Hot air solder leveling

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HASL or hot air solder leveling is a type of finish used on printed circuit boards (PCBs).

The PCB is typically dipped into a bath of molten solder so that all exposed copper surfaces are covered by solder. Excess solder is removed by passing the PCB between hot air knives.

Advantages of HASL[edit]

  • Excellent wetting during component soldering
  • Avoids copper corrosion.

Disadvantages of HASL[edit]

  • Low planarity on vertical levelers may make this surface finish unsuitable for use with fine pitch components. Improved planarity can be achieved using a horizontal leveler.
  • High thermal stress during process may introduce defects into PCB

See also[edit]