High-temperature anti-electrochemical migration behavior of Ag-In composite paste

Low temperature sintered nanosilver pastes have superior thermal, electrical and mechanical properties, making them one of the die-attach materials in wide band semiconductor devices. However, the oxidation and decomposition of sintered silver at high temperatures cause the occurrence of electrochemical migration, which may lead to short-circuit failure of electronic devices. Therefore, the competitive oxidation method is used, the electrochemical migration of sintered Ag is suppressed by adding In particles with higher oxygen affinity to the nano-Ag paste. The electrochemical migration lifetimes of sintered Ag-3In and Ag-5In pastes were significantly improved to 779 min and 804 min compared to sintered nano-Ag solder paste (382 min), which is about two times higher. Subsequently, the inhibition mechanism of In particles on the electrochemical migration of sintered silver in high temperature dry environment was analyzed. During the service process, In particles reacted with oxygen in preference to Ag particles to form In₂O₃, which inhibited the oxidation, decomposition and ionization of sintered Ag and significantly improved the electrochemical migration failure time of sintered silver. Meanwhile, the shear strength of sintered Ag-1In and Ag-3In pastes was improved by 30.92% and 32.37%, respectively, compared with that of sintered Ag paste. It was shown that the introduction of the appropriate proportion of In particles was effective in improving the shear strength of the die-attach samples while improving the electrochemical migration lifetime.