[SI-LIST] Re: Regarding the air gap between via hole and copper
- From: "Pang Ning" <pangning2000@xxxxxxxxx>
- To: "Dagmara Avanindra" <dagmara.avanindra@xxxxxxxxx>
- Date: Sat, 16 Jul 2005 09:57:08 +0800
Hi Dagmara,
Yes, it's anti-pad. But because it's positive plane, it's different from the
anti-pad on negative plane. Currently, the via hole aperture diameter is
8mil, and the outer ring of the via is 18mil(diameter). The anti-pad
diameter is 28mil. In this way, the pouring copper will have only 5mil air
gap to the via pad.
I have checked with some PCB manufacturers. Some of them told me the gap is
a little small, but I thought it's better for power integrity because power
plane is much wider with 5mil gap, right?
Thanks,
Peter
----- Original Message -----
From: "Dagmara Avanindra" <dagmara.avanindra@xxxxxxxxx>
To: <pangning2000@xxxxxxxxx>
Cc: <si-list@xxxxxxxxxxxxx>
Sent: Saturday, July 16, 2005 1:29 AM
Subject: Re: [SI-LIST] Regarding the air gap between via hole and copper
Peter,
Sounds like you are talking about the size of antipad, and the size
of your antipad is 10 mils larger than pad, correct? (5 mils all
around).
Depending on who you use to manufature this board, there should be
no problem with this antipad size.
I wouldn't worry much about the xtalk either, unless you are talking
about some super-sensetive analog planelet, in which you have lots of
extra vias for noisy signals.
Dagmara
On 7/15/05, Pang Ning <pangning2000@xxxxxxxxx> wrote:
> Dear Experts,
>
> I have a simple question about the gap between the via hole pad and
> surrounding copper. In VCC layer, I used positive plane. Because the board
> size is small, in order to give wider spacing for power between via holes,
> I
> used 5mil air gap between via pad and the copper. I don't know whether
> this
> spacing(5mil) will cause some problems such as crosstalk from via holes,
> low
> yield issue... Is 5mil too small for the gap? Could you give me some
> suggestions if you think there is anything wrong?
>
> Thanks,
> Peter
>
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