DEVELOPMENT OF LEAD FREE PACKAGE AND ITS RELIABILITY

摘要

In this report, the major challenges of lead-free package development are well described. It contains the hygro-scopic properties of plastic material and its effect on package de-lamination, warpage changes before and after ball mount process, solder joint reliability for lead-free alloy system and composition determination and lead-free electro-plating. Due to higher melting temperature of lead-free solder, the reflow temperature is expected to be elevated 30 to 40℃ higher than that of the Sn-Pb eutectic solder. As a result, the overall package material set is necessary to be changed to avoiding package de-lamination. The solder joint reliability of lead-free package is much better than that of eutectic solder ball, but compensated by the difficulties of in-line ball mount process such as coplanarity instability. On the other hands, the key points to develop the lead-free solder plating technology are to study the free of whisker growth and cracking of solder plating composition, manufacturability, solder solderability, and solder joint reliability. The Sn-Cu was the final alloy system and copper percentage is 2%.