ASTM 5470 is a standard test method for thermal transmission properties of thin thermally conductive solid electrical insulation materials.(ASTM, 1995). The flow meter was designed to this standard. The design incorporated some improvements deemed necessary from earlier testing on a similar meter at the University of Limerick, Ireland.

Figures 1 and 2 show photographs of the Guarded Heat Flow Meter in use designed specifically for Thermal Interface Resistance measurements.

Fig 2 Guarded Heat Flow Meter

Figure 3 shows the heart of the apparatus, the test column, which comprises of the Upper and Lower Meter bars, machined from aluminium, and the reference

calorimeter. The material selected for the reference calorimeter was 302 Stainless Steel. The reference calorimeter is used to determine the rate of heat flow through the specimen.

The heat source was a guarded thermally controlled heater unit. The unit was made up of an inner heater block and an outer guard heater block. The heater block was surrounded with a layer of epoxy thermal insulation and encased within the outer guard heater. Cooling was achieved by a continuous flow of mains water through the cooling unit.