| In order to meet the needs of integration and miniaturization of electronic products,a new type of interconnect structure called chip copper column micro-convex interconnect comes into being.Copper column microbumps have the characteristics of high density,high speed,low power consumption,reliability and low delay,which can meet the requirements of detail distance,microsize and ultra-high I/O density in current chip packages.However,with the continuous increase of energy consumption of electronic products,the micro-convex points of copper column are under the action of multiple physical fields such as electric heating,and its structural stability and reliability are greatly weakened,which will seriously affect the reliability and life of electronic products and equipment.However,as a new type of structure,the copper column micro-convex is not thoroughly studied,so the reliability and influencing factors of the system under the action of thermoelectric field coupling need to be further analyzed.Therefore,the finite element method is used to conduct thermal analysis,electrical analysis and thermoelectric coupling analysis on the micro-convex interconnect structure of the chip copper column,and the influence of solder cap height,current and temperature on the micro-convex points of the chip copper column is discussed.The work content of this paper is as follows:(1)Based on the principle of heat transfer and thermodynamics,the failure mode of micro-convex points in copper column under temperature load is studied by finite element numerical simulation method,and the distribution of temperature field and temperature gradient inside micro-convex points in copper column is analyzed.The results show that the temperature gradient and the maximum thermal stress are distributed on the copper trace interconnect,and excessive thermal stress will lead to the failure of the microconvex points.(2)Based on Maxwell’s equations and Ohm’s law,the current density distribution of copper column is analyzed by finite element numerical simulation method.The simulation results show that under the influence of current,the maximum current density of the microconvex points of copper column is concentrated in the copper trace interconnect area,which will lead to increased power consumption,serious heating and shortened life.(3)Based on the basic principle of thermoelectric effect,the failure of copper column micro-convex interconnection under the action of thermoelectric coupling field is analyzed by finite element numerical simulation method.It is found that the temperature and temperature gradient increase slightly when the current is applied to the microconvex point of the copper column.As the increase in current density leads to more heat generation,the stress will also increase slightly under the thermoelectric coupling field,which will gradually push the maximum equivalent stress towards the strength critical point of the copper column’s microconvex point.In addition,the maximum equivalent stress under the thermoelectric coupling field appears earlier when the current is added to the temperature field than when only the temperature field is added,indicating that the thermoelectric coupling will accelerate the failure rate of microconvex points in the copper column.(4)Based on the basic principle of Taguchi method.Orthogonal experiment was carried out with Minitab software.With cap height,current and temperature as variables,the maximum stress of microconvex spot of copper column as response value.The results show that the temperature has the greatest effect on the stress of the microbumps of copper column,followed by the current,and the height of solder cap has the least effect on the maximum stress.In this paper,the failure of micro-salient interconnect in copper columns under multi-field coupling is studied,and the main causes of the failure are analyzed,which has a certain reference value for engineering application of micro-salient interconnect structure in copper columns. |
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