True Temperature Measurement of Electronic Components Using Infra‐red Thermography

Abstract

Great savings can be achieved by detecting and isolating design problems early in an electronic programme. Many design problems, including electrical overstress, poor thermal design and circuit layout problems, are detectable by their infrared (I‐R) signature. A reliability and design improvement tool utilising current I‐R scanning technology has been developed. Specifically, an I‐R scanning method for making accurate temperature measurements for the purpose of electronic design reliability improvement and qualification has been developed and verified experimentally. Field‐actual conditions, in which radiative and convective heat losses from the components are negligible, are simulated with a thermally insulating enclosure. The enclosure is designed for rapid removal just before the scan, obviating the need for exotic materials that are transparent to I‐R in the scanner's passband. With typical hardware thermal lags, the method allows determination of true temperatures simulating field conditions. Corrections for unwanted scanner‐produced radiation and for the target emissivity are made with a three‐scan method and specially designed apparatus. An integral part of this apparatus is the aforementioned quickly removable thermal enclosure. The three scans take approximately an hour for a typical circuit board after initial set‐up time. True‐temperature measurements of circuit boards can be made with the I‐R design improvement tool now.