Touch screens are exhibiting higher levels of performance and reliability at a lower cost. One reason for this is that indium tin oxide (ITO) is beginning to be replaced by newer materials.
What is indium tin oxide?
The compound element indium tin oxide can be a ceramic or alloy, depending on the oxygen content. Phone and tablet touch screens have been made out of ITO for a long time. Now, however, we are seeing the replacement of ITO with increasing frequency.
Why replace ITO?
One reason this change is occurring is due to the trend of integrating touch into the LCD panel, rather than manufacturing a clear touch screen overlay. This results in a thinner, lighter touch screen, with optical benefits as well.
What are the other materials?
Copper microwires, silver metal mesh, and silver nanowires are being used in touch screen production. Though not yet commercially available, graphene is in its early stages of development.
How does this development affect pricing?
When masks, lasers, chemicals, etching, and other tooling are needed for touch screen production, costs go up. Writing directly onto a substrate material without a mask saves time and money. Copper microwires, for example, are one of the sources mentioned above that can be written directly onto the substrate.
Another requirement that can affect cost is the number of layers needed. Because copper microwires can be insulated, they can form a single layer. Silver nanowires and metal mesh typically require two or more layers.
Touch Screen Resistance
Touch screen resistance determines sensitivity to touch as well as signal-to-noise ratio (SNR). When working with higher resistance materials, the amount of current flowing through conductors is restricted, making the touch screen difficult to use.
Compared to ITO, silver nanowires have better resistance, roughly 30 to 500 per square on a PET film substrate. Silver metal mesh possesses a resistance of 15 to 300 per square, rendering it an apt choice for touch screens up to 65 inches. At 50 per square or less, copper microwires are an excellent choice for larger touch screens that exceed 100 inches.
The Availability and Longevity of ITO Substitutes
Copper microwire touch sensors have been used in the industry for 20 years. Over time, this material has proven to work well in large touch screen technology.
Silver metal mesh and nanowire-based touch technologies are relatively new to the scene. Time will tell how durable they are.
New products are continually emerging in today’s evolving market, making the need for an agile production partner with advanced expertise and state-of-the-art capabilities essential to achieving long-term success.
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