Study Of Femtosecond Laser Drilling And Etching Micro Line On FR-4 Copper Clad Lamiinate

Femtosecond laser has the advantages of ultra-high peak power,ultra-short pulse width and short acting time.During processing,the thermal diffusion distance in the material is short,the processing accuracy is high and the processing quality is superior.It has the characteristics of non-hot melt processing,and has unique advantages in micro nano processing.With the development of electronic information technology,the development cycle of electronic products is constantly shortened,highly integrated and precise.For the above requirements,this paper proposes the femtosecond laser based multi pulse drilling and micro circuit etching forming technology of FR-4 copper clad laminate.The specific research contents are as follows(1)In this paper,the mechanism of femtosecond laser removal of metal materials and polymer materials is studied from two aspects of energy absorption mode and material removal form.The two-temperature equation and two-photon absorption model are analyzed,and the femtosecond laser ablation analytical model is obtained.The critical ablation threshold of FR-4 copper clad laminate was calculated by experiments.(2)Based on the two temperature equation,the multi pulse simulation of the change of electron and lattice temperature in the process of FR-4 copper clad laminate is carried out by using MATLAB software.The ablation mechanism of femtosecond laser and copper foil is discussed from the aspects of peak electron temperature,change rate of electron and lattice temperature,heat balance temperature of lattice and heat balance time of electron and lattice The influences of the four factors,such as electron lattice coupling coefficient,pulse width,pulse interval time and laser energy density,on the changes of electron and lattice temperature are analyzed.(3)The femtosecond laser is used to punch the copper layer of FR-4 copper clad plate The influence rules of single pulse energy,repetition frequency,number of pulses,defocusing amount and other process parameters on the quality of micropores are described.In the orthogonal test,the influence weights of different process parameters on the inlet diameter,outlet diameter and hole taper are obtained,and the number of pulses on the inlet diameter and outlet diameter of holes are obtained Diameter and taper have the greatest influence.Then,the optimal drilling parameters are obtained by using the comprehensive balance method.(4)According to the measurement results,the forming rules and forming conditions of single and double row wires are discussed.On this basis,the etching test of double row conductor with 135 ° corner is carried out,and the conducting circuit with line width and line spacing of 45?m is made.Then,the local conductive circuit is made,and then holes are drilled at the end of the wire to verify the feasibility of femtosecond laser processing of the whole layer circuit to realize the electrical connection of different layers of circuit through micro holes.The results show that the femtosecond laser can punch and form FR-4 copper clad plate with high quality and precision after adopting the optimized process parameters.Compared with the traditional manufacturing method,it reduces the processing flow and improves the processing quality.It shows that the femtosecond laser processing method has a good feasibility in practical processing application.