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Fabricating thin with photochemical etching

How the flexibility of photochemical etching built a business

Figure 1
A thin metal blank undergoes photochemical milling (PCM) at Faspro Technologies.

Igor Shkarovsky remembers working the second shift and making near minimum wage as a press setup technician in the early 1990s.

“I came to America in 1991 with $36 in my pocket.”

He spoke little English, but the pressworking trade was in his blood; he came from a long line of Ukraine-born Jewish tool- and diemakers. That skill eventually landed him a metal forming job, first as a setup technician on the night shift, then as a tool- and diemaker. A few years later he was working at a company that did work for telecom industries such as Motorola, Nokia, and Sony Ericsson. This experience introduced him to the U.S. electronics sector and ultimately shaped his career.

The experience revealed an unmet need—specifically, shorter lead-times. “At that time the general lead-time for a prototype was two weeks,” he said. “Motorola was looking for something shorter, and they couldn’t get it faster from anybody.”

He soon realized that the lion’s share of prototyping time in the electronics business wasn’t spent actually building a prototype but instead waiting for the parts to be returned from an outsourced process. He realized if a shop had all the equipment needed in-house, it could turn around a prototype within a week, a few days, or a few hours, depending on the job.

With this idea Igor Shkarovsky launched Faspro Co. in 1995 out of the basement of his townhouse. By 1997 he expanded to photochemical etching, a thin-gauge cutting process that has become pervasive in electronics manufacturing. The circuit board components in your smartphone were almost certainly made with photochemical etching, also called photochemical milling (PCM) (see Figure 1).

At the same time Shkarovsky installed some plating baths, and eventually he expanded into assembly. To achieve quick response, he didn’t want to rely on subbing out work for every job (see Figures 2-4).

As Scott Smith, Faspro’s vice president of sales and marketing, explained, “He identified a need in the combination of photochemical etching, metal forming, and plating that was being unfulfilled, especially in the area of creating blanks for board-level components in the electronics industry.”

PCM Basics

Coming out of 1960s circuit board manufacturing, PCM has become a popular method for cutting extremely precise features in thin blanks. The industry usually uses PCM for material between 0.001 and 0.063 inch thick.

The company receives a 3-D CAD file from the customer, unfolds it, and tweaks the blank size to account for forming—all typical in custom fabrication, but that’s where the similarity ends. A pattern is then printed onto a photographic film, a photonegative of the final part that shows the kerfs in black. This so-called “phototool” is adhered to both sides of the sheet metal blank, which is treated with a UV-sensitive coating called a photoresist. The plate is exposed to UV light, which develops the pattern, protecting the solid sections from acid and leaving the kerf sections unprotected. It then goes through a multichambered machine with spray nozzles, which spray acid to etch or completely remove those unprotected sections. Kerf widths and other features can be extremely fine and narrow.

Figure 2
For many jobs, Faspro can fit dozens or hundreds of small parts on a single blank.

The entire etch is made in one cycle of the chemical spray. The etching cycle depends more on plate thickness and depth of etch, less on the number of components to be etched. A nest with a few features can have the same etching cycle time as a nest with hundreds of features. The company can etch features as narrow as 0.005 in.

PCM can etch partway through the sheet thickness to create geometries like a channel or pocket, or throughout the entire thickness to create a kerf. “The etching process itself occurs from both sides, so the chemicals can etch the entire material thickness,” Shkarovsky said. “If you apply the chemicals to just one side, you can do what’s called a half-etch. How long you leave the chemicals on the blank determines how deep that etching goes. It’s typically 30 to 60 percent of the material thickness.” One set of chemicals works well for cold-rolled steel, stainless steel, as well as copper, nickel, and other alloys. Another set of chemicals work well on titanium and other exotic materials.

Commonly etched products include shields that protect microchips on circuit boards. “Anything that has to do with wireless communication, which these days is just about everything, there’s a need for board-level shielding,” Smith said, “and it all starts with photochemical-etched blanks. For instance, in your smartphone, you have anywhere from three to seven wireless antennas built into the package. Those are very fine and detailed metal components that start with photochemical etching of the blank.”

Your smartphone’s antennas were probably made in Asia, where most electronics manufacturing takes place. In production environments, components are stamped using hard tools. For applications too critical even for high-precision progressive dies, a production shop uses PCM in a reel-to-reel inline system that coats the strip in chemicals, etches the material, and then shuttles it to downstream processing and packaging.

