Effect of collet on the die stress during die pick-up

In the semiconductor packaging, the die pick-up consists of a needle displacement at the bottom and the collet pickup force at the top. During this process, peeling the tape from the die attach film (DAF) induces stress in the die and will lead to die crack. A suitable collet material and collet geometry should be used to mitigate the die crack. This paper presents a finite element (FE) approach to evaluate the impact of collet hardness and collet geometry on the die stress during die pick-up. It is observed that as the collet hardness increases from 53 to 80, the die stress increases and thereafter, as the collet hardness increases, there is steep decrease in the die stress. An optimal collet design with a specific collet hardness is proposed to achieve minimal stress on the die during die pick-up.