What Is Polyimide Tape? — Kapton™ Alternatives, What They Cost & What to Buy
It's the amber tape on almost every circuit board line: it masks gold fingers through wave solder and HASL and insulates coils to Class H. Here's what polyimide tape is, how it differs from "Kapton tape", what the two grades we stock publish, what they cost, and which one to buy.
Polyimide tape is a thin, heat-resistant tape made from polyimide film coated with a high-temperature silicone adhesive. The film is usually transparent amber or gold. It's often called "Kapton tape" after DuPont's Kapton™ polyimide film, but Kapton™ is a DuPont trademark, not a type of tape. KPT-1 and KPT-2 from Adhesive Tape Products are Kapton™ alternative polyimide tapes. They do the same jobs: they mask gold contacts from molten solder, hold up to 392°F (200°C) for 30 minutes, and insulate coils and transformers to Class H.
Ready to order? Both grades come in 1″ and 2″ x 36 yd rolls, sold by the pack or case.
Shop KPT-1 → Shop KPT-2 →How polyimide tape works
A polyimide tape has two layers: a polyimide film backing and a silicone adhesive. Each layer does a different job:
Polyimide film keeps its strength at soldering temperatures and is a strong electrical insulator. Film thickness affects electrical insulation and mechanical performance. Both KPT grades have the same published temperature rating.
A high-temperature silicone adhesive holds through the heat cycle. The KPT data sheets state it thermosets during processing, so adhesion increases in process, and removes with minimal residue.
Is polyimide tape the same as Kapton tape?
"Kapton tape" is what most people call polyimide tape, in the same way people say Band-Aid for an adhesive bandage. Kapton™ is DuPont's trademark for its polyimide film. Tapes made with other polyimide films, like KPT-1 and KPT-2, are Kapton™ alternatives: the same type of tape, used for the same jobs, but not DuPont products.
"Kapton tape" is a nickname, not a specification. If a drawing or work instruction names a specific product or spec, order to that callout.
Read the claims as written. The supplier states that the polyimide film meets UL 510 and that the adhesive is formulated to meet MIL-P-46112B. "Formulated to meet" is a supplier statement, not a MIL qualification certificate.
What polyimide tape is used for
The KPT-1 and KPT-2 data sheets list the same core applications:
Protecting gold contacts on circuit boards from molten solder during wave soldering. The transparent film lets operators see the board underneath.
Masking during hot air solder leveling. The tape leaves minimal residue on removal, which cuts cleanup and rejects.
General masking where very high temperatures are involved, up to 392°F (200°C) for 30 minutes.
Wrapping and fixing electronic components, coils and transformers. KPT-2 adds generators. Both are rated Class H insulation.
The KPT data sheets also list resistance to acids, oils, solvents, aging, staining and water immersion.
What the data sheets actually say
These figures are taken directly from the two Adhesive Tape Products data sheets. The supplier notes they are typical laboratory values, not specifications.
| Property | KPT-1 | KPT-2 |
|---|---|---|
| Film grade | Electrical grade | Commercial grade |
| Film thickness | 1.0 mil (0.025 mm) polyimide | 2.0 mil (0.050 mm) polyimide |
| Total tape thickness | 2.6 mil (0.065 mm) | 3.5 mil (0.090 mm) |
| Adhesive | Transparent high-temp silicone | Transparent high-temp silicone |
| Adhesion | 23.8 oz/in | 27.4 oz/in |
| Tensile strength | >20.6 lb/in | >36.5 lb/in |
| Elongation | >30% | >70% |
| Dielectric strength | >4000 V | >8000 V |
| Insulation class | Class H | Class H |
| Temperature resistance | 392°F (200°C) / 30 min | 392°F (200°C) / 30 min |
| Film color | Gold (transparent) | Amber (transparent) |
| UL 510 | ✓ Film meets | ✓ Film meets |
| MIL-P-46112B | Adhesive formulated to meet | Adhesive formulated to meet |
| Core | 3″ plastic | 3″ plastic |
| Stocked sizes | 1″ and 2″ x 36 yd | 1″ and 2″ x 36 yd |
| Data sheet | TDS (PDF) ↓ | TDS (PDF) ↓ |
Source: Adhesive Tape Products KPT-1 and KPT-2 product data sheets (ref. 1701VYANH01), plus the supplier's Kapton™ Alternative Polyimide Tapes catalog page. The data sheets state that test procedures follow ASTM and PSTC methods, but they don't name a method for each value, so none is shown here.
