AUTOMOTIVE
Micromanufacturing & photo-chemical etching in the automotive industry
Dr Angel Lopez, Director of Business Development at Micrometal GmbH discusses the role of photo chemical etching in the manufacture of precision metal parts and components in the automotive industry
he automotive industry is a driving force when it comes to innovation and development of micro-systems, with demand for high volume production, unlike the more niche applications in the aerospace sector. It is likely that the automotive industry - along with the medical device sector - will be a major stimulus behind the growth in the micro manufacturing space in the short to medium term. As such, the automotive industry is an early adopter of photo-chemical etching (PCE), which today is the go-to technology for the production of ultra-precise metal parts and components at volume and repeatably. The automotive sector is characterized by demand for cars that emit less in the way of pollutants, and run economically and efficiently. This has a knock-on effect to manufacturers that find themselves forced to design more and more sophisticated engines, which demand more and more accurate components made out of increasingly innovative materials. Weight - while not an issue at the level of importance it is in aerospace - is also a major factor in the automotive sector. Micro manufacturing is helping to address these dual needs - increased sophistication and efficiency while also reducing weight - through miniaturisation. The ability to manufacture micro-sensors, for example, not only saves on weight when compared to traditionally-sized sensors, but also means that more can be used to monitor vehicle performance parameters in greater depth and detail.
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What is photochemical etching Photochemical etching employs chemical etching through a photo-resist stencil as a method of material removal over selected areas. The use of photo-resists allows for the manufacture of high-resolution parts with complex geometries or with large arrays of variable aperture profiles in thin, flat metal sheet.
Commonly misrepresented as merely a prototyping technology, photo-chemical
10 SEPTEMBER 2021 | ELECTRONICS TODAY
etching is in fact a versatile and increasingly sophisticated metal machining technology, with an ability to mass manufacture complex and feature-rich metal parts and components. The process is characterised by retention of material properties, burr-free and stress-free parts with clean profiles, and no heat-affected zones. As a machining technology, PCE has been around for over fifty years, but it is still a relatively low profile process in industry. In recent years, however, with the explosion in demand for more and more precise, smaller, and complex metal parts, automotive OEMs are increasingly turning to PCE, which due to its versatility is stimulating innovation and is allowing the manufacture of previously “impossible to make” parts. Tooling is a key area where PCE has the edge! As a process it uses easily re-iterated and low-cost digital or glass tooling, which makes it cost-effective when compared to many traditional machining technologies such as metal stamping, pressing, CNC punching, and laser and water-jet cutting. Traditional machining technologies often produce undesirable effects in metal at the cut line, often deforming the material being worked, and leaving burrs, heat-affected zones, and recast layers. In addition, these processes struggle to meet the detail resolution required in the ever smaller, more
complex, andmore precise metal parts that many industry sectors (especially the medical device sector) require. There are instances — typically when an application requires multiple millions of parts and absolute precision is not a priority - when these traditional processes may be the most cost-effective. However, if manufacturers require runs up to a few million, and precision is key, then PCE with its lower tooling costs is often by far the most economic and accurate process available. Another factor to consider in process selection is the thickness of the material to be worked. Traditional processes tend to struggle when applied to the working of thin metals, stamping and punching being inappropriate in many instances, and laser and water cutting causing disproportionate and unacceptable degrees of heat distortion and material shredding respectively. While PCE can be used on a variety of metal thicknesses, one key attribute is that it can also work on ultra-thin sheet metal, even as low as 10 micron foil. It is in the manufacture of intensely complex and feature-rich precision parts that PCE really finds its perfect application, as it can be applied to any shape and configuration of product, however complicated or unusual. The nature of the process means that feature complexity is not
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