A Soldering System for Aluminum.
Falke-WL; Neumeier-LA; Lee-AY
Weld J 1985 Jan; 64(1):37-44
A method that permits the "soft" soldering of aluminum and aluminum alloys with standard tin-lead solders and fluxes was devised by the Bureau of Mines. The method employs the application of a thin nickel-copper alloy coating to the substrate prior to soldering. This alloy preplating enables the solders to readily wet and spread over the areas to be joined. With conventional technology, aluminum and aluminum alloys are extremely difficult to soft-solder because the tenacious surface oxide films prevent wetting and spreading of the solder. With the Bureau method, the aluminum substrate is mechanically or chemically cleaned to facilitate application of a minute layer of zinc that is subsequently applied with an electroless zincate solution. The nickel-copper-alloy (30 to 70 pct ni) coating is then applied electrolytically over the zinc, using immersion-cell or brush-coating techniques. Development of acetate electrolytes has permitted deposition of the proper nickel-copper- alloy coatings. The coated areas can then be readily joined with conventional tin-lead solders and fluxes. The joints so formed are ductile, strong, and relatively corrosion resistant, and exhibit strengths equivalent to those formed on copper and brass substrates when the same solders and fluxes are used. The method also has been used to soft-solder magnesium alloys.
Weld. J., V. 64, No. 1, Jan. 1985, PP. 37-44