Transient dual interface measurement — A new JEDEC standard for the measurement of the junction-to-case thermal resistance

The junction-to-case thermal resistance Rth-JC is an important thermal characteristic for power semiconductor devices. Its value is often one of the main criteria for the decision whether a device can be used in a thermally demanding environment, and a low Rth-JC therefore is a competitive advantage for the semiconductor manufacturer. On the other hand the vendors must ensure that their data-sheet values do not underestimate the actual Rth-JC values. Hence accurate and reproducible methods to measure the Rth-JC are required. Unfortunately these requirements are not easy to meet, which is reflected by the fact that until very recently there existed no JEDEC industry standard for the determination of this thermal metric. During the last three years we have intensely tested and further developed a new transient measurement method for the Rth-JC of power semiconductor packages with a single heat flow path. The so called transient dual interface measurement (TDIM) which allows measuring the Rth-JC with higher accuracy and better reproducibility than traditional methods has now been accepted as JEDEC standard JESD51-14.