Indentation Tests for Sintered Silver in Die-Attach Interconnection After Thermal Cycling

Thermomechanical reliability assessment for sintered silver is a crucial issue as sintered silver is a promising candidate of die-attachment materials adopted for power devices. In this paper, the nano-indentation tests are performed for sintered silver in typical die-attach interconnection under different thermal cycles. Based on thermal cycling test, the Young's modulus and hardness of sintered silver layer have been presented. It is found that the Young's modulus and hardness of sintered silver layer changes slightly although the microstructure of sintered silver also presents some variations. The stress and strain curves for different thermal cycling tests of sintered silver are also given based on reverse analysis of nano-indentation. The results show that the elastoplastic constitutive equations change significantly after thermal cycling tests, and the yielding stress decreases remarkably after 70 thermal cycles. The experimental investigation also shows that the cracking behaviors of sintered silver depend on its geometry characteristics, which implies that the possible optimization of sintered silver layer could enhance its thermomechanical performance.