“The steadily expanding FPC market"- the scale of the global FPC market in 2019 has already grown to approximately US$17 billion (including RF). In the past decade, the FPC market has continued to expand at an average annual growth rate of about 7%, and its current scale is twice that of 10 years ago. This accounts for 25% of the global circuit board market (about US$66 billion). 

 

An example of this is 5G smartphones which are expected to correspond with high frequencies of 30GHz/20Gbps and it is predicted that the next generation of 6G will exceed 100Gbps. Some of the reasons for this is AR applications, CMOS image sensors (cameras) that conduct high-resolution, online, and live broadcast on 5G network communications, as well as the expanded application of high-resolution image transmission for SoC (AP). The applications of these 5G-compatible devices (smartphones, tablets, game consoles, PCs, etc.) have to be conducted via "Sub-6" and "millimeter waves", while the required antennas and feed lines will also have to use FPC. For these FPCs, high-frequency correspondence has already become the norm.
        

To achieve the high-frequency correspondence of FPCs, the following three qualitative methods are used:

(1) Reducing the dielectric loss of organic parts such as thin-film resin materials (tanδ: Df);

(2) Reducing the relative permittivity of organic parts such as thin-film resin materials (εr: Dk);

(3) Shortening the wiring length (L).

It is difficult to develop high-frequency FPC materials that optimize all the aforementioned conditions. Besides MPI and LCP, at present, various low-Dk and low-Df materials are also being developed to apply to high-frequency FPC materials.

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Of the low dielectric properties of fluorine-containing high-speed hybrid materials as well as MPI and LCP introduced in this article, high-speed hybrid materials are found with even better high-speed characteristics (low dielectric) than MPI and LCP. Although current high-frequency FPC has primarily employed LCP and MPI, it is expected that fluorine-containing (denatured PFA) hybrid materials will gradually be adopted in the future. Apart from this, the development of other new materials that use other high-speed super engineering plastics (including LCP) as their core material should continue.