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By Sandy Dick | Jul 11, 2017
CONMED membrane switch assembly

CONMED, a global medical technology company, came to GM Nameplate (GMN) in need of a membrane switch for the control panel of their surgical generator. With diverse capabilities and decades of experience working with the medical industry, GMN was able to provide not only each component of the membrane switch, but the complete, value-added assembly of the part as well.

The graphic overlay was printed using a combination of screen and litho printing and included multiple display windows and LED indicators. The overlay’s background colors were screen printed to achieve a high opacity, which helped to prevent light bleed from the illuminated LEDs. Litho printing was used to apply fine details and halftone patterns to the part. A halftone dot pattern was printed on top of the background to create a gradient effect on the keys and along the top of the overlay. Creating a halftone pattern that achieved the customer’s desired aesthetic proved to be challenging, but the ideal look was reached after several trials of testing various pattern constructions (altering dot size and space between the dots). GMN also printed the membrane circuit that goes behind the overlay and connects to the LEDs and switches.

Another challenge faced during this project was choosing the correct snap domes for the different-sized keys to create a good tactile feel. The difficulty stemmed from the unusual shapes of the keys and various sizes of domes. As a consistent layer across the entire part, the spacer interacts simultaneously with every dome and affects each dome size differently. Therefore, GMN had to carefully review the stack-up to include a spacer layer with the optimal thickness to give every dome size enough room to provide a crisp tactile feel.

A variety of layers were required in the stack-up in order to ensure that the part would function properly. ESD shielding was placed under the circuit connector to protect from static discharge and an aluminum subpanel was added to support the otherwise flexible structure. A foam gasket surrounded the outside of the panel to seal the area from outside moisture and fluids. Finally, due to a concern of the closeness to the electrical components beneath the panel, an insulating layer was added to the backside of the subpanel to prevent the electrical components from shorting out against this metal layer.

From early development through full-scale production, GMN worked closely with the customer to develop this product and provide design considerations for part manufacturability. As a product used in the operating room, GMN held multiple pilot runs to ensure the part functioned as intended and met the customer’s standards. 

CONMED surgical generator with GMN's membrane switch assembly.

By Steve Baker | Jun 16, 2017
GMN's membrane switch assembly for Welch Allyn.

GM Nameplate’s (GMN) Singapore Division supported Welch Allyn, a medical company, to develop and manufacture a membrane switch panel with backlit indicators for their resting electrocardiogram (ECG) device. As a device used to test a patient’s heart activity, it is critical that the backlighting appropriately indicates how much battery power the device possesses.

GMN offers an array of backlighting options including discrete LEDs, fiber optic weave, light guide film, and electroluminescence. The part had strict spacing requirements between its tactile buttons, which influenced GMN to choose discrete LEDs. Discrete LEDs are cost-effective and ideal for lighting up small indicators.

Instead of using three different colored LEDs, GMN installed one bi-color LED to occupy as little space as possible and reduce costs. The two colors within the LED were green to indicate the battery was charged, and red to indicate the battery was dead. To create the amber color that indicates when the device needs charging, the LED was positioned off-centered from the indicator window to effectively blend the red and green colors together.

Another factor GMN had to consider was the material for the overlay. GMN utilized polyester (PET) film, a common overlay material for devices in the medical industry due to its resistance to abrasion and harsh chemicals. As an extremely durable, long-lasting material, PET film is ideal for applications with tactile switches because it’s abnormal for the material to crack. 

By Rachel Wienckoski | May 18, 2017
Polyester and polycarbonate are both popular overlay materials.

Have you ever walked up to an ATM machine or gas pump and noticed the cracking, fading numbers on the keypad? This is a prime example of why material selection is vital for graphic overlays. At GMN, the two most common materials used for graphic overlays are polyester and polycarbonate. Depending on the application, there are advantages and disadvantages for both materials.

When evaluating overlay materials, one of the most important factors to consider is durability. Polyester and polycarbonate are both extremely durable materials, but polyester is generally known as the more durable option. Polyester has a longer actuation life (over 1 million actuations vs. 200,000 actuations), meaning that it can endure more switch actuations before the overlay will start to crack or deform. As a result, polyester is a great choice for membrane switches and overlay designs that include embossed buttons. Polycarbonate has a wider thickness range, and increasing the thickness of an overlay can help make it more durable. However, polycarbonate is best suited for applications with minimal flex requirements because continual flexing can cause stress fractures over time. Therefore, in the scenario above, polycarbonate was likely chosen for those overlays, when polyester would’ve been a better choice.

In addition, polyester is resistant to abrasion and significantly more resistant to acids and chemicals, making it an ideal substrate for the medical, industrial, and appliance industries. Polycarbonate is flame retardant while polyester is flammable, making polycarbonate perfect for industries in which safety is of high importance, such as the aerospace industry. Alternatively, hard-coating can be used to significantly improve the durability of either material.

While polyester has an edge in terms of durability, polycarbonate has some cosmetic advantages over polyester. Polycarbonate offers a wider range of textures and finishes, which can be attractive when design is the most important factor. It also has very high clarity and color brilliance. If an overlay is being used purely for appearances and won’t be exposed to frequent use, polycarbonate may be the most appropriate substrate choice.

In terms of production, polycarbonate tends to process easier than polyester. It’s very easy to cleanly print on polycarbonate of all thicknesses. Polycarbonate is also easier to die-cut and emboss, which can help to reduce cost.

The cost difference between the two types of materials is minimal, so the application and use considerations are typically the main factors to consider. However overall, polyester is slightly more expensive than polycarbonate.

