Research On Copper Electroplating Of Semi-additive Flexible Printed Circuit Board

With the increasing demand for portability of consumer electronics and the gradually popularization of wearable smart devices,the demand for miniaturization,lightening and thinning,high integration and flexibility installation of printed circuit boards is growing.Therefore,the manufacture technology of flexible printed circuit board(FPCB)has obtained more attention,copper electroplating is a very important link to realize the interconnection of through-hole,so the industry has put forward more challenges for copper electroplating.This paper focuses on two aspects of cathode and anode,one is to explore the effect of plating bath and other controllable parameters on the Throwing Power of flexible printed circuit boards,which solve the problem of the imperfect electroplating effect of the flexible printed circuit board in the industry;The second is to explore the reasons for the unstable Throwing Power of through-hole plating by speculating the side effects of anode additives.The adsorption effect of additives on the cathodic plate can be changed by controlling different parameter during the electroplating.Different candidates were evaluated by cyclic voltammetry,and the best among them was selected as an inhibitor of electrolyte.Then,concentration of copper sulfate and sulfuric acid were optimized by through hole electroplating which were carried on the test coupons of thickness of 85?m and hole-diameters of 200?m,it is found that the Throwing Power is related to the ratio of anion and cation concentration in the bath,and obtained basic plating solution is applied to the flexible plate electroplating.Further,single factor experiments were performed on concentration of accelerator,concentration of inhibitor,air flow rate and current density,It reveals that the concentration of accelerator and current density have a significant effect on Throwing Power of the through-hole plating.Finally,the performance difference between the optimal formula and special additives for flexible board electroplating(VP100,FP-2)was compared,it is found that the optimal formula is more advantageous in the Throwing Power.The technology of copper electroplating has put forward higher requirements for the diversification of additives,developing a composite functional additive is also a development trend of electroplating industry.This paper developed a kind of multi-performance accelerator with good copper layer and stable bath,the corresponding functional group were detected by infrared spectroscopy,difference of performance between the synthesized accelerator and SPS?DPS were investigated by electrochemical test,the difference of Throwing Power were analyzed between he synthesized accelerator and SPS by electroplating experiment.The results show that the synthesized accelerator can solve the problem of reducing the Throwing Power of the flexible circuit board because of the strong adsorption of leveling agent or causing the roughness of plate,protruding of the holes,the appearance of copper particles and the instability of the Throwing Power owing to lack of leveling agent.The reason why the additives are unstable in the plating solution and affect the throwing power are complicated.This paper mainly analyzed the morphology,composition and structure of anode slime produced by acid copper plating systems with PEG or EO/PO,SPS,JGB,it's found that the composition of the anode slime are different from that of additives-free bath by previous studies.The effects of different additives on the changing morphology of anodic film and the synergistic effect of these additives on the anode were studied by electrochemical impedance and time-potential curves,it is found that the different additives have a certain influence on the formation of anodic film,and the molecular structure has a greater influence than the molecular weight.Finally,the complex reaction between the anode and plating solution was initially discussed,which can help us understand the consumption of modern additives,metabolic pathways,and the reason for the change of plating performance,it has important theoretical significance and application value for maintenance and management of acid copper plating solution,the development of next-generation additives,and the improvement of plating performance.