SURFACE FINISHES COMPARED
Immersion tin or hard gold: which PCB surface finish?
Hard gold keeps longer before assembly: 12+ mo against 6–12 mo for immersion tin.
- Known risk with immersion tin: Whiskers/IMC.
- Known risk with hard gold: Cost/selective.
Immersion tin and hard gold, as published
| Property | Immersion tin | Hard gold |
|---|---|---|
| Cost, USD per square inch | 0.08–0.12 | Variable |
| Shelf life | 6–12 mo | 12+ mo |
| Reflow passes | 3–4 | not published |
| Minimum pitch, mm | 0.5 | not published |
| RF performance | Good | not published |
| Gold wire bonding | No | No (soft only) |
| Aluminium wire bonding | No | No |
| Standard | IPC-4554 | MIL-G-45204 |
| Known risk | Whiskers/IMC | Cost/selective |
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.