is a high-density interconnect flexible circuit board that uses blind and buried hole technology, designed specifically for electronic devices with limited space and the need for high-frequency signal transmission. Its core features and technical specifications are as follows:
1, Core structural characteristics
Blind hole: Only connects the surface layer (top/bottom layer) with adjacent inner layers, with a precise depth control of 0.2-0.5mm and a minimum aperture of 0.1mm, avoiding penetration through the entire board to save wiring space.
Buried hole: completely hidden between inner layers, achieving interconnection between adjacent inner layers, with a pore size range of 0.08-0.2mm, freeing up surface space for component layout.
2, Key technical parameters
Minimum aperture: blind hole 0.1mm, buried hole 0.15mm.
Line width/spacing: minimum 30 μ m/30 μ m, supports high-precision signal transmission.
Layers: Supports flexible stacking of 1-12 layers, suitable for complex circuit design.
<0.5dB/inch (@ 10GHz), meeting the requirements of millimeter wave applications.
Material: Polyimide (PI) or Liquid Crystal Polymer (LCP), temperature resistance range -200 ℃~300 ℃, dielectric constant Dk <= 3.0.
3, Core manufacturing process
Laser drilling: UV laser (wavelength 355nm) precisely controls the depth with an error of<5 μ m.
FR-4 substrate requires 10W power/500ns pulse, PI substrate requires 15W power/300ns pulse.
Hole filling electroplating: Pulse electroplating technology, gradually increasing the current density from 1A/dm ² to 3A/dm ² to ensure that there are no gaps in the copper filling inside the hole.
<± 25 μ m, ensuring precise interconnection of multi-layer circuits
4, Application scenarios and advantages
Consumer Electronics: TWS Earphone Charging Case: Achieving 0.3mm Ultra Thin PCB Design.
Smart watch: 1-3 order blind hole stacking supports flexible circuits.
5G communication: 8-layer buried blind hole FPC solves the heat dissipation and signal attenuation of millimeter wave antenna modules, with a yield rate increased to 99.3%.
Industrial equipment: servo drive: buried hole isolation of high voltage and signal layer to reduce interference.
5, Design Challenges and Countermeasures
Signal integrity: Optimized wiring through 3D electromagnetic simulation to reduce 75% of residual stub effects.
Thermal management: Reduce the number of through holes to reduce thermal conduction interference and improve structural strength.