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58 DESIGN007 MAGAZINE I JULY 2022 Article by Anaya Vardya AMERICAN STANDARD CIRCUITS Introduction Not understanding the cost drivers in the PCB manufacturing process is one of the big- gest challenges facing PCB designers. is article is the latest in a series titled DFM 101 that discusses these cost drivers (from the PCB manufacturer's perspective) and the design decisions that impact product reliability. Purposes of Final Finishes Final finishes provide a surface for the com- ponent assembler to either solder, wire bond, or conductively attach a component pad or lead to a pad, hole, or area of a PCB. e other use for a final finish is to provide a known contact resistance and life cycle for connectors, keys, or switches. e primary purpose of a final fin- ish is to create electrical and thermal continu- ity with a surface of the PCB. Final Finishes—ENIG and ENIPIG ere are several final finishes in use in the industry today, including: • ENIG (electroless nickel, immersion gold) • ENIPIG (electroless nickel, immersion palladium, immersion gold) • ENEPIG (electroless nickel, electroless palladium, immersion gold) • ImmAg (immersion silver) • ImmSn (immersion tin) • Sulfamate nickel/hard or so gold (electrolytic nickel/gold) • HASL (hot air solder leveling) › SnPb (63/37 tin/lead) › LF (lead free) • OSP (organic solderability preservative) Final finishes are primarily application driven, so there are several considerations that