Preparation And Characterization Of Copper Terminal Electrode Paste For Multilayer Ceramic Capacitors

At present,the multilayer ceramic capacitor has become one of the important electronic components,and its performance will directly affect the overall function of the electrical production.With the gradual miniaturization and high capacity of multilayer ceramic capacitors,the thickness of the dielectric layer will decrease while the number of layers will increase.The reliability of the internal and external electrode connections will become a necessary part of the terminal electrode researches.At the same time,the increase in capacitor production makes the production cost of Ag terminal electrode higher,and Cu-based terminal electrodes have become the key of MLCC research and manufacture.Because the composition and the preparation process of the terminal electrode,and many other factors will inevitably affect the performance,therefore,a deep understanding of the sintering evolution process of the main components inside the terminal electrode is of great significance to improving the performance of the multilayer ceramic capacitor.This article mainly explores the influence of glass powder and copper powder on the structure and performance of the copper terminal electrode and analyzes the sintering mechanism of two components during the sintering process to find the composition suitable for copper conductive paste for multilayer ceramic capacitors.The main findings are as follows:(1)The glass transition temperature of SiO₂-BaO-ZnO glass powder is high,and the interaction with the ceramic body is weak,resulting in more glass phases existing in the terminal electrode;ZnO-B₂O₃-SiO₂ glass powder precipitates glass bubbles on the surface of the terminal electrode,and a thick interlayer was formed between the terminal electrode and the ceramic body.After the size is reduced,the crystalline orientation is enhanced,which promotes the precipitation of more glass bubbles on the surface of the terminal electrode,and the interface reaction between the glass phase and the ceramic body is intensified,forming a thicker intermediate layer,which influence the connection of inner electrode and terminal electrode.Adding BaO-ZnO-B₂O₃ glass to ZnO-B₂O₃-SiO₂ glass powder whose D50 is 1.5?m,the chemical stability of the glass phase is weakened,thereby ensuring the flatness of the sintered terminal surface after corrosion,and the composite glass is suitable for the conductive paste for the copper terminal electrode;(2)When the sintering temperature is low,glass crystals are precipitated on the surface of the terminal electrode.When the sintering temperature is high,the glass crystals decrease and disappear,and glass bubbles precipitated on the surface at the same time.The glass crystals reappear after corrosion;As the sintering temperature increases,the sintering degree of the copper particles gradually increase,copper particle size gets bigger,but the glass content increase on the surface of the terminal electrode up to some extent,and the copper particle size gets smaller.Moreover,the conductive paste with higher glass content has obvious corrosive effect on the substrate after sintering,the surface of which has more glass phase.The resistivity shows a trend of first decreasing and then increasing with the increase of glass content.When the glass powder content is 5%,the terminal electrode structure and performance are good;(3)The shape of the copper powder has a certain influence on the performance and structure of the terminal electrode.The shear characteristic of the paste prepared by the flake copper powder is better,and the film prepared by the spherical copper powder has a higher density,but its conductivity is relatively poor.The conductivity,density,roughness of spherical and flake copper powder combinations is not much different.And there are holes in the bonding surface of the terminal electrode prepared from spherical copper powder and the ceramic body,and the sintered surface of the flake copper powder with big superficial area has no obvious grain boundaries.After adding the spherical copper powder,the dissolution rate of the copper powder is accelerated,and the sintering rate of the terminal electrode is accelerated;The degree of sintering of the flake copper powder with small superficial area is also better,and the shearing performance is better.