Abstract: The soft soldering of an aluminium or aluminium-based alloy member to another member of a metal or alloy capable of being soft soldered to aluminium at a joint site is effected using a lead/tin soft solder alloy in conjunction with a flux containing as one of the essential constituents a silver halide so that sufficient silver is deposited with the soft solder alloy at the joint site to prevent corrosion of the joint.

Abstract: There is described a method of soft soldering aluminium or alloys thereof using a fluxed solder composition. The fluxed solder composition comprises a soldering flux suitable for use in soft soldering aluminium and its alloys and a soft solder alloy of lead, tin and silver and, optionally, up to 3% copper. The composition of the soft solder alloy is such that it contains at least 35% lead and 10% tin, and x% silver wherein x=0.1+(5.times.10.sup.-4)(Sn).sup.2 +(1.times.10.sup.-5)(Sn).sup.3, (Sn) being the percentage by weight of tin in the alloy.