For flexible printed circuit fabrication, selecting the right substrate directly determines yield, thermal cycling life, and signal integrity. Our company operates as a specialized polyimide sheet manufacturer with in-house resin synthesis, casting, and slitting capabilities. The resulting polyimide sheet for flexible printed circuit exhibits a glass transition temperature above 360°C, which prevents sudden softening during lead-free reflow. In multilayer FPC stacks, the same base film functions as a polyimide sheet for high temperature insulation, isolating copper traces from heat-generating components without adding excessive thickness. Downstream applications include semiconductor test sockets and probe cards, where the product is supplied as a PI sheet for semiconductor handling with ultra-low ionic contamination. For rigid-flex designs or backplane stiffeners, we offer a polyimide plate heat resistant variant that retains the same electrical and mechanical properties in thicknesses from 0.5 mm to 50 mm. Every lot ships with a certificate of analysis covering dimensional tolerances, dielectric strength, and moisture content.
The PI Sheet for Flexible Printed Circuit is produced by casting a fully imidized polyamic acid solution onto a precision drum, then drying and curing in a class 10,000 cleanroom. This solvent-cast process eliminates pinholes and ensures isotropic mechanical properties in the machine and transverse directions. The base film is available in three surface finishes—gloss, matte, and corona-treated—to match different adhesive systems and direct metallization processes. The following list summarizes the main product configurations, and the table below provides the core electrical, thermal, and mechanical values used for design verification.
| Property | Test Method | Typical Value | Unit |
|---|---|---|---|
| Dielectric constant at 1 MHz | ASTM D150 | 3.4 | – |
| Dissipation factor at 1 MHz | ASTM D150 | 0.0020 | – |
| Volume resistivity | ASTM D257 | >10¹⁶ | Ω·cm |
| Surface resistivity | ASTM D257 | >10¹⁶ | Ω/sq |
| Dielectric strength (25 μm) | ASTM D149 | 220 | kV/mm |
| Tensile strength (MD/TD) | ASTM D882 | 165 / 145 | MPa |
| Elongation at break (MD/TD) | ASTM D882 | 55 / 75 | % |
| Young's modulus | ASTM D882 | 2.5 | GPa |
| Coefficient of thermal expansion (20–150°C) | TMA | 12 | ppm/°C |
| Glass transition temperature | DSC | 360 | °C |
| Moisture absorption (24 h, 23°C) | ASTM D570 | <0.8 | % |
| Thermal conductivity | ASTM E1530 | 0.12 | W/m·K |
| Oxygen index | ASTM D2863 | 46 | % |
For high-volume flexible printed circuit production, this polyimide sheet is available in both roll and sheet formats with custom slitting, sheeting, and surface treatment options. Vacuum-sealed packaging with desiccant ensures zero moisture uptake during transit. Material certificates include UL 94 V-0, IPC-4204/11 compliance for flexible base dielectrics, and RoHS/REACH declarations. Engineering samples are supplied with a full dimensional report, including thickness mapping across the web. Standard lead time for slit rolls is 7–10 business days from stock, while custom thicknesses or plasma-treated surfaces typically ship within 3–4 weeks. The film can be further processed by adhesive lamination, electroless copper plating, or direct bonding to polyimide stiffeners. For designers working on dynamic flex applications, the material provides excellent flexural endurance: after 10 million cycles at a 2.5 mm bend radius, no cracking or significant loss in insulation resistance is observed. This durability makes it suitable for foldable device hinges, drone gimbal cables, and industrial robotics where repeated motion is unavoidable. Technical support includes finite element analysis of bend profiles and dielectric layer stack-ups, helping OEMs reduce design iterations and accelerate time-to-market.
