Packaging substrate, packaging structure and welding structure of circuit board

The invention discloses a packaging substrate, a packaging structure and a welding structure of a circuit board, the packaging substrate and the packaging substrate are used for welding components, aplurality of grooves are formed in the surface of one side, used for welding the components, of the packaging substrate, bonding pads are arranged at the bottoms of the grooves, and the bonding pads are arranged corresponding to pins of the components. And the groove is used for accommodating liquid soldering tin when the soldering tin of the welding pin and the bonding pad is melted. According tothe packaging substrate, the packaging structure and the welding structure of the circuit board provided by the invention, the plurality of grooves are formed in the packaging substrate, and the grooves can accommodate liquid soldering tin to accommodate liquid soldering tin in a secondary backflow process, so that short circuit of components caused by overflow of the liquid soldering tin is avoided; by arranging the plur