RE: [SI-LIST] : skin effect

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From: Baikuan Wang (wangbk@sigrity.com)
Date: Thu Aug 31 2000 - 13:42:40 PDT


Sunil,

You are right. Both height and width are equal to contribute perimeter.

However, to reduce the resistance of strip line,
we try to increase the effective area, which is propotional to Perimeter,
and reduce the area of cross section relatively.

Therefore, the question is related to a classic question:
Square has the largest area, if all rectangles have same perimeter.

According to this, the larger the ratio of width/height is, the
larger the perimeter is.

Conclusion: Increase width is more effective than increasing height.

Regards.

Brian

-----Original Message-----
From: Sunil Kumar [mailto:sunilb@cdotb.ernet.in]
Sent: Thursday, August 31, 2000 11:15 AM
To: Baikuan Wang
Cc: Muhammad S. Sagarwala; si-list@silab.eng.sun.com
Subject: RE: [SI-LIST] : skin effect

Brian..

Perimeter=2(width+height)

So effect of changing height or width is same. Have I misunderstood
something?

Sunil

On Thu, 31 Aug 2000, Baikuan Wang wrote:

> Hi, Muhammad,
>
> Skin effect means that most of the current flows along the surface of the
> conductor.
> In this way, the effecient area current goes through is more dependent on
> the perimeter rather than the real
> area (Height x Width). Therefore, inreasing width is more effecient that
> increasing height in view of reducing
> the resistance of traces.
>
> Regards.
>
> Brian
> -----Original Message-----
> From: owner-si-list@silab.eng.sun.com
> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Muhammad S. Sagarwala
> Sent: Thursday, August 31, 2000 9:45 AM
> To: si-list@silab.eng.sun.com
> Subject: [SI-LIST] : skin effect
>
>
> Hello Si Gurus,
>
> I just had an interesting discussion with my boss on "skin effect on pcb
> traces".
> I was of the opinion that increasing the trace thickness from 1/2 oz. to
> 1oz. would help reduce the
> skin effect but according to him skin effect does not reduce
significantly
> with the increase in trace thickness.
> He was of the opinion ( and also had some data to back him up) that skin
> effect is more dependent on the
> width of the trace.
>
> I always thought that if one increases the overall perimeter of the pcb
> trace - regardless of whether it is done by
> increasing the width or increasing the thickness - the skin effect would
> reduce. I would appreciate if somebody
> could come up with a better explanation...
>
> Muhammad
>
> p.s.: when we talked about pcb traces we were talking about striplines
in
> particular...
>
>
>
>
>
> Muhammad S. Sagarwala
> Design Engineer
> Schlumberger SABER
> Ph. (408) 586 7065
> Fax (408) 586 4668
>
>

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