Void Eliminating Process of Sintered-Silver Die Attachment in Anaerobic-Sintering Atmospheres

This paper performed a void eliminating approach of pressure-less silver sintering using the traditional vacuum reflowing system. A non-contact heating was developed to achieve a temperature-rising rate less than 5 °C /min during silver sintering drying stage. An anaerobic-sintering atmosphere was controlled by the vacuum pumping and nitrogen flooding. The Evolution of void defects under different chamber pressure was observed by X-ray. The results showed that chamber pressure has obvious effects on the defect formation of sintering voids in sintered silver layers during drying stage. In order to eliminate those sintering voids, a pre-heating approach was proposed. In addition, the typical sintering temperature profile was also achieved. The sintering approach could not only achieve void-less sintering, but eliminate the oxidation issues of packaging components, e.g. power terminals and copper substrates without metallization.