Study On Short Pulse Laser Through-hole Machining And Application Of AlN Ceramics

With the rapid development of microelectronic technology,multi-functional radar frequency conversion module is developing towards large-scale integration,miniaturization,high efficiency and high reliability.The improvement of system integration leads to the increase of power density of electronic devices.Effective electronic packaging must solve the heat dissipation problem of microelectronic system.At present,it is impossible to solve the problem fundamentally by reducing the system temperature,so it is necessary to develop a new packaging material substrate with high thermal conductivity and good comprehensive performance.As one of the first choice of frequency conversion module,Al N ceramic substrate has excellent heat dissipation performance,high density of three-dimensional wiring,good electromagnetic shielding effect and other excellent properties.However,the problem of high quality and efficient processing of its microstructure needs to be solved.In this study,the hard and brittle materials of Al N ceramics were taken as the research sample,and the short pulse laser precision machining technology of its microstructure and surface holes was studied.In this paper,the machining methods of femtosecond laser percussion drilling and nanosecond laser trepanning are proposed.In percussion drilling,the influence of laser ablation threshold and multi pulse cumulative effect on ablation threshold of Al N Ceramics,the formation process of holes on the surface of Al N Ceramics processed by femtosecond laser,and the multi parameters(including pulse energy,number of pulse,repetition rate)are studied to affect the processing quality of the hole and the optimization of the percussion drilling parameters;In the trepanning,the influence of several basic processing parameters(including scanning speed,scanning times,laser power and repetition rate)on the hole diameter and morphology was studied,and the design and optimization of the scanning path parameters(including jump direction,scanning mode and filling line spacing)were carried out on the premise of optimizing the basic parameters.The mechanism of material removal in the process of trepanning is discussed.Based on the optimization of single hole processing technology,the experiment was carried out on the surface of Al N Ceramic substrate with industrial standard sizes of 0.25 mm,0.38 mm and 0.5 mm,and the inlet diameter was 30?m? 500 ?m.Finally,in cooperation with 38 Institute of CETC,a filter microstrip transmission line device was designed and fabricated based on Al N ceramic with large area group holes.The test results show that the insertion loss is less than 1 d B and the return loss is more than 15 d B near 10 GHz,and its performance meets the requirements of radar frequency conversion module.In the process of research,the key problems of poor machining accuracy,many defects,poor controllability,low reliability and high cost in the processing of ceramic packaging substrate were fully solved,which provided reliable technical support for the laser processing industry of hard and brittle materials.