A component with lead pitch less than 20 mil V Via A hole through a PCB connecting various layers or unattached but serving as a component anchor point. Vias are usually plated. See also Blind and Buried Via W Wetting Ability of a liquid to flow across a surface as opposed to sticking to itself. Wetting occurs when the attractive surface energy of the pad or lead is greater than the surface energy of the solder , drawing a molecularly thin layer of solder across itself. Heating solder adds to the surface energy in the solder, so the cooler the solder the better the wetting.
Good wetting is indicated by a low contact angle between the fillet and the base metal.
Wicking Ability of solder to travel towards a heat source or fill a through-hole. Caused by the same dynamic forces that control wetting. They are sister processes.