Faspro’s forte is not in production, but in prototyping and low-volume work. “We typically don’t go over 100,000 pieces, in terms of annual demand, for any given part number,” Smith said, adding that in total the shop processes millions of components a year. That may sound like a large amount for conventional custom fabrication, but these are small parts; dozens or even hundreds fit on a sheet of material.

PCM exhibits the same flexibility in thin material as laser cutting does in conventional sheet metal fabrication. There’s no hard tool, only a printed photo- tool. “The lead-time for a stamping tool can take more than several weeks,” Smith said. “The photo- tool takes all of two hours. And we can nest variations of the same design on one large sheet, all in a single process with a single phototool. This gives engineers a lot of opportunities to test their theories.”

Forming Thin

Faspro also does extensive forming of these blanks, but it’s not like any forming department of a typical custom fabricator. The company now employs more than 100 people, and a good portion of them work in a custom forming department that delicately forms material too thin for conventional press brakes.

Tools are custom, but again, to speed turnaround time, they are made in-house, often by the operators themselves. Some are designed to do multiple forms at a time, depending on the part’s complexity. The technicians grind and polish the tools to a specific shape required for the job, then set up and operate the press to perform the forming. Presses range from 1 to 15 tons, and some are pneumatic while others are mechanical.

“These products are pretty much hand-formed,” Smith said, “and we have many of these presses in the plant. We do millions of parts a year, and it’s all small lot size, high-SKU mix.” Setups are manual and can be fairly quick, but every form, or group of forms, requires a different setup—hence the need for numerous presses.

Radius tolerances typically are within one material thickness, but some precise forms might need to be within half a material thickness—and that’s saying something when you’re working with 0.008-in.-thick material. But the greatest forming challenge for many of these small parts is coplanarity. A formed part might have two notched feet (the notches being etched during PCM), and the edge of one foot needs to line up on the same plane as the edge of the other foot. This ensures that they can be mounted precisely on the surface of a circuit board, so they don’t fall off the board before being soldered.

Figure 3
A technician immerses an etched sheet into a bath for plating.

Technicians perform the forming operations with a matching punch and die coming together to form a specific angle and radius. But as Smith explained, they also perform air bending and drawing. “If we make a board-level shield that encompasses a circuit board, there might be multiple levels of draw features, and each is formed individually. In a production environment, this kind of forming tool might cost as much as $60,000. But if you do it in a hand-form environment, you create a separate form tool for each of those pockets that are drawn. This might require 15 setups, but the total tooling investment is very low. Should the design change—and it always does when you’re in the early stages of product development—you can just swap out one of those tools.”

It’s an age-old process, going back to Shkarovsky’s grandfather’s day, applied to form high-tech components. Training such workers involves shadowing and a lot of hands-on trial and error. This isn’t a CNC operation, and much of it is about getting the right feel.

Expanding to Conventional Fabrication

As the company grew, the shop changed its name to Faspro Technologies Inc., and this year it moved in a new direction—into the “macro” arena of conventional fabrication. Faspro’s electronics customers not only use thin material inside components, but they also house those components in sheet metal racks and other structures.

“About 90 percent of our metal fabrication starts with photochemical etching blanks,” Smith said. “But this year, with the acquisition of new machinery, we’re now going to take our same business model and apply it to material from 0.050 in. up to 0.250 in. We’re going from board-level components to the thicker components that wrap around the board, including the rails, the racks, and the enclosures.”

To start a sheet metal division, Shkarovsky didn’t want to hire dozens of people. Instead, he invested in systems such as an Amada punch/laser combination machine and a CNC press brake with an automatic tool changer with manipulators that switch out punches and dies.

“[These machines] condense our time to produce the prototypes and short runs tremendously,” Smith said. “The electronics business is a got-to-have-it-yesterday industry. That’s just the way it is, and we’ve found a way to support that.”

“We like to take on what’s difficult,” Shkarovsky said, adding that such challenging high-product-mix work hits the sweet spot not only for his own business, but for U.S. manufacturing overall.

Images courtesy of Faspro Technologies Inc., 500 W. Campus Drive, Arlington Heights, IL 60004, 847-392-9500, www.fasprotech.com.

Figure 4
A technician inspects a cut blank with an optical comparator.

About the Author
The Fabricator

Tim Heston

Senior Editor

2135 Point Blvd

Elgin, IL 60123

815-381-1314

Tim Heston, The Fabricator's senior editor, has covered the metal fabrication industry since 1998, starting his career at the American Welding Society's Welding Journal. Since then he has covered the full range of metal fabrication processes, from stamping, bending, and cutting to grinding and polishing. He joined The Fabricator's staff in October 2007.