Alan,
Your question has raised another one I have. We have some products with carbon
ink for button contact. We also use no-clean, but have tended to use water
soluble for these products to eliminate residues on the carbon ink surface. Do
you mask the carbon ink before fluxing or does the no-clean residue pose no
problems for button contact?

Regards Evan

Evan Jones
Manufacturing Engineer
IBM Wangaratta
Ph 61 3 5720 2539       Fax 61 3 5720 2412
Email [log in to unmask]

---------------------- Forwarded by Evan Jones/Australia/IBM on 08/01/98 08:49
---------------------------


[log in to unmask] on 07/01/98 21:59:35
Please respond to [log in to unmask] @ internet
To: [log in to unmask] @ internet
cc:
Subject: [TN] Gold Flash benefits over HAL


We are wave soldering double sided PHT boards using  a No Clean flux.
There is a proposal to replace the hot air levelled solder over bare
copper(HAL ) finish with gold flash, about 5u inch thick, over 100u inch
of nickel.

The proposal would allow us to drop the carbon ink screening requirement
used for contacts to a rubber keypad.

I see no other benefits to this, only the following problems:- gold
contamination of the solder pot and weaker solder joint strength. Does
anyone know of any other benefits?
Alan Shaw

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