JPH03187251A - Heat radiator - Google Patents

Abstract

PURPOSE:To radiate heat easily from an active device by employing an auxiliary heat radiation board thermally coupled with a main heat radiation board, arranged in a cover, and exposed to the outside. CONSTITUTION:An auxiliary heat radiation board 24 having a holding fork 26 is held, in heat transmitting relation, at the end of a main heat radiating board 16 secured with an active device 14 which is fixed to a circuit board 12. The main heat radiation board 16 is held vertically on the circuit board 12, whereas the auxiliary heat radiation board 24 is held on the bottom of the circuit board 12 through the holding fork 26. The auxiliary heat radiation board 24 constitutes a part of a cover 10 surrounding the circuit board 12. At this time, the holding part 26 of the auxiliary heat radiation board 24 is inserted, in heat transmitting relation, into the main heat radiation board 16 in order to transmit heat from the main radiation board 16 to the auxiliary radiation board 24 and to radiate the heat therefrom. By such arrangement, heat can easily and positively be radiated from an active device.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat dissipation section r! The present invention relates to a so-called heat sink that effectively radiates heat generated by an active device that generates a large amount of heat, such as a power transistor connected on a circuit board.

[Prior art and its problems]

BACKGROUND OF THE INVENTION As semiconductor device technology such as integrated circuits (ICs) progresses, electronic equipment becomes increasingly denser and faster, and as a result, generates a large amount of heat. Efficiently dissipating such heat to lower the temperature of active devices is essential for improving the reliability of electronic circuits. As electronic devices become smaller, the problem of heat generation becomes more apparent. In particular, when it is necessary to cover electronic circuits, for example in engine control units of automobiles, it is an urgent issue how to solve the heat generation problem of various active devices used in the electronic circuits.

Conventionally, active devices are generally attached to a heat sink made of metal such as aluminum using screws or other means to radiate heat naturally. However, if such a heat sink is housed within a narrow cover, the ambient temperature inside the cover will rise, so it will not function effectively. In such a case, it may be possible to attach only the active device that generates heat externally and interconnect it with the main body using lead wires, but connecting it at a physically distant location will significantly slow down the operation speed. In addition to the problems of noise and the like, there is also the problem that it cannot be applied to removable modular electronic circuits that are connected to the main body of electrical equipment via connectors.

[Purpose of the invention]

Therefore, it is an object of the present invention to provide a novel auxiliary heat radiating device which is detachably attached to a main heat radiating plate to which an active device (heating element) is fixed, and which improves the heat radiating effect of the main heat radiating plate.

Another object of the present invention is to provide a novel heat radiating device that can easily and reliably radiate heat generated by an active device substantially surrounded by a cover.

[Summary of the invention]

The heat dissipation device of the present invention comprises an auxiliary plate-like part having a relatively large plate-shaped part that is clamped to the end of the main heat dissipation plate to which the active device attached to the circuit board is fixed, and has a fork-like clamping part attached in a heat conductive manner. Equipped with a heat sink.

The main heat sink is held perpendicularly to the circuit board, and the auxiliary heat sink is preferably held on the bottom surface of the circuit board via fork-shaped clamps. This auxiliary heat sink forms part of a cover surrounding the circuit board. Such a covered circuit board and the electronic circuit formed thereon are preferably modules connected to the electronic device body via electrical connectors. The auxiliary heat radiating plate forming the bottom surface of this module is fixed to a heat radiating member such as a shunt of the main body of the electronic device with, for example, screws.

In addition, if the circuit board to which the active device is connected is completely surrounded by an insulating cover, etc., an elongated opening is formed in the outer wall of the cover corresponding to the end of the main heat sink inside the cover, and the By inserting the holding portion of the auxiliary heat sink into the main heat sink and coupling them in a heat conductive manner, the heat of the main heat sink is conducted to the auxiliary heat sink outside the cover and radiated.

〔Example〕

The present invention will now be described in detail with reference to the accompanying drawings, which illustrate preferred embodiments of the invention.

