Hot air solder leveling

HASL or HAL (for 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.

HASL can be applied with or without lead (Pb), but only lead-free HASL is RoHS compliant.

Advantages of HASL

Excellent wetting during component soldering.
Avoids copper corrosion.

Disadvantages of HASL

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 the process may introduce defects into PCB.

References

↑ Salleh, Mohd Arif Anuar Mohd (2022). Recent Progress in Lead-Free Solder Technology: Materials Development, Processing and Performances. Topics in Mining, Metallurgy and Materials Engineering Ser. Mohd Sharizal Abdul Aziz, Azman Jalar, Mohd Izrul Izwan Ramli. Cham: Springer International Publishing AG. ISBN 978-3-030-93441-5.

[1] Salleh, Mohd Arif Anuar Mohd (2022). Recent Progress in Lead-Free Solder Technology: Materials Development, Processing and Performances. Topics in Mining, Metallurgy and Materials Engineering Ser. Mohd Sharizal Abdul Aziz, Azman Jalar, Mohd Izrul Izwan Ramli. Cham: Springer International Publishing AG. ISBN 978-3-030-93441-5.

Hot air solder leveling

Advantages of HASL

Disadvantages of HASL

See also

References