The Research On Action Mechanism Of Additive Used In Through-Hole Copper Plating And Its Selection

The variety of domestic products are few, and there are a lack of serialization and high-quality products; Foreign products occupy most of the domestic market. Facing the status quo of this development in copper plating additive used in PCB manufacture, the experiment in this article was conducted in order to gain satisfactory product used in electronic plating. The crystalline structure, morphology of copper plating, and the aspect ratio of that could be achieved in through-hole plating were investigated by the measurement of X-ray diffraction (XRD), metallographic microscope, scanning electron microscopy (SEM), and deep-plating performances test of the solution system.The electrochemical behaviors of additive ingredients were studied by EIS test. Combined with the measurements of Cathodic polarization curve and chronopotentiometry curve, the adsorption behavior and the mechanism of additive ingredients in the through-hole plating were investigated.The roles of the additive ingredients were investigated with the indicators of the Hull cell sample appearance and the the aspect ratio that could be achieved in through-hole plating. It was shown that the grain could be refined in the low density current areas of Hull cell sample with DE addition, but the brightness was reduced in the high current density areas; Application of PN could improve the surface topography of the hull cell sample,and the cathodic polarization, and the optimized range of PN concentration is 0.03~0.09g/L;A good effect could be achieved when SP,L-64,PN,GISS and DE were applied with reasonable combination.The combination of SP, L-64, PN, GISS and DE was optimized with the composite indicator composed by the Hull cell sample appearance and the aspect ratio that could be achieved in through-holeplating, and an optimized additive formula was gained. The addition of 0.4ml/L of alcohol to the optimized additive formula could improve its anti-foaming ability of the system greatly,but improve its brightness in low current density slightly. And the capabilities of deep-plating and uniform-plating of the additives composed of optimized formula and alcohol were found well. At last, the effect of additives on the morphology of copper plating were studied,and it was found that both SP and L-64 play a role of grain refining.In addition, the electrochemical behavior of each additive ingredient of double optimized formula was investigated by the electrochemical impedance spectra measurement. The adsorption of each additive ingredient on electrode surface was investigated by CV measurement with the pretreatment of electrodes in the additive contained solution, and it was found that all the additive ingredient could adsorb on electrode surface in the open circuit potential. Combination with the measurements of SEM photographs of copper sheet gained after its immersion into the additive cotained solution , it was found that L-64 adsorbed on electrode surface strongly and its adsorption was infected by SP addition. Also with the measurement of cathodic polarization curve and chronopotentiometry curve under different rotation speeds, the adsorption behavior and the mechanism of additive ingredient in the through-hole plating were investigated,and it was found that both accelerant and inhibitor owed to improving the uniform-plating in the through-hole.