TECHNICAL FIELD

The present disclosure relates to a semiconductor device having excellent heat radiation performance and electromagnetic wave suppression effect.

BACKGROUND

Recent years have seen size reductions of electronic devices. Meanwhile, because power consumption cannot be significantly changed in order to cover a variety of applications, heat radiation measures for the devices have become more important.

As heat radiation measures for electronic devices, for example, radiator plates, heat pipes, and heatsinks made of metallic material having high heat conductivity such as copper or aluminum are widely used. Such a heat radiation component with excellent heat conductivity is located near an electronic component, such as a semiconductor package, which is a heating portion in an electronic device, to achieve heat radiation effect or temperature relaxation in the device. Further, the heat radiation component with excellent heat conductivity is located from the electronic component which is the heating portion through to a low-temperature region.

However, this causes the following problem: The heating portion in the electronic device is an electronic component such as a semiconductor element with high current density, and high current density means that the strength of an electric field or a magnetic field which can cause an unwanted radiation component is likely to be high. If the heat radiation component made of metal is located near the electronic component, the heat radiation component not only absorbs heat, but also picks up a harmonic component of an electric signal flowing in the electronic component. Specifically, since the heat radiation component is made of metallic material, the heat radiation component acts as an antenna for the harmonic component or acts as a transmission path for the harmonic noise component.

The development of techniques to achieve both heat radiation performance and electromagnetic wave suppression effect is therefore desirable.

For example, PTL 1 discloses a technique of providing, in a shield member having a large opening hole hole, a semiconductor package with a lid attached thereto and an annular lid contact portion in electrical contact with upper peripheral edges of the lid, and electrically connecting the lid contact portion and the shield member.

The technique described in PTL 1 produces certain levels of heat radiation performance and electromagnetic wave suppression effect. However, in the case where a substrate or a cooling member is large, electromagnetic resonance occurs, and sufficient electromagnetic wave suppression effect cannot be achieved. Moreover, further improvement in heat radiation performance is needed.

CITATION LIST

Patent Literature

PTL 1: JP 2012-164852A

SUMMARY

Technical Problem

It could therefore be helpful to provide a semiconductor device having excellent heat radiation performance and electromagnetic wave suppression effect.

Solution to Problem

Through extensive studies, we recognized that excellent electromagnetic wave absorption performance can be achieved by covering a semiconductor element with a conductive shield can connected to a ground. However, simply providing such a conductive shield can cannot achieve sufficient heat radiation performance. We accordingly conducted further studies, and discovered that, by forming an opening hole hole in the conductive shield can and forming a heat conductive sheet so as to at least pass through the opening hole hole to connect the semiconductor element and a conductive cooling member, heat radiation performance can be improved without a decrease in electromagnetic wave absorption performance. We further discovered that, by providing a conductive member between the upper surface of the conductive shield can and the lower surface of the conductive cooling member and electrically connecting the conductive shield can and the conductive cooling member, electromagnetic wave suppression effect can be improved even in the case where the conductive shield can has the opening hole hole.

Hence, a semiconductor device according to the present disclosure can achieve both heat radiation performance and electromagnetic wave suppression effect at higher level than conventional techniques.

The present disclosure is based on these discoveries. We thus provide:

(1) A semiconductor device comprising: a semiconductor element formed on a substrate; a conductive shield can connected to a ground and having an opening hole hole; a conductive cooling member located above the conductive shield can; a heat conductive sheet formed between the semiconductor element and the conductive cooling member at least through the opening hole hole of the conductive shield can; and a conductive member formed between an upper surface of the conductive shield can and a lower surface of the conductive cooling member, and electrically connecting the conductive shield can and the conductive cooling member.

With such a structure, excellent heat radiation performance and electromagnetic wave suppression effect can be achieved.

(2) The semiconductor device according to (1), wherein a spacing between parts of the conductive member facing each other with the heat conductive sheet therebetween is less than or equal to 1/10 of a wavelength at a maximum frequency of the semiconductor element.

(3) The semiconductor device according to (2), wherein the conductive member is connected to the conductive shield can and the conductive cooling member, to form an electrically closed region.

(4) The semiconductor device according to any one of (1) to (3), wherein a resistance value of the conductive member is 2Ω or less.

(5) The semiconductor device according to any one of (1) to (4), wherein the conductive member has tackiness or adhesiveness at a surface thereof.

(6) The semiconductor device according to any one of (1) to (5), wherein the conductive member contains a cured resin.

(7) The semiconductor device according to any one of (1) to (6), wherein the conductive member contains a conductive filler.

(8) The semiconductor device according to any one of (1) to (7), wherein the heat conductive sheet contains carbon fibers.

Advantageous Effect

It is thus possible to provide a semiconductor device having excellent heat radiation performance and electromagnetic wave suppression effect.

