We used to have this requirement when we were using a type ER conformal
coating.  It was a royal pain in the butt!!  It cost us a lot of extra
time and money, and the coating we were using at the time was only
marginally reworkable.  After using this coating for about 2 years we
gave up on these coatings and used only type AR and UR after that.  With
those coatings there was no sleeving required and the ability to rework
was greatly enhanced.

Keith S. Calhoun
Product Engineer
SoPark Corporation
3300 South Park Avenue
Buffalo, New York 14218
Phone:  716-822-0434 Ext. 237
Fax: 716-822-5062
email: [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Lee Whiteman
Sent: Tuesday, June 09, 2009 8:22 AM
To: [log in to unmask]
Subject: [TN] CONFORMAL COATING ON GLASS BODIED COMPONENTS

We have the following requirement on one of our space programs:

All glass-bodied electronic parts which are bonded, encapsulated or
conformally coated shall be sleeved with sleeving that remains resilient
over the temperature range specified for the equipment. Surface mount,
non-axially leaded, glass-bodied diodes that are conformally coated do
not require sleeving if the coating Tg is below all application and test
temperatures.

I am confident that this came from NASA STD 8739.1A as well as the IPC
Space Addendum. The question is why? Have there been documented failures
of glass-bodied electronic parts without sleeving which failed when
conformal coating was applied?

Should glass-bodied components be masked from conformal coating?

Thanks again...

Lee Whiteman, PMP
Senior Member Engineering Staff
L-3 Communications East
Telephone: (856) 338-3508
FAX: (856) 338-2906
E-Mail: [log in to unmask]

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