attached to the heat radiating plate 1 by fixing the heat generating element 2 to the heat radiating plate 1 by the elastic force of the fastener 4 attached to the heat radiating plate 1. Then, the lead terminals 8 of the heat generating element 2 are electrically connected by being soldered to the pattern of the printed board 7.

As shown in FIG. 2, the safety plate 9 is made of a shape memory alloy and formed into a flat plate at room temperature (FIG. 2 (a)). When the temperature of the heat generating element 2 rises to a predetermined temperature of 100 to 200 ° C., the safety plate 9 is transformed into a corrugated plate shape (FIG. 7B). The deformation of the safety plate 9 reduces the contact area of the heat generating element 2 with respect to the heat radiating plate 1, reduces the heat radiation due to conduction heat transfer, and the heat generating element 2 rapidly becomes hot and is destroyed. The safety plate 9 may be provided simply by inserting it, by screwing or adhering it, or by attaching an insulating material to the heat radiating plate.

In the above description, the example of the type in which the heat dissipation plate is fixed with screws is described. However, the heat dissipation plate is not limited to the above embodiment, and for example, a locking claw is formed on the main body part and the locking claw is formed. It may be inserted into the hole of the printed board and fixed to the printed board by a clinch type in which the projection of the locking claw presses and fixes the hole wall. Also, the safety plate has been described as an example formed of a shape memory alloy, but may be bimetal. In addition, the presence or absence of a heat sink, a safety plate, and an insulating material are not limited to those in the above embodiment. The point is that between the heat generating element and the heat sink to which it is attached, when the heat generating element becomes hot, it deforms to reduce the contact area with the heat sink and reduce the amount of heat transferred and heat to raise the heat generating element to high temperature. It may be a flat member that is to be destroyed.

[0010]

[Effect of device]

 As described above, according to the heat dissipation plate of the present invention, when the heat generating element rises to an abnormally high temperature, the safety plate is deformed and the contact area of the heat generating element to the heat dissipation plate is reduced to reduce the conductive heat dissipation, The heat generating element is heated to a high temperature and destroyed. This prevents the heat generating element from being used in an abnormally high temperature state, protecting other circuits and preventing malfunctions.

[Brief description of drawings]

FIG. 1 is a perspective view illustrating an embodiment of a heat sink according to the present invention.

2 is a sectional view taken along the line AA in FIG. 1, where (a) shows a normal state and (b) shows a high temperature state.

FIG. 3 is a perspective view showing a conventional heat sink.

[Explanation of symbols]

 1 Heat sink 2 Heat generating element 7 Printed circuit board 9 Safety plate

Claims (1)

[Scope of utility model registration request] 1. A heat radiating plate having a heat generating element attached thereto via an insulating material and fixed to a printed circuit board, wherein a safety plate whose shape changes in accordance with a temperature rise of the heat generating element radiates heat to said insulating material. A heat radiating plate characterized by being provided between the plate and the plate.