Please refer to IPC-D-275 Table 3-1, column A7, External Component lead/
termination, with conformal coating (any elevation). Your voltage
category is 16-30 and the minimum spacing (inches) is .005. This takes
into account all process tolerances (over/under-etch, over/under plate,
etc.), so make sure that you consider the maximum material condition of
your conductors. The reason that I recommend using column A7 is that in
the condition you described, no amount of conductor spacing on an
average PCB will be a sure substitute for conformal coating. Also
remember, it is voltage that determines the arcing distance, not
amperage.
Chris Taylor
Senior Printed Circuit Designer
LXE, Inc.
125 Technology Parkway
Norcross, GA 30092
voice: (770) 447-4224 X3242
fax: (770) 447-6928
[log in to unmask]
>----------
>From: IDKitty6[SMTP:[log in to unmask]]
>Sent: Monday, March 09, 1998 10:11 AM
>To: [log in to unmask]
>Subject: [DC] To Prevent Arcing
>
>Hello,
>I'm hoping someone can verify this for me. In order to prevent arcing on a
>board running 12-16vdc, 23 amps, to be used in external weather conditions,
>95% humidity ( I don't know the temperature above ambient ), what should the
>minimun conductor width and spacing be? According to IPC-D-275, the minimun
>conductor spacing should be 25 mils. This seems so small to me, especially
>if
>the conductor width minimum is somewhere between 140-300 mils. Can anyone
>give me a good guess on what to use? Is 25 mils enough to prevent arcing
>here?
>Thank You So Much,
>Kitty Hines
>
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