Pulse knocking technology influnced surface roughness of Polyimide capsule

As one of the most important ignition capsule，the polymide capsule was prepared by depolymerizable mandrels technique combined with vapor deposition polymerization method. Instead of the plane pan and piezoelectric vibration model，the mesh pan and pulse tapping was selected to reduce microsphere collision and improve surface quality in polyimide fabrication. Experiments and theory results showed that the capsule surface was more rough because of collisions between microspheres and the pan. The mesh pan could reduce microsphere collisions,which was also lessened by changing piezoelectric vibration into pulse tapping model. As a result,root-mean-square value ranged from 52-93nm to 28-44nm.There were many advantages of pulse tapping model,.such as better controllability,lower bounce rate and less static.however piezoelectric vibration model was slightly better than pulse taping in wall thickness uniformity.The measurements of single microsphere showed that the deviation of the former with 0.68μm was better than the latter’s with 0.73μm.For the average value of microspheres in the same batch,the former with 0.26μm was also better than the latter with 0.57μm