Research Of Laser Thermal Stress Cutting Of Aluminum Nitride Ceramics

Aluminum nitride ceramics are considered as the most ideal substrate and packaging materials for high power devices because of their high thermal conductivity,good mechanical properties and excellent electrochemical properties.At present,the research of aluminum nitride ceramics mainly lies in its casting forming technology and sintering technology,and the processing research of it is less,and because of its high brittleness,the general processing methods can not meet the requirements of high efficiency and low cost.Based on the above background,this paper uses laser thermal stress cutting technology to carry out processing experiments in light of the characteristics of high brittleness of aluminum nitride ceramics.This processing technology uses laser instead of cutting tools.It belongs to non-contact processing,and the cutting section is smooth and smooth,and the material is pollution-free and without defects.Meet the requirements of low cost and high efficiency in actual production.Firstly,the finite element software was used to model the AIN ceramics.The sequential thermal coupling method was used to load the temperature field into the stress field.Through the simulation analysis of the temperature field and the corresponding stress field,it is obtained that the temperature distribution of the temperature field and the corresponding stress distribution of the stress field are symmetric about the cutting path,which verifies the feasibility of linear symmetric cutting of aluminum nitride ceramics.It is also obtained that the maximum temperature of each node and the maximum temperature of the cutting path are roughly the same,which verifies that the maximum temperature of each node in the cutting process will not be different due to heat accumulation,which lays a foundation for the single factor simulation analysis.Second,the laser power,laser scanning speed and workpiece thickness of these parameters for single-factor simulation,to obtain their influence on the temperature field and stress field law:temperature maximum and power is proportional to the power,the greater the power the greater the temperature gradient,resulting in greater stress;laser speed and temperature maximum is roughly inversely proportional,the lower the speed the greater the temperature gradient,resulting in greater stress values;the thinner the thickness the higher the temperature stress is greater;and the greater the fracture stress caused by stress concentration phenomenon is more obvious,the poorer the final cut quality.Then,according to the influence law obtained by simulation,the experimental platform is built,through the power of 36W,42W,48W;Speed 4mm/s,5mm/s,6mm/s;A series of single factor experiments were performed with the thickness of specimens 0.5mm,0.6mm and 1mm.By comparing diamond cutting tool cutting,laser melting cutting and thermal stress cutting,and observing by optical microscope and scanning electron microscope,it can be seen that the cutting section of thermal stress cutting is more smooth and even.Finally,a large number of single factor experiments were carried out according to the experimental scheme,the experimental results were detected by scanning electron microscopy,and the fracture composition was analyzed.By observing the morphology of the section and the morphology of the slit,the influence of laser power,scanning speed and workpiece thickness on the machining quality was summarized:When the laser output power increases,the roughness of the material section increases and the cutting quality becomes worse.The thickness of the material and the speed of laser processing increases,the ripple of the section becomes smaller,the roughness of the material section becomes smaller,and the cutting quality is high,and the reaction of aluminum nitride ceramics and oxygen in the cutting process has little influence on the quality of the section.The simulation conclusions and the experimental conclusions are compared,and the conclusions are found to be consistent.The results of simulation and experiment provide guidance for optimization of cutting parameters in actual production.