Kapton is the brand name of reknowned polymer producer DuPont used for their Polyimide foils. As often the case with successful product pioneers Kapton achieved the status of the genere name why in large parts of the industry Kapton is used synonymously for Polyimide.
Kapton, respectively Polyimide flexible heaters can be operated up to 180 °C when attached by self-adhesive film (most common execution) and up to 200 °C when pressed to the object or surface to be heated.
In general, a Kapton film heater is always more expensive than a silicone heater or polyester heater. Where chemical resistance or the weight of the flexible heating element plays an important role, however, Kapton heaters are the ideal solution.
The resistance of Kapton Polyimide to fungi, bacteria, ozone, weather, ageing and most chemicals, acids and solvents is very good, so that heating elements made of Polyimide (Kapton) are an ideal solution for many critical applications. Kapton foil heaters are also silicone-free and are characterised by an even heat distribution. The dielectric strength of a Polyimide film is very high and so the flexible Kapton (Polyimide) heater can be very thin. Due to the small thickness, the heat transfer to the component is improved and higher surface loads are possible. Typical applications for Kapton film heaters are: Laboratory technology, aircraft electronics, printing technology, diagnostic instruments, vacuum chambers, medical equipment and many more.
In general, it is difficult to predict which temperature a Kapton heating element will reach in the application, as there are numerous influencing factors. These include not only the power or surface load, but also the mass and type of material to be heated (thermal conductivity, surface finish, etc.), the installation/mounting situation (glued, clamped, etc.), the ambient temperature, air currents and, of course, the control technology used.
As a rule of thumb: the lower the surface load on the heating foil, the longer the service life. We recommend a maximum surface load of 0.8 W/cm2 for a Kapton heating element.
Technical data for Kapton Polyimide Heaters vs. Silicone Heaters and Polyester Heaters
(up to 200°C)
|Flat Heating Elements
|Wire Wound||Etched Foil|
|* higher surface loads can be achieved, depending on the application, with very good heat consumption and fast control
(No warranty claims can be derived from this table)
|Continuous temperature resistance||-60 °C - 200 °C||-60 °C - 200 °C||-269 °C - 200 °C||-30 °C - 90 °C||350 °C||450 °C|
|Continuous temperature resistance with self adhesive foil||-60 °C - 180 °C||-60 °C - 180 °C||-60 °C - 180 °C||-30 °C - 90 °C||-||-|
|Short term temperature resistance||250 °C||200 °C||200 °C||100 °C||700 °C||900 °C|
|Recommended max. watt density*||0,8 W/cm²||0,8 W/cm²||0,8 W/cm²||0,2 W/cm²||4,0 W/cm²||5,0 W/cm²|
|Power tolerance||+5 / -10%||+5 / -10%||+5 / -10%||+/-10%||+5 / -10%||+5 / -10%|
|max. dimension||940 x 3000 mm||595 x 2500 mm||285 x 550 mm||1000 x 600 mm||2000 x 1000 mm||2000 x 1000 mm|
|min. dimension||30 x 30 mm||20 x 20 mm||25 x 25 mm||25 x 25 mm||30 x 30 mm||30 x 30 mm|
|min. height||1,1 - 3,0 mm||0,8 - 1,5 mm||0,2 mm||0,2 mm||2,0 mm
|Dimension tolerance||+/- 1 mm||+/- 1 mm||+/- 1 mm||+/- 1 mm||+/- 1 mm||+/- 1 mm|
|Quantities||from 1 piece||from 1 piece||from 1 piece||from 25 pieces||from 1 piece||from 1 piece|
|min. bend radius||5 mm||5 mm||2 mm||5 mm||-||-|
|Adhesive foil possible||yes||yes||yes||yes||no||no|
Geometry of Flexible Polyimide Film Heaters
For technical production reasons, the size of Kapton heaters is limited to a minimum of 25 x 25 mm and a maximum of 285 x 550 mm. The minimum thickness is 0.2 mm.
Within these dimensions practically any shape and contour is possible, round, angular, with cut-outs and holes. Even extremely small bending radii of min. 1 mm are possible with flexible Kapton heating foils. Towards the edge and cut-outs we need at least 10 mm insulation distance. If the space between two cut-outs is to be heated, their distance must therefore be larger than 20 mm.
Manufacturing Process of Flexible Kapton Foil heaters
Kapton resp. Polyimide heaters are, in contrast to silicone heaters, manufactured exclusively with etched resistance foil. Tooling costs are incurred with each new design. For pre-series or small quantities it is possible to use a temporary tool, which is cheaper, but not suitable for larger production quantities.
Mounting Options for Flexible Kapton (Polyimide) Heaters
95% of our Kapton heaters are supplied with self-adhesive foil. The subsequent application of an adhesive is not possible. Therefore, the only possibilities of attachment are by self-adhesive foil, which is already laminated on the Kapton-Polyimide foil in production, or by pressing the foil heater onto the surface to be heated.
- self-adhesive foil
- not removable
- good heat transfer
- temperature resistant up to 180 °C
- suitable for any shape and size
- download bonding instructions for flexible heaters here
Mounting Parts for Kapton (Polyimide) film heaters
In principle, as with silicone heaters, it is possible to use thermocouples or similar attachments. However, these would then have to be attached to the heater with silicone, which in turn is not permitted in many applications using Kapton-Polyimide heaters.
Leads for Flexible Kapton foil Heaters
Type, length and position of the supply lead can be freely selected. Please note that the connection area is always slightly higher than the rest of the heater. PTFE leads are most commonly used for Kapton heaters because they are thin, light and flexible. Silicone leads and glass fibre leads are also possible, but both are not silicone-free.
The length and type of the connecting leads can easily be changed for subsequent orders of an existing heater design. For a change of the connection position on the heater, however, a new tool must be created.
In principle, it is possible to provide the leads of Kapton flexible heating elements with a protective sleeve. However, fixing the sleeve with silicone would result in a significantly thicker termination area. This would eliminate two main advantages of Kapton heaters, their low installation height and their silicone-free design.
Also, the thermal protection plays only a minor role due to the comparatively low operating temperatures of Kapton (Polyimide) film heating elements. For mechanical protection, however, there are numerous alternatives available, from glass fibre sleeves to silicone sleeves and shrink sleeves.
Conformities & standards
Our Kapton heaters resp. Polyimide heaters are manufactured according to the strictest test criteria and fulfill all relevant standard requirements and safety specifications as far as these are applicable due to the nature of the product. You will find general organisation or product group related certificates of conformity in our download centre under Service > Quality. Product-specific confirmations are available on request.
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