Chemical Etching / Photo Etching - the process
(What is Photo Etching? What is Chemical Etching?)
Chemical Etching / Photo Etching is normally performed in a series of eight steps: Photo tooling preparation, metal cutting, cleaning, laminating, printing, developing, etching, and stripping.
Chemical Etching / Photo Etching step-by-step:
1. Photo tooling preparation
Data is received electronically from the customer in a variety of formats such as DXF / DWG; or via a fully dimensioned drawing; etching compensations are then added. A front and back registered film (Photo tool) is plotted from the data. It is important that the data / drawing received represents the finished component required.
2. Metal cutting
Suitable metal is sorted by allocated stock, type, thickness, grade and cut to applicable sheet size.
The metal to be used is chemically cleaned to remove any rolling oils or contaminants from the surface, this is important as contamination will inhibit the application of the photo resist and could negatively impact the quality of the finished etched part.
Dry film photo resist is applied to the metal sheet through heated rollers to bond the photo resist to both sides of the sheet.
The Dry Film laminated sheet has the photo tool image applied to it by exposing the image onto the metal using a UV (Ultra Violet) light source. The component image is transferred to the metal sheet.
Chemically develop the metal sheet washing away the areas where the etchant is going to attack.
Etching is the actual immersion of the metal sheet into the etching machines and the action of the etchant on the unprotected metal areas to be milled. The etching rates of the metal sheet are based on a number of factors including the concentration and composition of the etchant, the material to be etched, and temperature conditions. Etch rate is normally determined by using a small sample of the same material to be etched. Critical dimensions taken from the customer drawings are dimensionally checked at this stage and first off evaluation is carried out prior to the batch etching.
Rinse and strip the photographically resistant dry film from the metal sheet, the etched sheet is now ready for final inspection.
Components can now have secondary operations applied such as forming, plating, heat treatment, etc..