I would think it would depend on what the human in question is / was doing just before the exposure. Some substances can be rather nasty, coffee had a tendency to be acidic, as do some carbonated beverages, cigarette smoke has nasty stuff in it, etc. An engineer I used to work with described once where they would get thick film hybrid circuits that the circuit traces, I think they were gold, would be received from a supplier and the traces were gone. It seems that when the operator came back from coffee break and exposed the uncoated bare hybrids to coffee breath the acidity would attack the traces. 


On Mon, 11 Jul 2011 20:18:26 -0400, Kenneth J. Wood <[log in to unmask]> wrote:

>Hi all...
>I have an odd one for you all.
>I'm working on a PCB that will be used to detect human inhalation and will
>be directly breathed upon.
>Question is...what is the best surface finish and solder for this
>application?
>Thanks
>Ken
>
>_____________________________________
>Kenneth J. Wood
>Saturn PCB Design, Inc.
>www.saturnpcb.com
>
>
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