[SI-LIST] Re: High speed signal on top layer

Istvan, good point.  Capping isn't my first choice.  But it is an 
option.  I don't know if George's issue is thickness, cost or both.   But 
if he wants to run 3Gbs microstrip, I think he needs to be very 
careful.  Capping avoids adding planes with all the attendant benefits and 
caveats.

Best Regards,


Steve.
At 09:23 PM 5/30/2005 -0400, Istvan Novak wrote:
>Steve, John,
>
>Tradeoff with capping is it also means an extra layer (and for symmetry 
>reasons,
>probably two layers) in the PCB .
>
>Regards,
>Istvan
>
>
>steve weir wrote:
>
>>John, that is where dielectric caps the uppermost signal etch.  This 
>>controls the copper dimensions, affording much better impedance control.
>>
>>Regards,
>>
>>Steve.
>>At 07:41 AM 5/31/2005 +1000, Jon Keeble wrote:
>>
>>
>>>Hi Steve ..
>>>
>>>What is 'capping'?
>>>
>>>Regards
>>>
>>>Jon Keeble
>>>
>>>----- Original Message -----
>>>From: "steve weir" <weirsi@xxxxxxxxxx>
>>>To: <george_dai@xxxxxxx>; <si-list@xxxxxxxxxxxxx>
>>>Sent: Tuesday, May 31, 2005 6:49 AM
>>>Subject: [SI-LIST] Re: High speed signal on top layer
>>>
>>>
>>>
>>>
>>>>George,
>>>>
>>>>1. Possible, but there are several pitfalls, including control over
>>>>plate-up and solder mask.  Capping could help with those.
>>>>
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