Hydrocarbon resin has gradually become the new favorite for high-speed and high-frequency copper clad laminates!
1. Low dielectric materials have become the key to the new generation of communication substrates, and are one of the most ideal matrix resins for hydrocarbon resins.
The high-reliability, low-latency communication requirements of electronic equipment have put forward higher requirements for all electronic device carriers and component interconnect materials that carry signal transmission, conversion and recording functions. Printed circuit boards (PCBs) not only need to have a higher level of integration, but also need to have greater data transmission capacity. PCB materials, stacking design, channel design, power noise filtering, terminal solutions, etc. will have a great impact on its data transmission capabilities. Generally speaking, substrates with low dielectric constant (Dk) and dielectric loss factor (Df) can better achieve high-fidelity and low-latency effects during high-frequency signal transmission.
Copper clad laminate production process
The low polarity of C-H in the hydrocarbon resin molecular chain (the electronegativity of C is 2.5 and the electronegativity of H is 2.1), and the molecular chain is in a zigzag-arranged conformation, gives it excellent dielectric properties. Therefore, hydrocarbon resin is one of the ideal matrix resins for high-frequency copper-clad laminates. At present, the matrix resins used in high-frequency and high-speed copper-clad laminates include epoxy resin, polyphenylene ether resin and modified polyphenylene ether resin (PPO), cyanate ester resin (CE), polyimide resin (PI), poly(phenylene ether resin), Tetrafluoroethylene resin (PTFE), BT resin and hydrocarbon resin.
Due to the small electronic polarizability of C-C bonds and C-H bonds, hydrocarbon resins exhibit low dielectric constants and ultra-low dielectric loss factors over a wide frequency and temperature range. At the same time, hydrocarbon resin has excellent processing properties. Compared with other high-frequency copper-clad laminate resin materials, its molding process is simple and low-cost. It is considered to be the next generation of high-frequency and high-speed copper clad laminates, especially the resin material of choice for high-frequency copper clad laminates.
2. The common hydrocarbon resin system is the polybutadiene system that has been studied the most, but the multi-component composite system is the mainstream solution.
Hydrocarbon resin copper-clad laminates are mainly made by compounding hydrocarbon resin and low-dielectric ceramic powder to prepare glue, and then impregnating glass fiber cloth to prepare prepreg and pressing it. Commonly used hydrocarbon resin systems for copper-clad laminates include polybutadiene system, polystyrene-butadiene (SB, SBS) copolymer system, cyclic olefin copolymer (COC, DCPD) system, SI and SIS copolymer system, EPDM copolymer system, PPO modified polybutyl styrene system, PPO modified SI and SIS copolymer system, etc.
(1) Polybutadiene system.
Polybutadiene is a thermosetting hydrocarbon resin, which mainly includes polybutadiene, cis-1,4-polybutadiene, trans-1,4-polybutadiene, 1,2-polybutadiene, etc. , has been widely used in the fields of electronics, insulation, adhesives, coatings, automobile tires and toughening modifiers. The side chains of high 1,2-polybutadiene contain a large number of double bonds and are mainly used as adhesives and sealants. The lack of polar groups limits its application range to a certain extent. For low molecular weight non-vulcanized polybutadiene liquid rubber, its easy creep characteristics make it difficult to form a stable coating film at room temperature. Therefore, the development of polybutadiene system low dielectric materials for high-frequency copper-clad laminates has also become a difficulty in its research. At present, most of the polybutadiene system high-frequency copper-clad laminates are based on polybutadiene system, which is compounded with other hydrocarbon resin systems to form a binary or ternary system. However, polybutadiene system high-frequency copper-clad laminates also have problems such as easy glue flow during the preparation process and lack of aging resistance that need to be further solved.
In response to the above defects, filler SiO2 is commonly used for surface modification and other methods to improve the performance of hydrocarbon resin high-frequency copper-clad laminates. Such as silica/polybutadiene (SiO2/PB) composite material, which exhibits extremely low dielectric constant and dielectric loss in both low-frequency and high-frequency bands. Because the cross-linking reaction between the vinyl groups on the SiO2 surface and PB macromolecules greatly inhibits the interfacial polarization of the SiO2/PB composite material.
High-frequency copper-clad laminates prepared from pure polybutadiene systems have problems such as low bonding strength at the interface between resin and copper foil and easy creep, making it difficult to adhere and laminate with other materials (such as copper foil). The general solution is to mix other resins on the basis of polybutadiene to improve the current defects of the polybutadiene system. Polyphenylene ether (PPO) resin has extremely low Df, second only to PTFE resin among commonly used resin matrices. In addition, PPO also has the advantages of high glass transition temperature, low CTE, excellent mechanical properties, acid and alkali resistance, etc., but its compatibility with PB resin is poor. In the industry, styrene-based polyphenylene ether (SPPO) and low-polarity thermosetting polybutadiene resin are used to prepare high-frequency matrix resin systems with excellent electrical and thermal properties.
(2) Cyclic olefin system.
Cyclic olefin copolymer (COC) is a new type of transparent engineering material with excellent electrical properties in microwave, millimeter wave and even terahertz bands. It is mainly used in fields such as optics, packaging materials, biomedicine, and electronic components. Cyclic olefin copolymers also have extremely low dielectric constant and dielectric loss factor (Dk is 2.2, Df is 0.0002 at 10GHz), low thermal expansion coefficient (CTE is 60×10-6℃-1) and low water absorption (< 0.1%), suitable as a substrate material for high-frequency rigid circuit boards. The COC film also shows good flexibility and can be introduced into SEBS/BN composites to reduce the dielectric loss factor and water absorption.
