Crevice Elimination and Stitch Integrity Improvement on Leaded Packages Thru Shifted Lead Neck Design

The intensive drive of zero delamination for highest reliability has been one of the top priorities of packaging an integrated circuit. Delamination has been a constant challenge to the lead forming process due to the high stress induced to the lead and mold interface - this phenomenon can result to a very minute separation between the mold compound and leadframe (crevice). This very tiny opening can potentially serve as external path for moisture which can result to oxidation of adjacent stitches which can lead to package reliability concerns. This paper will focus on an innovative lead design to further improve reliability on leaded packages thru crevice elimination. The design incorporates angular lead termination from the package vs conventional perpendicular lead formation. This angular and shifting lead termination reduces the forming force applied directly to the lead during forming process, reducing risk of crevice, thus improving overall package reliability.