Method of laser bonding electrical members

Details Method of laser bonding electrical members Method of laser bonding electrical members

1989-09-08

1991-04-16

Albritton, C. L.

Electric heating

Metal heating

By arc

21912175, B23K 2600

Patent

active

050085123

ABSTRACT:
A method is disclosed for laser bonding two highly reflective electrical members. The first electrical member is coated with a material that is well absorbent of laser energy at the laser beam wavelength, has a lower melting point than either the first or second electrical members, and has a low solubility in a solid alloy of the electrical members. The laser characteristics are selected so that as bonding occurs an alloy of the electrical members solidifies and a solidification front drives the molten coating and molten compounds containing the coating away from the bond interface towards the exterior periphery of the bond, and substantially all of the solidified bond interface consists of an alloy of the first and second members. The coating can also aid in wetting the bond interface. In one example a copper electrical member coated with tin is bonded to a gold electrical member using a pulsed YAG laser with a beam diameter of 0.002 inches, a wavelength of 1.064 microns, an energy output of 1/4 to 1/2 joule, and a pulse time of 1 millisecond. Substantially all of the resulting bond interface consists of a copper/gold alloy without any tin intermetallics.

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