At present, the market has higher and higher requirements for the anti-yellowing performance of the photosensitive solder mask white oil for printed circuit boards. Only by finding the cause of the yellowing of the photosensitive solder mask white oil can we find ways to reduce the yellowing condition, which will affect the yellowing of the photosensitive solder mask white oil. There are many reasons for the change, such as ink performance, circuit board manufacturing process, abnormal wave soldering furnace temperature, etc. The following editor will talk about it in detail.
The reason for the yellowish white oil of the circuit board:
The yellowish white oil should be considered from two aspects: whether the customer will deal with it again
1. Before processing:
（1）The performance of white oil ink does not meet the requirements (impurities in the ink). Generally, Sun ink and Nanya ink will not have this problem.
（2）Anti-soldering residue stripping liquid.
（3）There is a problem in the solder mask exposure and curing process (after the development machine is developed, the water stains are not dried and the water is baked) （4）Caused by spraying tin (the immersion tin time is too long).
2. After processing:
（1）The temperature is set too high and the speed is too slow when the customer is doing reflow soldering.
（2）The quality of the flux is not good, which accelerates the discoloration of the board surface.
（3）The osp film is directly adhered to the board without being removed. After baking, a regular yellowing mark appears on the white oil board.