SURFACE FINISHES COMPARED
Immersion silver or EPIG: which PCB surface finish?
Immersion silver is the cheaper of the two, at $0.08–0.12 per square inch against $0.12–0.22 for EPIG. EPIG keeps longer before assembly: 12+ mo against 6–12 mo for immersion silver.
- Known risk with immersion silver: Tarnish.
- Known risk with EPIG: Wire bond (EPIG).
Immersion silver and EPIG, as published
| Property | Immersion silver | EPIG |
|---|---|---|
| Cost, USD per square inch | 0.08–0.12 | 0.12–0.22 |
| Shelf life | 6–12 mo | 12+ mo |
| Reflow passes | 3–4 | 5+ |
| Minimum pitch, mm | 0.5 | 0.3 |
| RF performance | Excellent | Excellent |
| Gold wire bonding | No | EPAG only |
| Aluminium wire bonding | No | Limited |
| Standard | IPC-4553A | Under dev. |
| Known risk | Tarnish | Wire bond (EPIG) |
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.