Relationship of adhesion, delamination, preconditioning and preplating effects at the plastic to leadframe interface

Adhesion has been identified as one of the key factors in preventing popcorn problems in surface mount devices (SMD). The objective of this project was to study, by use of a controlled experiment, the impact on adhesion and delamination of plastic packages using various preplated leadframes that had been subjected to stringent manufacturing preconditions. This paper will ultimately show, through statistical analysis, that there is a very strong relationship between tab adhesion and percent delamination. A Design Of Experiment (DOE -4/spl times/5/spl times/5 full factorial) was set up to study four semiconductor molding compounds/spl times/five industry standard preplated finishes/spl times/five typical preconditioning stages. The statistical results showed that all the factors (mold compounds, preplated leadframes and preconditioning) and all the 2-factor interactions were significant. Two key-examples were a very strong relationship between computerized digital image analysis (CDIA) and Tab Pull, and the use of oxidized leadframes which show exceptional tab pull strength and near zero percent delamination via CDIA, under all conditions. Further work will study the relationship of tab adhesion and percent delamination to popcorn effects.