IMHO (In My Hallucinate Opinion) :

- zillions of microscopical bubbles does not matter
- bubbles higher than 50% of the coating thickness do not matter if only few
-bubbles higher than 50% and building clusters matters
-all bubbles with an extension 10 times the coating thickness matters
-if the above is repeated on many boards, the MRB should suspect a process
failure
-for all coatings

Inge

On 21 March 2013 16:18, Douglas Pauls <[log in to unmask]> wrote:

> OK, Minions, your next question in the quest to improve J-STD-001 and
> A-610 relates to bubbles in the conformal coating.
>
> I think we can all agree that the ideal conformal coating layer contains
> no bubbles or voids and is "purdy".    BUT:
>
> 1.  Are there bubbles in coatings in areas where they will not impact
> reliability and their presence should be viewed as a "Process Indicator"?
> If so, where and what limits would you use?
>
> 2.  What would you classify as a bubble requiring disposition, i.e.
> Becomes an actionable defect?  If so, where and why?
>
> 3.  Would any of your answers change depending on what KIND of coating it
> is, i.e. Acrylic vs. silicone vs. Parylene?
>
> Well, OK, that is three questions.  I'm on a roll.
>
>
> Doug Pauls
> Chairman, IPC Cleaning and Coating Committees
> Galactic Emporer
>
>
>
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