New design for a lead frame used for high pin counts and high-power LSI package

To meet the requirement of high speed driving LSI package with powerful output, combining flexible printed circuits (FPC) with the lead frame has been designed, and has been manufactured using TAB tape carriers by chemical etching. The back side plain metal laminated with high modulus adhesive allows for high speed wire bonding on it and used as electrical grounding and a heat spreader. The Au/Sn eutectic microsoldering method by heat press is applied for combining FPC and lead frame. The combining lead frame has some excellent characteristics. Electrical impedance of the lead can be easily controlled by the rearrangement of lead width, gaps, and dielectric insulation etc. The use of thin copper foil results in increasing pin count and narrow pitch lead frame. The heat spreading effect by plain metal with apparent thermal resistance is excellent. Insulation level of the dielectric is kept stable for a long time because of the selection of materials which has resistivity to electro-migration