Cleaning Issues #1

Poor surface preparation is the leading cause of defects in plating shops. In fact, ask the wife of my engineer Brian what gives him the most headaches and her first guess will be poor surface preparation. Thus, I will do a weekly Q&A on this topic.

Q: My cleaner is producing defects, what could be the issue?

A: This depends on the type of defect you’re experiencing. Let's look into the 5 main defects and how to fix them

1. Soil not being removed: Make sure you haven’t changed the type of cleaner or that the type of soil hasn’t changed. Is the solution too old? Replace. If soil still cannot be removed from the surface look at raising the temperature, increasing the concentration, and lengthening the immersion time. Always use sufficient agitation to distribute the cleaning agent evenly across the part surface. If all else fails it is possible that you need a different type of cleaner.
2. Substrate attack: Some cleaners will naturally attack certain substrates, it is always important to ensure you have the right cleaner for the substrate. For example, aluminum is attacked by sodium hydroxide, so don’t use a heavily alkaline cleaner on aluminum. Otherwise, look at decreasing the immersion time, temperature, and concentration of the cleaner until you no longer see substrate attack.
3. Oil film on surface: Cleaners can do 1 of 2 things with oil, it can split or emulsify oil. If you have an oil splitting cleaner install a weir to remove the oil layer, do consistent analysis on the bath and make additions based off the analysis. If you have an emulsifying cleaner run an analysis to test the strength of the cleaner and if you find it is weak make additions or remake the cleaner.
4. Darkening of the substrate: The factors that darken a substrate are similar to the factors that attack the substrate. I recommend a similar prescription to rectify the issue; lower the immersion time, concentration, and temperature of the cleaner bath.
5. Stains after plating: Stains are caused by chemical entrapment so it is important to pay attention to your rinsing step. Mechanical agitation, ultrasonics, and fog rinsing should all be considered to minimize chemical entrapment. These efforts will also improve the cleaning ability of the system and should be employed when possible.