I can recall a recent program we ran here where a large radial leaded cap
that was bonded to a circuit board with RTV 3140 had broken leads after
going through qualification vibe. So I can second Guy Ramsey's observation
about components bouncing. We ended up changing to a soft epoxy with a low
CTE and the bonded parts survived quite nicely. We were quite surprised at
the difference in characteristics when we vibe tested fully instrumented
components with different bonding materials and applications. We found that
the soft epoxy worked the best. Please note that our performance
requirements superceded any priority that related to the time to prepare,
apply and cure the epoxy. So, I'm not suggesting that this method is fast
and easy, it's probably the opposite.

Bill Kasprzak
Moog Inc. Manufacturing Engineering, Electronics


> -----Original Message-----
> From: Guy Ramsey [SMTP:[log in to unmask]]
> Sent: Wednesday, February 13, 2002 11:02 AM
> To:   [log in to unmask]
> Subject:      Re: [TN] Adhesive Recommendations?
>
> I wondered if anyone was going to caution the group on this fact. I have
> seen RTV damage the printed circuit right through solder mask.
>
> The other thing I have observed is that it isn't that good at absorbing
> shock. If you hit it hard it can simply tear or worse bounce and actually
> return energy to the component.
>
> I think in the context originally described in this thread, used in
> conjunction with a wire hold down, it may be okay.
>
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]]On Behalf Of bbarr
> > Sent: Wednesday, February 13, 2002 8:54 AM
> > To: [log in to unmask]
> > Subject: Re: [TN] Adhesive Recommendations?
> >
> >
> > Use caution if you buy a general purpose RTV at a hardware store. Many
> of
> > those products will be corrosive to electronics. If it smells like
> vinegar
> > when it cures it is no good for electronics. You must use an electronic
> > grade of RTV on boards. We use Dow Corning 3145 all the time for staking
> > with excellent results. We too transfer it to a syringe and use an EFD
> > dispenser.
> >
> > Bob
> >
> > =======================
> > Robert Barr
> > Manufacturing Engineering
> > Formation, Inc.
> > Voice: 856-234-5020 x3035
> > Fax: 856-234-6679
> >
> > > -----Original Message-----
> > > From: TechNet [mailto:[log in to unmask]]On Behalf Of Phil Nutting
> > > Sent: Wednesday, February 13, 2002 8:15 AM
> > > To: [log in to unmask]
> > > Subject: Re: [TN] Adhesive Recommendations?
> >
> > >
> > > For instant gratification there are several clear RTV products
> > > available at the local hardware store that are used for general
> > > bonding and sealing. Like replacing those tiles in the bathroom
> > > that have come loose.
> > >
> > > It isn't high tech but it has worked for many years.
> >
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