Soldering

• Most common solder:
  • 60/40 tin/lead rosin core
  • 300-325 C

Types of Solder

• Lead based solder
  • 60/40 (tin/lead) ( Sn60Pb40 ) - most common mix
  • 180-190°C - melting point
  • soft solder
• Lead free solder
  • higher melting point
  • could have nickel ( or use other techniques )
• Flux core solder
  • has a core of flux

flux

• reverses/reduces oxidation
• improves wetting
• cleaner electrical connection
• rosin core for electronics
• acid core for plumbing and other things

Solder Additives

””” Antimony increases mechanical strength without reducing wettability while preventing tin pest. Bismuth significantly lowers the melting point and improves wettability. Inhibits growth of tin whiskers. Copper lowers the melting point and improves wetting properties in the molten state. Indium lower the melting point, improves ductility, and is used for soldering to gold or for cryogenic applications due to its high resistance to temperature swings. Indium alloys are expensive and prone to corrosion. Nickel in solder alloy can protect UBM (under bump metallization) layer from dissolution. Silver provides mechanical strength, but with lower ductility than lead. It can improve resistance to fatigue from thermal cycles in lead-free solders. “””