Patent ID: 6630251
Filing Date: 2003-10-07
Classification: B23K,C22C,H05K,Y10T

Abstract:
An electronic assembly comprising a solder joint bonded to a silver-containing thick-film, the solder joint being formed of a solder alloy consisting essentially of, by weight, about 5% to about 70% tin, up to about 4% silver, palladium, platinum and/or gold, copper and/or nickel in a total amount of greater than 1% to about 10%, the balance lead and incidental impurities, the amount of copper and/or nickel in the solder alloy inhibiting leaching of silver from the thick-film during forming of the solder joint by reflow, the solder joint comprising a diffusion barrier layer of CuSn and/or NiSn intermetallic compounds at an interface between the solder joint and the thick-film, the diffusion barrier layer inhibiting solid-state interdiffusion between silver from the thick-film and tin from the solder joint.