Printed circuit board manufacturing is developing rapidly in the direction of multi-layer, multilayer, functionalization and integration. With the rapid development of microelectronics technology, micro holes, narrow spacing and thin wires are widely used in the design of printed circuit. It makes the manufacturing technology of printed circuit board more difficult, especially the aspect ratio of through holes in multilayer boards exceeds 5:1 and the deep blind holes widely used in laminated boards, so that the conventional vertical electroplating process can not meet the technical requirements of high-quality and high reliability interconnection holes.

The main reason should be analyzed from the current distribution state of the electroplating principle. During the actual electroplating, it is found that the current distribution in the hole presents a waist drum shape, and the current distribution in the hole gradually decreases from the hole edge to the hole center, resulting in a large amount of copper deposition on the surface and the hole edge. It is impossible to ensure that the copper layer at the position requiring copper in the hole center should reach the specified thickness. Sometimes the copper layer is very thin or there is no copper layer, which will cause irreparable losses in serious cases, A large number of multilayer printed circuit boards are scrapped. In order to solve the problem of product quality in mass production, deep hole electroplating has been solved from the aspects of current and additives. In the copper electroplating process of printed circuit boards with high aspect ratio, most of them are carried out under the auxiliary action of high-quality additives, combined with appropriate air agitation and cathode movement, under the condition of relatively low current density, so that the electrode reaction control area in the hole is enlarged, and the function of electroplating additives can be shown. In addition, the cathode movement is very conducive to the improvement of the deep plating ability of the plating solution and the polarization of the plated parts, The nucleation rate and the grain growth rate compensate each other during the electrodeposition process of the coating, so as to obtain a high toughness copper layer.

However, when the aspect ratio of through holes continues to increase or deep blind holes appear. Then horizontal electroplating technology occurs. The continuous development of vertical electroplating technology is a new electroplating technology developed on the basis of vertical electroplating process. The key to this technology is to produce a compatible horizontal plating system, which can make the plating solution with high dispersing capacity show more excellent functions than the vertical plating method under the cooperation of improved power supply mode and other auxiliary devices.