Thermal Characterization of Electrically Conductive Adhesives and Pressureless Sinter Pastes Comparison of Data Sheet and Real Application

Thermal transient measurements on MOSFET packages are used in this work to compare the thermal resistance of different die attach materials. Samples were built using various die attach materials, ranging from electrically conductive adhesives to pressureless sinter pastes, and characterized both as-manufactured and after ageing. In addition to the thermal conductivity provided as a bulk material property in data sheets, the thermal transient measurements are able to reveal contact resistance effects that occur in real setups. The results offer a ranking of different die attach materials that differs from the ranking based on the bulk thermal conductivity. In asmanufactured samples, some electrically conductive adhesives are able to reach similar thermal performance as pressureless silver sinter pastes. Thermal transient measurements after ageing reveal that hybrid sinter adhesives are more stable in their thermal performance than pressureless sinter pastes under the given test conditions. The results provide a better understanding how to interpret data sheet values for thermal conductivity and show that additional measures must be considered when designing a product. Using thermal transient measurements, a screening of the thermal performance of die attach materials can be done prior to a product qualification.