[PCB_FORUM] Re: Anti-pads

True...we've been lucky in that we're not doing much with high-speed (over
100 MHz) design.

 

Thinking about it, our 25-mil antipads over 10 mil drills are only 7.5 per
side anyway.

 

We do have some LVDS video running around a couple of our boards...have to
be more careful about those.

 

/s/jar (alan.ritter@xxxxxxxxxx)

      http://www.mtritter.org

 

  _____  

From: Macindoe, Gary [mailto:Gary.Macindoe@xxxxxxx] 
Sent: Friday, December 14, 2007 2:01 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Anti-pads

 

Alan,

 

This sounds like a lot, 10 per side over the drill (30 mil anti-pad for a 10
mil drill).

When you have several high speed traces at minimum spacing between vias,
that's more than you can afford.

Those high speed traces don't like to run over the hole (anti-pad) in the
reference plane.

 

Thanks for the reply.

 

 

Gary E. MacIndoe
PCB Design Engineer
Fort Collins, Colorado

amd.com

gary.macindoe@xxxxxxx

  _____  

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Ritter, Alan
Sent: Friday, December 14, 2007 12:25 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Anti-pads

 

Smallest anti-pad we have used is 25 mils for 8-mil (BGA) and 10-mil vias.
35 mils for 15-mil "power" vias, etc.  We figure a minimum of 10 per side
over the drill.

 

/s/jar (alan.ritter@xxxxxxxxxx)

     http://www.mtritter.org

 

  _____  

From: Macindoe, Gary [mailto:Gary.Macindoe@xxxxxxx] 
Sent: Friday, December 14, 2007 1:11 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Anti-pads

 

Thanks Gerry.

 

I haven't thought about it for quite a while, I was forgetting that anti-pad
to drill is what matters.

I suppose with an anti-pad that small, you have to make sure you suppress
unused inner pads.

A drill of 10 mil probably has a 20 mil pad, so a 16 mil anti-pad to a 20
mil pad would be too close otherwise.

 

Thanks again,

Gary

 

 

Gary E. MacIndoe
PCB Design Engineer
Fort Collins, Colorado

amd.com

gary.macindoe@xxxxxxx

  _____  

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Gerry Meier
Sent: Friday, December 14, 2007 11:48 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Anti-pads

 

16 mil over the drill size - 10 mil drill 26 mil anti-pad

 

Gerry Meier, Sr. PCB Designer

Freedom CAD Services. Inc

Voice: (256)776-7470 or (603) 864-1350

Email:gerry.meier@xxxxxxxxxxxxxx

visit us at http://www.freedomcad.com

 

 

  _____  

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Macindoe, Gary
Sent: Friday, December 14, 2007 12:28 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Anti-pads

 

Hey guys,

 

We haven't thrown around anti-pads for a while!

 

What is the smallest anti-pad for an inner plane that you have successfully
used?

 

Has anyone used down to 5 mils a side anti-pad to pad?

 

Thanks,

Gary

 

 

Gary E. MacIndoe
PCB Design Engineer
Fort Collins, Colorado

amd.com

gary.macindoe@xxxxxxx

 


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