Study On Preparation And Technology Of Thick Film Electronic Paste For AlN Ceramic Substrate

We prepared the ZBS?ZnO-B₂O₃-SiO₂?glass powder which achieves good compatibility with AlN ceramics by the method of cooling after high temperature melting.The conductive silver paste for AlN ceramics was prepared by using this glass powder,and the silver metallization of AlN ceramics was realized by thick film method.In order to achieve the optimum process parameters the printing properties of the paste,including viscosity,fineness,the resolution and surface roughness of the printing film,the effects of sintering process,glass binder and CuO additive on the properties of metallized AlN ceramic substrate was studied.Finally,the electrical properties of the metallized substrate were further optimized by adding a certain amount of nano-silver and flake silver.And we also studied the influence of different sizes of micron silver powder on the electrical properties of the silver paste.The main achievements can be summarized as the following:1.The 30ZnO-60B₂O₃-10SiO₂glass which has low softening temperature,good thermal properties and good compatibility with AlN ceramics can be used as glass binder for electronic paste of AlN ceramics.2.The fineness of the paste can reach 7.5?m after rolling through a three-high mill.When the solid content of the conductive paste is 73%?viscosity is 112pa·s?,the smoothness of the paste is the best and the resolution of the printing film is the highest.The printing film has the lowest surface roughness when the surfactant content is 2%.3.When the sintering temperature is 850?and the holding time is 15 min,the density of the coating is the highest?the lowest porosity is 3.96%.?.And when the content of glass powder is3%and 5%,the metallized AlN ceramic substrate can obtain the lowest sheet resistance and the highest shear strength.4.When the particle size of glass powder was reduced to 2.69?m by ball milling,the silver layer was densest?the lowest porosity is 2.41%?and the sheet resistance of metallized AlN ceramic substrate was the lowest.5.The mechanical properties of metallized AIN ceramic substrates can be greatly improved by doping nanometer CuO in the paste.When the doping amount is 3%,the contact between the silver layer and the substrate is more fully and the electrical properties are better.6.Nano-silver and flake silver can reduce the gap between silver powder.Doping a certain amount of nano-silver and flake silver into the paste can effectively improve the electrical properties of metallized AIN ceramic substrate.When the doping amount of nano-silver and flake silver is 10%and 30%,The sheet resistance of silver layer can be reduced to 6.8m?/?and6.2m?/?,respectively.7.It has been found that smaller spherical micron silver powder can be used to prepare conductive silver paste with better electrical properties.