PCB Tech - Principle and introduction of OSP surface treatment technology

- OSP Principle:

OSP surface treatment is mainly for the protection of the copper foil solder pad on the circuit board, to avoid surface pollution and oxidation so as to mount tin bad.

OSP thickness is generally controlled in 0.2-0.5 micron.

- Process: water washing - micro etching - water washing - acid washing - pure water washing -OSP- pure water washing - drying.

- OSP material types: Rosin, ActiveResin and Azole.

- Features: good flat surface, no IMC formation between OSP and copper of PCB solder pad, allowing direct welding of solder and PCB copper during welding (good wettability), low temperature processing process, low cost (lower than HASL), less energy use during processing, etc.It can be used in both low-tech circuit boards and high-density chip packaging substrates.(1) appearance inspection is difficult, not suitable for multiple reflow welding (general requirements for three times);(2) OSP membrane surface easy to scratch;(3) storage environment requirements are higher;(4) storage time is short.

- Storage method and time: vacuum packaging for 6 months (temperature 15-35 degree Celsius, humidity RH≤60%)