Trends in lead frame technology for plastic packaging

Lead frames make up the largest portion of the materials costs in plastic packages; especially Quad Flat Packages (QFP's). For stamping lead frames the costs can be up to 60% of total while for etched lead frames it can run up to 75% of total. Additionally, from performance perspectives lead-frames are a critical component of the packaging system. Lead frames must be strong to withstand handling, yet compliant to tolerate bending. They must have high thermal conductivity to dissipate heat generated by the IC device and good electrical properties so as not to deteriorate the IC device performance. In addition, lead frames are a critical part of the reliability of the overall packaging system. Lead frame properties can affect solder joint fatigue, delamination in moisture tests, and wire bonding integrity. The SIA and SEMATECH packaging road maps represent significant new challenges for lead frames. In upcoming years not only lead frame materials will have to be stretched to their limits, but it will have to be done much more cost effectively. The TRP Low-Cost Packaging Consortium looked at two critical areas: very high strength reasonable conductivity alloy development and adhesion improvements for delamination resistance. This paper discusses lead frame technology trends to the year 2000 and TRP development work to date.