Mark,

You have asked the same question I did last year. No one has attempted
to answer me. I wish you luck this time and hoping to bank on your luck,
someone will be kind enough to give us a good explanation?

Regards,
Wee Mei

Mark Holmes wrote:

>Hi all,
>
>I am looking at IPC-2222 9.1.2 regarding thermal relief pads. It provides a
>formula for
>the web width based on the minimum pad size.
>
>I can use this method with my current software, which allows me to create a
>thermal
>relief for each pad. But, I also use a system that only allows me to specify
>thermal
>relief pads for 'non-vias' in a particular plane.
>
>My questions are, what are you guys using to calculate your thermal relief
>pads?
>Do you calculate the web size for each pad used, Or do you have some other
>method of calculating the web width.
>
>Any advice, rules of thumb etc. would be most appreciated.
>
>Just one more thing, could anyone confirm what is meant by "Standard
>Manufacturing Allowance"
>in IPC-2222 Figure 9-1. Is this the same as IPC-2221 table 9-3 "Minimum Hole
>Location Tolerance, dtp"?
>
>Regards.
>
>Mark
>
>Mark Holmes PCB Designer
>Helvar Merca Ltd.
>Hawley Mill
>Hawley Road
>Dartford
>Kent DA2 7SY
>Tel: 01322 222211
>mailto:[log in to unmask]
>
>Visit our NEW updated website at:
>http://www.helvar.co.uk
>
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