if it is mission critical part, there is always solder foil (flux  
build in or flux sticky on both side), you can order at volume - (not  
cost effective - however, you can cut on your own  if you only make  
less than 30ish) - for either prototype, or low volume extremely  
pricy stuff.  you can minimize the voids for sure.
On Mar 5, 2018, at 4:51 PM, Wayne Showers wrote:

> Dave et al,
> You can add me to the list of companies that will provide voiding  
> data.  I am data mining variations of the print pattern to reduce  
> voiding and I am in the process of marrying up stencil design to  
> void and fill percentages.
>
> I can echo the voiding request from Blackberry.  The original  
> request was 90% coverage and no more than 3 voids with no single  
> void greater than 5%.  Even to get to the 70%, I ended up using a  
> custom solder slug and still had voiding due to via in pad.
>
> I would like to see a standard that reflects something similar to  
> the following:
> Class 1: Undefined
> Class 2: Shall be 50% coverage with no single void exceeding X% or  
> as defined by customer or part manufacturer.
> Class 3: Shall be 70% coverage with no single void exceeding X% or  
> as defined by customer or part manufacturer.
> Note 1: Customer Requirements supersede
> Note 2: Manufacturer Recommendations/Requirements supersede
> Note 3: VIA in Pad and other design factors shall be considered and  
> evaluated if criteria cannot be met.