This technical information has been contributed by
Duratech Industries

Wisconsin Firm Advances Manufacturing of Flexible Circuits

Flexible Circuits

In-Mold Electronics Shunting PCBs Aside

By Mark Langlois, Senior Editor
Design-2-Part Magazine

DuraTech Industries is an industrial printer, but the company's expertise goes well beyond the printed word. DuraTech prints electronics on bendable plastic that may replace manual switches and switch boxes.

The process, in-mold electronics (IME), may someday shrink much of the electronics on a car's dashboard and center column, opening up space inside a car. Someday, a slim sheet of printed electronics on flexible plastic may replace a printed circuit board. Someday soon.

Steve Roelich, printed electronics development engineer at DuraTech, and Paul Hatlem, DuraTech's sales manager, discussed DuraTech's in-mold electronics and in-mold decoration (IMD) in a series of emails and telephone interviews with Design-2-Part Magazine

"In-mold electronics" refers to DuraTech's process of printing electronics on a thin substrate of clear plastic that an injection molder then molds to a part. The printed words (in-mold decoration) and the printed electronics (in-mold electronics) are printed together on the thin, clear plastic. That plastic is then molded together with the plastic part in the injection molding process. The clear plastic covers and shields the words the customer reads. It shields, for example, the word "wash," which the customer presses to turn on the machine, and it shields the electronics behind the word that makes it work.

Thin, Robust, Flexible Electronics to Replace Bulky Boxes

"It's robust. It lasts a very long time. That's why it's attractive to the appliance manufacturer. Ten or 15 years down the road, the graphics look like it did when it was brand new," Hatlem said. The decoration looks new because a layer of durable plastic, called the substrate, sits between the consumer's finger and the printed words. The substrate also shields the electronics that were first printed and then were molded inside the part.

The thin-printed electronics replace other bulkier electronics. Because the electronics are encapsulated in plastic, they are more resistant to water. One example of that came from a competitor's healthcare appliance.

"It was a competitor's product and they brought it to us because they were seeing failures, and the competitor couldn't provide a solution," Roelich told D2P in a phone interview. "We looked at it and we accepted the challenge. We proposed a solution and reengineered it. It had a membrane switch that had been used for many years. It was in a hospital setting and it was failing when they wiped the equipment down– they sprayed it with a cleaner that's common for disinfectant.

DuraTech Prototype Demonstrates In-Mold Electronics Manufacturing Process

DuraTech Industries and Jabil won the In-Mold Decoration Association Gold Award for Best Prototype Part at the 2016 TopCon and IMDA Symposium.

DuraTech's part, made in cooperation with Jabil, appeared similar to a traditional in-mold decorated label– with a few amped-up improvements. The label includes in-mold electronics (IME) that function like a membrane switch assembly without the switch.

"Best of all," the association wrote in giving the award, "the decorative and fully functional panel can be easily modified to appeal to changing consumer tastes, language preferences, and more. It can even be quickly modified for use on a wide array of products, including stoves, refrigerators, and other appliances." The association also said, "The Jabil washer control panel is unique and innovative because it replaces a traditional printed circuit board (PCB), eliminating the need for post-molding decoration and hardware for illumination."

Jabil described the process of creating this prototype on its website as follows. "Over the course of many months, a Jabil advanced technology engineering team, led by Arnold Reta, created a working prototype of a novel capacitive touch in-mold electronics (IME) clothing washer control panel that incorporates an in-mold label (IML). As a result, production is simpler, less costly and faster."

The award highlights the in-mold electronics process, which is a newer manufacturing technique. Paul Hatlem, sales director for DuraTech, said the company is now developing the IME process for commercial use. He said the IME potential is huge.

"We've shown the technology to both Whirlpool and GE," Hatlem said. He met with major auto manufacturers to discuss the IME process in November. "The technology is very new on this. Big companies don't jump at some of this stuff until it's proven."

"It was leaking or ingressing into the electronics and the switches and the devices were failing," Roelich continued. "They brought that challenge to us. We were able to use our expertise and our knowledge to modify their design to incorporate a full perimeter seal to keep that liquid out without changing the look or the feel to the end user. They had no idea we had revised the design and heavily modified it. We were able to deliver what appeared to be the exact same product, aesthetically and functionally, but we corrected the issue of water ingress. They no longer have that problem."

A Single Layer Replaces Seven, and Manufacturing Innovates to Improve

In one layer, IME may replace existing technology, such as a membrane switch assembly, which averages six or seven layers to do the same thing. Those layers sometimes fall apart. Someday, IME may replace an entire printed circuit board. When that happens, appliances may shrink and the interior of a car may open up as IME technology replaces the switch boxes now sitting under the dash board and center column.

"We're developing the manufacturing process for commercialization," Hatlem said. "We didn't invent the technology and we don't claim to. We're inventing the manufacturing process. It's new, so there's no playbook. We have to figure out how to overcome every step. We're asking manufacturing steps to do things that have never been done in those processes before. There are challenges in the printing. There are challenges in the forming. There are challenges in the molding. There are others working on it. We're working on one that is unique and works for DuraTech. We're very close to having that process fully commercialized. The challenges I mentioned earlier, we've overcome all or almost all of them."

