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Development Story

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Development of a New Material to Expand the Possibilities of Next-Generation Telecommunications with Low Transmission Loss

Development Background

Recent years have seen the rapid development of infrastructure and terminal equipment for millimeter-wave radar and 5th generation wireless systems (5G); both will be for the Advanced Driving Assistant System (ADAS) of automobiles, data centers for processing information handled by them, and o related facilities. Next-generation information and telecommunication systems will have higherfrequency, and process requirements. To support innovation in these areas,. materials with low transmission loss are currently attracting attention.

Thermoplastic resins, including low-dielectric fluorinated resins and liquid crystal polymers, have generally been used as low-transmission-loss materials. Thermoplastic resins have problems with both adhesiveness and heat resistance, making them unsuitable for adhering copper wire to conventional substrate material. High-profile copper foil can be used for adhering the resins to copper wire, however, the high profile of the foil causes high circuit loss and increases transmission loss.

To improve high adhesion to copper wire, and workability, thermosetting resinschould be used. Unfortunately, they have a high dielectric constant and high dielectric loss tangent and therefore do not exercise their full transmission potential, even when low-profile copper foil is used.

Our challenge was to develop a material that takes advantage of the adhesiveness and workability of thermosetting resins while maintaining the low-dielectric property of thermoplastic resins. To reduce transmission loss, permit greater flexible circuit design, and it could expand the possibilities for new circuit design.

Gaps in Technology

Our development personnel began by creating a new thermosetting resin. Initial samples obtained had superior adhesion, but exhibited high thermal expansion. To counteract this, researchers decided to impregnate glass cloth, commonly used as a support base material, with the resin. Since the dielectric constant of the glass cloth was higher than that of the resin, the required level of transmission could not be obtained. Replacing glass cloth with an alternate low-dielectric material resulted in workability issues.

Developing a material with all the required properties: low-dielectricity, adhesion, and workability, was proving to be more challenging than we originally thought.

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