The PCB manufacturing industry needs the electroplating technology of high aspect ratio and small hole PCB. It is the driving force to promote the development of high-level Multilayer PCB manufacturing technology. Because of the reliability of the hole coating, it plays a key role in the application of PCB. How to ensure the high aspect ratio deep hole plating is the scientific and technological task of all the PCB workers, and it is the most important problem to face. Therefore, many research departments have begun to carry out planned research and development. There are many methods of Tuji from the current scientific and technological data, including pulse plating, chemical vapor deposition, solution impact plating, all chemical copper plating and air stirring technology with improved (high acid and low copper). Now, the technology of this part is introduced as follows:

Pulse plating technology

Pulse plating technology, which has been used in electroforming process, is a mature technology. However, a lot of technological tests must be carried out in the application of high aspect ratio small hole plating. Because the pulse power supply is different from the general DC power supply, it is to turn the rectifier on / off at the speed of us through a switching element, and provide pulse signal to the cathode. When the rectifier is in the off state, it is more effective than DC to supplement copper ions to the boundary layer in the hole, so that the deposition layer of PCB with high aspect ratio is more uniform. At present, the pulse rectifier has been developed and applied to the fully closed horizontal electroplating production line, and the effect of the application has been very obvious economic and technical results.

The “timing reverse pulse” is adopted to make the current be changed in the power supply mode and reverse plating (i.e. anode dissolution) alternately according to the time proportion, which makes the deposition of copper plating difficult to obtain the corresponding copper layer thickness in the conventional power supply mode. When the PCB on the cathode is in the reverse current, the copper layer in the high current density area of the orifice can be dissolved rapidly. Due to the effect of additives, the effect on the low current density area is very small, so the thickness of copper layer in the hole will be gradually equal to that of the copper on the plate surface.