How to Deal With The Discoloration of The Gold Surface of PCB Circuit Board?

Question: The discoloration of the gold surface of PCB board is generally related to the gold plating potion in this process and the SOLDMASK in the previous process. As a former engineer of SOLDMASK, I think that it may be that the plate is not clean during the development of this process. This should be solved only by the follow-up of professional engineers of SOLDMASK. Otherwise, it is caused by external pollution in the production process. This is more troublesome and requires the cooperation of influential people from different departments to effectively control the source of pollution.

Answer: 1. It is not the problem of soldermask, but the problem of the process. The root cause of the discoloration of the gold surface here is that the potion enters the hole and cannot be cleaned, causing the gold surface to be polluted. Improving the wet film process and strengthening cleaning will help.

The discoloration of gold surface is one of the most common problems, and it is mainly solved from the following aspects:

1. Copper pollution in the nickel tank

2. The conductivity of deionized water washing before gold plating

3. Metal contamination of the gold slot

4. Pure gold concentration