membrane switch assembly

Key Word Search

Filter by Category

Popular tags

3M
ECG
EMI
EP
GMN
GMP
IMD
IQ
ISO
LED
NC
OCA
OQ
PQ
RBH
Tag
VHB
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 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.