CIRCUIT BOARD AND SURFACE TREATMENT METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To obtain a metal layer which is excellent in solder wettability and bonding connectability by a method wherein the surface of a joint is irradiated with a laser beam to be cleaned up, and then solder is fused by heating to connect a component to a circuit board. SOLUTION: A conductor 2 of W and Cu is provided onto a ceramic 1 of alumina or the like. The conductor 2 is successively plated with a nickel plating layer 3 of thickness 5μm or so and a gold plating layer 4 of thickness 3μm or so and thermally treated at temperatures of 750 deg. or so for 10 minutes for the formation of a joint. The mother material formed as above is transferred in the direction of an arrow as irradiated with an excimer laser beam of wavelength 308nm through the intermediary of a reflecting plate 7 and a condensing lens 8. By this setup, the nickel 3 and the gold 4 are instantaneously fused and solidified to form 811 Ni-Au alloy 5 which contains a small amount of nickel, whereby a metal layer excellent in solder wettability and bonding connectability can be obtained at a low cost.