HASL or HAL (for hot air (solder) leveling) is a type of finish used on

printed circuit board A printed circuit board (PCB), also called printed wiring board (PWB), is a Lamination, laminated sandwich structure of electrical conduction, conductive and Insulator (electricity), insulating layers, each with a pattern of traces, planes ...

s (PCBs). The PCB is typically dipped into a bath of molten

solder Solder (; North American English, NA: ) is a fusible alloy, fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces aft ...

so that all exposed

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

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 Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

(Pb), but only

lead-free The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Uni ...

HASL is

RoHS The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Uni ...

compliant.

Advantages of HASL

* Excellent

wetting Wetting is the ability of a liquid to displace gas to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. These interactions occur in the presence of either a gaseous phase or ...

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

{{Reflist Printed circuit board manufacturing Soldering

Advantages of HASL

Disadvantages of HASL

See also

References