Statistical Analysis of the Thermal Performance and Reliability in the Heat Sink With Heat Pipes for the Power Electronics Module

Abstract

Cooling devices are often used with power electronics systems to allow them to operate stably over long periods of time, they help guarantee not only thermal performance but also reliability. To understand the performance of these cooling devices it is important they are verified by various types of testing, also the test results themselves should be quantified and analyzed using recognized statistical methods. For this paper, we investigated an air-cooled heat sink with heat pipes by conducting heat load, high/low temperature storage limits, accelerated life, and transport vibration tests. The collected experimental data were analyzed by statistical methods such as the independent samples t-test, the paired samples t-test, correlation analysis, process capability analysis, and the tolerance interval analysis. A newly manufactured power conditioning system had one heat sink on which the two power electronics modules were attached while providing a heat load of up to 3.2 kW. It was found that there was no deterioration in the thermal performance of the heat sink due to vibrations while being transported from the Republic of Korea to the United States. If such a heat sink is used over 20 years, it is anticipated that there will be a performance degradation of 6.2% over those years with a 95% confidence level for a B10 life. Based on our accelerated life testing, the heat sink is capable of dealing with a heat load of up to 3.1 kW over the design lifetime of 20 years. Thermal engineers should eventually introduce design margins in consideration of the reduction in quality and reliability that can occur over the lifetime of a cooling device.