The Coated Aluminum Entry Boards For PCB Drilling: Optimization Of Fabrication Technology And Research On Application Performance

The aluminum foil were used as the baseplates and the mixer of PEG, PEO, adhesive, etc. were used as the coated resin, and three kinds of coated and aluminous entry boards (CABs) for printed circuit board (PCB) drilling were successfully prepared. During the experiments, in order to prepare good solution, the ratio of three main components were optimized by orthogonal experiments, the viscosity of adhesive solution and coating performance were adjusted by adding suitable surfactant at the same time. The results showed that the best formula of main components were20weights of PEG,8weights of PEO and140weights of adhesives;0.25weights of thickeners (U500) could control the viscosity of solution at the best value (800mPas);5weights of compound additives could effectively improve the surface effect. The properties (appearance, endothermal property, drilling property) of products were tested and analyzed by using modern analytical methods. According to the SEM observation, it was found that the surfaces of CABs showed smoother and more uniform than the common aluminum foil, which would improve the hole location accuracy and reduce the aiguille’s break. On the DSC analysis, the crystalline components (PEG and PEO) were founded in the coated resin, and their transition temperature were at about59.5℃and their enthalpy (△H) variation were about104.2J/g. Thus, the melt of PEG and PEO would bring away the aiguille’s heat and lubricate the aiguille during the drilling process. The CABs’ functions mentioned above were approved when they were used in the PCB drilling. On the one hand, the hole location accuracy of all CABs were better than that of the common aluminum foil, and the CPK values showed improvement tendency (2.43<2.66<3.23) with the increase of the aluminum foil and coated resin. On the other hand, the CABs were also better than the common aluminum foil in quality of hole’s wall, resisting abrasion and preventing intertwist. In addition, all of products were applied to0.15mm drilling performance test analysis of increasing the number of pack. According to the experiment:Due to the excellent functions of aluminums entry boards, such as endothermic, lubricating and buffering, there were better CPK values and hole’s wall quality in CAB series. Especially the CAB-1390, either a regular toughening or extended toughening drilling test, the results were always good. Its CPK values stayed above1.1, and the quality of hole’s wall had an obvious improvement. Besides, the CAB series did well in preventing intertwist, resisting abrasion etc, of which could not only meet the requirements of ordinary producing, but also effectively improve the drilling efficiency, indicating that the use of coated and aluminous entry boards has certain advantages compared with ordinary aluminum while increasing the number of PCB material (substrate thickness). In a word, as a new type of entry board, the coated and aluminous entry boards had a broad prospect, it could applied to the PCB drilling of high density, high precision and small aperture.