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February 2012

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Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Brian Ellis <[log in to unmask]>
Date:
Wed, 29 Feb 2012 20:01:30 +0200
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text/plain
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text/plain (33 lines)
All fluxes, by definition, must have some form of corrosive ion for it 
to be able to reduce metal oxides. Even pure rosin isomers have a 
carboxylic acid group. From your description, it seems probable that you 
have what is effectively a short-circuited battery with gold and copper 
as your electrodes with bare copper where the fingers are cut or the 
gold plating is too thin/porous/worn through. Any condensation would 
provide you with an electrolyte, exacerbated by tthe presence of any 
ionogenic and/or hygroscopic contaminant (not necessarily from your 
flux, which you don't want on gold-plated fingers, anyway).

Brian

On 29/02/2012 16:53, Victor Hernandez wrote:
> Fellow TechNetters;
>
>     Do No Clean LF fluxes, Rosin Core/molten solder, have a corrosive ion?   Every so often when conducting analysis on Field Return Product I notice small amount of corrosion product on gold plated contact on DIMM and PCI Slot connector.   Sometimes on other gold plated connector leads.   So I am trying to understand which component had a corrosive ion waiting for the right conditions to flourish.   Small amount of greenish/bluish residue.   It can be seen on wipe zone and/or stamp edge of contact.   Where is this active corrosive ion coming from?
>
>     Can someone provide the link to Stevezea home page for posting pictures?
>
> Victor,
>
>
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