초록 ▼

A process by which molten solder is purified in-situ, making the soldering process more efficient and yielding better results, particularly for lead-free soldering. Lead-free solder becomes practical for use since the temperature for reliable soldering is reduced. A layer of active additive is maint

A process by which molten solder is purified in-situ, making the soldering process more efficient and yielding better results, particularly for lead-free soldering. Lead-free solder becomes practical for use since the temperature for reliable soldering is reduced. A layer of active additive is maintained on the surface of molten solder for scavenging metal oxide from the solder and assimilating metal oxide into a liquid layer. The active additive is an organic liquid having nucleophilic and/or electrophilic groups. As an example, a layer of dimer acid maintained on a wave soldering apparatus scavenges metal oxide from the bath, and assimilates dross that may form on the surface. Scavenging metal oxide cleanses the bath and lowers viscosity of the solder, and PC boards or the like soldered on the wave have reliable solder joints.

대표청구항 ▼

What is claimed is: 1. 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 th

What is claimed is: 1. 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).