Most cycloolefin copper-clad laminates mix cycloolefins with other resins or add cycloolefin films to other resin base layers to improve the performance of hydrocarbon resin high-frequency copper-clad laminates. For example, adding cyclic olefin copolymer resin to the 1,2-polybutadiene (PB)/styrene-butylene-styrene (SEBS) binary resin system can prepare products with better dielectric properties, mechanical properties and water absorption properties. PB/SEBS/COC terpolyolefin system. At present, there has been great progress in laboratory research on the application of cyclic olefin copolymers in hydrocarbon resin high-frequency copper-clad laminates, but there are still relatively few applications in actual industry.
(3) Other systems
In addition to polybutadiene and cycloolefin systems, the base resin of hydrocarbon resin high-frequency copper-clad laminates, polybutadiene systems, cyclopentadiene systems, etc. are also currently being actively developed, and judging from the patent application status, polybutadiene styrene systems The system also receives focus in the R&D systems of each company.
For example, some units have prepared core-shell structure EPDM/SiO2 particles with different shell thicknesses by coating the SiO2 surface with ethylene-propylene-dicyclopentadiene (EPDM), and some have also used toughened modified polyphenylene ether (MPPE)-based resins. and styrene-ethylene/butylene-styrene (SEBS) resin-based systems to prepare high-performance copper-clad laminates, and the use of 1,2-polybutadiene/styrene-butadiene-styrene triblock copolymer/ethylene -Propylene-dicyclopentadiene (1,2-PB/SBS/EPDM) system to prepare copper-clad laminates.
3. The mainstream hydrocarbon resins are mainly produced by American and Japanese companies, and domestic companies are catching up.
At present, hydrocarbon resins are monopolized by companies such as Sartomer and Kraton Polymers in the United States, Nippon Soda and Asahi-Kase in Japan, and TOPAS in Germany. There are basically no comparable similar resins in China. Although some Chinese companies have also applied for a large number of patents in this field, such as Shengyi Group, Huazheng, Taiyao, etc., there is still a certain gap between the overall research and development level and foreign countries.
Overseas, the hydrocarbon resin copper-clad laminate developed by Rogers Company in the United States has particularly excellent performance. Its base materials mainly include hydrocarbon resin-filled ceramics, hydrocarbon resin-filled ceramics plus glass cloth, etc. Among them, the RO4725JXRTM product has a Dk of 2.64 and a Df of 10GHz. It is 0.0026, which belongs to the category of hydrocarbon resin plus ceramics and glass cloth. There are only a few commercialized substrates in China, such as the RF and microwave circuit substrate S7136H product developed by Guangdong Shengyi Technology Co., Ltd., which has a Dk of 3.42 and a Df of 0.0030 at 10GHz. It belongs to the category of hydrocarbon resin plus ceramics and glass cloth. At present, most high-end PCBs manufactured in China use high-performance substrates developed and manufactured by foreign companies.
At present, some domestic companies have begun the research and development and production of hydrocarbon resin high-frequency copper-clad laminates, such as Shengyi Technology, Wuxi Ruilong New Materials, Zhongying Technology, etc. They have caught up in terms of scale and technology, and there is huge room for domestic substitution of hydrocarbon resin high-frequency copper-clad laminates. The research and development system of domestic hydrocarbon resin high-frequency copper-clad laminates mainly focuses on two directions.
One is based on hydrocarbon resin with excellent dielectric properties and processing properties, and prepares hydrocarbon resin high-frequency copper-clad laminates with excellent performance by adjusting the ratio of hydrocarbon resin, fillers and various additives. Wuxi Ruilong New Materials and Zhejiang University used one or more of polybutadiene polymer, polybutadiene-styrene copolymer, styrene-butadiene-styrene copolymer, etc. as the matrix to conduct comparison. Try more;
Another idea is that the research and development system is to modify hydrocarbon resin with other resins to prepare high-performance hydrocarbon resin high-frequency copper-clad laminates. AAC Technology uses one, two or more of polydiene resins, cyanate resins, benzocyclobutene resins or polyphenylene ether resins to prepare hydrocarbon resin high-frequency copper-clad laminates with a relatively low dielectric loss factor. Low, but the dielectric constant is relatively high. The resin matrix of Guangdong Quanbao Technology is modified polybutadiene resin and benzoxazine resin; the resin matrix used by Guangdong Shengyi is polybutadiene or polybutadiene and styrene containing more than 60% vinyl. Copolymer resin.
4. Summary.
Generally speaking, hydrocarbon resin is the current research hotspot for high-frequency copper-clad laminate materials. Due to its excellent performance, it has been widely used in high-frequency copper-clad laminates and is an ideal choice for the next generation of high-frequency and high-speed materials. At present, the matrix resins used in hydrocarbon resin high-frequency copper-clad laminates mainly include polybutadiene systems, cyclic olefin systems, and a small amount of polybutadiene systems. Whether hydrocarbon resin is modified or blended with other resins, the current technology is not very mature. Most hydrocarbon resin high-frequency copper-clad laminates still have shortcomings such as weak adhesion and poor filler compatibility. Its poor heat resistance is also a difficulty in current development. Hydrocarbon resin high-frequency copper-clad laminates need to be further researched from aspects such as fillers and modifications to develop special materials for high-frequency and high-speed copper-clad laminates to achieve complete localization.
First Material Intelligence has established an electronic chemicals exchange group to jointly discuss the development trends and material development progress of high-speed and high-frequency copper-clad laminate related industries.
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