Low fractal dimension modified drilling‐hole wall for PTFE high‐frequency board copper plating with plasma treatment

Fabrication of Cu Micromembrane as a Flexible Electrode

A Cu micromembrane is successfully fabricated and validated as a porous flexible electrode. The Cu micromembrane is prepared by functionalizing individual polypropylene (PP) fibers in a polypropylene micromembrane (PPMM) using a mixture of polydopamine (PDA) and polyethyleneimine (PEI). The mixture of PDA and PEI provides adhesive, wetting, and reducing functionalities that facilitate subsequent Ag activation and Cu electroless plating. Scanning electron microscopy reveals conformal deposition of Cu on individual PP fibers. Porometer analysis indicates that the porous nature of PPMM is properly maintained. The Cu micromembrane demonstrates impressive electrical conductivities in both the X direction (1.04 ± 0.21 S/cm) and Z direction (2.99 ± 0.54 × 10^-3 S/cm). In addition, its tensile strength and strain are better than those of pristine PPMM. The Cu micromembrane is flexible and mechanically robust enough to sustain 10,000 bending cycles with moderate deterioration. Thermogravimetric analysis shows a thermal stability of 400 °C and an effective Cu loading of 5.36 mg/cm². Cyclic voltammetric measurements reveal that the Cu micromembrane has an electrochemical surface area of 277.8 cm² in a 1 cm² geometric area (a roughness factor of 227.81), a value that is 45 times greater than that of planar Cu foil.

Recent Advances in Surface Activation of Polytetrafluoroethylene (PTFE) by Gaseous Plasma Treatments

Fluorinated polymers are renowned for their chemical inertness and thus poor wettability and adhesion of various coatings. Apart from chemical methods employing somewhat toxic primers, gaseous plasma treatment is a popular method for the modification of surface properties. Different authors have used different plasmas, and the resultant surface finish spans between super-hydrophobic and super-hydrophilic character. Some authors also reported the hydrophobic recovery. The review of recent papers is presented and discussed. Correlations between plasma and/or discharge parameters and the surface finish are drawn and the most important conclusions are summarized. The concentration of oxygen in the surface film as probed by X-ray photoelectron spectroscopy is inversely dependent on the concentration of oxygen in gaseous plasma. The predominant mechanism leading to hydrophilic surface finish is bond scission by deep ultraviolet radiation rather than functionalization with reactive oxygen species.