Polyamic acid coating of microspheres by oriented thermal vapor deposition

In this paper, a study on the oriented thermal vapor deposition device which is used for coating microspheres with polyamic acid (PAA) is developed. Influences of the processing of monomer material and the adjusting of heating process on the deposition rate are discussed. Two different monomers are poured into two evaporators and evaporated independently, the deposition rate and film thickness are measured via two film thickness measuring probes with the crystal vibration. Space position and symmetry of sample pan, two probes and the oriented tube tip are adjusted so that two monomers’ deposition ratio approximates to stoichiometric ratio. High quality coating of PAA on poly-aipha-methylstyrene microsphere is acquired by intermittent piezoelectricity vibration or striking which accompanie