I have seen solder wet up the PTH and not wet to the component lead.  
There is a little known or discussed problem with the J-STD-002. It does 
not require wetting close to the component.
I have also seen examples where the solder wets up the lead and PTH but 
where a contaminate on the PTH (solder mask) prevents required 
circumferential wetting.

And on one time I saw nearly 100% vertical fill 100% wetting, but a 
defect condition because of a crack in the PTH at the interface of the 
rolled copper foil and the plated copper wall, took a cross section to 
find it.



On 3/16/2016 2:45 PM, Stadem, Richard D. wrote:
> In response to question #1, solder cannot flow up into a hole unless it is molten.
> If it is molten, one has to assume it will wet to the hole wall. The only way it would not is if the hole wall was contaminated. That I have never heard of.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> Sent: Wednesday, March 16, 2016 1:33 PM
> To: [log in to unmask]
> Subject: [TN] Hole Fill and Thermal Relief
>
> Maybe I should know better than to ask two questions in the same email, but they're related...
> I got into a discussion about the hole fill requirement for some large through-hole power devices and connectors. The supplier is worried about using a "percentage" hole fill measurement, because he says that even if the hole is 75% full (or whatever percentage we want to use) the hole wall will not be WETTED 75%. He maintains that the cold solder can extend up farther than the actual portion that makes a good joint. So he is looking at the TOP PAD WETTING for verification of a good solder joint, even though we don't require it.
>
> Q1) It seems like an inspection procedure looking for WETTING instead of HOLE FILL is not what is intended in IPC, but does he have a point? The hole fill problem is with Selective Soldering, not Reflow
>
> Q2) Wanting to provide bare board designs using good DFM practices, I would be willing to reduce my thermal spoke widths so the solder will flow better, but I can't find a calculation that would tell me what I need for something like 10A. There is nothing about this in the IPC-2152 Current Carrying standard. Is there a rough guideline I can use for current through planes using thermal relief??
>
> thanks
> Jack
>
>
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