The Adjustment Of Zeta Potential On The Surface Of Copper Powder And The Preparation Of Glass-coated Copper Powder

The copper electronic paste has a good development prospect because its low price and good electrical conductivity.In this paper,the influence of four glass systems,SiO₂,SiO₂:B₂O₃:Ca O=8:1:1,SiO₂:B₂O₃=4:1 and SiO₂:B₂O₃=3:2,on the coating effect of pretreated copper powder was studied.The surface zeta potential of the copper powder was adjusted by changing the solvent ratio,the p H value and the concentration of CTAB.The effects of different coating temperature,time,SiO₂ content and concentration of CTAB on SiO₂-coated copper powders were studied.The copper electronic paste was prepared by SiO₂-coated copper powder.After screen printing the copper paste on LTCC substrate,the sample was binder burn-out in N₂/H₂O atmosphere and co-fired in N₂ atmosphere.Zeta potential,SEM,oxidative weight gain and other analytical methods were used to study the microstructures and properties of the copper powder,the glass-coated pretreated copper powder,the SiO₂-coated copper powder,and the copper film.The zeta potential of copper powder was adjusted by many methods.The absolute value of zeta potential of copper powder was less than 3 m V by changing the solvent ratio,and the zeta potential of copper powder was always negative by changing the p H value.CTAB had the greatest influence on the zeta potential of copper powder,and could change the zeta potential from a negative value to a large positive value.When the solvent was water and p H was 4,both the silica sol and CTAB were stable.Under this condition,when the CTAB concentration was 1×10^-4 mol/L,the zeta potential of copper powder was the largest,which was 98.2 m V.The coating morphology and oxidation resistance at 300? of the four kinds of glass-coated copper powders were poor.The zeta potential was adjusted to the maximum.When the coating temperature was 70? and the coating time was 3 h,the coating morphology and oxidation resistance of SiO₂-coated copper powder were better.As the content of SiO₂ increased from 1 wt.%to 11 wt.%,the coating amount of SiO₂on the surface of copper powder increased and the oxidation resistance of copper powder was enhanced.However,the coating surface of SiO₂-coated copper powder became rough and uneven.When the content of SiO₂ was 1 wt.%,with the increase of CTAB concentration,the surface of copper powder was gradually coated with SiO₂,and the oxidation resistance of copper powder was enhanced.After co-firing,the connectivity of copper film was better,the combination with substrate was closer,and the sheet resistance of copper film was reduced.When the coating temperature was 70?,the coating time was 3 h,the content of SiO₂ was 1 wt.%,and the concentration of CTAB was 1×10^-4 mol/L,the coating morphology of SiO₂-coated copper powder was the best.In addition,the sheet resistance of copper film was minimum,which was 1.8 m?/?.