The Rinsing Process For Electronics Assemblies

Q: What is The Risk of Poor Rinsing?

A: It depends on what you’re rinsing, the nature of your contamination, and how well it rinsed. If ionic materials are left behind, that can lead to dendritic growth and assembly failure. If it is non-polar materials, it can still cause issues that may not be as obvious. You can have conformal coating issues downstream if there are organics left behind.

Q: What Causes Intermittent Rinsing Issues?

A: These crop up from time to time. Concentration would be one. Are you using Process Control to make sure the concentration is not high. Also, you should check your cleaning equipment to make sure everything is operating properly. Finally, you should look at the bath loading. It’s a good idea to use NVR testing to see if the intermittent rinse issues are being observed as the loading increases.

Q: How does the Rinse Water penetrate tight spaces to fully rinse out the lower surface tension wash solution?

A: Rinse water is at 72 dynes per centimeter, while wash solution is around 30-40. If you took all the cleaning done properly, and the cleaning agent itself is left behind, you would think the rinse water would not penetrate under to clean. Rinse water is hitting the board’s surface, and leaving cleaning agent behind, lowering the surface tension of the rinse water to less than 72 dynes.