Photo etching is a manufacturing process that uses digital photo tooling to produce and modify prototypes in risk-free design optimization. Also referred to as chemical etching, chemical etching, or photochemical milling (PCM), it uses ferric chloride as etching chemistry to design intricate and highly precise metal components.
Photo etching provides a quick turnaround solution compared to other manufacturing processing such as punching, laser cutting, water jet, and stamping for very fine metal components in most metal types. If maintaining the component integrity is essential, photo etching is the most suitable metal machining technology since it does not impact the properties of the metal. No heating or mechanical force is used in photo etching processes, so the components remain free from stress and burns.
The process of photo etching
The chemical etching process involves printing a design of a component into photoresist laminated onto a metal. Then the areas of the photoresist not printed are removed, exposing the metal that is etched away. Let’s learn more about the photo etching process step by step.
Any metal can be photo-etched, including steel, stainless steel, copper and its alloys, aluminum, titanium, and its alloys, nickel and its alloys, and other specialist metals.
After selecting the metal, it is chemically cleaned, including degreasing to eliminate debris, rolling oils, waxes, and other contaminants that could affect this other step.
During this step, a light-sensitive photoresist is applied to the sheet. The purpose of precleaning before this step is because good adhesion is vital for blemish-free components. Any problem that occurs with the laminate bonding can make the etchant come into contact with the protected surfaces of the metal during etching which ultimately compromises the final product.
Next, the component design is transferred to the photoresist via exposure of the sheet to ultraviolet light. That happens through a photo tool mask.
The photoresist part which is not exposed is removed to display the raw material. The hardened resist is meant to protect the part during etching.
Ferric chloride, which, as earlier mentioned, is the etchant chemistry, is sprayed onto the developed sheet. Skilled technicians determine the etching time by evaluating things such as the material type, thickness, grade, and size which impact the final product.
Stripping involves removing the remaining photoresist to display the etched components finally.
Visual and dimensional inspection
The etching process is not over yet. Technicians use high-grade optical inspection equipment to visually and dimensionally inspect the etched components.
Etching can be completed by other processes such as plating, passivization, electropolishing, forming, wire EDM, brazing, and diffusion bonding.
Photo etching is the most cost-effective solution for producing custom parts with intricate designs from a wide range of metals since costs rarely increase with design complexity. Photo etching is entirely stress-free and burr-free, with no mechanical heat applied to the metal during the process. Any artwork in CAD format can be transferred into a photo tool, making it simple to implement any design changes at a cost-effective solution. That means photo etching is quick to produce parts within a few days.