Electrical stability solder replacement

A new area of concern for electrical stability arises because of the increasing use of conductive adhesives as replacements for solder. Some conductive adhesives show unstable electrical-contact resistance when used on non-noble metal surfaces such as copper or tin-lead solder. Although stable on gold, palladium, platinum, and silver surfaces, the same adhesives were found to be unstable on tin, tin-lead, copper, and nickel surfaces.The unstable resistance and increase in resistance in temperature-humidity exposures have been attributed to the growth of an oxide layer separating the filler particles from the substrate at the interface, a mechanism similar to that for the loss of backside contact in die-attach materials. 

The plateability and hydrolytic stability advantages of polysulfone/ABS blends have been utilized to make selected appliance, plumbing, and sterilizable equipment parts, replacing polycarbonate. Polysulfone/ABS blend has also been evaluated for plateable components of electrical and electronic parts, circuit boards and connectors. However, the lack of adequate heat resistance (DTUL lower than polysulfone) for vapor phase solderability limited its use only in conjunction with other high heat resins as laminates. 

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