The cost of the PCB spray tin board is relatively low, because it only sprays tin on the PCB on the pad, and the tin plating also includes tin in the circuit.

PCB tin, as the name suggests, is to use chemical methods to deposit a layer of tin on the PCB pad position. The thickness is very thin, usually 10 to 30 microns. The main purpose is to prevent oxidation. The most important is SMT tin fusion, which is actually compatible. Huajin, OSP, have the same purpose. In SMT, it needs to be tinned.

　　PCB spray tin is to spray a layer of tin by physical method, the thickness is generally 50~150 microns, which is relatively thick. Don't apply tin during smt, just melt tin paste.

　　 The composition of the two kinds of tin is different. PCB tin is made of tin salt, which is an acidic solution containing tin. But PCB spray tin generally uses tin alloys, generally divided into lead and lead-free (no pure tin, high melting point).

　　Chemical tin, also known as tin tin, is a form of surface treatment to protect the surface of the pad. Like OSP, immersion gold, immersion silver, etc., it mainly protects the surface copper foil (PAD bit).

Tinning is a process of pre-etching protection for circuits, copper holes, etc. when the PCB factory takes the second copper process. After etching, the protective tin is removed, and then transferred to the next production process solder mask process for solder mask Printing! So the tinning process is not seen in the SMT placement factory.