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October 2012

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Subject:
From:
Steven Creswick <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steven Creswick <[log in to unmask]>
Date:
Thu, 11 Oct 2012 12:26:51 -0400
Content-Type:
text/plain
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text/plain (163 lines)
Mark - Not a problem.  

Just remember that with all things that sound too good to be true -
sometimes they don't quite live up to expectations.  I've had times where I
left it too long, or too hot, and it doesn't look pretty....

I have often wanted to try this stuff heated, but with ultrasonics to help
break up the matrix a bit more.  Unless there were large voids, I would not
expect the wirebonds to be affected by the U/S as they were uncovered,
but...

Good luck and vent!


Steve Creswick
Sr Associate - Balanced Enterprise Solutions
http://www.linkedin.com/in/stevencreswick
                         616 834 1883



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Woolley, Mark D. (Mark)
Sent: Thursday, October 11, 2012 11:34 AM
To: [log in to unmask]
Subject: Re: [TN] Glob Top removal

Sorry, Steve,
Didn't read far enough.
Thanks,
mark

-----Original Message-----
From: Paul Edwards [mailto:[log in to unmask]]
Sent: Thursday, October 11, 2012 9:11 AM
To: Woolley, Mark D. (Mark); 'TechNet E-Mail Forum'
Subject: RE: [TN] Glob Top removal

A little busy there, Mark...

Steve made the reference...


Paul

Paul Edwards
Process/Quality Engineering
Surface Art Engineering


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Woolley, Mark D.
(Mark)
Sent: Thursday, October 11, 2012 8:08 AM
To: [log in to unmask]
Subject: Re: [TN] Glob Top removal

Thank you much Paul.
I will get some and try it.
mark
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Paul Edwards
Sent: Thursday, October 11, 2012 9:00 AM
To: [log in to unmask]
Subject: Re: [TN] Glob Top removal

Great Steve...

Just what I've been looking for...

Paul

Paul Edwards
Process/Quality Engineering
Surface Art Engineering


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Thursday, October 11, 2012 2:38 AM
To: [log in to unmask]
Subject: Re: [TN] Glob Top removal

Mark,

I used to use a material called Decap from Dynaloy - based out of
Indianapolis, IN.  Here is their web site.
http://www.dynaloy.com/dynaloy-chemical-solutions-products/specialty-che
mist
ries/epoxy-products.html

The Decap will work for many glob tops, but you must keep an eye on
temperature.  Some are removed better with warm temps, others with hot
temps.  You really have to test for yourself unless you know the composition
of the glob top material.  DO NOT use without a vented hood.  The stuff
reeks something terrible.  Make you wish you lived next to a pig barn!

What I would do is suspend the part in the solution and periodically shake
it around a bit to dislodge the silica particles from the 'glob', thereby
exposing new epoxy to the chemical.  It is not perfect, but is far less
hazardous than fuming nitric!


They also have materials for Urethane CC removal, but not necessarily
localized removal...

Steve Creswick
Sr Associate - Balanced Enterprise Solutions
http://www.linkedin.com/in/stevencreswick
                         616 834 1883



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Woolley, Mark D.
(Mark)
Sent: Wednesday, October 10, 2012 11:59 PM
To: [log in to unmask]
Subject: [TN] Glob Top removal

Does anyone know of a way to remove the epoxy that is used to cover CoB ICs,
while maintaining the integrity of the PWB-CoB Assembly afterwards?
I have tried hot Nitric Acid, which does remove the epoxy nicely, but also
removed the copper on the PWB and swelled during the decap process and
ruptured the bondwires.  I believe Red Fuming Nitric would also swell the
epoxy lifting the bondwires.  Most aggressive solvents don't remove epoxies
well. So I am pout of ideas at present.

Thanks,
mark

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