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.