Design of 0.35-mm-pitch QFP lead and its assembly technology

The solder joint reliability of a 0.35-mm-lead-pitch, 42 mm wide /spl times/42 mm long /spl times/23 mm high, 396 pin, ceramic quad flat package (QFP) was studied in terms of: A. Finite element analysis simulation using NISA II, B. Temperature cycling test between -65/spl deg/C and +125/spl deg/C. Using the study results, physical design of the QFP leads, in terms of thickness, stand-off, and Au surface finish were optimized. Also, we developed a thermocompression (T/C) soldering process for the QFP.<
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