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Photo etching is a process to create line or tone in integrated circuits. The plate may or may not be etched, but there is always little variability in tone because of the uniformity in depth of the etch. Etching is a process that can either be wet or dry. Wet etching is the dissolving of a material in a chemical solution, while dry etching is the dissolving of a material with the help of ions or vapor.
Photo etching goes by several names, including chemical etching, chemical milling, photochemical machining, chemical machining and metal etching. It combines a procedure called photolithography with basic etching. Photolithography is a process by which patterns are formed using photoresist-covered substrates, or molecules acted upon by enzymes. This leads to the development of the photoresist when it is exposed to ultraviolet light and viewed through a photomask. The substrate is then etched, and the photoresist becomes a barrier that allows only the chosen part of the etched material to be etched.
Photo etching is referred to as a half-tone process because gray colors can be formed by either converting to half tones or by etching the plate several times at different lengths to create varying plate depths. Detailed metal parts can be formed by etching, and one advantage of this procedure is that it makes the resulting product very difficult to reproduce. Additionally, the process makes both the product and its design more flexible, it allows for more variety in types of materials, it eliminates stress problems on the product, it saves money on hard tools and it shortens the lead times.
Photo etching requires precision tools, as it involves a very intricate, fine method of cutting and engraving metal. The result of the process is an extremely thin metal, usually ranging from just .002 to .2 inches (.05 to 5 mm) in depth. A variety of materials can be used, including aluminum, brass, bronze, silver, nickel, copper, steel and iron.
Different companies specialize in different types of parts. Some can photo etch metal parts that are light gauge, which allows for very precise components. Other combine the process with blanking, a process used in forming parts for universal tooling. This method allows for the creation of more complicated designs and patterns. Still other companies use various tools that can support thicker metals, which can be used to produce grooves in the metal’s surface.
I think that it is amazing that chemists have found a way to use light like a natural artist's stencil. With the physics of visible light being so exact and precise, it makes sense that this incredible medium has been used as a modern way of "keeping inside of the lines." In what a kindergartner could only imagine, these exact means of keeping color or paint where you want, using light as a means of painting conductive material is an insight unlike many others. While it might seem slight to the lay user, the use of photo etching to create accurate circuit boards and other means of light stencils is an amazing accomplishment that has let other technologies dependent on
it to advance.
By blinding the material with a chemical that will not react to it, you essentially create a two dimensional construct in which the user can say what areas should be painted with the conductive metal. This very basic art tool is combined with the physics of electronics to create a very good combination of how we can make technology work for us.
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