FreeLists / si-list / [SI-LIST] Re: Vias on decoupling pads

[Ray Anderson <Raymond.Anderson@xxxxxxx>]

Vincenzo Kreft-Kerekes wrote:
> I've always wondered about this, from both the design and manufacturing
> standpoint, how is a via-in-pad any different from a via with a non-circular
> capture pad? Why would you use a microvia instead of lets say a 14 mil via
> in the center of a 40x40 mil 0603 pad which would practically be a large via
> capture pad with corners? Why would a fab house worry about the shape of the
> capture pad, they don't seem to handle octagonal capture pads for through
> hole vias differently? Or plane stitching vias with practically board size
> capture pads? Thanks a lot for your help.
> 
> Best,
> Vincenzo
> 

The issue is with the solderability of components to the pads after the 
bare pcb is fabbed.

If the via hole is too big or unfilled, your solder may wick down the 
hole causing insufficient solder on the pad.


-Ray

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