SURFACE FINISHES COMPARED
Lead-free HASL or immersion silver: which PCB surface finish?
Lead-free HASL is the cheaper of the two, at $0.05–0.08 per square inch against $0.08–0.12 for immersion silver. Immersion silver leaves a flat pad, which fine-pitch parts need; lead-free HASL does not.
- Known risk with lead-free HASL: Flatness.
- Known risk with immersion silver: Tarnish.
Lead-free HASL and immersion silver, as published
| Property | Lead-free HASL | Immersion silver |
|---|---|---|
| Cost, USD per square inch | 0.05–0.08 | 0.08–0.12 |
| Shelf life | 6–12 mo | 6–12 mo |
| Reflow passes | 6+ | 3–4 |
| Minimum pitch, mm | 0.5 | 0.5 |
| RF performance | Poor | Excellent |
| Gold wire bonding | No | No |
| Aluminium wire bonding | No | No |
| Standard | not published | IPC-4553A |
| Known risk | Flatness | Tarnish |
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.