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Unveiling the Secret Sauce: How Electronic Resin Shapes Copper Clad Laminate Performance

The copper-clad laminate production process mainly includes: glue mixing, glue impregnation, prepreg slicing, typesetting, loading copper foil hot pressing, cutting and inspection. Electronic resin is used in the glue mixing process, which is the core process of copper clad laminate production. Since the physical and chemical properties, dielectric properties and environmental performance of copper-clad laminates are mainly determined by the glue formula, copper-clad laminate manufacturers develop different glue formulas to adapt to the diverse and differentiated needs of PCB companies and end customers.

1. The copper clad laminate glue formula system is highly complex.

The main components of the copper clad laminate glue formula include main resin, curing agent, additives, fillers, organic solvents, etc. Among them, the main resin and the curing agent are the two components with the largest consumption. The glue formula is mainly composed of the main resin and the curing agent. Glue components mainly include:

(1) Main resin. Traditionally, the main types include brominated epoxy resin, high bromine epoxy resin, MDI modified epoxy resin, DOPO modified epoxy resin, bisphenol A-type novolac epoxy resin, and new non-epoxy resins (benzene Oxazine resin, etc.). The main resin provides various physical and chemical properties of the copper clad laminate, such as copper foil peel strength, glass transition temperature, dimensional stability, thermal expansion coefficient, low signal loss, insulation performance, long-term environmental reliability, etc., to achieve UL-94 V0 flame retardancy .
(2) Curing agent. It mainly includes dicyandiamide, novolac resin, phosphorus-containing phenolic resin curing agent, etc. Most of the main resins are thermosetting resins, which need to be heated and cured to form a three-dimensional cross-linked network structure, so that the base material has support Function.
(3) Additives. Mainly include curing accelerators, toughening agents, coupling agents, flame retardant additives, etc. There are many types of additives, which can promote the curing reaction, improve the flame retardancy, and increase the toughness of the copper clad laminate.
(4) Filling. Mainly include silica, aluminum hydroxide, talc, etc. Fillers have a compatibilization (volume) effect, and because of their dimensional stability, they can reduce the thermal expansion coefficient of copper-clad laminates, improve fluidity, and assist in flame retardancy.
(5) Organic solvents. Methyl ketone, toluene, etc., adjust the viscosity of the glue to facilitate production control.
The glue formula does not only contain a single type of electronic resin, but is composed of a variety of electronic resins of different categories and properties in a certain proportion. Because there are many compounds involved in the formula and their properties are different, the differences between the components after mixing There are various cross-reactions, and various properties may promote or inhibit each other. Therefore, slight adjustments in the type and proportion of components may affect the performance expression of the formula. CCL manufacturers need to find the best reaction ratio to achieve the best overall performance of their products. They also need to consider factors such as cost and performance-price ratio to meet mass production needs.

2. Electronic resin is the main factor that determines the performance of copper clad laminates.

The polar group structure and curing method of the electronic resin affect the copper foil peel strength and interlayer adhesion of the copper clad laminate; the high benzene ring density and high cross-linking density of the electronic resin help to increase the glass transition temperature of the copper clad laminate. , Enhance the dimensional stability of the copper clad laminate and reduce its thermal expansion coefficient. The above-mentioned performance improvements of copper-clad laminates make PCBs more reliable in processing. The higher the content of bromine and phosphorus flame retardant elements in the electronic resin, the higher the flame retardant grade of the copper clad laminate; the highly regular and symmetrical molecular structure of the electronic resin and the low content of polar groups can effectively reduce the flame retardancy of the copper clad laminate. Electrical signal loss to adapt to application scenarios in the field of high-speed and high-frequency communications; while high-purity, low-impurity electronic resin can improve the insulation performance and long-term environmental reliability of copper-clad laminates (such as high temperature and high humidity). The above-mentioned performance improvements of copper-clad laminates can adapt to the characteristic requirements of different PCB application scenarios.

3. Environmental protection and high performance are the two main lines of the evolution and development of resin systems.

