I dunno, it seems as though 10 should be enough for
a connection to power. That's 10x4 or 40 mils.
I would check with your board house and get an explanation
as to why the webs are smaller. You did measure them
to be sure, right? In any case, the board house should
be able to tell you what they are.
I think you have all of the answers as to how to change the
web width so I won't bother you with that.
Kevin McCowan Sr. PCB Designer TSI Telsys
That should be DYN_FIXED_THERMAL_WIDTH-----------------------------------------------------------
It is Friday, my two typing fingers are tired :)
--
/George Patrick/
*Tektronix, Inc.*
Central Engineering, PCB Design Group
P.O. Box 500, M/S 39-512
Beaverton, OR 97077-0001
Phone: 503-627-5272 Fax: 503-627-5587
http://www.tektronix.com <http://www.tektronix.com/> http://www.pcb-designer.com <http://www.pcb-designer.com/>
/It's _*my*_ opinion, not Tektronix'/
-----Original Message----- *From:* Patrick, George H *Sent:* Friday, January 14, 2005 15:36 *To:* icu-pcb-forum@xxxxxxxxxxxxx *Subject:* [PCB_FORUM] Re: thermal webs
If the gerbers show 10 MIL and the boards have less than that, you
should talk to your board manufacturer. How are you measuring them?
10 MIL thermals on a power plane sounds rather thin to me, too, but
that is just based on what I am used to. We use 12 MIL for our
smallest vias (10 mil drill), and more for larger pads (a 62 MIL pad
would use 30 MIL gaps by default.)
With positive planes the web widths in 15.x are set in one of two ways:
* By default, web width traces are set by the trace width used by that signal for that layer. For example, if the signal has a trace width of 10 MIL set in the constraint set or constraint manager, any plane will generate thermal voids using that value. This is the only way static shapes can adjust this. * If the pin/via has a DYB_FIXED_THERMAL_WIDTH property attached, the value of the property will be the width of the web. This method is 'sposed to work only with dynamic shapes, but I haven't tried manually voiding a pin with this property in a static shape so I can't verify that
-- /George Patrick/
*Tektronix, Inc.*
Central Engineering, PCB Design Group
P.O. Box 500, M/S 39-512
Beaverton, OR 97077-0001
Phone: 503-627-5272 Fax: 503-627-5587
http://www.tektronix.com <http://www.tektronix.com/> http://www.pcb-designer.com <http://www.pcb-designer.com/>
/It's _*my*_ opinion, not Tektronix'/
-----Original Message----- *From:* alan fisch [mailto:alanfisch@xxxxxxxxx] *Sent:* Friday, January 14, 2005 15:12 *To:* icu-pcb-forum@xxxxxxxxxxxxx *Subject:* [PCB_FORUM] thermal webs
OK I'm having a seniors moment and I'm not old enough to have one... so that tells you what kinda' day I'm having.
I received a board back from the manufacturers and my customer pointed out that the webbing on the thermals looks very fine. I looked back on the database and it reads 10 mil. The gerbers read 10 mil but the webbing on the board isn't??? I'm waiting to hear back from the vendor on that.
So my question is where in Allegro 15.1 do I find the control device to change/set web widths. I use positive artwork only therefore no apertures. I know I've set this in the past but can't find the menu now...ugggggggggggg And help menus don't help..:-)
Al
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