Refined manufacturing processes are the direct guarantee for FPCs to achieve high-density interconnect (HDI) and miniaturization. Current technological breakthroughs are mainly reflected in circuit forming, high-density assembly, and special application processes.

• Precision Circuit Fabrication: Utilizing 405nm ultraviolet laser direct imaging (LDI) technology, combined with a vacuum adsorption platform, linewidth/spacing at the 25μm level can now be stably achieved, significantly improving accuracy compared to traditional exposure processes. In the etching stage, by optimizing the etchant formulation and process parameters, the etching factor can exceed 4:1, effectively preventing over-etching or lateral etching of micro-circuits.

• High-Density Interconnect Technology: To meet the demands of advanced packaging for high-density, three-dimensional wiring, new assembly methods are constantly emerging. For example, an innovative "flux-free FPC flexible cable processing and assembly method," combining ball bonding and FPC processes, can reduce the minimum pad size to 0.2mm and the finest line width and spacing to 0.1mm, achieving high-density, flexible interconnection between different carrier boards and breaking through the spatial and flexibility limitations of traditional wire bonding and connectors.

• Specific scenario process optimization: For areas with extremely high dynamic bending requirements, such as the hinge area of foldable screen phones, rolled copper foil with an elongation exceeding 30% is used, along with a laser-precision windowed cover film with an accuracy of ±5μm, to minimize stress concentration. For high-frequency applications such as 5G millimeter-wave antennas, ultra-smooth electrolytic copper foil with a surface roughness (Ra) ≤0.1μm is required to reduce signal transmission loss.