What's the difference between via and pad in the circuit board

The via in the printed circuit board is called a hole, with holes, blind holes and buried holes. It is mainly used for the connection of wires of the same network on different layers, and is generally not used as a welding element.

The pad in the circuit board is called the welding disc, which has the points of the butt welded plate and the table affix plate;The butt welded plate has a hole, which is mainly used for welding pins.There is no weld hole in the table sticking plate, which is mainly used in the welding table mounting element.

Via mainly plays the role of electrical connection, via the pore diameter is generally small, usually as long as the plate processing technology can do enough, and the via surface can be applied to prevent welding ink, also do not apply;And pad not only have the effect of electrical connection, but also the effect of mechanical fixation, pad of the aperture (of course refers to the pin pad) must be large enough to through the component pin, otherwise it will cause production problems;In addition, pad surface must not have the resistance welding ink, because this will affect the welding, and generally on the pad surface coated with the flux;Also, there must be a certain standard between the diameter of the pad and the aperture of the pad. Otherwise, it will not only affect the welding, but also cause the installation to be unstable.