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February 2004

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Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 16 Feb 2004 17:22:52 +0200
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I guess you have to analyse the situation. Theoretically, tin on copper
on iron should be readily solderable. Can we find why it isn't? Starting
at the tin: is it massively oxidised? Was the copper properly prepared
to receive the tin? Is it electroplated? If so, how pure is it? Is it
porous? Are there organics co-deposited with the tin? Is it hot-tinned?
If so, has it been wiped, so that the tin layer is non-existent, just an
intermetallic layer? Has the intermetallic layer been properly formed?

Going down to the copper, what is its thickness? What kind of plating
bath was used? How pure is the copper? Has it been cleaned with
abrasives? Are there organics co-deposited with the copper? Is it porous?

By now, you should have found the cause but, if not and if the tin and
copper plating is too thin, then it is just possible youmay find the
problem at the copper/iron interface.

No one here can solve your problem for you, we can only tell you where
to start looking.

Brian

Poh Kong Hui wrote:

> Hi Technetters,
>
> I would like to know if there is such kind of plating step.
> The lead's base material is made of Iron (Fe), coated with Copper (Cu) and
> next the outer with Tin (Sn).
>
> The issue faced is that the leads of the component has serious
> solderability issue.
> We do re-tin , but not 100% work. Some leads work fine and some are not.
>
> Please advise me if there is way to resolve the solderability.
>
> Thanks.
>
> Poh
>
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