SURFACE FINISHES COMPARED
ENEPIG or immersion tin: which PCB surface finish?
Immersion tin is the cheaper of the two, at $0.08–0.12 per square inch against $0.12–0.25 for ENEPIG. ENEPIG keeps longer before assembly: 12+ mo against 6–12 mo for immersion tin.
- Known risk with ENEPIG: Cost/complexity.
- Known risk with immersion tin: Whiskers/IMC.
ENEPIG and immersion tin, as published
| Property | ENEPIG | Immersion tin |
|---|---|---|
| Cost, USD per square inch | 0.12–0.25 | 0.08–0.12 |
| Shelf life | 12+ mo | 6–12 mo |
| Reflow passes | 5+ | 3–4 |
| Minimum pitch, mm | 0.4 | 0.5 |
| RF performance | Poor (Ni loss) | Good |
| Gold wire bonding | Yes | No |
| Aluminium wire bonding | Yes | No |
| Standard | IPC-4556 | IPC-4554 |
| Known risk | Cost/complexity | Whiskers/IMC |
How this was counted
Both columns come from the surface finish table in the MPBxChange material catalogue, as its sources published them. Costs are indicative ranges in US dollars per square inch, not quotations, and move with the gold price and the fabricator. "Not published" means the source gave no value, not that the answer is no.