Abstract
Failures in soldering sometimes occur even with the electric and electronic parts on which metals having good solderability are electroplated. In this paper, the effects of pretreatment processes prior to plating and thickness of electroplated coatings were examined to prevent these failures. In order to keep good solderability during 24 hour vapor treatment, bright tin-lead alloy coating on a copper panel was found to be effective than bright tin or dull tin-lead alloy coating, even if the lead content in the bright tin-lead alloy coating was only 5%. The bright alloy coating of 1μ in thickness was sufficient to keep good solderability on a copper panel. For other metals, however, copper undercoating of 0.5μ on kovar, 1μ on brass and phosphor bronze, and 3μ on steel were required to prevent deterioration of solderability when the thickness of bright alloy overcoating was only 1μ. In the case of nickel undercoating, severe deterioration of solderability occurred upon vapor treatment. When thickness of the overcoating was 3μ, undercoating was not required except a brass panel. Moreover, copper or nickel undercoatings of 0.5μ in thickness on brass and other base metals were also effective to keep good solderability.
