FLUORORESIN BASE MATERIAL AND FLEXIBLE PRINTED CIRCUIT BOARD

摘要

The purpose of the present invention is to provide a fluororesin base material with which it is possible to achieve a low dielectric constant and a low coefficient of thermal expansion while maintaining a smooth outside surface, and with which transmission loss in high-frequency bands can be reduced. A fluororesin base material according to one embodiment of the present invention has one or multiple dielectric layers of which a fluororesin is the main component, wherein at least a portion of the dielectric layers contain air bubbles, the average air bubble density in proximity to the outside surface of the air-bubble-containing dielectric layer being lower than the average air bubble density in the interior. In preferred practice, the air-bubble-containing dielectric layer has a first dielectric layer which contains air bubbles, and a second dielectric layer which does not contain air bubbles, the second dielectric layer being arranged on the outside surface side of the first dielectric layer. Additionally, the air bubbles may be configured from hollow particles or porous particles.