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What’s OSP Surface Finish?

What’s OSP Finish?

OSP is one of the PCB surface finishes, means Organic Solderability Preservatives, which is applied upon the bare copper to prevent PCB from being oxidized. OSP is RoHS compliant and can be quickly removed in the PCB assembly processing.


What is OSP looks like?

OSP looks basically transparent, which is extremely difficult to detect its existence in visual so that the OSP PCBs and the bare copper PCB do not look too different in appearances. But experts can tell that by refraction.

OSP surface finish


What is the advantage of OSP PCB?

The advantages are of OSP,

  • flat surface, good for SMD,
  • about 6 months soldering validity time if well stored,
  • cheap price,
  • excellent soldering joint strength.

But also some disadvantages,

  • difficult in reworking,
  • not good for micro-vias,
  • the surface is susceptible to acid and humidity,
  • not suitable for use in high-temperature for a long time.

In general, OSP is suitable for use in the consumer products which need one-time mass production.


How to create OSP surface finish?

  1. Acid Cleaning: Remove remained fingerprints, grease and other pollution,
  2. Micro Etching: Produce the uniform and flat copper surface. In this processing, PS Electronics will use H2HO4-H2O2 as etching reagent to make the subsequent OSP finish more fine and uniform,
  3. OSP Finish: OSP coat gets grown on the copper surface, the thickness range of which is generally 0.2 to 0.6 um,
  4. Drying: To ensure that the OSP coat and the holes are dry, need to get dried in hot air at 60-90°C for seconds.


How to store OSP PCBs?

  • Avoid contact with acid gases
  • Storage temperature requires 15-25°C
  • Humidity should be less than 50%
  • Best used in 3 months
  • The maximum validity time is about 6 months


What kind of OSP materials does PS electronics use?

We now frequently use the Glicoat-SMD series OSP materials from SHIKOKU, which possesses excellent thermostability. Please feel free to conact us if you’ve any question or request about OSP PCB, .

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