A multilayer flexible printed circuit board (ML-FPCB) is a circuit board composed of alternating layers of flexible substrates and conductive layers, characterized by its thinness, flexibility, and high-density wiring.
Number of Layers: Typically 2-12 layers, high-end products can have over 20 layers, with interlayer thickness controllable between 0.05-0.2mm.
Materials: The substrate must be heat-resistant (e.g., PI with a temperature resistance of over 260°C), resistant to chemical corrosion, and the copper foil purity must be ≥99.8% (commonly rolled copper or electrolytic copper).
Process: Utilizing precision technologies such as laser drilling (minimum hole diameter 50μm) and vacuum lamination (pressure 0.5-1.5MPa) to ensure interlayer alignment accuracy (within ±25μm).