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RE: Lead Free (was Re: CD MMC caps from DigiKey...)



Original poster: "Dave Halliday" <dh@xxxxxxxxxxxxxx>

They used ceramic instead of printed circuit materials because of high
impedance and it was non-porous (it would not absorb water or pollutants
from the atmosphere).

They formed the contact areas by depositing a thin film of silver.

Normal solder will dissolve this and highly degrade the silvers adhesion
to the ceramic.

End result -- use lead solder and your parts will fall off the terminal
strips with the slightest jar.

This is not fixable because once the bond between the ceramic and the
silver is gone, it is gone.


> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Friday, December 16, 2005 2:14 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: Lead Free (was Re: CD MMC caps from DigiKey...)
>
>
> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
>
> The book for my Tek scopes (535a/545a) says to only use silver
> bearing solder, as using regular solder will damage the ceramic
> things all the parts are soldered to, it is very old I know, but it
> is electronic... is this silver migration thing something I should
> worry about?
>
> -Rich (in Berkeley)"
>
>     By coincidence those are the same scopes I have.  I can't imagine
> silver migration problems as these terminal boards are big and crude.
> Ed
>
>
>
>