Sintered silver (Ag) as lead-free die attach materials

This paper documents the feasibility study of using micrometer-scale Ag paste as a lead-free (Pb-free) die attach material for microelectronic packaging. Currently, there is no viable Pb-free die attach in the market which can pass the reliability testing regimen. Sintered Ag was explored as an interconnect material because of its relatively low processing temperature and robust joint after sintered. This report suggests a possible route for using Ag paste as a Pb-free die attach by dispensing as per current production epoxy die attach. This feasibility study reports the mechanical integrity, electrical and reliability testing of a surface mount power package with four types of dispensable Ag pastes. Separate lots of this surface-mount power package with current die attach materials were also evaluated as controls. This paper is expected to be of interest to companies that are exploring alternative Pb-free die attach materials.