Abstract:
With the development of high-frequency communication technology, the demand for polymer materials used in high-frequency printed-circuit board (PCB) is increasing, such as low dielectric loss for reduced signal loss as it passes along a transmission line on a dielectric material, low moisture absorption and low dielectric constants for higher signal propagation speeds, high glass transition temperature for plated through hole reliability and high heat resistance for short term resistance of products to solder processing. However, the performance of traditional printed circuit board based on phenolic resin and epoxy resin cannot meet the requirements of the high-frequency communication technology. Consequently, developing the new materials with low dielectric constant, low dielectric loss, heat resistance, low moisture absorption and excellent dimensional stability is significant to high-frequency signal transmission. Polybenzoxazine, cyanate ester, polytetrafluoroethylene, polyimide and polyphenylene oxide have attracted much attention for relatively lower intrinsic dielectric constant and dielectric loss, enormous research has been done. In order to further reduce dielectric constant and dielectric loss, and improve comprehensive performance of polymers, recently, enormous research has been done. For instance, to reduce dielectric constant and dielectric loss, extensive work has been directed to design molecular structure, which includes the incorporation of low polarizability groups, space-occupying groups and fluorinated monomers, and some works focused on adding nano porous materials, such as polyhedral oligomeric silsesquioxane, mesoporous silica and hollow silicon tube, or introducing pore structure in polymers. To improve thermal stability or mechanical property, some research concentrated on blending two or more polymers together, and special performance materials are obtained by playing the advantage of each component polymers. In this review, the up-to-date research progresses in the field of low dielectric polymers for high frequency PCB and the relationship of chemical structures and properties of these polymers are discussed.