Polyimide (widely known by the DuPont trade name Kapton) and PTFE-glass cloth tape sit at the top of the high-temperature tape hierarchy. Both belong to the roughly 260°C service class, both typically carry silicone adhesives, and both far outlast PET (~120–220°C) or PVC (~60–80°C) backings under sustained heat. That overlap leads many buyers to treat them as interchangeable — and they are not.
The backings do fundamentally different work. Polyimide is an engineered film prized for dielectric strength in an extremely thin profile, which is why it dominates electronics assembly. PTFE-glass is a woven fiberglass fabric coated with PTFE, valued for its non-stick, low-friction surface and mechanical durability on production equipment. A quick rule before reading further: if the job involves insulating or masking electronics, look at polyimide; if it involves releasing, sliding, or heat sealing, look at PTFE-glass. For the broader selection framework, see our guide on how to choose high-temperature tape.
Polyimide tape uses a film backing typically 1–2 mil (25–50 µm) thick that withstands roughly 260°C in continuous service, with short excursions toward 300°C — enough to ride through lead-free solder reflow profiles without melting, shrinking, or charring. Despite that thinness, polyimide film delivers high dielectric strength per unit of thickness, making it a standard material for Class H electrical insulation work. We cover the time-temperature behavior in more detail in our Kapton tape temperature rating article.
Typical applications follow directly from those properties: masking gold fingers and plated contacts during SMT reflow and wave soldering, wrapping transformer coils and motor windings, insulating layers inside lithium battery packs, and securing thermocouples during thermal testing. The thin film conforms tightly around small components and fine wires, and the silicone adhesive releases cleanly after the heat cycle — no baked-on residue to scrub off a finished PCB.
The trade-off is cost relative to need. Polyimide film commands a premium over polyester, so specifying it for processes that never exceed roughly 150–200°C wastes budget; a PET-based or mylar tape often covers that range. Polyimide also offers no release function — hot plastics and adhesives will stick to it — which is exactly where PTFE-glass takes over.
PTFE-glass tape starts with woven fiberglass cloth — related in construction to fiberglass thermal tape — that is impregnated and coated with PTFE (polytetrafluoroethylene). The fiberglass core provides dimensional stability and tensile strength under repeated mechanical load; the PTFE coating provides one of the lowest coefficients of friction of any solid material and a surface that almost nothing bonds to. Continuous service sits around 260°C, matching polyimide's class.
Those properties make it the default covering for heat-sealing equipment: impulse sealer jaws, L-bar and band sealers, vacuum packaging machines, and blister-pack tooling. Molten polyethylene film presses against the hot bar, seals the package, and peels away without sticking. Beyond sealing, PTFE-glass lines laminating platens, guide rails, chutes, and hoppers wherever hot or tacky material must slide instead of accumulate, and it survives thousands of compression cycles that would wear through a thin film tape.
Its limitations mirror polyimide's strengths. At typical thicknesses of several mils, PTFE-glass cloth is too bulky and stiff to wrap fine wires or mask small pads, and it is rarely the right answer for thin-gap electrical insulation even though PTFE itself is an excellent dielectric. It is equipment tape, not electronics tape.
Backing chemistry sets the temperature ceiling, but the adhesive usually fails first if mismatched. Both tape families are most often coated with silicone pressure-sensitive adhesive — the common adhesive class that maintains tack above 200°C and removes cleanly afterward, without the carbonized residue that rubber or standard acrylic systems leave behind. Acrylic adhesives excel at UV and aging resistance for long outdoor service, and rubber adhesives offer high initial tack at low cost, but neither is built for sustained 260°C exposure. Our acrylic vs rubber adhesive comparison breaks this down further.
When comparing datasheets, check that peel adhesion values reference ASTM D3330 under matching conditions, since results from different methods are not comparable. Note that PTFE-glass tape is also sold adhesive-free, as a mechanically clamped cover for sealing bars — a useful option where adhesive transfer onto product is unacceptable. For electronics supply chains, request current RoHS and REACH documentation for the specific grade, not just the product family.
Work through four questions. First, function: does the tape need to insulate and mask (polyimide) or release and reduce friction (PTFE-glass)? Second, geometry: tight radii, fine wires, and small masking areas demand a thin conformable film; flat bars and large surfaces tolerate — and benefit from — heavier cloth. Third, thermal profile: distinguish continuous operating temperature from short peaks like a reflow cycle, since ratings differ. Fourth, removal: if the tape comes off after each cycle, clean silicone-adhesive release matters; if it stays installed for months on a sealer bar, abrasion life matters more.
Many production lines legitimately use both — polyimide on the boards moving through reflow, PTFE-glass on the packaging sealers at the end of the line. And where neither thickness nor format fits off the shelf, custom slitting and die-cutting into discs, frames, or masking dots usually closes the gap more economically than over-specifying a roll.
HONGFU manufactures the full 260°C-class range discussed here, including polyimide (Kapton-type) tape and PTFE-glass and other high-temperature tapes, with RoHS/REACH documentation, custom widths, log rolls, and precision die-cutting for masking dots and gaskets. For datasheets, samples, or a quotation against your thermal and dimensional requirements, send an inquiry with your application details.
| Property | Polyimide (Kapton) Tape | PTFE-Glass Cloth Tape |
|---|---|---|
| Continuous service temperature | ~260°C, short excursions toward ~300°C | ~260°C continuous |
| Backing | Thin polyimide film, typically 1–2 mil (25–50 µm) | Woven fiberglass impregnated with PTFE; noticeably thicker and stiffer |
| Key property | High dielectric strength in a very thin profile | Non-stick, low-friction release surface |
| Typical adhesive | Silicone (clean removal after heat exposure) | Silicone, or supplied adhesive-free as a wrap/cover |
| Conformability | Excellent; wraps fine wires, small components, tight radii | Limited; suits flat bars, platens, and large surfaces |
| Primary applications | SMT reflow masking, gold-finger protection, coil and transformer insulation, battery wrapping | Heat-sealing jaws, laminating platens, chute and guide lining, release surfaces |
| Electrical use | Core application (Class H insulation work) | Secondary; bulk limits use in tight electrical gaps |
| Relative cost basis | Priced per area of thin film; economical for masking dots and strips | Higher per square meter, but long service life on sealing equipment |
Usually not. Both survive reflow temperatures, but PTFE-glass cloth is far thicker and stiffer than 1–2 mil polyimide film, so it cannot conform tightly around gold fingers, connectors, or small components. The non-stick PTFE surface also resists marking and handling. For PCB masking, polyimide tape remains the standard choice.
PTFE-glass cloth tape. Its woven fiberglass core resists the repeated mechanical pressure of sealing jaws, and the PTFE surface prevents molten packaging film from sticking. Polyimide film would survive the temperature but offers no release function and wears faster under repeated mechanical sealing cycles.
Typically yes — silicone pressure-sensitive adhesive is the usual choice for both, because it is the common adhesive family that maintains tack in the 200°C+ range and removes cleanly afterward. Acrylic versions exist for lower-temperature jobs where UV and aging resistance matter more than peak heat.
Confirm both datasheets reference the same method — ASTM D3330 (180° peel on stainless steel) is the common standard — and the same dwell time and substrate. Values reported under different methods or angles are not directly comparable, so request test conditions in writing when qualifying a new supplier.
They can be, but compliance depends on the specific adhesive formulation and any flame-retardant additives, not just the backing. Reputable manufacturers supply RoHS and REACH declarations per product. For electronics assembly, also ask whether a halogen-free grade is available if your customer specifications require it.
HONGFU manufactures 59 categories of industrial tape, factory-direct with custom die-cutting.
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