Assessment of Temperature Distributions in Electronic Circuits

A study has been undertaken into the use of thermal imaging techniques to determine the temperature distribution of electronic equipment. The suitability of such techniques was investigated to determine the level of confidence that could be established with regard to temperature readings obtained. The study consisted of the comparison of temperatures measured directly using fine wire thermocouples with those obtained from a thermal imaging system. Results showed that surface emissivity was a crucial factor in the determination of accurate temperatures by imaging techniques. However, by coating areas to be studied with a light deposit of aluminium chlorohydrate, a constant highly emissive surface could be obtained. This permitted temperature measurements to be made with an accuracy to within <±1 °C over the temperature range 30° to 90°C. The thermal imaging system was used to study the effect of component colour and of component density on temperature distribution. It was found, with respect to the component spacing, that the maximum component temperature was critically related to the spacing between the devices.