Circuit Plate hole solderability is not good, will produce virtual welding defects, affecting the parameters of components in the circuit, resulting in multi-layer board components and inner Line guide instability, resulting in the failure of the entire circuit function. The so-called solderability is the metal surface by the molten solder wetting properties, that is, the metal surface of the solder on the formation of a relatively uniform continuous smooth adhesion film. The main factors affecting the solderability of printed circuit boards are: (1) The composition of the solder and the properties of the solder. Solder is an important part of welding chemical treatment, it is composed of chemical materials containing flux, commonly used low melting point fused metal for Sn-Pb or Sn-Pb-Ag. The impurity content should have a certain ratio control, in order to prevent the oxide produced by impurities to dissolve the flux. The function of the flux is to help the solder moisturize the surface of the welded plate circuit by transferring heat and removing rust. White rosin and isopropyl alcohol solvents are generally used. (2) The welding temperature and the cleaning degree of the metal plate surface will also affect the solderability. The temperature is too high, then the solder diffusion speed is accelerated, at this time has the very high activity, will make the circuit board and the solder melt surface rapid oxidation, produces the welding defect, the circuit board surface pollution will also affect the solderability and thus produces the defect, these defects include the tin bead, the tin ball, the open circuit, the gloss is not good.