Connect, no.156, September/October 2008, p.8

Improving thermal management

One of the key issues in the development of electronic systems is the increasing requirement for the dissipation of heat generated by active devices. The temperature of electronic devices is important because it impacts on their performance and reliability. The objective of thermal management is to maintain device temperatures within a fixed range in order to operate functionally as specified.

As part of a recent Core Research Program project the Ceramics group has used a solid state joining technique for joining Al to Al2O3 to produce an aluminium heat sink, as shown in Fig.1, to address the issue of thermal management.

Fig.1. Heat sink produced via a solid state joining technique

Conventionally adhesives are used to attach heat sinks to devices/circuits. Thermal conductivity values of a typical adhesive tape, alumina and aluminium can be seen in Table 1. This shows that the adhesive tape is a poor thermal conductor and can act as a barrier to heat flow. Hence, removing the adhesive layer from the joint interface should reduce the thermal resistance and help extract and dissipate more heat from the device into the heat sink.

Table 1 Thermal conductivity of adhesive, alumina and aluminium

The heat sink was tested in the thermal performance test bed, a wind tunnel (Fig.2), and its thermal performance was superior to adhesively joined heat sinks.

Fig.2. General view of the wind tunnel

If you require further technical information please contact ceramics@twi.co.uk