Chemical etching is a sheet metal fabrication process that provides many benefits for industries seeking thin metal parts with low tolerances and precision.
The process works by using a photoresist material (similar to a film) applied to a metal plate. A UV light is then used to harden certain areas of the material. The plate is then immersed in a chemical etchant (or etch solution) which eats away at the parts of the plate that were not hardened by the light. The results are smooth and clean, burr-free surfaces.
There are other types of sheet metal fabrication processes for thin metal parts, including laser-cutting, wire EDM, stamping, CNC punching, and water jet cutting. Although all these processes can cut metal, not all provide the same etching benefits depending on the metal thickness, tolerances, part design, features, and production volume
It can be confusing and overwhelming for design engineers to decide which process is best for their part. This article will help take some of the guesswork out of your decision by looking at which industry components can achieve the best quality with photo etching and often with the lowest costs and lead times.
Photo Etched Automotive Parts
Carmakers are transitioning to metals like aluminum, which has a low weight to high strength ratio, to maximize efficiency and safety. Aluminum is also highly corrosive and temperature resistant, making it an excellent choice for automotive parts exposed to extreme temperatures and corrosive fluids.
Etching with aluminum is becoming more frequent for parts in automotive manufacturing such as shims, gaskets, washers, and electronic parts. Aluminum electronic contacts, connectors, and flat springs can also replace copper as automakers become more sustainable to lower carbon emissions. Aluminum is recyclable, cheaper than copper, yet highly conductive.
Conversely, with photo etching, there is no point of contact with a heat source, and the temperature is easily controlled, so the machine and metal remain unaffected.
The stamping process is another popular machining method to produce automotive parts. It is cost-effective when using steel and large volume production, but aluminum can present some challenges.
Unlike steel, aluminum can spring back into the workpiece because it is a softer material than steel. Galling, friction between the metal sheet and hard tooling, is often a problem that can create burring and require a secondary elimination process.
Electric Vehicle technology is growing, and automakers are making the transition steadily. These fuel-efficient energy systems use fuel cells and bipolar plates in their vehicles to manage cooling and heating in thermal systems. Traditionally, these plates are made of steel for their strength and anti-corrosive properties.
Stainless steel etching is typical among these components because it is easy and cost-effective to machine the numerous grooves and unique channels necessary for fluid and heat exchange.
Using a single workpiece as in the laser cutting method or CNC would take too long to create these channels and result in longer lead times, with increased costs. Since plates usually have microchannels on both sides, they are faster to produce and more economical with etching because they are machined simultaneously in one operation.
Benefits of Photo Etching Automotive Parts
- Aluminum is easy to etch
- Channels and grooves are etched simultaneously
- Photo etching tooling is inexpensive and easy to revise for prototyping and testing
Photo Etched Aerospace Parts
The aerospace industry demands some of the highest-quality materials that must withstand extreme temperatures. When manufacturing, they must remain free from thermal distortion or burrs to eliminate the risk of failure.
Stamping or CNC punching can lead to structural deformation depending on the strength of the metal and the design of the part.
For example, nickel alloys and some specialty metals like Inconel and HyMu are high in strength, making stamping difficult. These metals are easy to etch and yet remain burr-free.
Laser cutting and wire EDM can pose problems such as thermal distortion due to exposure from either heat or gas. These distortions can also cause the metal to bow and compromise the planarity of the part.
On the other hand, chemical etching dissolves the unwanted metal without heat eliminating unwanted distorted edges, burrs, or altered the metal structure.
Some of the most common parts we etch in the aerospace industry include grounding contacts, terminals, heat exchangers, and flat springs. When requirements call for small to medium batches, these are popular parts that can be more economical than stamping due to the low-cost tooling.
And as mentioned before, if the part has complex features, etching is the best choice for quick lead times and low-cost with larger volumes.
These components are made of copper, nickel alloys, steel, and aluminum. Aluminum is also popular in this industry because it is conductive with high strength, is low-weight, corrosion-resistant, and can withstand extreme temperatures.
Benefits of Photo Etching Aerospace Parts
- Aluminum, Inconel, and HyMu are easy to etch
- Eliminates burrs and stress deformation
- Low-cost tooling
- Microchannels and complex designs are economical to manufacture
Etched Electronic Components
These are the most common types of etched parts because there is a need for electronic parts in a variety of industries that manufacture or assemble connected devices, navigational systems, and medical devices.
The electronics industry is driven by innovation, and a significant amount of resources and time goes into research and development to design and make improved parts and products. Therefore, design engineers seek manufacturing processes that will preserve the metal properties and be free from flaws in the finished product.
The photo etching process is an alternative to other manufacturing methods such as stamping and laser-cutting for companies producing thin metal parts that require low to medium volumes, have complex designs, or requires etching or on both sides.
Photo etching offers many benefits to the electronics industry, including accuracy, minimal cost and time commitment, no residual stress from cutting or heating processes, a wide range of available materials.
One of the benefits of using photo etching over other sheet metal processes is that the tooling is low compared to the hard tooling for stamping or CNC machining. Chemical etching tooling costs are generally a couple of hundred dollars and generated in a matter of hours. Most importantly, it is easy to revise, which is perfect for prototyping.
Alternatively, hard tooling jobs can cost thousands to produce and take months to make. And in some cases, more than one die is required to finish a complex design. Design engineers need flexibility in a fast-changing industry.
Metal Etching is particularly economical with small to medium production volumes with intricate parts such as lead frames found in semiconductor packages, filters used in cooling systems, or EMI/RFI shielding components because all features are manufactured simultaneously.
In lead frames, many features require extreme accuracy and low tolerances to provide a conductive connection to the semiconductor die. Additionally, these are often made of copper and typically with a metal thickness less than .010", and the part must remain flat.
Stamping could compromise the planarity and cause stress in such intricate designs and metal thickness. With such complexity in design, progressive stamping would require multiple dies to achieve the desired results. Therefore, stamping could prove to be too inexpensive or inefficient when it comes to quality.
Filters are an integral part of electronics cooling to prevent system high-temperature overload. They are very complex parts because of the number of openings and sometimes narrow thin lines in between, which make them very delicate.
Photo etching capabilities are perfect for these components as all features are etched simultaneously with precision and efficiency without the stress of hard tooling.
And finally, other common electronic parts we etch are EMI and RFI shielding covers, lids, and housings. These components are found on PCBs that power devices across many different industries. They are typically made from nickel silver, a solderable material that does not require plating, copper, copper alloys, stainless steel, or aluminum.
Although standard sizes are available through distributors, there is always a high demand for custom parts. With the low-cost, flexible tooling available with chemical etching, prototypes are inexpensive and easy to revise.
Another photo etching benefit for EMI/RFI shielding is half-etched or"bend lines" that make hand forming possible. Additionally, logos or part numbers can be etched simultaneously to save time and money.
Other processes like laser cutting would take longer to manufacture with production volumes. And since wire EDM only works with conductive metals, it is not always suitable when non-conductive metals are required.
Electronic parts will always benefit from the etching process because it is guaranteed to be free from burrs and stress while preserving the metal properties. Any imperfection between mating components could cause friction and system failure. Performance is vital in the electronics industry, and chemical etching is an excellent choice for simple or complex designs.
Benefits of Photo Etching Electronic Parts
- Parts are burr and stress-free
- No thermal distortion: parts remain flat
- Logos and part numbers etched without extra cost
- Bend lines and half-etched features manufactured simultaneously
- Large metal selection
- Low-cost tooling: flexible and easy to revise for prototyping