Yes....I heard of this problem....

Whenever our engineers ask us to do so, we refuse, as we know it creates
this assembly/reflow problem. We as PCB Designers want to design PCB"S that
assemble properly, so knowing this in advance helps. It's an ideal RF design
which would have the via within the pad, BUT it creates a manufacturing ( &
lower yield) problem.

Instead, we give them several more vias near the pad & closer to it....

I am interested in hearing how others handle this also.....

Regards
TDK



> -----Original Message-----
> From: Zweigart, Siegmund [mailto:[log in to unmask]]
> Sent: Monday, April 15, 2002 10:09 AM
> To: [log in to unmask]
> Subject: [DC] Redesign Via in Pad
> 
> 
> Hello to all
> 
> We have to redesign different board's because of Via in Pad:
> Situation now:
> FR4, thickness 1,5 mm, OCC finish
> Through Hole Vias in Pads (middle, diameter 0,15..0,3 mm)
> 
> The problem is the sucking of solder form to the top to the 
> bottom side
> (causing low solder on top and bumps on test points on the 
> bottom side)
> Because of place limitations dog bones can't probably not be used.
> 
> What is your recommendation?
> Using Blind Vias (problem of Voids in the solder joint?) ?
> Epoxy (with Ag or what else) filled Vias?
> Vias on the edge of the pad?
> More ideas?
> 
> All input is welcome
> 
> Best regards
> 
> Siggi
> 
> 
> --------------------------------------------------------------
> --------------
> -
> Kind regards / Mit freundlichen Grüßen
> 
> Dr. Siegmund Zweigart
> 
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