Polyimide (PI) tape, often marketed under well-known brands like Kapton®, is a high-performance adhesive tape valued for its thermal stability, electrical insulation, and chemical resistance. But what exactly should you look at when evaluating a PI tape? Let’s break down the key material specifications that matter for industrial applications.

1) Base Film Properties
The polyimide film is the heart of the tape. Its properties directly impact performance:
• Thickness: Typically 25μm (1 mil) to 50μm (2 mil), influencing flexibility, strength, and dielectric strength.
• Tensile Strength: Measures resistance to breaking under tension—important for mechanical durability.
• Elongation at Break: Indicates flexibility before snapping, crucial for wrapping or bending applications.

2) Adhesive Type and Performance
Polyimide tape is paired with high-temperature adhesives—commonly silicone or acrylic:
• Silicone adhesive: High heat resistance (up to 260°C), leaves minimal residue, excellent for PCB solder masking.
• Acrylic adhesive: Stronger initial tack, better chemical resistance, but slightly lower max temperature rating.
• Adhesion Strength: Measured in N/25mm—affects how securely the tape bonds to different surfaces.

3) Thermal Properties
• Continuous Temperature Rating: Typically -73°C to 260°C for standard PI tape; high-temp grades may reach 300°C.
• Short-Term Peak Temperature: The highest heat the tape can withstand for a brief period without damage.
• Thermal Class: Often Class H (180°C) or higher, based on insulation performance.

4) Electrical Properties
• Dielectric Strength: Usually >6 kV, indicating how well the tape insulates against electrical breakdown.
• Volume Resistivity: High resistivity ensures minimal current leakage—essential for electronic applications.

5) Chemical Resistance
Polyimide tape resists a broad range of chemicals:
• Solvents (IPA, acetone, MEK)
• Acids and alkalis
• Oils and flux residues
This makes it ideal for harsh industrial environments.

6) Dimensional Stability
• Shrinkage Rate: Affects precision in masking or alignment during high-temperature processing.
• Outgassing: Low outgassing is critical for aerospace, semiconductor, and cleanroom applications.

Conclusion
When selecting a polyimide tape, don’t just look at “high temperature resistance.” Key specifications—film thickness, adhesive type, dielectric strength, chemical resistance, and dimensional stability—determine how the tape performs in your specific application.
