Etching polymer coating off e.g. terminals - and detecting radiation intensity from face which is etched to determine if enough coating has gone

摘要

In a process of thermal etching by laser beams one material is removed from another material. The degree of etching is checked by the presence of the first and/or the second in the plasma or the flame which is montiored by at least one radiation detector to measure the intensity of the radiation emitted by the plasma or flame in the wave length bands which are characteristic of the first and/or second material. ADVANTAGE - The method makes it possible to stop processing as soon as the required level has been reached. - The figure shows the system for etching plastic coatings off electrical terminals which have been sprayed with polymer as they are parts of electrical components. The component (B) thus has terminals (A) coated with e.g. polyphenylenesulphide which must be removed by the laser beam (Ls). Beam detectors (Sd1, Sd2) measure the intensity of radiation (S) from the plasma and their signals are amplified (V1, V2) before being transmitted to an instrument. The instrument (AS) determines directly or by difference whether the coating has been etched away to the desired extent and whether accordingly the process can be stopped by a signal (Si); max. intensity at detector (Sd1) shows that all the coating has gone.