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Date: | Wed, 22 Oct 1997 11:20:50 +0100 |
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John Peavoy@ISL
22/10/97 11:20
Glenn / David,
I believe that Alpha Advanced Products Div. (among others) had a product
with just what you mention i.e. "hard spiky bits"(!) to penetrate through
the oxide layer. I believe that this was/is called Polysolder. Not sure if
it's still on the go, or has been superceded.
Regards,
John Peavoy
Viasystems
[log in to unmask] on 21/10/97 21:33:48
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Subject: Re: [TECHNET] FAB: Silver-filled epoxy with tin or solder
Glenn,
The problem with using them with tin or tin-lead is that the quite stable
layer of oxide that forms on tin can result in poor conduction. If you
melt the tin/tin-lead during epoxy cure then the silver filler in the
epoxy may leach into the solder, leaving a silver depleted and therefore
non-conductive layer of adhesive - I have heard of people getting away
with this through very carefull process control, but I think it would be
better not to risk it if possible. I believe the adhesives engineered to
work with tin have "hard spiky bits" to penetrate the oxide layer.
David Whalley
>David,
>Very interesting. What would be the reasoning for not using silver-filled
>epoxy with tin or solder surfaces?
>
>Glenn Pelkey
>Quality/Reliability Engineer
>| The general rule for using silver filled epoxys is not to
>| use them with tin or
>| solder finishes. Some manufacturers do market materials
>| designed to work with
>| them and I have also talked to people who have had success
>| with other materials
>| by very carefully controlling the curing process so that
>| the solder layer just
>| briefly melts, but if you can switch to another finish on
>| the wire you are less
>| likely to have problems.
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