SURFACE FINISHES COMPARED
Lead-free HASL or OSP: which PCB surface finish?
OSP is the cheaper of the two, at $0.05–0.07 per square inch against $0.05–0.08 for lead-free HASL. OSP leaves a flat pad, which fine-pitch parts need; lead-free HASL does not.
- Lead-free HASL keeps longer before assembly: 6–12 mo against 3–6 mo for OSP.
- Known risk with lead-free HASL: Flatness.
- Known risk with OSP: Handling.
Lead-free HASL and OSP, as published
| Property | Lead-free HASL | OSP |
|---|---|---|
| Cost, USD per square inch | 0.05–0.08 | 0.05–0.07 |
| Shelf life | 6–12 mo | 3–6 mo |
| Reflow passes | 6+ | 4–6 |
| Minimum pitch, mm | 0.5 | 0.4 |
| RF performance | Poor | Excellent |
| Gold wire bonding | No | No |
| Aluminium wire bonding | No | No |
| Standard | not published | IPC-4555 (draft) |
| Known risk | Flatness | Handling |
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.