Thanks Mel,

I hear ya about the conformal coating & CTE - good info.  The conformal
coating is a substitute since the original used injected foam.  I'm
considering a double conformal coat - polyurethane for the first layer and
silicone over that.  It's what the US Army uses on some of the assemblies in
the M1A tank.

Hans

Integrity First  -  Service Before Self  -  Excellence in All We Do
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Electronics Engineer
Warner Robins - Air Logistics Center (WR-ALC/LUGE)
226 Cochran Street
Robins AFB GA 31098-1622

mailto:[log in to unmask] <mailto:[log in to unmask]>

Com: (478) 926 - 5224
Fax:   (478) 926 - 4911
DSN Prefix: 468


-----Original Message-----
From: Mel Parrish [mailto:[log in to unmask]]
Sent: Tuesday, January 08, 2002 1:33 PM
To: [log in to unmask]
Subject: Re: [TN] Staking compounds


Hans
Recommend looking very closely at the Z, CTE characteristics of the RTV
also.  I had some hardware reliability issues in defense products years back
where the PTHs were partially extracted from the board due to RTV staking
under the components. More specifically these were PGAs.
Also recommend keeping in mind that the conformal coating is a limited
environmental barrier at best for moisture.

Mel Parrish


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Hinners Hans M Civ
WRALC/LUGE
Sent: Tuesday, January 08, 2002 6:44 AM
To: [log in to unmask]
Subject: Re: [TN] Staking compounds


Hi All,

This is great information.  I've had an Assembly supplier suggest using an
RTV to stake discrete components to FR-4.  Graham confirmed that it wasn't a
good combination with a silicone based conformal coating.  (Thanks Graham.)
The last thing I or the customer needs is dewetting of the conformal
coating.  My applications are hi-rel military avionics - in a rather harsh
environment: high vibration, high humidity and some salt water.

Is there some cutoff point when it's better to go with mechanical staking?
I'm new to staking.

Hans

Integrity First  -  Service Before Self  -  Excellence in All We Do
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hans M. Hinners
Electronics Engineer
Warner Robins - Air Logistics Center (WR-ALC/LUGE)
226 Cochran Street
Robins AFB GA 31098-1622

mailto:[log in to unmask] <mailto:[log in to unmask]>

Com: (478) 926 - 5224
Fax:   (478) 926 - 4911
DSN Prefix: 468


-----Original Message-----
From: Dieselberg, Ron [mailto:[log in to unmask]]
Sent: Tuesday, January 08, 2002 7:28 AM
To: [log in to unmask]
Subject: Re: [TN] Staking compounds



Doug, we have used CONAP K-20 for a long time with good results. We have
also used Loctite 416 with 18580 activator. The Loctite is easier to use
since it "sets" more quickly.

All depends on how you want to use it and how much time you have available
for curing.
In either case be sure the materials that you are going to stake to are
"sqweekey" clean!

Ron Dieselberg
Trainer/Auditor
CMC ELECTRONICS
CINCINNATI
[log in to unmask]

        BM__MailData-----Original Message-----
From:   [log in to unmask] [ mailto:[log in to unmask]
<mailto:[log in to unmask]> ]
Sent:   Monday, January 07, 2002 14:41 PM
To:     [log in to unmask]
Subject:        [TN] Staking compounds

        Good day all,

        I am curious as to what all y'all use for staking compounds (to fix
wires
or components in place) on your assemblies, especially if you are in the
high-rel area or aerospace sector.  Thanks.

        Doug Pauls
Rockwell Collins


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