The number in the name is the film, not the tape. "1 mil" and "2 mil" refer to the polyimide film alone. With adhesive, KPT-1 is 2.6 mil total and KPT-2 is 3.5 mil total. If you're checking clearance under a connector or stack-up thickness, use the total.
How much does polyimide tape cost?
The supplier's minimum order is six 1″ rolls or three 2″ rolls per product, so we sell packs that meet it, plus full cases at a lower per-roll price.
Minimum purchase is six 1″ rolls or three 2″ rolls. Per-roll prices drop by the case.
| Product | 1″ x 36 yd | 2″ x 36 yd |
|---|---|---|
| KPT-1 | 6-roll pack $67.80 ($11.30/roll) Case of 36 $363.60 ($10.10/roll) | 3-roll pack $66.00 ($22.00/roll) Case of 24 $475.20 ($19.80/roll) |
| KPT-2 | 6-roll pack $103.80 ($17.30/roll) Case of 36 $558.00 ($15.50/roll) | 3-roll pack $101.10 ($33.70/roll) Case of 24 $727.20 ($30.30/roll) |
Prices update automatically from each product page. Widths from 1/4″ to 4″ and jumbo logs are available on request. Lead time is typically 1–2 weeks.
KPT-1 or KPT-2: which should you buy?
Both use high-temperature silicone adhesive and carry the same 392°F / 30 minute rating. The difference is the film. KPT-2 has higher published dielectric, tensile and elongation values. KPT-1 is thinner overall (2.6 mil vs 3.5 mil), which helps with tight clearances.
Take KPT-1 for fine masking and tight clearances, anywhere total thickness matters. It's 2.6 mil total and the lower-cost grade. Take KPT-2 when you need more than 4000 V of dielectric strength, a tape that survives more handling, or the stretch (>70%) to wrap irregular windings. If your work instruction names a thickness or dielectric value, that decides it.
Cross-reference: what KPT-1 and KPT-2 replace
The supplier's catalog lists these tapes as alternatives. Find the part number from your old order:
| Brand | Part number | Skytapes alternative |
|---|---|---|
| 3M | 5419 | KPT-1 1 mil |
| 3M | 5433 | KPT-1 1 mil |
| American | 304-2 | KPT-2 2 mil |
| Anchor | K-350 | KPT-2 2 mil |
| Berry Global | 2345-2 | KPT-2 2 mil |
| Chemfab | 360-1S | KPT-1 1 mil |
| Dewal | 304-1 | KPT-1 1 mil |
| Dewal | 303-2 | KPT-2 2 mil |
| Dielectric Polymer | NT-590 | KPT-1 1 mil |
| Electro Tape | 95-2 | KPT-2 2 mil |
| Ideal | 9321 | KPT-1 1 mil |
| Ideal | IT-7170 | KPT-1 1 mil |
| Ideal | 9322 | KPT-2 2 mil |
| Lanmar | 595-1 | KPT-1 1 mil |
| Permacel | P-221 | KPT-1 1 mil |
| Permacel | P-222 | KPT-2 2 mil |
| Saint-Gobain / Furon | 2345-1 | KPT-1 1 mil |
| Scapa | 557 | KPT-1 1 mil |
| Shurtape | 6325-01 | KPT-1 1 mil |
| Specialty Tapes | S2210 | KPT-1 1 mil |
| T&F | 3903 | KPT-2 2 mil |
| Taconic | 6325-02 | KPT-2 2 mil |
| tesa | 4428 | KPT-1 1 mil |
| tesa | 4429 | KPT-2 2 mil |
| TLC | CT961 | KPT-1 1 mil |
A cross-reference is a starting point, not a substitution approval. It identifies a tape in the same class. If your process is qualified to a specific part number, check thickness, dielectric strength and temperature rating against that product's data sheet, and get your engineer's approval before switching.