FIG. 1 is an exploded perspective view showing a preferred embodiment of a heat dissipation device according to the present invention. FIG. 1(A) shows the upper cover lO,
FIG. 1(B) shows the main body of the electronic circuit, and FIG. 1(C) shows the bottom cover/auxiliary heat dissipation part 24.

The main body includes a circuit board 12 and an active device 14 that is a heat generating element such as a plurality of power transistors connected to the circuit board 12 by wiring.
and a main heat dissipation plate 16 made of, for example, a rectangular thick aluminum plate, which is coupled to these active devices 14 in a thermally conductive relationship. Although not shown, it goes without saying that a large number of active and passive circuit devices (components) other than these active devices 14 are connected to the circuit board 12. In this embodiment, the main heat sink 16 is mounted in a substantially perpendicular relationship to the circuit board 12. A fixing block 18 for interconnecting (interfacing) with an external circuit is fixed to the front (left) end of this circuit board 12 by well-known means, and a power contact tab 20 is attached to a vertical wall 24 of this fixing block 18.
A large number of signal contacts 22 are arranged in a fixed manner. Although not shown, these contacts 20, 22 are interconnected with external circuitry by separate glue septacle type connectors. It should be noted that the active devices 14 are attached to both ends of the main heat sink 16 with sufficient space provided.

The upper cover 10 has a generally rectangular parallelepiped shape with a low height and an open bottom and front surface, and may be made of metal, plastic, or plastic coated with a metal film. The main body, on which each electronic component is assembled and wired, is housed in the upper cover 10 while being accurately positioned by a guide groove (not shown) or the like.

However, as mentioned above, since the electronic unit is miniaturized by surrounding the main body with a low-profile upper cover, the volume of the cover lO is limited, and even if the main heat sink 16 is used, the heat cannot be sufficiently radiated. Therefore, the inside of the cover 10, especially the active device 14, becomes high temperature. Therefore, in the present invention, as shown in FIG.
As shown in C), below the circuit board 12, that is, as the bottom surface (wall) of the cover 10, a bottom plate/auxiliary heat sink 24, which can be a tin-plated iron plate or an aluminum plate, is used. The auxiliary heat radiating plate 24 has, for example, two fork-shaped elastic clamping parts 26, which are formed with slits 30 to form a fork shape, and are elastically clamped to both ends of the main heat radiating plate 16. In this way, the auxiliary heat radiating plate 24 is thermally coupled to the auxiliary heat radiating plate 24, and the auxiliary heat radiating plate 24 is mechanically coupled to other parts, that is, the main body and the cover part 10. This auxiliary heat sink 24
has a sufficient surface area and is exposed to the outside, so that the heat of the high-temperature main heat radiating plate 16 can be effectively conducted to the outside via the clamping portions 26 and can be radiated and cooled. Furthermore, in order to effectively radiate heat from this electronic unit, an auxiliary heat radiating plate 24 is installed on the equipment that uses this electronic unit, such as the body of a vehicle.
Fix by direct contact. For this purpose, the auxiliary heat sink 24 has holes 28 for attaching screws and the like. In order to maximize the effect of the auxiliary heat sink 24, the thickness of the clamping portion 26 is made sufficiently thick to increase the contact area with the end of the main heat sink 16, and
It is preferable to impart elasticity so that the material can be held with sufficient contact pressure. Further, it is preferable that the width of the clamping portion 26 is sufficiently wide.

FIG. 2 is a perspective view showing the assembled state of the electronic unit shown in FIG. Notched. In this embodiment, each clamping portion 26 has a slit 3.
0 is formed to sandwich both sides of each end of the main heat sink 16. However, if the main heat sink 16 is relatively short and thick enough, a slit 30 is formed in each clamping portion 26. without forming a concave groove or simply forming a concave groove, a pair of clamping parts 26
It is also possible to contact and hold the end surface of the main heat sink 16 between them.

Furthermore, if there is a gap in the middle part of the main heat sink 16 in addition to both ends, three or more clamping parts 26 may be formed so that many of the auxiliary heat sinks 24 can be inserted through the openings of the circuit board. Clamping part 2
6 may be combined with heat conduction. In this case, the holding portion 26 may be formed by punching a plate-shaped portion of the auxiliary heat sink 24.

