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By Steve Baker | Aug 11, 2017
Printed electrodes are often used for electrochemical test strips and devices.

This blog is the first in our new series on technical printing. Throughout this series, we will describe the procedures involved in creating technical printing solutions, from start to finish. To begin, this blog will focus on defining what technical printing is and what it’s used for.

Technical printing is a generic term used for functional printing projects that fall outside of industry standards, materials, processes, and specifications. These projects require extremely tight tolerances and critical product specifications, typically belonging to highly regulated industries, such as the medical industry. The processes follow current Good Manufacturing Practices (cGMP), which are regulations enforced by the FDA to ensure products are consistently produced and meet quality standards. Technical printing and functional printing are both used for similar applications, such as for membrane switches. However, they differ in that functional printing has more forgiving specifications and technical printing has much tighter specifications.

A common example of technically printed parts is printed electrodes, which are strips manufactured for electrochemical analysis. This involves technical printing because they are typically used in the highly regulated medical field, in applications such as diabetic test strips. When manufacturing printed electrodes, conductive lines are finely printed in great detail on polyester substrates, typically using conductive inks including carbons, silvers, and silver-silver chlorides.

With technical printing, applying a conductive ink to a surface is similar to how you would apply frosting to a cake. When you squeeze a bag of frosting, a controlled amount comes out of an opening at the end. This same process is how conductive inks are applied as circuit lines on polyester substrates during technical printing.

GMN frequently manufactures electrodes for electrochemical test strips and devices, such as diabetic test strips or quick diagnostic labs. GMN prints electrodes with silver, carbon, or various conductive inks in order to measure a current or other signal. Our customers will then apply a reagent on top of the electrodes. When those reagents are exposed to bodily fluids such as blood, a chemical reaction takes place, and the electrodes will detect that reaction and send the signal to the device it is powered to. This is done on a very small scale, and the readings of signals must be completely accurate, which is why this part requires technical printing with a high degree of scrutiny. Because it has such a small trace, you can’t afford to have large variances in the circuit itself, which is why the tighter tolerances are so necessary.

Many variables go into technical printing projects, such as the curing times and quality of inks, as well as the substrates and thicknesses used. These variables are controlled closely, especially when making electrodes for medical equipment. These parts go on very important equipment and could mean life or death in certain situations, such as buttons for a medicine administration device used for hospital patients or printed electrodes used in diagnostic labs for diseases. With years of experience in the medical industry and other highly regulated industries, GMN is a trusted manufacturer for technical printing projects.

Our next blog will explore the development of technical printing projects. For more information on printed electrodes, click here

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.