Research On The Effect Of Laser Processing Microgrooves On The Surface Morphology And Bonding Strength Of Aluminum Substrate

With the continuous development of integrated circuit technology,microelectronic packaging technology is also developing towards miniaturization,high density and high complexity.The structure of the packaged device is becoming more and more complex,and the reliability problems that arise with it are becoming increasingly prominent.Die attach generally adopts the structure of substrate+interconnection material+chip,and the bonding strength of the interface between the interconnection material and the substrate directly affects the service performance of electronic components.In order to improve the bonding strength of the interface,it is a feasible solution to modify the surface of the substrate.Based on the bonding strength of the aluminum substrate and the epoxy resin interface,the surface of the aluminum substrate is modified by laser processing microgrooves to explore the influence of laser processing parameters on the surface morphology of the aluminum substrate and the bonding strength between the aluminum substrate and the epoxy resin..1.Study the effect of laser processing surface microgrooves on the surface morphology of aluminum substrates.Analyze the influence of laser power density,scanning distance and scanning times on the surface morphology,roughness,surface area increase ratio and microgroove geometry characteristics of aluminum substrates.The results show that the roughness Ra,the surface area increase ratio Sdr,the actual depth H of the microgrooves and the actual width D of the microgrooves increase with the increase of the power density.When the power density I=1.83×10~3W/mm~2,the morphology formed inside the microgrooves is relatively smooth;when the power density I=3.66?9.15×10~3W/mm~2,as the power density increases,the pores inside the microgrooves have obvious characteristics.When the scanning distance increases from L=50?m to L=100?m,the bump height h decreases,and the increase in roughness Ra and surface area increase ratio Sdr descent rate is faster.The roughness Ra and the surface area increase ratio Sdr increase with the increase of the scanning times,the actual depth H of the microgrooves increases with the increase of the scanning times,and the actual width D of the microgrooves decreases with the increase of scanning times.When scanning times N=3,the depth d of the microgroove is relatively large,and most of the sputtering material is accumulated on the side of the microgroove.2.Study the effect of laser processing surface microgrooves on the bonding strength of aluminum substrates.Measure the bonding strength of the specimen according to the quasi-static shear test standard.Combined with the macroscopic characteristics,microscopic characteristics of the joint section of the aluminum substrate and the failure mode of the interface,the influence of the laser power density,scanning distance and scanning times on the bonding strength of the aluminum substrate is studied.The results showed that the bonding strength of the untreated aluminum substrate was?=5.41MPa,and interface failure occurred in the joint section.After laser processing the microgroove,the bonding strength increased by at least 88%,and the cohesive failure occurred in internal of the microgroove.When power density I=5.49×10~3W/mm2,scanning distance L=50?m,and scanning times N=1,the maximum bonding strength is?=27.02MPa.There are three types of main microscopic regional features of the joint section.Type E:All cohesive failures occur.Type C:Cohesive failure occurs inside the microgroove,part of the aluminum substrate surface has cohesive failure,and part of it has interface failure.Type B:Cohesive failure occurs inside the microgroove,and interface failure occurs on the surface of the aluminum substrate.In the transition from type B to type C and then to type E,the main microscopic area characteristics of the joint section will increase the area of cohesive failure,which is conducive to improving the bonding strength of the aluminum substrate.3.Study the influence of the surface morphology of the aluminum substrate on the bonding strength.Analyze the influence of roughness Ra and the surface area increase ratio Sdr on the bonding strength,and establish the relationship between the actual depth of the microgrooves?_H,the actual width of the microgrooves?_D,the bonding strength,and the type of microscopic area of the joint section.The results show that when the microgroove structure completely covers the bonding area,the maximum bonding strength is?=27.02MPa,and the main microscopic area of the joint section is characterized by all cohesive failures.When the microgroove structure does not completely cover the bonding area,the bonding strength generally increases with the increase of the roughness Ra,the surface area increasing ratio Sdr,the actual depth ratio of the microgrooves?_H,and the actual width ratio of the microgrooves?_D.When the actual height of the microgrooves H>25?m,the actual depth of the microgrooves?_H>0.20,and the actual width of the microgrooves?_D>0.30,the main microscopic area type of the joint section is Type C,and a relatively excellent bonding strength can be obtained.