The Photo Etching Process: Step-by-Step

The tool designer creates a compensated rendition of your part geometry that accounts for the etching allowance needed by the metal thickness. Compensation makes the outsides a little bigger and the insides a little smaller on the phototool so that the metal part comes in to the correct dimensions. This version is stepped and repeated and processed to generate a Gerber file for plotting.

The Gerber file is output to a high resolution photo-plotter and Mylar phototools are developed and registered. The silver emulsion sides of the Mylars are registered face to face within .001″ of alignment.

Metal is measured and sheared from coils. Although most metal is stocked in coil form, it is also sometimes purchased in large sheets, depending on the alloy and thickness.

Metal sheets are scrubbed, cleaned and rinsed. Starting with completely clean metal surfaces is critical to achieving bond adhesion with the photoresist film.

Clean, dry metal is laminated with photopolymer film in a safe-light clean room. Avoiding incidences of dust or other debris prevents pinholes or other gaps in the film.

The phototool and the laminated metal are precisely positioned in a vacuum frame UV exposure unit. Top to bottom registration is maintained by precision pin punches.

The exposed sheets are developed to remove the unexposed photopolymer, leaving bare metal to be etched. The exposed and hardened resist, despite being barely .0015 inches thick, is enough to protect the covered metal.

The heated etching acid is sprayed at the metal from both sides, dissolving the unneeded metal areas. Since the excess metal is essentially washed away, there is no thermal or mechanical stress. The metal sheets are rinsed four times.

The photopolymer is stripped using a heated solution of caustic and water. The parts are rinsed multiple times and dried in a turbo dryer. The clean, dry parts are delivered to our Quality Inspection department.

The parts are thoroughly inspected in accordance with our Quality Management System and to the customer’s specifications. Conforming parts are packaged and shipped.