few place to look for the voids on ground plane: (1) via outgas -  
limited floor life of the board or bake the board.  (2) via poor  
wetting - normally filled via might using epoxy, it outgas and non- 
wet... Check via fill material and solder compatibility (3) Ground  
plane of the board sink too much heat (slow reflow process at ground  
plane) - change pre=heat.  (4) stencil print pattern - use "X"  
pattern and pick and place using "over travel" rather than drop -  
push the part down a bit... make sure no parts tilt (solder paste  
65-68% coverage with channel allow flux to escape).  (5) you need to  
know the parts inside structure,  if it is small, no problem, if it  
consists of multiple ground, you need to make sure uniform coverage  
of solder under the parts (my spec used to be no 20% void in any  
guardroom,  with overall <30% to avoid any thermal runaway of the  
parts - you need to know your design... e.g. 3 thermal vias connect  
to a particular plane, if all three are not soldered, what will be  
the impact, not only thermal, but could be any electrical impact?)...  
etc.etc.  IMHO.
Best of luck.
jk
On Jan 8, 2018, at 11:26 AM, Guy Ramsey wrote:

> We are having trouble with a lot of boards.
> We are seeing excessive voids like the ones on page 18 of this
> presentation.
>
> https://www.google.com/url? 
> sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwj27JnJ38HYAhUF5YMKHWYI 
> CvcQFggpMAA&url=https%3A%2F%2Fwww.eptac.com%2Fwp-content%2Fuploads% 
> 2F2012%2F06%2Feptac_07_18_12.pdf&usg=AOvVaw2OX6J_YRqkuNUNNgDBvmwZ
>
>
> The vias are filled and plated. Anyone seen this, resolved it?
>
>
> Guy