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September 1998

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From:
"Collins, Graham" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 14 Sep 1998 08:57:30 -0300
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Graham
A suggestion (more from my woodworking experience than cca assembly...). 
Could your customer do a two pass routing operation?  The first pass to take
off most of the waste but leave some of the unwanted edge, this would heat
up the coating as you have seen, A second pass (after doing other sides and
letting the area cool off) would remove much less coating and should be
cooler.  Hopefully it would remove any stringing that occurred in the first
pass.
 
As a long term fix, using connecting tabs and depanalization with a
singulation die would avoid this problem and be faster as well.
 
Good luck! 

Graham Collins 
Process Engineer 
Litton Systems Canada 
(902) 873-2000 extension 215 

-----Original Message-----
From: Graham Naisbitt [mailto:[log in to unmask]]
Sent: Friday, September 11, 1998 12:12 PM
To: [log in to unmask]
Subject: [TN] Routing conformal coatings


Hi TechNetters,
 
I hope you can help. We have a customer who needs to route (de-panellise)
his assemblies after Conformal coating. The coating is an acrylic.
 
The problem is that when he does this routing operation, the coating (not
surprisingly) goes into a state of partial melt so that the coating is
stringing on the underside making a problem for clean-up which is costly.
 
He cannot route from the other side. He has tried chilling the assembly but
this is impractical because of the time constraints. He cannot selectively
NOT coat the affected area because his selective coating system then takes
too long for the operation.
 
Does anyone have any suggestions? 
 
Regards, Graham Naisbitt
 
[log in to unmask]
 
Concoat Ltd             Phone: +44 1276 691100
Alasan House          Fax:      +44 1276 691227
Albany Park
CAMBERLEY 
GU15 2PL UK
 
Any opinions expressed are those of this employer.

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