Circular Kapton Heater — Polyimide Etched-Foil

A circular Kapton heater brings even heat to round parts that have no room for a conventional heater — discs, end caps, optical components, valve bodies and cylindrical sensor housings. The element is an etched metal foil sealed between two layers of polyimide film, shaped to the diameter so it warms the whole face uniformly and reaches temperature in seconds without adding bulk.

Because the foil carries the heat and the film stores almost none, the heater follows a controller closely, and the polyimide outgasses very little — the two properties that put these heaters into vacuum chambers, clean tools and sealed assemblies.

Purpose — Even heat on a round face, with nothing to spare

Round components are awkward to heat evenly, and many cannot take a conventional heater: there is no clearance, the added thermal mass would slow the response, or a bulkier heater would outgas into a vacuum or contaminate a clean step. Left unheated, optics fog, sensors drift in the cold, and temperature-sensitive parts sit out of spec.

A round polyimide film heater removes that compromise. At 0.2 to 0.3 mm it disappears against the face of the part, spreads heat evenly across the disc, and stays clean enough for the most sensitive environments.

How it works in practice

The self-adhesive version is pressed onto a clean, flat or single-curve round face; the plain version is held in place by a clamp or fixture. The heater runs from a 12 V DC supply sized to the load, controlled by a thermostat or controller reading a sensor. The thermostat measures the temperature of the foil itself, not of the part, so a heater that is well bonded runs safely while a poorly bonded one can overheat at the same setting.

Key features

• Round etched-foil element in polyimide (Kapton) film, 0.2 to 0.3 mm — even heat on a disc where a thicker heater cannot fit
• Very low outgassing, CVCM 0.02% to ASTM E595 — works in vacuum and clean processes without filming nearby surfaces
• Silicone-free construction — safe on processes that silicone would spoil, such as paint preparation, optics and electronics
• 12 V DC, SELV — no shock hazard and no electrical approval needed on the element, suitable in wet, laboratory and medical settings
• Two power levels per diameter — gentle holding and anti-condensation, or faster warm-up against a heat path
• Self-adhesive or plain backing — bonded mounting to about 180 °C, or clamped mounting to 200 °C

Certification & Approvals

• Outgassing tested to ASTM E595: CVCM 0.02%, TML 1.54%, WVR 0.64%
• 12 V DC — SELV (safety extra-low voltage); no electrical certification required on the element

The standard range is not offered with UL or VDE recognition; a UL-recognised polyimide construction is a custom build.

Technical Specifications

• Material: polyimide (Kapton) film, encapsulated etched-foil element
• Voltage: 12 V DC
• Operating temperature: −40 to +200 °C (film)
• Mounting temperature: self-adhesive to about 180 °C, plain to 200 °C
• Thickness: 0.2 mm plain, 0.3 mm self-adhesive
• Maximum surface loading: 0.8 W/cm² in open air
• Leads: 0.3 m, 22 AWG
• Outgassing (ASTM E595): CVCM 0.02%, TML 1.54%, WVR 0.64%
• Backing options: self-adhesive (low-outgassing 3M PSA) or plain, non-adhesive
• Diameters and power: Ø 50 mm (2 or 12 W); Ø 75 mm (4 or 26.5 W)

Applications

• Optical components, mirrors and lenses needing even, low-mass heat
• Cylindrical sensor and valve bodies, end caps and discs
• Semiconductor and vacuum-process tooling
• Laboratory instruments and medical devices
• Anti-condensation and defrost on cameras, sensors and optics
• Battery and pack warming for round cells and modules

Operational Requirements

• Requires a 12 V DC supply sized to the load and a thermostat or controller with a sensor — the heater does not self-regulate
• Flexible but not elastic — apply to flat or single-curve faces only; never force onto compound or spherical shapes or the foil circuit will crack
• Self-adhesive backing is rated to about 180 °C; above that, clamp the plain version between plates with a thin (about 0.5 mm) silicone buffer
• Not intended for continuous immersion — moisture eventually enters at the laminated edges
• Bond the heater well to its surface; high surface loading without a heat path will overheat the element

Selection guidance

Choose the lower power for gentle, even warming such as anti-condensation or holding a temperature, and the higher power for faster warm-up where the heat is carried away into a substrate. Pick self-adhesive for mounting up to about 180 °C, or plain when the surface runs hotter and the heater is clamped in place. If you need higher watt density with the heat path designed in, temperatures toward 260 °C, mains voltage at 115 or 230 V, a bespoke shape, or an integrated sensor, request a custom heater. To compare with the rectangular version and the wider range, see our Kapton heater category.