Autocatalytic Cobalt as Barrier Metallization for Tin Solder Alloys

摘要

Soldering process in microelectronics is normally made with eutectic or near eutectic tin-lead solders.The new legislation restricts the use of lead,due to environmental and lexicological concerns.Environmental friendly lead-free solders are proposed as alternative to traditional tin-lead alloys,among them tin-silver-copper is considered a good choice.Copper surface finishes showed a lack of reliability,when soldered with tin-reach lead-free alloys.The autocatalytic nickel/immersion gold finish is affected by failures,related to tin-nickel intermetallic compound formation in the tin layer and Ni_3P formation in the NiP layer.