Surface Finishes
PCB Surface Finishes vary in price, availability, shelf life, reliability and assembly processing.
While each finish has its own benefits, in most cases the process, product or environment will dictate the surface finish that is best-suited for the application. It is recommended that the end-user, designer or assembler work closely with their PCB supplier to select the best finish for the specific product design. Canadian Circuits' extensive experience in lead-free manufacturing of printed circuit boards has been instrumental in successfully converting countless projects from solder to a lead- free alternative.
| Finish | Description |
|---|---|
sHASL |
Solder deposited on SMD features and in PTH pads and holes. Typical solder thickness is 0.1-1.0 mils on surface features. Solder thickness varies by board geometry, aspect ratio, and hole size and is therefore considered unfavorable in higher technology SMD applications. The solder coating consists of 63%-37% eutectic SnPb. |
| OSP (Organic Solderability Preservative) |
A transparent organic coating deposited on solderable features after the solder mask process. |
| ENIG (Electroless Nickel, Immersion Gold) |
Electroless nickel-immersion gold deposited on solderable features. Typically 100-200μ of nickel is deposited and 2-8μ of gold. Applied after the solder mask process. Full ENIG coverage under solder mask is manufacturable, but not desirable due to reduced mask adhesion and increased cost. |
| Gold Flash | Electrolytic nickel-gold deposited on solderable features. Typically 200-400μ of nickel is deposited, and 3-10μ of hard gold. Gold flash is applied to solderable features after pattern plating. Additional gold thickness (30-50μ) can be plated in selective areas. |
| Immersion Silver | Silver deposited on solderable features. Typically 5-25μ of silver is deposited, with a nominal thickness of 15μ. Immersion silver is applied after solder mask. |
| White Tin | Immersion tin deposited over copper. Typically 30-40μ is deposited. White tin is applied after solder mask. |
| Combination Finishes | Typically a global solderable finish after a selective hard/soft gold finish has been applied. The preferred solderable finish in combination applications is OSP. Other solderable finishes are possible, but involve more process steps, which may increase the risk and associated costs. |
| Carbon Paste | A conductive carbon filled polymer paste used for wear protection on selective copper contacts. Typically applied 18-24 microns. |
| Soft Gold (Wire Bondable) | Electrolytic gold deposited to the customer’s specified thickness (typically 30-50μ). Gold deposit has a purity >99.9%, a hardness of 50-90 Knoop. Soft gold is typically applied to selective features, but can be employed as a solderable coating. |
At Canadian Circuits we believe that as a successful company has to be always evolving, always improving, building a great team by hiring the best most experienced peopleMore+