What are the benefits?

"We're looking at higher tech, so we're updating user interfaces to touch technology," Hatlem continued. "We're integrating the electronics, graphics, and plastics all into one piece. Because of that, you're going to see a bill of materials reduction in your final assembly. So if you have a widget you make, and you have to buy a printed graphic overlay with adhesive from supplier A, a plastic part from supplier B, and electronics from supplier C, you have to bring all them in and inventory them and warehouse them."

The process keeps going. "You have to pull them and there are assembly techniques to put them all together," Hatlem explained. "We can roll all that into one, so you're buying one part from supplier A. You remove all that assembly labor and you also remove all that inventory. The buyer doesn't have to buy and manage that inventory."

The benefits of this process include less waste, no assembly, and more reliable, encapsulated electronics. The process is lead free and RoHS compliant. It eliminates bulky boxes, it has no moving parts, and it is less costly and more reliable than membrane switch assemblies. The electronics and decoration (words) on the prototype were about 0.010 inch thick. The membrane switch assembly is about 0.040 to 0.060 inch thick.

"It's built into the plastic. We don't really add any thickness to it," Roelich said. "We have very good technical people in the inks and adhesive side of things. Not every ink is going to work with every substrate. Not every ink is going to work with every adhesive. There's a lot of chemistry involved in this. And knowing that and being able to come up with the right combination the first time is very important."

DuraTech's La Crosse, Wisconsin, headquarters is the center of a worldwide manufacturing enterprise with other factories in Bangor, Wisconsin; Raleigh, North Carolina; and Beijing, China. The company employs 270 people working three shifts in the 85,000-square-foot La Crosse manufacturing plant and another 130 people working in the plants in Bangor, Raleigh, and Beijing. The three have 5,000 square feet, 10,000 square feet, and 20,000 square feet of manufacturing space, respectively.

DuraTech, which has been ISO compliant since 1998, updated its manufacturing processes by purchasing 4 new Sakurai rotary screen printing presses in the last three years, Hatlem said. DuraTech supplies labels using the in-mold decoration (the printed words) process for parts used in appliances, cars, computers, electronics, industrial uses, and medical devices. Its newest technology, IME, adds printed, flexible electronics behind those words.

Customers Discover Their Own Uses for In Molded Electronics

Hatlem and Roelich said the technology is so new they learn new things about it as they explain it to potential customers. The customers look at it and see possibilities DuraTech hasn't yet imagined.

"From a design standpoint, you can now create three dimensional functional capacitive touch buttons, which is not something that is easily accomplished with printed circuit boards," Roelich said.

For instance, one customer they approached took them in a surprising direction after they confirmed the ink is flexible and conductive. It can conform to curved shapes? It can be molded onto the lens of an LED truck light? Why?

The LED doesn't generate heat like a traditional car or truck headlight, the customer explained. The modern headlights on a snowplow use LED bulbs. They don't warm up the lens, so it ices up as the driver plows the street. With the IME molded to the lens, the lens warms up and melts the ice, solving the problem. "There is huge potential growth there," Hatlem said.

How else can it be used in a car?

"Your HVAC (heating, ventilation, and air conditioning), stereo, your windows, interior exterior lighting," Hatlem said. "We don't know what their requirements are for auto manufacturers, but it could be any user interface; anything you switch on and off right now could be replaced with this technology. In theory, all the controls. You could put it into gear with this.

"Now industrial designers can think outside the box," he continued. "We're giving them a new tool, a big one. So they can say 'What if the microwave front face where you normally enter the buttons was different?' We're doing it very cost effectively. We can do that now because we can print conductive inks. We can form them. We can't do that with a printed circuit board. The design advantage is a large one."

Changing the shapes people can design is a game changer, Hatlem said.

"All engineers, new products, or industrial design folks, one of their goals every single year [that] they're going to hear from marketing, the whole company is: product differentiation. Why do people want to buy my widget instead of the next guy's widget?" Hatlem said. "When you walk into Sears and there are 20 washers there, why do I want to buy the Kenmore, or why do I want to buy the GE? They're constantly striving to have something different from the other guy to draw your attention to it.

"So then that design advantage of the third dimension, adding the third dimension gives all those ID folks and engineers that flexibility, so now you can walk into Sears and, immediately, your eyes will be drawn to 'Oh, what's this? This is different than anything I've seen. This is different.' You have product differentiation right there."

Roelich said that someday, people may print high-definition television screens that roll up and fit in a backpack. What if they interconnected so you could fill the side of your house with one huge screen and host a football party?

"We slowly reduce and potentially eliminate the printed circuit board," Hatlem said. "Transparent conductors? What if the window of your car has all the switches on it?"

This technical information has been contributed by
Duratech Industries

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