Microwave dielectric ceramic powder filled fluororesin intermediate dielectric layer and preparation method thereof

Abstract

The invention relates to a microwave dielectric ceramic powder filled fluororesin middle medium layer, which comprises, by mass, 20-45 wt% of a fluororesin, 40-75 wt% of a microwave dielectric ceramicpowder filler, and 5-15 wt% of an inorganic reinforcing filler. According to the present invention, the microwave dielectric ceramic powder filled fluororesin middle medium layer has advantages of high dielectric constant, low loss, low thermal expansion coefficient, high microwave dielectric ceramic powder content and high application value, and can be used as the dielectric material in the highfrequency microwave transmission line with the frequency of 10 GHz and above.

Description

technical field [0001] The invention relates to the field of dielectric materials and processing of high-frequency microwave transmission lines with a frequency of 10 GHz and above, in particular to a microwave dielectric ceramic powder-filled fluororesin high-frequency base material and a molding method. Background technique [0002] With the rise of the Internet of Things and the increasingly rich content of the mobile Internet, especially the storage and transmission of massive data from the cloud to the client, and the real-time transmission of high-definition video, higher requirements are placed on the transmission rate of mobile communication networks. The fifth generation (5G) wireless Mobile communication technology emerges at the historic moment and develops rapidly. At the same time, 5G will also penetrate into various other industries, and deeply integrate with industrial facilities, medical equipment, and Internet of Vehicles to effectively meet the diverse busi...

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Problems solved by technology

(3) The thermal expansion coefficient of the copper foil is as consistent as possible. When the circuit board passes through high temperature, the thermal expansion coefficient of the material and copper is different due to different expansions, which leads to the failure of the reliability of the PTH (PlatedThrough Hole) via.

Since PTFE is a non-polar thermoplastic material with extremely low dielectric constant and small loss dielectric loss, which is lower than 1×10-3, PTFE is the mainstream dielectric material for high-frequency substrates, but the Z-axis of PTFE materials The coefficient of thermal expansion (CTE) is an order of magnitude higher than that of copper. The main method to reduce the Z-axis expansion coefficient of PTFE substrates is to fill ceramic powder with a very low thermal expansion coefficient, and limit the movement of PTFE molecular chains under thermal stress through intermolecular physical cross-linking. ability, or through the molding process, the ceramic particles are oriented in the Z-axis direction in the PTFE organic phase, which weakens the deformation ability of the material and reduces the thermal expansion coefficient. The glass cloth reinforcement is only regularly arranged in the horizontal X-axis and Y-axis directions, without any reinforcement in the Z-axis direction, and the molding process is single, it is difficult to improve the Z-axis expansion coefficient of the substrate; due to the extremely low dielectric constant of PTFE, The existing glass cloth impregnation technology is limited by its mature process setting, and the filling amount of ceramic powder is limited. Glass fiber cloth impregnated with PTFE can achieve low dielectric constant substrate, but the high dielectric constant substrate containing high filling amount of ceramic powder filled PTFE At present, the product and technology in China are basically blank, and it is difficult to meet the miniaturization needs of future 5G technology circuit boards.

[0005] Secondly, the main difficulty of the existing high-filling inorganic particle modified PTFE technology is how to highly uniformly disperse the inorganic particles in the organic phase of PTFE fluororesin, and improve the interface bonding between the inorganic phase and the organic phase.

The existing dry dispersion method in China mainly uses mechanical high-speed stirring, and the dielectric loss of the dispersed composite material is high after molding, causing high insertion loss, resulting in signal attenuation, and it is difficult to meet the requirements of high-frequency line transmission; wet dispersion The main method is to add inorganic particles to PTFE concentrated dispersion liquid to prevent particles from agglomerating and settling through mechanical stirring or ultrasonic action. After dispersion, the dielectric loss of the composite material is very low, but the existing impregnation process limits its filling amount, and it is difficult to meet high requirements. Dielectric constant and miniaturization requirements; foreign authorized patent US4335180 is currently a mainstream high-filling content PTFE substrate processing technology in Europe and the United States, but its process is complicated, and the mixed slurry needs to be settled by flocculant. A large amount of wastewater is produced in the process, which is difficult to meet the increasingly stringent environmental protection requirements. In addition, mechanical agitation is required during the flocculation process, resulting in partial fibrosis of the fluororesin, which can easily cause internal stress in the final product and affect the product qualification rate.

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