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DFM 101: Final Finishes—ENEPIG and IAg
September 29, 2022 | Anaya Vardya, American Standard CircuitsEstimated reading time: 1 minute
Introduction
One of the biggest challenges facing PCB designers is understanding the many cost drivers in the PCB manufacturing process. This article is the latest in a series that will discuss these cost drivers (from the PCB manufacturer’s perspective) and the design decisions that will impact product reliability.
Final Finishes
The primary purpose of a final finish is to create electrical and thermal continuity with the surface of the PCB. Final finishes provide a surface for the component assembler to either solder, wire bond, or conductively attach a component pad or lead to a pad, hole, or area of a PCB. The other use for a final finish is to provide a known contact resistance and life cycle for connectors, keys, or switches. The primary purpose of a final finish is to create electrical and thermal continuity with a surface of the PCB.
There are a number of 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)
- IAg (immersion silver)
- ISn (immersion tin)
- Sulfamate nickel/hard or soft 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 a number of considerations that should be part of any decision to choose a final finish.
To read this entire article, which appeared in the September 2022 issue of Design007 Magazine, click here.
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