> Gary Camac wrote:
>
> Jim
>     Your quoted chapter and verses bring up a question that I have been
> struggling with.  With todays ever shrinking lines and spaces, what is
> considered the "minimum electrical spacing"?  It seems to me that
> different sections of a PWA could have different spacing requirements.
> How is this spacing being documented so that the information can be
> related to production personnel?
>
>
        Gary,

                Minimum electrical spacing is dictated by voltage. IPC-D-275
requires .005 for a finished assembly with 0-15V between adjacent
conductors. The spacing requirements increase with voltage and whether or
not the assembly is conformally coated (which has a higher dielectric
constant than air). It's common for different sections of an assembly to be
operating at different voltages and so have different spacing requirements.
                As for documenting that information for production
personnel, it's not usually done, since by the time it gets into production,
it's too late to fix an insufficient spacing problem. Instead, the approach
is to make right by design.


 Michael Hiteshew
 Lockheed Martin Launching Systems
 [log in to unmask]
 (410) 682-1259

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