Mr. Crawford, I read your question on the Technet about concerns on
spraying silicone conformal coatings.  We just received a new spray and
cure system that we will be spraying our boards with.  We have been
using silicone coating for about 15+ years and do not want to change
because of our success with this coating.  Two of the vendor selling
points of the variety of spray systems that we investigated are that
these systems utilize very low or even no air pressures to apply the
coating, and the spray heads are of unique efficient design.  Thus, very
little overspray, thus very little chance of airborne contamination.
The spray cabinets are also fairly well enclosed and can be hooked up to
forced exhaust systems.   Additionally, the coating we are using is self
priming so that when spray hits the targeted surface, it will stay where
it is applied.

While this message does not directly answer your question, I hope it
adds insight.  I hope that others on the Technet can contribute
something better from actual experience.  I look forward to hearing from
them.

 ----------
From: [log in to unmask]
To: [log in to unmask]
Subject: ASSY: SR Conformal Coating in Mfg Area
Date: Tue, Feb 11, 1997 3:10PM


I sent this up to the server last week, but can't find that I ever got a
"come-back" copy, so here goes again.

Following is posted for one of our clients:

"I have a vendor that has installed a closed system conformal coat spray
machine in the middle of an area where surface mount and through hole
processing occurs.   The coating being used is silicone based.  I'm
concerned about silicone contamination of other materials in the work
area,
due to unintentional migration (overspray in the atmosphere,
fumes/gasses
from curing process, etc.) over time, that could affect the soldering
processes.  Are there any specifications or guidelines for SR coating
controls in a printed circuit board assembly house?  Is this a valid
concern?  Does anyone have a good or bad history of a similar
situation?"

Thanks for inputs anyone has. Jack

***ALL NEW EMPF PHONE NUMBERS***

Jack Crawford, HelpLine Coordinator
Electronics Mfg. Productivity Facility
****NEW--317.655.3688
****FAX  317-655-3699
714 N Senate Ave, Suite 100
Indianapolis IN  46202-3112
VISIT OUR HOME PAGE AT: http://www.empf.org
[log in to unmask]


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