Polyimide (PI) PCB material is a special substrate material designed specifically for high-performance, high-reliability printed circuit boards (PCBs). Made of polyimide resin, its core characteristics lie in its excellent resistance to extreme high temperatures (typically operating stably above 260°C for extended periods) and outstanding thermal stability. It maintains excellent electrical insulation, high mechanical strength, and good chemical stability even under drastic temperature changes. This material is particularly suitable for manufacturing flexible printed circuit boards (FPCs) and rigid-flex boards, and is widely used in fields with extremely stringent requirements for heat resistance, dimensional stability, and reliability, such as aerospace, military electronics, automotive engine control units, and core components of high-end mobile devices.
Key Properties of Polyimide PCB Material:
Glass transition temperature (Tg) ranges from 250°C to 350°C, with some high-performance variants exceeding 400°C. It maintains stable operation in extreme environments from -269°C to 400°C and withstands short-term exposure above 500°C, making it ideal for aerospace engines and automotive engine peripherals.
Tensile strength reaches 100-300MPa, bending modulus 2-5GPa, combining high strength with flexibility. This supports foldable/curved designs for flexible electronics like foldable smartphones and wearable devices.
Volume resistivity is 10^16-10^18 Ω·cm, dielectric constant 3-4 (reduced to below 2.5 with fluorine or nano-air incorporation), and low dielectric loss (about 1×10^-3). These reduce signal interference and transmission loss, ensuring stability in high-frequency and high-speed circuits.
Resistant to acids, alkalis, and organic solvents, though not concentrated sulfuric/nitric acid or halogens. Suitable for corrosive environments like chemical monitoring and marine electronics.
Retains 90% strength after 5×10^9 rad fast electron irradiation and exhibits low outgassing in high vacuum. This meets radiation protection and thermal control needs for satellites and medical implants.
Low coefficient of thermal expansion (CTE) of 2×10^-5/°C to 3×10^-5/°C, with biphenyl-based variants as low as 1×10^-6/°C, close to metal CTE. This minimizes warpage under temperature fluctuations, ensuring precision in high-density interconnect (HDI) designs.
Self-extinguishing with low smoke emission and over 50% char yield, complying with UL-V0/V1 standards for enhanced electronic device safety.
Non-toxic and certified for biocompatibility in certain models, suitable for medical implants and reusable surgical instruments requiring repeated sterilization.
Below is a detailed selection guide for polyimide PCB material:
Prioritize materials with glass transition temperature (Tg) ≥250°C and thermal decomposition temperature (Td) ≥360°C, such as DuPont Kapton series (Tg>250°C) or Ube Upilex S type (Tg>280°C), to ensure stability during high-temperature soldering (peak 260°C) and long-term operation (200-300°C).
For high-frequency scenarios (e.g., 5G antennas), focus on dielectric constant (3.4-3.6@1GHz) and dissipation factor (<0.003). Adhesive-free Pyralux series is recommended (30% signal loss reduction). For high-voltage applications, ensure insulation resistance ≥10³MΩ.
Tensile strength >200MPa, bending radius <1mm, fatigue life >100,000 cycles, suitable for dynamic applications like flexible screens and wearables.
Select materials with radiation resistance >100kGy and dimensional stability <50ppm/℃, such as Tenghui VT-901 (ESA certified) or Kaneka Apical (resistant to liquid helium low temperatures), meeting extreme environment requirements for satellites and Mars rovers.
Prioritize metal-based PI composite boards (aluminum-based thermal conductivity >2W/mK, copper-based >5W/mK) or high-Tg polyimides, suitable for IGBT driver boards and battery management systems with thermal and vibration requirements.
Choose biocompatible transparent PI (e.g., Mitsubishi AURUM, light transmittance >88%) or Apical series, ensuring non-toxicity, corrosion resistance, and compliance with FDA/ISO 10993 standards.
UL-94 V0 (flame retardant), ASTM D5204 (space radiation), ISO 9001 (quality system). European customers should focus on ESA, MIL-STD-810G aerospace standards; Japanese market requires JIS C 6481 compliance.
IPC-4101E (substrate specifications), IPC-6011 (performance requirements), RoHS/REACH (environmental restrictions), ensuring material traceability and compliance.
Balance performance and cost by application. Adhesive-free Pyralux series, though higher in unit price, reduces signal loss and long-term costs. Metal-based composite boards lower system costs in thermal management scenarios.
Prioritize suppliers with overseas factories or long-term partnerships, such as DuPont and Toray-DuPont joint ventures (market share >60%), ensuring delivery cycles and after-sales support.
Materials must pass RoHS 2.0, REACH SVHC list, avoiding hazardous substances like lead and mercury. Recyclable designs (e.
