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May 2001

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Subject:
From:
Kathy Bergman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 11 May 2001 11:15:01 -0700
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FYI, from a practical manufacturing point of view, I normally will ask that the clearance be
at least 15 mils, ID to OD of thermal relief. Anything less than 5 mils has a good chance of
turning into a direct connect.
kb

Ted Tontis wrote:

>         I am still fairly new to PCB design and I am studying for the IPC
> design cert. I cam across IPC -2222 9.1.2 Thermal relief in conductor planes
> which states the relationship between the hole size, land and web area is
> critical. Typically, divided 60% of the minimum land area diameter by the
> number of webs desired to obtain the width of each web in accordance with
> the following example:
>         I understand this with no problem but where does it state the air
> gap or expansion size? Is it the same value all the way around the land
> area? or does the current control the distance?
>
> Thank you,
>
> Ted Tontis
> Engage Networks Inc.
> [log in to unmask]
> PH 414.273.7600 Ext. 7607    <http://www.engagenet.com>
>
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