> We have been using vias without thermal pads for some time now, and have
> had no problem at all.  To my knowledge our fab vendors did not even notice
> the difference.  
> 
> Due to our heavy use of smt, virtually all our boards are 100% or 99.99%
> surface mount, removing the thermal pad and connecting our vias directly to
> the plane improved the emi-esd characteristics of our boards.  It has been
> a good deal all around.
> 
> In addition to this, we have also reduced the size of our anti pads.  We
> were having problems with signal quality due largely to "impedance bumps"
> which would occur when a trace passed a pad with a large anti pad.  This
> was because as the trace would pass over the anti pad, it would suddenly
> not have a ground layer to associate to.  To cure this problem, we have
> reduced our anti pads to a size where when traces pass by at minimum distance,
> there is adaquate coverage by the associated layer.
> 

Ditto...  This is exactly what we have done for the last 3-5 years, and have
gotten the same results and findings. Great work! and good wording.


Mitch Morey
Sr. PCB Designer
TRW, Inc.
Redondo Beach, CA 90278
Phone: (310)814-5765
Fax:   (310)812-4949
EMAIL: [log in to unmask]

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     PCB layout is like fine art. You have to DIE to be famous!
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