In recent years, with the development of electronic information technology, the miniaturization and densification of electronic device installation and high volume and frequency of information, there is a higher demand for overall properties of the circuit substrate including heat resistance, water absorption, chemical resistance, mechanical properties, dimensional stability, dielectric constant and dielectric loss, etc.
In terms of dielectric constant property, the relationship between signal transmission rate and dielectric constant Dk of insulating material in high-speed circuit is that: the lower the dielectric constant Dk of insulating material is, the faster the signal transmission rate is. Therefore, in order to achieve high frequency of signal transmission rate, substrates having low dielectric constant must be developed. As the signal frequency becomes high, the loss of signal in the substrate can no longer be ignored. The relationship among signal loss and frequency, dielectric constant Dk and dielectric loss Df is that: the smaller the dielectric constant Dk of a substrate is, and the smaller the dielectric loss Df is, the smaller the signal loss is. Therefore, the development of a high-frequency circuit substrate having low dielectric constant Dk, low dielectric loss Df and good heat resistance becomes a research direction commonly focused by CCL manufacturers.
Polyphenylene ether resin contains a large number of benzene ring structures in its molecular structure, and no strong polar group, giving excellent performances to polyphenylene ether resin, such as high glass transition temperature, good dimensional stability, low linear expansion coefficient and low water absorption, especially excellent low dielectric constant and low dielectric loss. However, as a thermoplastic resin, polyphenylene ether has disadvantages of high melting point, poor processability, poor solvent resistance and others. Since polyphenylene ether has excellent physical properties, heat resistance, chemical properties and electrical properties, etc., major companies in the world are attracted to modify it and have made some achievements. For example, a reactive group (such as vinyl group) is introduced to the end or side of the chain of the polyphenylene ether molecule to make it become a thermosetting resin. The resin has excellent overall properties of heat resistance, low dielectric constant and low dielectric loss and others after curing, and becomes an ideal material for the preparation of high-frequency circuit substrate.
An organosilicon compound containing unsaturated double bonds is used as a crosslinking agent for vinyl active group-modified thermosetting polyphenylene ether to prepare a high-frequency electronic circuit substrate.
CN 102993683 utilizes an organosilicon compound containing unsaturated double bonds as a crosslinking agent for modified polyphenylene ether. The prepared high-frequency circuit substrate has high glass transition temperature, high thermal decomposition temperature, high interlayer adhesive force, low dielectric constant and low dielectric loss. However, the organosilicon compound containing unsaturated double bonds adopted in this prior art has a structure of linear or cyclic organosilicon compound. The linear organosilicon compound containing unsaturated double bonds has good flexibility, and the high-frequency circuit substrate prepared therefrom has low bending strength. The prepared high-frequency circuit substrate by use of cyclic organosilicon compound containing unsaturated double bonds has good overall properties, but there is a problem of volatilization during the sizing and baking process due to its small molecular weight.
CN104650574A utilizes a composition comprising polyphenylene ether, polyperfluoroethylene emulsion, organosilicon resin and inorganic filler to prepare a high-frequency electronic circuit substrate. The prepared substrate has advantages of low dielectric constant, low dielectric loss, good processability and the like. However, the organosilicon resin used in this prior art is methylphenyl DQ organosilicon resin, which does not contain active groups and cannot be used as a crosslinking agent for vinyl-modified thermosetting polyphenylene ether.