[PCB_FORUM] Re: Anti-pads

Yeah, I haven't been paying as much attention to it as I should also.

Guess I've been lucky, no negative feedback.

 

  

Gary E. MacIndoe
PCB Design Engineer
MTS Systems Hardware Design
Mile High Design Center
2950 East Harmony Road
Fort Collins, CO 80528
Phone: (970) 226-9675
FAX:   (970) 226-9695

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 1:11 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [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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