Study On Fabrication Of Planar Micro Inductor By The Laser Micro-Cladding Technology

With the development of inductors for miniaturization,high frequency,high integration and high performance, more and more rigid requirements have been brought forward by researchers for micro inductor fabrication. However, with the disadvantages of low processing flexibility, long cycle and high cost, the conventional technologies can not satisfied with new requirements, so new technologies are urgent for the micro inductor fabrication. With the sponsors of the National Natural Science Foundation and the National "863" Program, a new technology of laser micro-cladding based on rotating process to fabricate micro inductor was presented in this paper, and the rectangle-type micro inductor with air core,the meander-type micro inductor with air core,the rectangle-type micro inductor with magnetic core and the meander-type micro inductor with magnetic core were fabricated successfully. By detailed research on this technology, the main results were as follows:The relation between the thickness of non-dry film and parameters of rotating process was systematically investigated, and the thickness distribution computing model of rotating process was discussed. The electrical performance of micro inductors and corresponding key factors were emphatically studied and the calculating model of inductance was preliminarily established. The experimental results showed that the non-dry film thickness became smaller with higher rotating speed, longer rotating time and less viscosity. Based on the thickness distribution computing model of plane rotating process, the model of cone rotating process was initially constructed. Ultimately, a uniform thickness distribution computing model was successfully established for both plane and cone rotating process.The law of the structural parameters to affect the electrical performance of the rectangle-type micro inductor with air core by this technology was studied in detail. The electrical test results showed that this inductor could obtain more inductance with increasing the turns,broadening the area,enlarging the line length and increasing laser power density in the frequency range of 100KHz～1MHz. At the same time, the experimental results demonstrated that the inductors fabricated by optimum structural parameters could increase the inductance and the inductance per unit area. In order to enhance the inductance further, the magnetic core, which was formed by the non-glass inductive pastes after laser sintering, was added to the micro inductor with air core. The contrastively experimental results showed that the rectangle-type micro inductor with magnetic core had higher inductance approximately by 26.08% than the ones with air core in the frequency range of 100KHz～1MHz.Finally, the idea of calculating inductance in the range of different frequencies was presented , and the calculating expressions of inductance in the frequency range of 20KHz～1000KHz were summed up using both Newton and Lagrange insertion method, and the fitting error of measured and calculated results was only up to 0.736%.