Low-pressure impaction technology has been applied to a new etch process using aerosol, called aerosol jet etching(AJE). Fine droplets(0.1 to 0.3㎛) produced by spray-evaporation-condensation method impinge on a substrate in low-pressure impactor and etches its surface. Investigations were carried out on the control of etchant droplet size, the critical diameter for impaction and the performance of AJE on patterned etching. The patterned etching on SiO₂ film reveals some advantages over conventional wet etching : the economic use of etchant, the reduction of waste disposal and the increase in controllability of etching. To make maximum use of the advantage of AJE, techniques of further decreasing the droplet size and depositing this small droplets on substrates need to be developed.