Development of low-loss millimeter-wave antennas on fluorine substrate using electro-fine-forming fabrication

Polytetrafluoroethylene (PTFE) has many desirable properties for substrates of millimeter-wave planar antennas such as low dielectric constant and loss tangent. However, it has weak adhesion to various metals. Surface treatment of PTFE via radiation-induced graft polymerization was carried out to improve the adhesion. The peel adhesion strength of the PTFE/Cu was attained to be 10.3 N/cm by the treatment. The dielectric function of grafted- PTFE remained almost unchanged after the graft polymerization. The design and fabrication of millimeter-wave antennas on the treated PTFE substrates have been performed using electro-fine- forming (EF2) technology.