The production method of 2 Layer PCB is generally made by inner layer pattern first, and then made into single or double side substrate by printing etching method, which is incorporated into the specified layer, and then heated, pressurized and glued. As for the subsequent drilling, it is the same as the plating through hole method of double panel. These basic manufacturing methods have not changed much since the 1960s, but as materials and process techniques (e.g., pressing and bonding techniques, improvements to the glue residue produced by drilling, film) have matured, the properties attached to the multilayer have become more diverse.