PET vs PI Tape for Transformer Winding | Insulation Guide

PET and PI adhesive tapes are both used in electrical insulation applications, including selected small and high-frequency transformer designs. However, they have different material properties and are not interchangeable in every application.

PET tape uses a polyester film backing, while PI tape uses a polyimide film backing. The best choice depends on the transformer's operating conditions, insulation requirements, available space, adhesive compatibility, and cost targets.

For many applications, PET tape is a practical option when its verified performance meets the design requirements. PI tape may be considered when the application requires a different thermal performance profile.

The decision should be based on the complete tape construction—not simply the backing film name.

These are general material-selection guidelines. Actual performance varies with film grade, adhesive type, total thickness, tape structure, and test conditions.

PET tape is worth evaluating when its mechanical, electrical, and thermal properties meet the requirements of the transformer design.

PET tape may be used between winding layers or in other suitable insulation positions. The required thickness and width depend on the winding design and electrical requirements.

PET tape can be used for outer wrapping in suitable transformer applications, helping provide an insulating layer around the winding assembly.

For automatic winding machines, the roll's width consistency, edge quality, winding density, and unwinding behavior are important considerations.

A tape with suitable material properties may still cause production problems if the roll is unevenly wound or incompatible with the machine.

Where PET tape meets the design and safety requirements, it may offer a practical balance between performance and material cost. The decision should be made using the specifications of the actual tape rather than general assumptions about all PET products.

PI tape may be appropriate when the application requires a different thermal performance profile or when the transformer design specifies polyimide film.

Polyimide film is known for its thermal stability. However, the operating temperature of the finished adhesive tape also depends on its adhesive system and construction.

Check the technical data for the specific PI tape, including the stated temperature conditions and any relevant test limitations.

PI tape may be considered for applications with defined electrical insulation requirements. Dielectric strength depends on film thickness, material quality, adhesive construction, and test conditions.

Do not assume that PI tape always provides a higher breakdown voltage than PET tape of the same nominal thickness. Compare actual product test data when dielectric performance is critical.

Some designs require a multilayer tape construction. For example, a double-layer PI tape may be considered when a single-layer construction does not meet the customer's electrical requirements.

In such cases, the complete structure—including the film layers, adhesive between layers, and bonding adhesive—must be evaluated as one system.

Choosing PET or PI is only the first step. Several other factors affect the tape's suitability for transformer winding.

Total thickness includes the film backing and adhesive layer. In multilayer constructions, all relevant layers contribute to the overall thickness.

A thicker tape is not automatically better. The selected thickness must meet the insulation requirements while fitting the available space in the winding design.

The adhesive should bond appropriately to the intended surface and perform under the expected operating conditions.

Depending on the application, consider initial tack, peel adhesion, holding performance, residue behavior, and temperature exposure.

The tape width should match the winding design and the machine's requirements. Narrow-width applications may require closer attention to slitting accuracy and edge quality.

For automated winding, roll flatness, winding consistency, and stable unwinding can affect production efficiency.

When comparing suppliers, evaluate the finished roll—not just the adhesive tape's material specification.

For small and high-frequency transformers, a practical selection process should begin with the actual winding design.

Step 1: Define the application. Identify whether the tape is used for layer insulation, outer wrapping, margin insulation, or another function.

Step 2: Confirm the electrical requirements. Determine the required insulation performance and any applicable product or safety standards.

Step 3: Confirm the thermal conditions. Consider the expected operating temperature and exposure duration. Verify that the complete tape construction is suitable.

Step 4: Select the material and thickness. Compare available PET and PI products against the design requirements, including adhesive compatibility.

Step 5: Confirm roll specifications. Specify width, width tolerance, length, core size, and any special requirements for winding consistency.

Step 6: Validate the tape in production. For automatic winding, test feeding, tracking, unwinding, and application performance under representative operating conditions.

This approach helps avoid choosing tape based on material names alone.

Changshu Liangyi Tape Industrial Co., Ltd. supplies PET/Mylar tape, PI/Kapton tape, and other adhesive tape materials for electrical and industrial applications.

Our manufacturing processes include adhesive coating, rewinding, and slitting. Depending on the product and order requirements, customers can discuss customized tape widths, thicknesses, lengths, colors, and roll specifications.

For transformer winding applications, we recommend sharing the tape's intended function, operating conditions, required dimensions, and electrical performance criteria. This information helps identify which available material constructions should be evaluated.

We also recommend confirming any critical roll-quality requirements for automatic winding, such as width tolerance, winding consistency, and unwinding behavior.

PET tape can be suitable for many transformer applications when the specific tape construction meets the design's electrical, thermal, and mechanical requirements. The final selection should be based on verified product specifications.

No. PI and PET have different properties and cost considerations. The better choice depends on the application requirements and the performance of the actual tape construction.

Breakdown voltage depends on film thickness, material properties, adhesive layers, construction, and test conditions. Compare verified test data for the specific products rather than assuming one material always performs better.

Custom slitting may be available depending on the product, required width, tolerance, and order quantity. Confirm the specifications with the supplier.

Provide the tape material, thickness, width, roll length, core size, intended application, and any required electrical or thermal performance criteria. If the tape is used on an automatic winding machine, also specify any special roll-quality requirements.

Looking for PET or PI insulation tape for transformer winding?

Contact Liangyi Tape with your application details and required specifications. Our team can help review the material options and discuss suitable tape roll configurations for your production process.

Email: ftrade2@liangyitape.com
WhatsApp: +86 13338711561

Request a quotation for customized PET or PI insulation tape rolls.