BY ALT Technologies | 27th January 2023
Automotive interiors and electric vehicles are upgrading with the latest advancements in flexible printed electronics, including seat and armrest heating and lighting displays.
Printed electronics and conductive ink applications have been around for decades, with OLEDs (organic light-emitting diodes), glucose strip tests and solar panels leading the way in functionality.
However, since the electric vehicle market is thriving with the latest automotive advancements, printed electronics have a new dynamic. Our articles will discuss these new developments under headings such as heaters, lighting, sensors and HMI, FFC including wire harness solutions and phygital grilles.
What do we mean when we say “printed electronics?” It involves printing technology that creates various applications such as RFIDs, sensors, electronic circuits, and displays. For example, you can print carbon-based, convectional inks on different flexible substrates such as PET.
The driving force behind this type of printing is how lightweight the solutions are, making them a sustainable choice due to their thin layers and less material. The emergence of interactive displays, controls powered by voice commands, remote devices and IoT connectivity are also key factors in the uptake.
Printed electronics allow automotive suppliers and developers to take their solutions to the next level. For example, in most cars, a lot of heat is wasted in space that the passenger does not occupy; a heat sink. With novel printed heater capabilities, they are flexible and self-regulated, making them easier to install in car seats and connect throughout the vehicle.
A typical flexible heater comprises a heating element, either an etched foil or a wire wound heating element. These heating elements are packed between material layers that allow heat transfer from the materials to the application. In addition, some form of resistance is used within the elements to create heat.
Wire heaters use very thick wires (measured in millimetres), so they must be covered in a thicker material so as not to feel the wires. However, printed ink layers are much thinner (microns instead of millimetres) and can be placed much closer to the surface, making them a more efficient choice.
Conductive ink is an essential component of the functionality of printed electronics. Inks such as silver or copper are used to conduct electricity. They are used to print flexible printed electronic circuits on various materials and make objects more communicative or capable of storing information.
PTC heaters are well known for their safety, elasticity, flexibility, and ease of use. PTC heaters work well by producing safe and comfortable low heat. PTC carbons work as electrical resistance and heat up when a current is applied. A full range of positive temperature coefficient (PTC) conductive inks can be combined with flexible substrates such as polyester (PET) or polyimide (PI).
Their carbon ink has resistive properties that change with temperature. As the heater reaches an equilibrium, the resistive elements stabilise, and the flow decreases through the heater. This process repeats, with minor fluctuations.
PTC carbon-based heating is self-limiting and does not require a controller. The heater is designed to “shut off” at a pre-determined temperature. This is considered a “self-limiting” heater without external diagnostics or controls.
Fixed resistance heaters are the most similar to traditional wired heaters. However, instead of wiring, fixed-resistance heaters have lines, or traces, of an ink printed onto a substrate material such as PET or TPU. These printed silver or carbon ink coils produce heat and can be regulated via an external controller or battery pack.
Thanks to a sophisticated blend of inks and substrates, these multilayer circuits offer high printing density with enhanced accuracy.
These circuits can be single- or double-sided with several layers, polyamide or polyester, or ENIG plating or screen printing. They allow for customised and flexible circuits.
This process blends the durability of traditional electronic circuits with the extreme malleability of flexible circuits. This creates a highly flexible, resistant solution that can adapt to various shapes.
With the large size of EV batteries, it is vital that OEMs keep vehicle weight to a minimum. One way of achieving this is through creative heating system solutions in the vehicle interiors. As mentioned above, printed heaters are temperature automated and flexible, unlike traditional automotive heaters, making installing car seats easy.
Heating-printed flexible electronics extends beyond just seats to armrests and the floor mats of the vehicle. Heat rises, so if the floor mat has heating properties then the rest of the car will also heat up too. They can be positioned much closer to the surface, therefore heating the car efficiently and responsively. We will even see transparent conductors coming to the fore and being placed directly on the surface of materials.
Advantages include:
• High thermal comfort (no hot spots).
• Rapid heating (approx. 2 minutes).
• Robust (good sound and vibration properties).
• Breathable (smart material technology).
• Easy integration (stitching and adhesive technology).
• Economic (better heats car occupants with high-tech materials).
• Lightweight compared to previous seat heaters.
Advantages include:
• High thermal comfort (43°C).
• Rapid heating (approx. 2 minutes).
• Low power (15 watts maximum).
• Thin and lightweight.
• Cost-effective (easy integration & innovative material technology).
Although there are clear advantages, such as flexibility and being lightweight, there are much more to vehicle interior printed electronics than meets the eye.
Comfort heating can be integrated with any area of the car to support interior heating, providing a premium customer experience. It also ensures the passenger is heated efficiently, therefore not wasting any energy heating areas of the car where the passenger is not situated. This is a crucial component in conserving energy in electric vehicles.
Active safety features within cars are those that attempt to prevent and mitigate collisions. LED tail-lighting systems now come with a much larger segment range, meaning more light-emitting options. Flashing, colour options and communication design can enhance these vehicles to alert other drivers and pedestrians when a car is turning, or when a car gets too close behind.
When passengers enter the cold vehicle, the comfort heating provides a pleasant temperature within minutes. PTC inks prevent overheating and other damage due to high temperatures, which makes them a sound choice in automotive interiors. The heater materials and heating element will impact the temperature range, so choosing an application-specific heating system is pertinent.
Although printed electronics have existed for some time, these automotive applications are relatively new. Working with esteemed automotive suppliers ensures your product solutions are tried and tested, and adhere to the strict automotive requirements and specifications.
ALT Technologies not only works day in and day out with these stringent demands, but we also have a combined 50 years’ worth of experience in the printing industry. Our knowledge of various substrates, inks and adhesive materials, printing processes and die-cutting, allows us to make light and heat product-driven decisions. In addition, our experience with curing, flexo screen printing, silver inks, resin and powders enables us to choose the correct printed electronics functioning.
Our teams constantly research materials that best upgrade and suit our customers’ applications. If you would like to learn more about these materials, processes or how we can work together on heating and lighting printed electronics, please contact us today.
Stay tuned for the next in our series of printed electronics articles on automotive sensors.
