I somewhat agree with Graham.  Nothing really likes to stick to silicones, 
including other silicones.  I often have to address the challenge of 
conformal coating delaminating over a spot where RTV silicones had been 
dripped and then wiped up.

I would suggest plasma etching, most likely oxygen and argon.  A fairly 
short duration is often effective at solving coating adhesion issues in 
problem cases.   Many of the mold release agents are either teflon or 
silicone based, so will be fairly chemically resistant.  That is why the 
Ensolv may not be addressing it.

Where I disagree with Graham is the approach of having the component 
manufacturer change their most release agent. If you are a Motorola or a 
Nokia, and going through a few million components a day, you might have a 
little leverage with the component manufacturer.  Most of us just have to 
take what we can get and don't have the leverage necessary to get changes 
made. 

Doug Pauls
Rockwell Collins




Graham Naisbitt <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
06/26/2008 06:05 AM
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Re: [TN] Solithane coating dewetting






Silicone not sticking to silicone - no surprise.

How to remove silicone? Not easy, maybe plasma etching or a really 
aggressive solvent.

You need to get back to the component manufacturer and have them 
change their mold release or at least control how much they use.

Graham Naisbitt

On 26 Jun 2008, at 07:33, Tan Geok Ang wrote:

> Hi All,
>                Quite often, I encountered Solithane coating dewetting 
issue
> over some IC moulding (rough or smooth, did not trace what moulding
> material is used) compounds across different suppliers, though the 
> whole
> PCBAs are being cleaned with EnSolv. What is the cause of the issue? 
> Is
> the cause due to the release agent used during the moulding compound
> process (but why cannot be clean away)?
>                Thank in advance!
> Regards
> GA Tan
>
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