I. Key Parameters & Specifications
| Item | Typical Value |
|---|---|
| Base Material | Polyimide (PI) |
| Total Thickness | 0.05–0.12 mm (thin) |
| Layers | Single / Double |
| Copper Type | RA (rolled annealed) / ED |
| Copper Thickness | 1/3–1 oz (12–35μm) |
| Adhesive | Acrylic / Epoxy (or adhesive-free cast) |
| Min Trace/Space | 3/3–5/5 mil |
| Coverlay | PI coverlay + adhesive |
| Operating Temp. | −65 ~ +150°C (high temp) |
| Bend Radius | Dynamic ≥10× thickness; Static ≥3× |
| Flex Life | 10k–100k+ cycles (RA copper) |
| Surface Finish | ENIG / Immersion Gold / OSP |
| Dielectric Strength | ≥15 kV/mm |
II. Design Principle
- PI-based substrates offer high-temperature resistance, a low profile, and flexibility, making them suitable for 3D assembly in compact spaces.
- Rolled-annealed (RA) copper is used for dynamic flexing applications due to its superior flex life, while electro-deposited (ED) copper is suitable for static applications.
- Traces in the bending zone must run perpendicular to the axis of bending; vias, pads, and cutouts are prohibited in this area.
A PI coverlay protects the circuitry, with cutouts provided to expose the pads. - Adhesive-less (cast-type) constructions offer superior flexibility, making them ideal for high-flex applications.
III. Manufacturing Advantages
- Ultra-thin: Total thickness of 0.05–0.12 mm; space-saving and lightweight.
- High-temperature resistance: PI withstands long-term temperatures of −65°C to 150°C and is compatible with reflow soldering.
- High flexural endurance: RA copper combined with PI coverlay allows for tens of thousands to 100,000 dynamic bending cycles.
- 3D assembly: Foldable and rollable; serves as a replacement for wire harnesses and connectors.
- Vibration resistance: Flexible structure absorbs vibration, ensuring reliability and durability.
- Laser windowing: Laser-cut openings in the coverlay provide precise, burr-free edges.
IV. Signal & Electrical Performance
- Low dielectric constant (εr ≈ 3.3–3.5) and low signal loss.
- Suitable for medium-to-low speed signals, low-level analog signals, and power connections.
- Lacks a continuous ground plane on one side, limiting impedance control; coplanar lines are used when impedance matching is required.
- Not suitable for ultra-high-frequency or high-speed applications (specialized high-frequency materials are used for such scenarios).
- High insulation resistance and good voltage withstand capability ensure electrical safety and reliability.
Volectronics Tech Co., Ltd is a one-stop service provider for PCB and PCBA manufacturing, covering the entire production chain under one roof — from PCB design and fabrication to component sourcing, assembly, and functional testing.
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