Study of top paddle delamination on Cu leadframe

The most influence factor of delamination between copper alloy leadframe and epoxy mold compound interface is the finishing leadframe surfaces. Based on leadframe manufacturing process, anti-tarnish is applied by dipping entire leadframe into a solution at the end of plating process. The anti tarnish will cover the surfaces of the die bond and wire bond pads, regardless of different types of metal plating, as well as exposed copper in the unplated areas. This paper will discuss the effect of anti tarnish on the top paddle delamination formation in copper leadframe packages. Leadframe from different supplier, grades of anti tarnish and plasma process control had been deliberated. Surfaces analysis techniques XPS and Tofsims were used to characterize and understand the chemistry of the leadframe surfaces. Furthermore, contact angle measurement was applied to analyse the material surfaces properties such as wettability, surface energy and adhesion. As a result, it has an indication of higher concentration of benzotrizole or its derivatives (BTA) from the anti tarnish coating significantly influence the top paddle delamination and Ar plasma process were employed to remove the anti tarnish layer on the Cu leadframe and consequently eliminate the top paddle delamination.