Patent ID: 7861915

Claim:
A soldering process comprising: (a) in a first region of a soldering apparatus, purifying solder in a molten solder bath by maintaining a single liquid layer comprising a major portion of liquid active additive on at least a portion of the surface of the solder bath, whereby the first region is delineated from an area where soldering occurs and comprises the liquid additive on the surface of the solder bath, wherein said liquid active additive (i) is a liquid at the temperature of the solder bath, (ii) comprises nucleophilic and/or electrophilic groups, (iii) acts as an oxygen barrier to the surface of the molten solder bath, and (iv) assimilates oxide of at least one metal in the bath, to thereby purify and lower a viscosity of the solder bath; (b) circulating purified solder from the first region to a second region where soldering occurs, where the circulated purified solder is devoid of active additive, and (c) contacting a surface to be soldered with the circulated purified solder from (b).