Numerical Simulation Of Properties Of Chip Interconnect Sintering Microstructure Based On Pore Characteristics

In the field of electronic packaging,the third-generation semiconductor materials represented by Si C and Ga N have been widely used in aerospace,consumer electronics,new energy vehicles and other fields due to their high thermal conductivity,high power density,stronger radiation resistance and the ability to withstand a stronger breakdown voltage.However,power devices may be affected by extreme harsh conditions such as high current density,high temperature in some cases,so the requirements of solder joints at the junction of the packaging devices are extremely stringent.Sintered silver solder paste,as a new type of high performance chip interconnect solder,is widely used in the field of high power devices.However,there are a large number of pores in the microstructure of sintered silver paste,and the existence of these pores is bound to affect the current density distribution and heat transfer performance of power devices.In this paper,the effect of pore characteristics on the current density distribution and heat transfer performance of chip interconnect sintering microstructure is studied.In this paper,the influence of the shape of the pores on the current density distribution of micron sintered silver was investigated by presetting the pores in the sintered tissue with the shapes of circles,squares,rectangles,ellipses,rhomboids and special arcs.The results show that the current density distribution around the pores is extremely uneven,and the electron flow is concentrated in the left and right sides of the pores in the sintered tissues with round,square,long and elliptic holes.For sintered structures with rhombic and arc-shaped holes,the electron flow is concentrated in the tip region.Among them,the maximum current density of sintered silver tissue with elliptic holes reached 1.831×10~8A/m~2,which was 3.662 times of the nominal current density value of 5×10~7A/m~2.The reason is that the transverse distance of the shaped hole is long,which makes the electron flow enrichment degree more serious.Secondly,the maximum current density value of the sintered tissue with arc-shaped pores is also very large,reaching 1.618×10~8A/m~2,which is 3.236 times of the nominal current density value,because there is a special concave arc structure,which obstructs the flow of electrons more seriously.Finally,the maximum current density of sintered silver tissue with rectangle,round,diamond and square pores was2.156 times,1.91 times,1.71 times and 1.568 times of the nominal current density,respectively.In this paper,the influence of the local distance of the randomly distributed circular pores on the current density distribution is studied.There is an obvious relationship between the current density distribution in the micron silver sintering structure and the local spacing of the pores.When the external distance of two circular pores is 0.24 microns,the maximum current density is 2.85×10~8A/m~2.With the decrease of the outer space of the pores,the maximum current density value between them gradually increases.When the distance between them is 0.01 micron,the maximum current density value reaches 1.44×10~9A/m~2,which is 28.8 times of the nominal current density value of 5×10~7A/m~2,which is extremely dangerous.The effect of porosity on the heat transfer performance of micron sintered silver tissue with randomly distributed pores was also studied.The results show that with the increase of porosity,the maximum heat flux of sintered silver increases gradually.