Hi Dean, I've gotten them by trying to cure the coating too quickly, the coating skins over before all the solvents have worked their way out. But here's a good Humiseal link that gives some various causes and ways to eliminate them: https://blog.humiseal.com/simple-techniques-to-avoid-bubbles-in-conformal-coating#:~:text=For%20example%3A%20curing%20too%20fast,vapor%20under%20the%20coating%20surface. Steve On Thu, Jul 16, 2020 at 10:56 AM Stadem, Richard D <[log in to unmask]> wrote: > One of the client companies I work for builds extremely high-reliability > propulsion control systems. For them, bubbles in the coating between > fine-pitch ASIC leads are a defect condition. We are exploring options for > elimination of the bubbles. > The bubbles are not present in the sprayed on coating, and we have tried > lightly brushing the leads to further "thin out" the coating before the > CCAs go into the curing oven. No webbing or bubbles are seen at that point > but manifest themselves after curing. > I am not an expert at coating but I do know a bit about it. I was > wondering just what might be the cause of the bubbles, and how to prevent > them from happening? Any information is greatly appreciated! > dean > -- Steve Gregory Kimco Design and Manufacturing Process Engineer (208) 322-0500 Ext. -3133 -- This email and any attachments are only for use by the intended recipient(s) and may contain legally privileged, confidential, proprietary or otherwise private information. Any unauthorized use, reproduction, dissemination, distribution or other disclosure of the contents of this e-mail or its attachments is strictly prohibited. If you have received this email in error, please notify the sender immediately and delete the original.