Advanced Chemical Etching Process Flow Chart (Photo Etching Step by Step)
The Etching Process to produce complex high precision burr and stress free metal parts
CAD data is created from customer supplied electronic data or fully dimensioned drawing, an etching compensation (offset) is applied depending upon the material and thickness and then an etchline. The image is then step and repeated to fill the required sheet size. A master tool (phototool) for the chemical etching process is generated.
The image is laser plotted onto dimensionally stable photographic film to produce a front and back phototooling match pair and using an automatic optical punch they are very accurately pierced and then photographically registered together.
Sheet metal or coil is selected from a comprehensive metal store (over 1830 different grades on database from 0.07mm to 1.5mm thickness) and is cut to required size. We only use high photo etching quality metal for all of our chemical etching processes. Material is allocated with a unique batch number traceable to incoming material certificates. Cosmetic inspection is carried out to ensure material quality is good.
The cut sheets are chemically cleaned to the process that suits the particular material type to ensure they are free from any dirt or contaminants. Once cleaned a water break test is undertaken to verify the material is clean before starting the coating process.
The cut sheets are laminate coated with UV light sensitive photo resist (laminar) which is applied to both sides of the sheets using heat and pressure. The excess laminar is trimmed from the sheets. This is now a 5-layer sandwich awaiting an image to be exposed.
The laminated coated metal sheets are carefully placed between the phototool match pair and exposed to UV light to create an image on the sheet. Clear areas on the film will become soft and black areas on the film will harden.
The exposed sheets are passed through a developer and chemically developed, chemistry washes away un-exposed soft areas and leaving the component shape protected.
Etch machine parameters are set depending on material grade and thickness. Acid strength, temperature, Baume are set and the conveyor speed of the multi-chambered etch machine is set depending upon material thickness. Developed sheets are loaded onto the etch machine driven-wheel conveyors. The etchant typically "Ferric Chloride" removes unprotected metal under precise control.
Etched parts are dimensionally checked against the customer drawing data / drawing. We always ensure each product matches the customers strict technical guidelines. During the etching process the etched sizes are checked to the target dimension on the customer drawing. A standard frequency of first, middle and last sheets are checked in three positions on each sheet.
After etching the sheets, the photo resist is chemically removed from the etched sheets / components leaving a clean finish on the etched components.
QA inspection on critical dimensions as agreed with the customer are undertaken using a CMM (Coordinate Measuring Machine). Finished etched components are visually inspected and final inspection of the parts is carried out to ensure they are cosmetically perfect for the customer. Inspection is carried out to different inspection procedures to suit particular customer requirements.
Pack & Despatch
The precision metal components are packed and despatched according to the customer required specification.
Above diagram shows the Advanced Chemical Etching Process Flow Chart (Photo Etching Step by Step).