Improving the accuracy of junction temperature measurement with the square-root-t method

Abstract

This paper discusses how the square-root-t method improves the measurement of the virtual junction temperature Tvj in a power cycling test setup. By applying this method, the measurement becomes more tolerant to measurement delays and EMC noise, thus it enables to sharpen the basis of life time estimations. However the virtual junction temperature remains a one dimensional mapping of the three-dimensional temperature gradient which combined with CTE-mismatch induces stress in the interconnection materials. Therefore Tvj-measurement data are compared to statements found in IR-images.