TOKYO -- DIC Corporation (TOKYO:4631) announced that it has developed a new specialty polyphenylene sulfide (PPS) film in collaboration with Japanese firm Unitika Ltd. that suppresses transmission loss at high frequencies. This product’s low dielectric properties make it suitable for use in a key for millimeter-wave printed circuit boards compatible with next-generation communications devices and for millimeter-wave radar. This new PPS film has already been evaluated by a number of electronics materials manufacturers and preparations are currently being made to commence commercial production.

Conventional high-frequency flexible printed circuit boards used in smartphones and small electronic devices, among others, are fabricated by bonding layers of liquid crystal polymer (LCP) film and copper foil. LCP creates in an uneven film-copper foil adhesive interface, a cause of higher transmission loss. Because next-generation communication devices use the millimeter-wave frequency band (30 to 300 GHz), they require materials with low dielectric properties, which minimize transmission loss.

The specialty PPS film developed by DIC and Unitika combines the former’s proprietary PPS polymerization and compounding technologies with Unitika’s film manufacturing technologies. This new film maintains the low moisture absorption, as well as the flame and chemical resistance, of PPS resin, while delivering the outstanding low dielectric properties, dimensional stability, reflow resistance and uniformity of thickness required for high-frequency printed circuit boards. In particular, this product demonstrates stable dielectric properties in high-temperature environments and at a wide range of frequencies (10 to 1,000 GHz), a performance feature difficult to achieve with LCP or other common films, as a result of which it is expected to be adopted for a wide variety of applications, from smartphones to automobiles.

This new film also boasts excellent adhesiveness with different materials, meaning that it is compatible with a broad range of flexible copper clad laminate (FCCL) processing methods, including sputtering and plating, as well as lamination with an adhesive. The sputtering and plating method, in particular, delivers a smooth adhesive interface that achieves lower transmission loss than commonly used films, including LCP or fluoropolymers.

The DIC Group is contributing to digitalization by developing functional materials that anticipate emerging needs in the development of infrastructure for next-generation communications, including 5G/6G, and generative AI, which are expected to see accelerated demand in the years ahead.