Flexible Heaters for the Aerospace Industry
Flexible heaters are used in a multitude of industries to help control the temperature of products, assist with heating certain processes, and to remove moisture from components. For the aerospace industry, instrument panels, spacecraft, and satellites experience unique environmental challenges where heating components using convection methods is not always possible. Flexible heaters have become the ideal solution for the aerospace industry for a variety of reasons.
Understanding Kapton® Flexible Heaters
One of the commonly used flexible heater materials is Kapton®, a polyimide film material that was created by the DuPont company. The material remains stable when experiencing different types of temperatures. To create a Kapton® flexible heater, the polyimide film layers will have an etched foil element layer that is sandwiched in between the polyimide as an adhesive, such as FEP or acrylic, is used to adhere the layers together.
Kapton® flexible heaters can achieve temperatures of up to 392°F. In addition, it can also handle a low temperature threshold of -320°F. The watt density for this flexible heater can start at 2.5W/in2 and can go up to a possible 50W/in2 for certain applications. A Kapton® flexible heater can be attached using self-fusing tapes, pressure sensitive adhesive, or by using mechanical methods.
Advantages to Using Kapton® Flexible Heaters in the Aerospace Industry
The aerospace industry uses a multitude of components, parts and equipment for applications. From airplane instrument panels to communication equipment in unmanned spacecraft, these components and machines sometimes require the use of flexible heaters to keep parts from freezing in sub-zero temperatures, remove moisture from semiconductors and circuits, or provide thermal heat transfer solutions. Here are some reasons why aerospace manufacturers may select Kapton® flexible heaters when designing and manufacturing products and equipment.
Lightweight and Thin
Kapton® flexible heaters are very lightweight. They can come in a thinness of as low as 0.007", which is ideal for aerospace applications where any added weight could impact the way that an aircraft, drone, missile, or spacecraft operates to get into the air. With electronic components and controls becoming smaller, the thinness of a Kapton® flexible heater also plays an important factor.
These flexible heaters also have exceptional flexibility as the heater can be bent to handle a range of curves and irregular surfaces in the application. A Kapton® flexible heater can be made to be very small as its maximum allowable size is only 10X 70".
Low Outgassing Characteristics
Aerospace equipment will use sensors for a variety of purposes, from tracking an aircraft's movements to relaying vital information. These sensors can be highly delicate and susceptible to any types of gasses that can interfere with their operations. When creating parts and components used for sensors or will be located near sensors, aerospace manufacturers must be careful to select materials that will not give off any gasses caused by the heat or through regular wear-and-tear and aging.
A Kapton® flexible heater possesses very little gases in its molecular structure. So, there is very little outgassing from the materials when heated or during extended periods of time when not in use. This feature will ensure that sensors will work without issues.
Superior Thermal Heat Transfer in Vacuum Environments
In the aerospace industry, not all equipment will be used on Earth. Communication satellites, manned and unmanned spacecraft, and space launch equipment will be used out in space where there is no air available. Due to the lack of air in this harsh environment, space equipment will experience extremely cold temperatures that can harm components.
Heating this equipment can be a challenge in the vacuum of space as convection heating methods are not available. Instead, a Kapton® flexible heater is used to provide thermal heat transfer capabilities in these environments. With the Kapton® flexible heater directly attached to the component, the equipment and machinery can quickly receive the right temperature it needs to operate as the temperature is maintained for long periods of time or for intermittent use. In addition, Kapton® flexible heaters provide a uniform, even thermal heat transfer. There will be no uneven heating or scattered cold spots.
De-icing and Defogging Applications
Instrument panels, sensors, lens, and other equipment can experience moisture and humidity buildup along the surface. This moisture and humidity can fog up sensors and lens, creating issues with their operations. When combined with lower temperatures, moisture will freeze on electronic components. This freezing can cause components to crack and break apart when the frozen moisture expands. When the components warm up again due to outdoor temperatures, the ice melts away as the component can retract. This issue can cause more damage.