With the expansion of terminal application fields and environmental protection requirements, the type of copper clad laminates has evolved from ordinary FR-4 to high-frequency and high-speed copper clad laminates, and the electronic resin formula system has also developed accordingly: in the early days, ordinary FR-4 copper clad laminates mainly used The combination of low bromine epoxy resin and traditional curing agent dicyandiamide satisfies the basic functions of base material insulation, flame retardancy and support, and has the advantages of simple formula and low cost.

With the strengthening of environmental awareness, the “lead-free process” of the PCB industry requires copper-clad laminate substrates to achieve higher heat resistance. In order to improve heat resistance, the industry generally uses novolac resin as the curing agent instead of dicyandiamide. However, this system has problems such as poor brittleness and insufficient adhesion to copper foil. Therefore, the industry began to use a variety of electronic products with various characteristics. System solutions with resin combinations may improve certain properties while inhibiting other properties (for example, excessive flame retardancy will reduce heat resistance), so copper-clad laminate companies need to achieve an effective balance between various properties and costs.

Later, the environmental protection of electronic products put forward hard requirements for the use of halogen-free environmentally friendly materials in the PCB industry, which meant that electronic resin formulations needed to use new flame retardants to replace halogen-containing flame retardants. In the formula system, there is no longer low bromine or high bromine epoxy resin, but epoxy resin or curing agent modified with phosphorus-containing monomers such as DOPO, combined with other electronic resins as a solution for halogen-free copper clad laminates The solution can also meet the requirements of PCB lead-free manufacturing process.

With the development of mobile communication technology, the PCB industry has continuously improved requirements for the dielectric properties of copper-clad laminates. Due to the molecular structure of the epoxy resin itself and the large number of polar groups it contains after curing, it has an adverse effect on the dielectric properties and signal loss of the copper-clad laminate. Therefore, it is gradually difficult for epoxy resin-based copper-clad laminate materials to meet the requirements of high frequency and high speed. Application requirements. After special design, new electronic resins such as benzoxazine resins, maleimide resins, and functionalized polyphenylene ether resins with regular molecular configurations and less polar groups produced after curing have emerged, forming excellent Material systems for dielectric properties and PCB processing reliability.

At present, the main resin manufacturers in the industry include:

(1) Olin Corp. Olin was founded in 1892. Its main business includes chemicals (including microelectronic materials), metal products and ammunition. It is headquartered in Missouri, USA. It is a company listed on the New York Stock Exchange.
(2) Hexion Holdings Corp., whose main businesses include specialty chemicals, adhesives, structural resins and coatings, is headquartered in Delaware, USA.
(3) KOLON Industries, INC. is mainly engaged in the manufacturing and sales of various industrial materials and is headquartered in Seoul, South Korea. Its main products in the chemical industry are petroleum resins, polyurethane, ester elastomers and glass fiber reinforced plastic products. Cologne Industrial Co., Ltd. is a Korean listed company.
(4) Nanya Plastics Industry Co., Ltd. was established in 1958. Its main business is the production and processing of various plastic processed products, chemical products, electronic materials, polyester fiber, mechanical and electrical engineering, etc. It is headquartered in Taiwan, China.
(5) Changchun Group was founded in 1949. Its business scope includes general chemicals, synthetic resins, thermosetting plastics and high-performance engineering plastics, electronic materials, semiconductor chemicals, etc. It is headquartered in Taiwan, China. Changchun Group’s printed circuit board material products include ordinary epoxy resin, special electronic epoxy resin for copper-clad laminates and semiconductor packaging resin materials.
(6) Hongchang Electronic Materials Co., Ltd. was established in 1995. Its main products are electronic-grade epoxy resin and copper-clad laminates. Hongchang Electronics was listed on the Shanghai Main Board in May 2012.
(7) Jinan Shengquan Group Co., Ltd., its main products include phenolic resin, resin for casting materials, composite materials, biomass chemical products, etc. Shengquan Group was listed on the Shanghai Main Board in August 2021.
(8) Sichuan Dongcai Technology Group Co., Ltd. was established in 1994. Its main products include new insulation materials, optical film materials, electronic materials, environmentally friendly flame retardant materials, etc.

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