FIG. 3 is an exploded perspective view showing another embodiment of the heat dissipation device according to the present invention. FIG. 3(B) shows the main body of the electronic unit, which is basically the same as the electronic unit shown in FIG. 1, except that substantially the entire surface is surrounded by a cover of 10° except for the connector portion at the front end. In particular, electronic control units for vehicles and the like require a completely enclosing configuration for waterproofing, drip-proofing, dust-proofing, electromagnetic shielding, and the like. In such a configuration, the temperature rise inside the cover 10° increases further.

Therefore, in this embodiment, an elongated slot 32 is formed in a part of the cover 10°, for example, on the upper wall surface, in alignment with the end of the main heat sink (not shown) inside the cover 10'.

A pair of clamping portions 36 of an auxiliary heat sink 34 as shown in FIG.
Thermal bonding is performed between the two. The dimensions of this auxiliary heat sink 34 can be freely designed as needed, but since the cover (or case) is exposed to the outside by 10°, the heat of the main heat sink 16 can be effectively conducted and radiated to the outside. Lower the temperature inside the cover 10° to a safe allowable temperature.

When the auxiliary heat dissipation plate 34 shown in FIG. 3(A) is attached to the top surface of the cover 10' of the electronic unit shown in FIG. 3(B), only the plate thickness needle protrudes to the outside of the cover 10'. Such a slight protrusion is not a problem in most practical situations, but if it becomes a problem, the thickness of the earthen wall surface of the cover 10'' should be made complementary thinner in accordance with the shape of the auxiliary heat sink 34. It may also be formed to have a substantially-shaped upper surface.

Incidentally, since the slot 32 of the cover 10' is substantially completely closed when the clamping portion 36 of the auxiliary heat radiating plate 34 is inserted, waterproofness, dustproofness, etc. are maintained sufficiently for practical purposes.

Further, the auxiliary heat sink 34 is not limited to the top surface, but may be placed on both side surfaces, or may be placed on the bottom surface if necessary.

〔Effect of the invention〕

As understood from the above description, the heat sink of the present invention uses an auxiliary heat sink that is thermally coupled to the main heat sink inside the cover (case) and exposed to the outside, making the electronic unit compact and waterproof. It is possible to effectively reduce the internal temperature rise even if it is formed as follows. Moreover, the auxiliary heat sink can also be made a part of the cover of the electronic unit.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of an embodiment of an electronic unit using the heat dissipation device of the present invention, Fig. 2 is a partially cutaway perspective view showing the assembled state of Fig. 1, and Fig. 3 is the heat dissipation device of the present invention. FIG. 3 is an exploded perspective view showing another embodiment of the present invention. 10. IO', Cover 12. ,,Circuit board 14,,,Active device (heating element) 16,,,Main heat sink (member) 24,34,,,Auxiliary heat sink (member) 26,36,
,, clamping part 32. ,,Aperture IG3

Claims (3)

[Claims] (1) at least one clamping part clamped at an end of a main heat sink mounted substantially perpendicularly to the circuit board in a thermal conductive relationship with at least one active device connected to the circuit board; A heat dissipation device comprising: an auxiliary heat dissipation section integrally formed with the section; (2) In a heat dissipation device for at least one active device connected to a circuit board substantially enclosed within a cover, the main heat dissipation member is attached substantially perpendicularly to the circuit board in a thermally conductive relationship with the active device. and a plate-shaped auxiliary heat radiating member having a clamping portion that is removably held at an end of the main heat radiating member, the auxiliary heat radiating member being a part of the cover. (3) a heat dissipation device for at least one active device connected to a circuit board substantially enclosed within a cover; Auxiliary heat radiation having at least one opening formed in the cover at a position facing the main heat radiation member, and a clamping portion disposed on the outer surface of the cover and attached to the main heat radiation member through the opening in a heat conductive relationship. A heat dissipation device characterized by comprising a member.