Frequently asked questions
What is polyimide tape?
Polyimide tape is a thin, heat-resistant tape made from polyimide film coated with a high-temperature silicone adhesive, usually transparent amber or gold. It's used to mask circuit boards during wave soldering and hot air solder leveling, and to insulate electronic components, coils and transformers.
Is polyimide tape the same as Kapton tape?
"Kapton tape" is the common nickname for polyimide tape. Kapton™ is DuPont's trademark for its polyimide film. KPT-1 and KPT-2 are Kapton™ alternatives: polyimide film tapes with silicone adhesive, used for the same jobs, but not DuPont products.
What is polyimide tape used for?
Mainly for masking gold contacts on circuit boards during wave soldering and hot air solder leveling, high-temperature masking up to 392°F (200°C) for 30 minutes, and wrapping and insulating electronic components, coils and transformers to Class H.
What is the difference between KPT-1 and KPT-2?
KPT-1 has a 1 mil gold electrical-grade film (2.6 mil total tape thickness, more than 4000 V dielectric). KPT-2 has a 2 mil amber commercial-grade film (3.5 mil total, more than 8000 V) with higher tensile strength and elongation. Both use high-temperature silicone adhesive and share the same 392°F rating.
How hot can polyimide tape go?
Both KPT-1 and KPT-2 are rated to 392°F (200°C) for 30 minutes. Longer exposures or higher temperatures are outside the published rating, so test first if your process runs hotter or longer.
Does polyimide tape leave residue?
The data sheets state the tape leaves minimal residue when removed after processing. The silicone adhesive thermosets during the heat cycle, which raises adhesion while the board is in process.
Do KPT-1 and KPT-2 meet UL 510 and MIL-P-46112B?
The supplier states that the polyimide film meets UL 510 and that the adhesive is formulated to meet MIL-P-46112B. That is a formulation statement, not a MIL qualification certificate. A free Certificate of Conformance is included with every order; it is not a MIL-P-46112B qualification certificate.
What is the minimum order?
The supplier's minimum is six 1-inch rolls or three 2-inch rolls per product, so we sell 1-inch in 6-roll packs and 2-inch in 3-roll packs, or by the case. Other widths from 1/4 inch to 4 inches are available on request. Lead time is typically 1 to 2 weeks.
What tapes do KPT-1 and KPT-2 replace?
The supplier lists KPT-1 as an alternative to tapes including 3M 5419, Permacel P-221, Shurtape 6325-01, Saint-Gobain 2345-1 and tesa 4428, and KPT-2 as an alternative to Permacel P-222, Berry Global 2345-2, Taconic 6325-02 and tesa 4429. The full lists are in the cross-reference table above. Confirm against your process before substituting.
Need polyimide tape for your line?
Tell us the width, quantity and any thickness or dielectric value your work instruction calls for. We'll confirm the right grade, lead time and pricing. A free Certificate of Conformance comes with every order.
Request a Quote →This guide is provided for general informational purposes. Performance figures come from the Adhesive Tape Products KPT-1 and KPT-2 product data sheets. Those sheets are the controlling source, and they state that the values are typical laboratory results, not specifications. Prices shown are pulled from each product page; the price in your cart is the controlling price. A cross-reference identifies a potentially matching product and does not constitute a substitution approval. Always verify suitability for your process against the controlling drawing or work instruction and the current data sheet. Kapton™ is a trademark of DuPont; KPT-1 and KPT-2 are not DuPont products. 3M, Permacel, Shurtape, Scapa, Saint-Gobain, tesa, Berry Global and other names are trademarks of their respective owners and are used for identification only.