TECHNICAL FIELD

The present invention relates to a circuit device and a power conversion device and more particularly to size reduction and high-heat dissipation mounting techniques for power electronic devices.

BACKGROUND ART

As a conventional circuit device, an example is disclosed, for example, in Japanese Patent Laying-Open No. 2006-253205 (PTL 1) in which an aluminum tube having a coolant channel is integrally stacked on a non-component mounted surface of a printed circuit board with an insulating layer interposed.

In a reflow process that is common inexpensive soldering means, first, a cream-like solder paste including flux in solder powder is screen-printed at an even thickness on a printed circuit board. A surface-mount component is then disposed on the printed circuit board, for example, by a mounter. The solder is thereafter melted in a furnace to bond the printed circuit board and the surface-mount component.

Most of surface-mount components used in the reflow process described above have a base plate having a thermal diffusion function on the mount surface side in contact with the printed circuit board. On the other hand, the non-mount surface side of the surface-mount component is sealed with a package made of a resin having electrical insulating properties with a low thermal conductivity. It is therefore difficult to efficiently cool the surface-mount component from the non-mount surface side. In Japanese Patent Laying-Open No. 2006-253205 above, heat generated in the mounted component is conducted to the printed circuit board and cooled using a cooler connected to the non-component mount surface of the printed circuit board.

CITATION LIST

Patent Literature

PTL 1: Japanese Patent Laying-Open No. 2006-253205

SUMMARY OF INVENTION

Technical Problem

There has been an increasing demand for smaller size and higher efficiency in power conversion devices and the like serving as power circuits using large current.

The size reduction and capacity increasing of circuit devices included in power conversion devices is therefore extremely important.

In order to meet the demand for size reduction and capacity increasing, it is necessary to connect the printed circuit board and the cooler with an insulating resin layer interposed, as in Japanese Patent Laying-Open No. 2006-253205. The insulating resin layer, however, does not have a good thermal conductivity. When an insulating resin layer is used, therefore, it is important to reduce the thermal resistance between the printed circuit board and the cooler. In order to do so, a technique is necessary that diffuses heat generated in the printed circuit board and transfers heat toward the cooler using a heat-transfer cross-sectional area as large as possible. However, increasing the size of the printed circuit board for increasing the heat-transfer cross-sectional area increases the entire circuit device, accordingly. It is necessary to avoid such a size increase of the circuit device and to increase the cooling efficiency from the printed circuit board to the cooler.

The present invention is made in view of the problem described above. An object of the present invention is to provide a circuit device capable of significantly improving the heat dissipation performance of a printed circuit board without increasing the size, and a power conversion device including the same.

Solution to Problem

A circuit device in the present embodiment includes a printed circuit board, a mounted component, a non-solid metal spacer, a cooler, and a resin layer. The mounted component is at least partially disposed on at least one main surface of the printed circuit board. The non-solid metal spacer is disposed on at least one main surface of the printed circuit board. The cooler is disposed at the non-solid metal spacer on an opposite side to the printed circuit board. The resin layer is disposed between the non-solid metal spacer and the cooler. The non-solid metal spacer has a shape that allows at least one hollow portion to be formed between the printed circuit board and the cooler.

Advantageous Effects of Invention

According to the present invention, the non-solid metal spacer disposed between the printed circuit board and the cooler functions as a heat spreader for the printed circuit board and a thermal bridge between the printed circuit board and the cooler. The non-solid metal spacer can significantly improve the heat dissipation performance of the printed circuit board without increasing the size of the circuit device. This configuration can provide a circuit device in which large current flows through a mounted component mounted on a printed circuit board, or components are densely mounted in a printed circuit board, and a power conversion device including the same.