Polyester and polycarbonate are both excellent material choices for overlays. Ultimately, the choice between the two will depend on the overlay’s design requirements and environmental conditions. For more information on how polyester and polycarbonate compare, visit GMN’s graphic overlays page.

By Sandy Dick | Nov 4, 2016
Adaptive Interfaces overlay produced by GM Nameplate.

Adaptive Interfaces came to GM Nameplate (GMN) to manufacture six different overlays for instruments used in aircraft cockpits. The six overlays had the same shape and colors, but varied in text according to the overlay’s purpose. GMN manufactured overlays for the decoder, encoder, electrical status, oil status, engine temperature, and engine performance monitors.

With GMN’s rapid prototyping capabilities, Adaptive Interfaces was able to receive prototypes quickly to use as a visual for board meetings and discussions. The prototypes were digitally printed using a textured substrate, allowing for fast delivery.

For the production run, the overlay was screen printed. The overlay’s graphics were printed with translucent ink for illumination in dim lighting, and the windows were printed using transparent ink so that the display behind the overlay could readily show through. The adhesive was laser cut and later lined up and adhered to the overlay before fabrication with a steel rule die. The lettering was backprinted and an anti-glare finish was applied the entire overlay.

At GMN, we provide design solutions to help customers navigate through any hurdles to ensure the production of high quality products. 

By Brian Rowe | Oct 12, 2016
Membrane switch panel for  Given Imaging's medical device.

Given Imaging, a medical technology company, came to GM Nameplate (GMN) to assemble a membrane switch panel for their medical device. When configuring a membrane switch, many factors about each component layer must be taken into consideration. 

As the user interface for a medical device, the screen printed and embossed overlay needed to satisfy stringent requirements. The overlay must act as a sealant to prevent moisture and fluids from reaching the membrane. Additionally, the overlay must be chemical and scratch resistant to combat the strain of daily use. 

Common overlay materials include polyester and polycarbonate. Both materials are affordable options that will protect the circuit membrane from scratches, chemicals, and liquids. Due to the durability of screen printed inks, backprinting is a frequent practice to mitigate product wear and tear from everyday use.    

This Given Imaging overlay contains three colors - teal, white, and a black opaque layer. The opaquing layer was selectively applied around the LEDs which allowed light to shine through and prevented light bleed through unwanted areas of the overlay. Because of the opaquing layer, light only showed through the indicator icon on a button instead of throughout the whole part.

When looking at membrane circuit materials, printed silver ink in lower volumes provides a cheaper option than copper etched circuits, such as Kapton, while still offering comparable performance capabilities. Finding the right membrane circuit for the product application is necessary to manufacture a quality membrane switch.

For more information about GMN’s membrane switch assemblies, visit our capabilities page.  

Rudy Vital, GMN
By Rudy Vital | Aug 18, 2016
Philips Respironics overlay and membrane

With several design and manufacturing challenges to address, Philips Respironics turned to GM Nameplate for a membrane and overlay for their ventilator. The issues included providing a way to block liquids from damaging the membrane circuit during cleaning, generating enough circuit power under membrane area restrictions, and preventing damage to the membrane tail during final assembly. Learn how GMN supported Philips Respironics by reading our case study.  

Anna Minzel, GMN
By Anna Minzel | Jul 7, 2016
Fluke graphic overlay

The Fluke Corporation, a manufacturer of electronic test tools, was in need of a graphic overlay for their latest communication tool. The overlay contained a unique combination of characteristics that made Fluke’s originally desired printing method costly. Due to GMN’s rapid prototyping services, an alternative printing solution was quickly uncovered that met Fluke’s distinct color, time, and cost requirements. Learn more about this program by reading our case study here.

Dean Karousos, GMN
By Dean Karousos | Sep 8, 2015
Medical custom manufactured overlay

During a recent conversation discussing problem solving capabilities at GMN, a project worked on a few years ago with Sotera Wireless was brought up. This project was unique because a standard polycarbonate, typically used for overlays, didn’t meet Sotera’s requirements. To overcome this challenge, our team needed to think outside of the box to create a solution.

Sotera Wireless, a leader in mobile patient monitoring medical devices, was looking for an overlay for one of their medical devices. Along with DD Studio, an industrial design studio hired to design the device overlay, GMN needed to find an overlay solution with optical clarity, impact resistance, and chemical resistance.

One of the greatest challenges with this project was finding the right material for the overlay. Originally, the plan was to use an injection molding process, but this was found to have problems when the material flowed around the small holes. Next, a laser was chosen to cut parts from sheet-stock, but this process introduced its own challenges. First of all, the chemical resistance was a concern on the cut edges. In addition, while an acrylic laser cuts cleaner and better than a polycarbonate, it isn’t as durable and is prone to chip or shatter on impact.

To solve these problems, a unique material was used, Eastman’s Tritan MP 100, a proprietary impact resistant co-polyester. The Eastman co-polyester material provides a cleaner laser cut edge than polycarbonate, and is available in 0.060” sheets, the desired overlay thickness. Lastly, an Exxene hard coat, the Flexform 200, was applied to the overlay.

One more challenge was faced during the project: identifying a metallic ink without metallic flakes. The ink could not contain any metal because it would interfere with IR scanner readings. GMN spearheaded the research and development needed to find a solution that satisfied both Sotera’s functional and cosmetic requirements.

Sotera Wireless was overwhelmingly pleased with the product. GMN’s cost effective solution not only provided design solutions but technological innovations as well. This overlay is a good example of the benefits of vendor consolidation, innovative processed and a solution-based approach.