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Soldering

Soldering is a group of joining processes that produce coalescence of material by heating it to the soldering temperature, using a filler metal (solder) having a melting temperature less than 840°F (450C°) and below the solidification temperature of the base metal. The solder is distributed between closely fitted faying surfaces of the joint by capillary action. The heating process selected should provide the proper soldering temperature, heat distribution, and rate of heating and cooling required for the product being assembled. Application of the solder and flux is determined by the selection of the soldering process.

Why Solder?

  • Base metal properties are minimally affected dueto the low process heat input
  • Low joining temperatures require little energy input,allowing precise control of the process
  • A wide range of heating methods can be used, allowingflexibility in design and manufacturing procedures
  • Modern automation produces large numbers of jointsin electrical and electronic circuits
  • High joint reliability is obtained with carefullycontrolled procedures
  • Soldered joints that are damaged are easily repaired

Limitations

  • Joint strengths are limited and can be used in certainapplications only
  • Parts must be cleaned properly for good wetting action
  • Flux residue must be removed upon completion of thesoldering operation
  • Manual processes are labor intensive and increaseoverall process costs

Soldering Alloys and Fluxes Selection Chart

The melting temperature of the fillermetal is less than 800°F.

Caution: Silversoldering is a term that is commonlymisused to discuss silver brazing. Silversolders usually consist of Tin and Silverwith a silver content of less than 6%.

Base Metal 1Base Metal 2Soldering AlloyFluxTemperatureTorch
StainlessStainlessTin Silver
Tin Antimony
Acid
Acid
430°F (220C°)
475°F (245C°)
Air/FG-2
Air/FG-2
StainlessCopperTin Silver
Tin Antimony
Acid
Acid
430°F (220C°)
475°F (245C°)
Air/FG-2
Air/FG-2
CopperBrassTin Silver
Tin Antimony
Acid
Acid
430°F (220C°)
475°F (245C°)
Air/FG-2
Air/FG-2

Flame Adjustment

For soldering and brazing, use a carburizing flame. Solders have tensile strengths of 3,000 to 10,000 psi. Brazing alloys have tensile strengths of 50,000 to 90,000 psi.

Caution

Never solder an oxygen line. OSHA and NFPA require brazing. If the line is copper, use ProStar® 15 with a nitrogen backup at 30 cfh and zero back pressure.