PCB - High current PTH
Generally speaking, I use several large-size vias when I need to ensure a reliable high-current path between top and bottom layers on a PCB. 

Large size, for me, is a 0.035" (~0.90 mm) hole with at least a 0.02" (~0.50 mm) anulus in the solder-mask around the hole. Plaster as many vias around the component lead as you have room - at least 4 or 5.

I find that we get 100% fill on vias when wave-soldering our boards.