Principle and introduction of PCB board OSP surface treatment process

- Dec 04, 2019-

Principle and introduction of PCB board OSP surface treatment process

Summary of content: Principle: An organic film is formed on the copper surface of the circuit board, which firmly protects the fresh copper surface, and can also prevent oxidation and pollution at high temperatures. OSP film thickness is generally controlled at 0.2-0.5 microns.


1. Process flow: degreasing → water washing → micro-etching → water washing → pickling → pure water washing → OSP → pure water washing → drying.


2. OSP material types: Rosin, ActiveResin and Azole. The OSP materials used by Shenzhen United Circuits are currently the most widely used azole OSPs.


What is the OSP surface treatment process of PCB board


3. Features: good flat surface, no IMC formed between the OSP film and the copper of the circuit board pad, allowing direct soldering of the solder to the circuit board copper (good wettability), low temperature processing, low cost (For HASL), less energy use during processing, etc. It can be used on both low-tech circuit boards and high-density chip packaging substrates. Tips for PCB proofing: The appearance of the board is difficult, and it is not suitable for reflow soldering (usually three times); ② The OSP film surface is easy to scratch; ③ The storage environment is high; ④ The storage time is short.


4. Storage method and time: 6 months in vacuum packaging (temperature 15-35 ℃, humidity RH≤60%).


5. SMT site requirements: ① OSP circuit boards must be stored at low temperature and humidity (temperature 15-35 ℃, humidity RH≤60%) and avoid exposure to acid-filled environments. Assembly of the OSP package should be started within 48 hours after unpacking; ② It is recommended to use it within 48 hours after the one-sided piece, and it is recommended to store it in a low temperature cabinet instead of vacuum packaging; ③ It is recommended to complete the DIP within 24 hours after the SMT is completed on both sides.


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