Heat sink device

Abstract

A heat radiator 1 includes an insulating substrate 3 whose first side serves as a heat-generating-element-mounting side, and a heat sink 5 fixed to a second side of the insulating substrate 3. A metal layer 7 is formed on a side of the insulating substrate 3 opposite the heat-generating-element-mounting side. A stress relaxation member 4 intervenes between the metal layer 7 of the insulating substrate 3 and the heat sink 5. The stress relaxation member 4 is formed of an aluminum plate 10 having a plurality of through holes 9 formed therein, and the through holes 9 serve as stress-absorbing spaces. The stress relaxation member 4 is brazed to the metal layer 7 of the insulating substrate 3 and to the heat sink 5. This heat radiator 1 is low in material cost and exhibits excellent heat radiation performance.

Description

TECHNICAL FIELD[0001]The present invention relates to a heat radiator, and more particularly to a heat radiator which includes an insulating substrate whose first side serves as a heat-generating-element-mounting side, and a heat sink fixed to a second side of the insulating substrate and which radiates, from the heat sink, heat generated from a heat-generating-element, such as a semiconductor device, mounted on the insulating substrate.[0002]The term “aluminum” as used herein and in the appended claims encompasses aluminum alloys in addition to pure aluminum, except for the case where “pure aluminum” is specified.BACKGROUND ART[0003]In a power module which uses a semiconductor device, such as an IGBT (Insulated Gate Bipolar Transistor), the semiconductor device must be held at a predetermined temperature or lower by means of efficiently radiating heat generated therefrom. Conventionally, in order to meet the requirement, a heat radiator is used. The heat radiator includes an insula...

AI Technical Summary

Benefits of technology

The present invention provides a heat radiator with low material cost and excellent heat radiation performance. The invention solves the problem of high thermal stress arising from a difference in thermal expansion coefficient between the insulating substrate and the heat sink. The invention includes a stress relaxation member that is formed of a high-thermal-conduction material and has a stress-absorbing space. The stress relaxation member can be metal-bonded or brazed to the insulating substrate and the heat sink. The invention also provides a heat radiator with a stress relaxation member that is formed of an aluminum plate with recesses or openings of non-angular shape and a percentage of the total area of the recesses or openings to the area of one side of the aluminum plate falling within a certain range.

Problems solved by technology

Under some working conditions, thermal stress arises from a difference in thermal expansion coefficient between the insulating substrate and the heat sink and causes cracking in the insulating substrate, cracking in a solder layer which bonds the insulating substrate and the heat sink together, or warpage of a bond surface of the heat sink bonded to the insulating substrate.

Such cracking or warpage impairs heat radiation performance.

However, the heat radiator described in Patent Document 1 must use the heat radiation member formed of a high-thermal-conduction material and a low-thermal-expansion material; thus, material cost is increased.

Furthermore, since the heat radiation member and the heat sink are merely screwed together, thermal conduction therebetween is insufficient, resulting in a failure to provide sufficient heat radiation performance.

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