The Photo Etching Process Made Easy
What is Photo Etching?
Photo etching is the process of using ultra-violet light to fix an image onto a sheet of metal, and then using chemicals (etching solution) to etch the shape into the metal, removing more and more of the material until only the shape is left – a metal component that is far more precise than anything that can be cut or machined.
Is There A Difference Between Photo Etching and Chemical Etching?
Photo etching is simply the name given to the process of using light and photo-tools to fix the image of the component to be etched. Photo etching can be used interchangeably with terms including chemical etching, chemical milling, chemietching and acid etching, although those terms may refer only to the chemical process of etching.
The Photo Etching Process In 8 Steps
Choosing The MetalSheet metal or coil is selected from a comprehensive metal store (over 2000 different types of metal on the database from 0.07mm to 1.5mm thickness) and is cut to the 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.
Metal CleaningThe 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.
LaminationThe 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.
PrintingThe 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.
DevelopingThe exposed sheets are passed through a developer and chemically developed, chemistry washes away un-exposed soft areas and leaving the component shape protected.
Photo EtchingSheets are placed on the etch machine conveyor, the etch speed is calculated based on the metal thickness and etch rate which is based on metal chemical composition. A pilot sheet is etched and measured, once the target size is correct the speed is set for the rest of the sheets and samples are periodically measured to ensure machine settings are constant.
StrippingRinse and strip the photographically resistant dry film from the metal sheet, the etched sheet is now ready for the final inspection. Components can now have secondary operations applied such as forming, plating, heat treatment, etc..
Inspecting & FinishingQA 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.
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Benefits Of The Photo Etching Process
Low set-up costs and fast lead times make photo etching a go-to process in batch sizes of one to multiple millions
The tooling for photo etching is digital, low-cost and can be modified quickly
Right First Time
No heat or force is used when photo etching, so the mechanical properties of the metal remain unaltered and parts are free from stresses and burrs
Component features are etched at the same time so part/feature complexity is not an issue