Through-hole plating

The conductive connection of conductors on both sides of printed circuit boards. Used for the electrical connection of circuit parts located on two or more layers of a printed circuit board. The walls of the boreholes consist of insulating base material, i.e. mostly epoxy resin and glass fabric, but also polyimide or Teflon. Desmearing is carried out for multilayers. For other base materials, especially Teflon, roughening and structuring is used to improve adhesion. The most important quality criteria are the faultless coating of the surface, the adhesive strength of the copper sleeve and the sufficient ductility of the copper layer deposited on the perforated wall. The process consists of conditioning, pickling, pre-immersion, catalysing, accelerating and chemical copper plating. A distinction is made between rack technology and basket technology.