Determination of Temperature of Integrated-Circuit Chips in Hybrid Packaging

This paper describes an infrared technique and an analogical method to determine the maximum temperature of a beam-leaded integrated-circuit chip, mounted on a ceramic carrier. The infrared technique employs a color thermogram camera to map the stepwise temperature distribution of a heated surface. From the color-digitized thermograms the chip temperature rise over the ambient air can be computed with the aid of thermocouple measurements. The color thermograms also help evaluate the thermal resistances of the chip and the ceramic carrier, which are used in the thermoelectric analogical analysis of steady-state heat flow from the chip t,o the surrounding air under free convection condition. The chip temperature rise as evaluated by the thermoelectric analysis checks reasonably well with the infrared and thermocouple measurements. These two methods have their respective advantages in determining the temperature of integrated-circuit chips.