Mechanical Properties Of Sintered Silver Nanoparticles Based On Nano-indentation Test

With the rapid development of electronic industry,a variety of new materials are produced.As a new type of electronic packaging material,sintered nano-silver has high thermal conductivity,electrical conductivity,excellent ductility,wettability and viscoplasticity compared with traditional solder joint materials,so it can gradually replace the traditional solder.However,due to the short time of appearance and application of sintered nano-silver,the research on its mechanical properties is not sufficient.At the same time,with the continuous development of the electronic packaging industry,the effective size of solder joint materials in service is developing towards refinement,and the nano-indentation test technology is needed to measure the mechanical properties of such materials.However,there is a non-uniqueness problem in characterizing the mechanical properties of materials,and the related analysis method needs to be further improved.Based on the above problems,this paper carried out the following research:(1)The indentation test of sintered nano-silver was carried out by using nano-indentation test technology,and the elastic modulus,hardness and load-displacement curves of the material were obtained.According to the basic principle of dimensional analysis method and finite element simulation,a set of dimensionless functions are constructed.On this basis,an inversion analysis method that effectively characterizes the elastplastic mechanical parameters of indentation materials is proposed by using the basic definitions of characteristic stress and characteristic strain points.The strain hardening exponent n and yield stressσ_yof sintered nano-silver were solved by the proposed method and the load-displacement curve obtained by experiments,and then the elastic-plastic constitutive relationship was determined.The elastic-plastic constitutive relation is input into ANSYS finite element software for indentation finite element numerical simulation.The load-displacement curves under the simulation and experimental conditions are compared,and it is found that the two are in good agreement,which verifies the accuracy and effectiveness of the method.(2)The creep properties of sintered silver nanoparticles were studied based on nano-indentation.The load-displacement curve and creep displacement time curve of sintered nano-silver at room temperature were obtained by indentation creep experiment.Based on the experimental data,the creep stress index of the material is solved,and the constant coefficient C in the power rate creep equation (?)=Cσ~n is obtained by finite element simulation.The determined power-law creep equation was simulated by finite element method,and the creep displacement–time curve under the simulation condition was obtained.Compared with the load–displacement curve obtained under the experimental condition,they were in good agreement,indicating that the power-law creep equation can well describe the creep deformation of sintered nano-silver.