Soldering of sheet aluminum

摘要

Soldering of aluminum soldering is thought to be problematic due to the tenaciousness of aluminum oxide, difficulty in heating the high-thermally conductive base material, and the concern of galvanic corrosion from solder. In this study, soldering on aluminum has been demonstrated on 611 and 5754 aluminum alloys with a soft solder, 91 wt% Sn-9 wt% Zn, and a hard solder, 80 wt% Zn-20 wt% Al. Appropriate fluxes were chosen, including a flux containing fluoroborates, and amines for Sn-9Zn soldering, plus another flux with a fluoride-base for 80Zn-20AI soldering. The soldering process with 91Sn-9Zn was done with a temperature-controlled hot plate at 308℃. However, the process with 80Zn-20Al solder, with its liquidus temperature near 480℃, utilized both diode laser and plasma arc high density infrared (HDI). HDI was found to be very effective in heating the base material and the solder very efficiently and is suitable for production soldering. With numerical simulations to determine the power output of the lamp needed to achieve appropriate soldering, HDI was able to create solder joint with a good capillary flow, few voids, and uniform microstructure in the metallurgical joint. Mechanical tests demonstrated that the joint area was stronger than the base metal. Laser soldering requires a defocus process with precise power control to prevent Zn penetration into the base material.