FR4 PCB Surface Finishes

When a PCB is designed several factors are considered; the PCB layout itself, the specification of materials, the laminates, inner layers and the board’s layer stack up. Engineers will however often not give as much consideration to the surface finish. Why is the PCB surface finish required? Bare copper on the PCB would oxidise which will compromise the components soldering. Which PCB finish should I choose? In general, the main considerations depend on required storage, the end application, the assembly process, the design of the PCB itself and of course the cost. A brief description of each is shown here. We would be pleased to help you further with any questions you may have regarding a suitable finish for your application.

OSP (Organic Solderability Preservative)

Usual thickness : 0.20-0.65µm
Shelf Life : 6 months

Unprotected copper will quickly oxidise which can cause soldering issues. OSP is a popular, low cost, environmentally friendly finish to prevent that oxidisation and provide an improved surface for solderability. OSP is suitable for multiple heat cycles during assembly process.

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