Board Finish

Comment

Electroless Ni / Immersion Au

Recommended in JEITA Pb-free roadmap and predominant in Japan and EU. Highest cost process, but good corrosion resistance for on-board contact pads and suitable for wire bonding pads for COB designs.

HASL [SnAgCu or SnCu]

Recommended in JEITA Pb-free roadmap and commonly used in Japan.

OSP

High volume, lost cost alternative. Commonly used. Solderability more easily degraded by multiple reflows.

Immersion Ag

Good solderability and an increasingly significant board finish.

Immersion Sn

Commonly used in EU. Presence of carcinogenic thiourea in solutions has limited its use in USA.