Surface finish is a critical coating applied to HDI PCB copper pads to prevent oxidation, enhance solderability, and ensure reliable electrical connections.
| Parameter | Typical range | Notes & selection driver |
|---|---|---|
| Flatness | Critical for fine-pitch components; ENIG and OSP offer excellent planarity | |
| Thickness | ENIG: Ni 3-6 μm, Au 0.05-0.15 μm; HASL: 1-40 μm; OSP: 0.2-0.5 μm | |
| Reflow Cycles | Withstands multiple reflow cycles (e.g., 3-5 for lead-free processes) | |
| Solderability | Maintained for 6-12 months depending on finish and storage | |
| Wire Bondability | ENIG and electrolytic Au suitable for gold or aluminum wire bonding | |
| Contact Resistance | Low and stable, typically < 20 mΩ for ENIG |
Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.
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Electroless Nickel Immersion Gold (ENIG) is widely used due to its excellent planarity, solderability, and suitability for fine-pitch components and wire bonding.
It prevents copper oxidation, ensures strong solder joints, and maintains electrical conductivity, directly impacting long-term reliability in harsh environments.
Lead-free finishes like ENIG and OSP are RoHS compliant; alternatives to gold (e.g., immersion silver) reduce cost and resource use.
Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.