I don't believe there is a specific spec for what you are looking
for...someone please correct me if I am wrong...
The IPC-2221 page 55 has an example requirement that says for UNCOATED (no
soldermask or conformal coating) boards, you need .75mm minimum but not less
than allowed by the electrical clearance requirements...
The things that would govern the amount of spacing from any mounting
hardware would be voltage on the line in question relative to any voltage or
ground potential on the hardware, tooling clearance to swage or mount the
standoff, and installation tool (screwdriver?) and hardware clearance from
any screws and washers used in mounting the standoff to a chassis or
bracket. Also be concerned about clearance to any nearby component body as
well as the conductive pattern or any conductive non-insulated lead(s) from
the component involved.
If you are doing UL or TUV certification, there are more stringent
requirements to be concerned about... The ability to prevent shock hazard by
not allowing the end user to get their finger or a tool into an area that
will get them electrocuted across the line or from the line to ground,
spacing between the primary line voltages and SELV or Safety Extra Low
Voltage requirements at 48VDC or lower... secondary voltages... Distances
from Ground to the line voltages, line to line voltages, and on and on...
They are also concerned with Fire hazard... a failure shall not cause a fire
hazard... etc... It's a little more complicated...
Best regards,
Bill Brooks - KG6VVP
PCB Design Engineer , C.I.D.+, C.I.I.
Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
e-mail:[log in to unmask]
http://www.dtwc.com
http://pcbwizards.com
-----Original Message-----
From: Gary M. Koven [mailto:[log in to unmask]]
Sent: Monday, March 28, 2005 10:11 AM
To: [log in to unmask]
Subject: [DC] Conductive pattern to mechanical hardware clearance
Which IPC specification will show the minimum clearance from conductive
pattern to mechanical hardware such as swage standoffs?
Right now I have approximately 0.025in (0.635mm) from via pad edge to
standoff lip edge, and want to make certain that distance will be
sufficiently robust for production.
The manufacturers' datasheets don't specify a recommended clearance, and
neither do the IPC-222X series specs.
Thanks,
======================
Gary M. Koven
Engineering Services Manager
Dynazign, Inc.
806 Tyvola Road, Suite 100
Charlotte, NC 28217
P: 704.405.1234 x210
F: 704.405.1402
http://www.dynazign.com/
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