Patent ID: 6013713
Filing Date: 2000-01-11
Classification: H01L,H05K,Y02P,Y10T

Abstract:
A paste for forming a conductive coating on a C4 bump containing Pb and Sn, said conductive coating having a conductivity greater than 1 ohm-cm comprising:a solvent for an unzippable polymer,an unzippable polymer selected from the group consisting of poly(.alpha.-methyl styrene) (PAMS), poly (propylene carbonate), poly (ethylene carbonate) and poly (chloral) dissolved in said solvent to form a solution, andparticles selected from the group consisting of Au, Sn and Au/Sn alloy suspended in said solution,said particles suitable for coating the surface of a C4 bump containing Pb and Sn wherein said particles form a first alloy with Pb or Sn wherein said first alloy melts in the temperature range from 150.degree. C. to 400.degree. C.,said unzippable polymer comprising 10 wt % or greater of said solution.