What Is Photo Etching? What Are The Photo Etching Benefits For Thin Metal Parts?
Photo etching is a precision manufacturing process for thin metal parts with simple or complex designs. In 2021, photo etching is the most popular industry term for the subtractive method, also known as chemical etching. The process is a multi-step operation using photo-sensitive material to transfer part images onto metal sheets before a chemical etchant dissolves the unwanted sections, leaving only the desired part dimensions.
Other terms for photo etching are metal etching, photo chemical etching, photochemical machining, and chemical milling.
The benefits of photo etching for thin metal parts are precision edges with low tolerances. The chemical metal etching process leaves a smooth even surface that is free of burrs, pits and stress deformations. Other attractive features of the etching process are speed and low-cost for parts with intricate features and complex designs.
The photo etching process achieves high precision with a variety of metals for all types of industry part designs and requirements.
Photo Etching Compared To Other Manufacturing Processes
The main benefit of chemical etching compared to other methods is that it is more cost-effective for parts with complex designs or numerous features. Parts with many small apertures such as slots and holes can be etched simultaneously. For instance, components such as filters, screens, sieves, and lead frames will not require additional time or cost to etch than step lids or washers, or shims. Each hole or slot will cost the same to metal etch whether it is one or a thousand! This benefit makes photo chemical etching a great cost-effective alternative and a faster process for larger volume runs than other machining methods. Businesses can scale their prototype designs to increased volumes at cost! Read our photo etching case study on how we provided cost solutions for a medical device development engineer with his prototype design.
- Laser Cutting - Can leave micro burrs on the surface as the metal is blasted away from the point of heat contact. In addition, it is possible to have thermal stress along the edges. Photo etching - burr-free without stress deformations, metal properties unaltered, less expensive for large production of complex parts than laser cutting.
- Stamping - Can leave partial burring and stress deformations from the hard tooling. Because the tooling takes weeks to create, there are longer lead times. Not suitable for soft or brittle metals. Photo etching - burr-free, no stress deformations, more suitable for soft, thinner metals and can hold tighter tolerances. Inexpensive tooling that is faster to create and easily modifiable for design changes compared to stamping.
- Wire EDM - Can leave micro burrs because there is a point of contact from the electrical discharge to the metal surface. Therefore, like laser cutting, there can be metal deformation and thermal stress. Wire EDM capabilities do not include conductive metals. Photo etching - No burring, metal deformation or thermal stress. Can etch conductive metals.
- Water Jet Cutting - This process can also leave micro burrs and some stress on the edges. Photo etching - No burrs or stress deformations, and a less expensive option for high volume complex parts with numerous features than water jet cutting.
Tooling is easy to modify and can be produced within hours.
Quick turnaround on short runs. Compound tooling combines more than one prototype with the same material.
Stress and Burr-Free
Eliminate costly deburring methods. There is no tooling wear and no metal stress in the finished photo etched part.
Intact Metal Properties
Hardness, grain structure, and ductility remain unaltered
Manufactured quickly and cost-efficiently whether small, medium, or larger volume production runs.
Photo etching techniques
Since the metal etching process is controlled by speed, the etching depth and tolerances can be regulated by the amount of time the metal remains in the etchant depending on the metal thickness. This control allows us to achieve the lowest tolerance possible. For more specific tolerance information, see our photo etching capabilities page.
Chemical etching capabilities include chemical machining on both sides of the metal which is perfect for logos, serial numbers, or decorative designs. Half-etch score lines on parts such as EMI and RFI board shielding make it easier to manually form parts made from thinner metals eliminating the physical stress from machine forming. Another application of half-etching is the fluidic channel design used to carry liquid and gases on fuel-cell plates and heat exchanger plates.
What is the Photo Etching Process?
Photo chemical etching is a subtractive manufacturing process for the production of thin metal parts. The chemical etching process has seven steps, digital tooling, metal preparation, exposure, developing, etching, stripping and inspection.
Our tooling engineers create a design using AutoCAD software to generate a repeating pattern to see how many parts will fit onto a metal sheet. The digital tooling is transposed onto two sheets of mylar film which will be placed on each side of the metal sheet.
We thoroughly clean the metal you have chosen for your part and its intended application of any residual oils and oxides. Only RoHS and DFARS compliant metals are used.
We apply a photoresist coating on each side of the metal sheet. The laminated metal is placed between two identical copies of the photo tool. The surface is exposed to a UV light source that will harden the photoresist on the metal part design that is to remain throughout the etching process.
The sheets move through a developing machine where an alkaline solution washes away the top and bottom film on each sheet of metal that wasn't hardened during exposure.
We process the metal surface with a chemical etchant that dissolves the bare metal and leaves the desired design and dimensions.
The etched sheets or dropout pieces are placed in a tank full of sodium hydroxide-based solution to remove the remaining photoresist film.
The parts’ surface and dimensions are thoroughly measured using a comprehensive approach consisting of several handheld calipers and electronic magnification machines that will analyze a part's surface and tolerances before carefully packaging.
What Are Common Chemical Etching Applications?
Since 1993, we have manufactured a large variety of photo etched parts for many different industries. Therefore, we are familiar with your design challenges, material selection and how to achieve the closest tolerances with precision.
What type of metals can be chemically etched?
Our metal etching capabilities accommodate many types of metal alloys required for all types of thin industrial components. We have a variety of photo etching metals in stock. Some of the more common metals are listed below. Click on a metal name to find out its properties and common chemical etching applications.
Photo etching, also known as chemical etching, photo chemical etching, and photochemical machining, is a high-precision, fast turnaround manufacturing process for the production of thin metal parts. In the process, a chemical etchant simultaneously dissolves the unwanted metal areas of parts, leaving only the desired dimensions.
Some of the benefits of chemical etching are low-cost digital tooling, and photo etched parts that are stress and burr-free without altered metal properties. Photo etching is ideal for parts with complex designs as it is more cost-effective than other manufacturing processes.
The photochemical machining process can produce many types of industrial components that belong to electrical/electronic and mechanical systems in the electronic, R/F microwave, automobile, aerospace, medical, and military industries. Some common parts include shims, contacts, connectors, EMI/RFI shielding, lead frames, flat springs, encoder disks, screen, sieves, meshes, fuel cell plates.