For de-icing and defogging applications, a Kapton® flexible heater is recommended as it is rugged and durable enough to withstand extreme temperatures, humidity, and moisture. The flexible polyimide heater can direct the right amount of heat to the sensor, lens, and electronics to dry up moisture and prevent fogging without causing damage to the equipment.
Won't Impede Moving Parts
Another advantage to the thinness and lightweight nature of Kapton® flexible heaters is when they are used around working parts. Some components have to move freely to perform specific functions, much like a mechanical robotic arm used to perform repairs to the outside of spacecraft and high orbit satellites when people cannot perform the work. These components must be able to move in the desired direction, while the electronic components need to be kept warm enough to function.
A Kapton® flexible heater provides thermal heat transfer while being thin enough to be placed around moving parts without impeding their movements. The polyimide resists abrasions and tearing as it can attach securely without the added worry of it being pulled off by the working components.
Radiation, Oil, and Chemical Resistance
Kapton® flexible heaters have excellent corrosion resistance. They will not rust or degrade when exposed to oil or chemicals. It is also resistant to fungus, which can grow in dark and warm environments that are located inside electronics and component housings where moisture penetration can be an ongoing issue. The material is inert to chemicals and oils, which also makes it ideal in aerospace applications where the presence of lubricants, oils, and chemicals will be in constant use to keep components operating efficiently.
Another interesting characteristic to a Kapton® flexible heater used in aerospace applications is its resistance to radiation. Ultraviolet radiation from the sun, and gamma radiation created from neutron stars, pulsars, and supernova explosions, will travel through space and the upper atmosphere. These types of radiation can impact manned and unmanned spacecraft, aircraft, and other applications. When using a Kapton® flexible heater, the polyimide materials resist the gamma and ultraviolet radiation, so the thermal management device continues to work efficiently. In addition, the Kapton® flexible heater also adds another layer of protection to a component from this radiation.
When to Use Kapton® Flexible Heaters for Aerospace Applications
There are many factors to take into consideration when deciding on the materials for your flexible heater. Evaluating the application itself and the needed requirements can help to drastically narrow down your choices. If your application will be in environments with extreme cold temperatures, oil, chemicals, radiation, and fluctuating humidity levels, then Kapton® flexible heaters will make a great choice.
Kapton® flexible heaters are also excellent choices when the aerospace application requires low gassing from its materials, a small and thin heater, excellent heat transfer options, and de-icing/defogging capabilities.
Keep in mind that Kapton® flexible heaters will have a maximum heat operating temperature of only 392°F. If you need higher temperature thresholds of 400°F to 550°F, then selecting a different material for the flexible heater would be appropriate, such as silicon rubber.
In addition, the space where the flexible heater will be placed, the types of attachments, and the size of the required heater will also dictate on whether a polyimide-based flexible heater can be used. If you need a very large heater, then a Kapton® flexible heater would not be appropriate as it has a size limitation. It can only be designed up to a size of 10X70". A silicon rubber flexible heater would need to be used. On the other hand, when there are space limitations where mechanical attachments cannot be used, then the self-adhesive and PEF adhesive attachments used with Kapton® flexible heaters can offer the right solutions.
Lastly, a manufacturer may also be looking for a flexible heater that adds additional protection and durability to the aerospace application along flat surfaces. Kapton® flexible heaters are usually reserved for surfaces that will have curves and bends. While the polyimide material is rugged and durable (it can possess double the tensile strength of fiberglass reinforced silicon), it doesn't offer the thickness that rubber silicone provides as rubber silicone can offer more dimensional stability to the application.
Reach Out to Epec for Flexible Heater Options
When you are looking for a flexible heater for aerospace applications, Kapton® flexible heaters are a great option for a variety of components and processes. Here at Epec, we can design and manufacture Kapton® flexible heaters for your electronics and electrical applications to meet your specifications. Contact us today to learn more about our engineering processes.