As lead is a harmful element, soldering in the electronicsindustry has moved toward elimination of lead from the solder alloy.Already there are a group of companies who have begun implementation oflead-free solder alloys. The scope of parts being tested for lead-freeprocesses is not limited to the solder material; the complete absence oflead from electronics parts, including the substrate, parts, and moduleis being envisioned in the near future. Therefore, for BGA and/or CSPbumps as well, there is no other option but to evaluate lead-freematerials. First in this paper, the microstructure and the shearstrength of the solder bumps were examined. The following lead-freealloys and the alloy containing lead were selected for this firstexamination: Sn-5Sb, Sn-0.75Cu, Sn-3.5Ag, Sn-3.5Ag-0.75Cu and Pb-63Sn.The bumps were soldered on a copperickel substrate with gold platingand were evaluated before and after a thermal cycle test. Second in thispaper, two types of lead-free alloys and the alloy containing lead wereselected as CSP bump materials. The mechanical reliability of thesoldering joint between the CSP package and PCB was evaluated before andafter thermal cycle tests. One of these lead-free alloys is: Sn-Ag-Cu,the most influential candidate for eliminating lead from the currentSn-Pb solder. The other is: Sn-Zn-Bi which has a lower meltingtemperature than Sn-Ag-Cu. Also, three (3) types of plating on thesubstrate of PCB (Bare Copper, Alpha Level Silver and Flash Gold) wereevaluated with CSP bump materials. The purpose of the evaluation was toselect the best material for using lead-free solder alloy as a CSP joint
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