Increasing the lifetime of electronic packaging by higher temperatures: Solders vs. silver sintering

Increasing the temperature in power electronic applications usually causes a decreasing lifetime and reliability. This study shows that packaging materials and technologies like silver sintering or gold germanium solders can easily deal with temperatures above 150°C. Furthermore the power cycling capability at increased temperatures can be much better than at room temperature. Active power cycling tests with 240 devices offered more cycles to failure at 120°C cooling temperature than at 40°C. The three tested sample groups consisted of silicon carbide diodes which were soldered (gold germanium/ tin lead) or silver sinter to copper-ceramic-substrates (DBCs). The reason behind this effect is the decreasing of Young's modulus, yield strength and ultimate strain over temperature. The materials are getting much more ductile and robust against load cycling at higher temperatures. The three mentioned material properties were measured by nano-indentation and tensile tests up to 200°C. In summary, packaging materials and their properties should be adopted to the intended application and its requirements, starting with a temperature-dependent analysis.