Sherman,
        Still fighting with that RTV, eh? I remember when we were building
those things for you at a previous employer, and that was one of the
messiest, most difficult parts of the process. Ask your illustrious boss why
it has to be RTV, rather than epoxy or some other medium. Expoxies could
give you lower viscosities and allow placing the units in a small vacuum
chamber to evacuate any entrapped air pockets. And I believe epoxy is used
on some of your units for final encapsulation, if my feeble memory serves me
right. Tell Jerry I said hello, and good luck in your quest....

Mike McMonagle
Telxon Corporation
http://www.telxon.com

-----Original Message-----
From: Sherman Banks [mailto:[log in to unmask]]
Sent: Thursday, February 17, 2000 7:37 PM
To: [log in to unmask]
Subject: [TN] Checking for voids


Hi Technetters!!!

Here's one for you.

We have an assembly with an area under a copper shield that must be filled
with RTV. It is important that there are no voids in the fill. We can only
fill from an open end and thus have to work a needle down to the bottom, and
fill from that point, withdraw the needle and hope it all settles in before
curing.

The shield is about 1 cm long, .5 cm wide and .2 cm off of the board the
open end is .2 cm by .5 cm. It is soldered onto the board along the bottom
and the closed end must remain that way. To disassemble is to destroy the
part. The board is 1.5 - 1.6 mm  FR-4.

Is there any way to assure that there are no voids that is not destructive,
such as Scanning Acoustic Microscopy?

Thanks in advance

Regards,
Sherman Banks
Finisar Corp.
1308 Moffett Park Drive
Sunnyvale, CA 94089
408/548-0940
[log in to unmask]

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