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Electroless Co–P for diffusion barrier in Pb-free soldering by L. Magagnin; V. Sirtori; S. Seregni; A. Origo; P.L. Cavallotti is a Engineering article available to read on EtoBox.

What is Electroless Co–P for diffusion barrier in Pb-free soldering about?

Lead-free solders with high tin content and high melting temperature limit the reliability of electroless nickel/immersion gold finish on copper as diffusion barrier. Autocatalytic cobalt-phosphorus is proposed as a barrier metallization for copper in lead-free soldering. Autocatalytic deposition of cobalt is carried out in hypophosphite containing electrolytes at 95 • C and pH 8. Autocatalytic Co-P/Au finish with about 4 wt% P content strongly limits interdiffusion and intermetallic compounds formation with respect to the Ni-P/Au finish with Sn-Pb and Sn-Ag-Cu solder alloys. Contact angle of Sn-Pb solder alloy with Ni-P/Au and Co-P/Au layers is comparable, while in the case of Sn-Ag-Cu alloy contact angle is much lower for Co-P/Au than for Ni-P/Au layers. Mechanical strength of lead-free joints for Ni-P/Au and Co-P/Au finishes is evaluated with shear test on BGA coupons, obtaining higher joint strength values for autocatalytic cobalt.

Who reads Electroless Co–P for diffusion barrier in Pb-free soldering?

Author

L. Magagnin; V. Sirtori; S. Seregni; A. Origo; P.L. Cavallotti

Publisher

Elsevier Science; Elsevier ; Elsevier Ltd.; Elsevier BV (ISSN 0013-4686)

Published

2005

Language

EN

Field

Engineering (Physical Sciences)