Recently, the United States has provoked a trade war with China, substantially increased tariffs on imports from China, and banned the export of high-tech products to China. China’s ZTE Corporation was banned as an example. In April this year, the US Department of Commerce issued an ban on exporting rights to ZTE, prohibiting US companies from selling parts, goods, software and technology to ZTE for a period of seven years. The ban immediately made ZTE The company entered a state of shock. By June, the US Department of Commerce agreed to lift the ban on the condition that ZTE paid a large fine, replaced the board of directors and management, and purchased more US products. ZTE Corporation is one of the world's largest communications equipment manufacturing giants, but its lifeline has been stuck in the United States because of the lack of core technology and the lack of core components and integrated circuits.

At this time, China held the Chinese Academy of Sciences and the Chinese Academy of Engineering academician conference at the end of May this year. At the meeting, General Secretary Xi Jinping delivered an important speech, which stated: "The shortcomings of China's basic scientific research are still outstanding, and enterprises pay insufficient attention to basic research. Lack of major original results, insufficient underlying basic technology and basic technological capabilities, bottlenecks such as industrial motherboards, high-end chips, basic hardware and software, development platforms, basic algorithms, basic components, and basic materials are still outstanding. The key core technologies are not subject to the human situation. Fundamental change."

The ZTE incident in Sino-US trade has sounded a warning to China's manufacturing industry. General Secretary Xi’s speech cuts the eyes and bottlenecks of science and technology and industrial development. It is worth pondering for our printed circuit manufacturing industry. What is the shortcoming of China's printed circuit industry? Is there a lack of core technology that will be shackled and stuck by foreign countries? Is the lifeblood of the printed circuit industry in its own hands?

2 High performance substrate is the next generation printed circuit board core

The electronic information industry is entering the 5G era, and 5G is coming! 5G means the fifth generation of mobile networks, not limited to mobile communications, from the Internet of Things, smart cities to driverless cars, all need 5G. Almost all walks of life are gearing up for the 5G big cake, the same is true for printed circuit boards, and 5G equipment brings a new generation of printed circuit boards.

The key to the manufacture of printed circuit boards (PCBs) is firstly the raw material-substrate. Without the substrate, the PCB cannot be fabricated. This is tantamount to the difficulty of cooking a rice without a rice. The PCB substrate includes a substrate (copper-clad laminate CCL), a prepreg (prepreg Pp), and a copper foil. Many of the main properties of the PCB are determined by the substrate, such as mechanical strength, dielectric properties, dimensional stability, Heat resistance and combustion resistance. PCBs made of phenolic paper-based CCL with poor mechanical strength and low electrical performance can only be used in low-end consumer electronic devices. In high-performance and high-reliability electronic devices, PCBs must be made of high-performance epoxy glass cloth or poly. The CCL of a resin such as tetrafluoroethylene and a liquid crystal polymer has a good fruit only if it is a good gene. Therefore, the substrate should be considered the core of the PCB.

PCB manufacturing process technology is not weak in mainland China. With the diligence and cleverness of Chinese people, as long as the materials and equipment conditions are available, the company has the ability to manufacture complex PCB products. At present, domestic enterprises have produced a variety of high-performance special PCBs, including embedded components, embedded copper blocks, metal-based heat dissipation, high-frequency mixed-pressure and other types of PCBs have reached the international advanced level. However, the high-performance substrates used in the new generation of high-performance PCBs are still dependent on foreign imports, highlighting high-frequency high-speed substrates and high thermal conductivity substrates. Many domestic PCB manufacturing companies have produced a variety of special PCBs, such as "56Gbps ultra-high-speed printed circuit board for 5G communication" and "5G car network high-density interconnect module", etc., which are internationally advanced by experts. PCB product results, unfortunately the substrate they use is foreign goods. At present, China is already the world's largest producer of PCB substrates in terms of production volume, but some high-performance substrates are still lacking in domestic production and relying on foreign imports.

Electronic devices have different design requirements for different frequencies. Circuits with different characteristics are required for circuits that are most suitable for different frequencies. In the search for circuit materials for microwave and millimeter-wave power amplifiers for 5G applications, in addition to the substrate must have low dielectric loss (Df) and low dielectric constant (Dk), there are circuit materials that enable efficient thermal management. Evaluating the thermal properties of a material has two parameters, thermal conductivity and dielectric constant temperature coefficient (TCDk). For amplifiers and other circuits in 5G systems, circuit substrates are required to have low Dk, Df and low TCDk values, as well as high thermal conductivity to produce high quality, high performance, high frequency power amplifiers.

Factors affecting the insertion loss on the microstrip circuit In addition to the insulator, the copper conductor becomes more critical. This is mainly determined by the smoothness of the copper surface, because in the very high frequency environment, the skin effect will occur, so the roughness of the copper foil is also an important factor, plus the thinning of the circuit requires thin copper foil and ultra-thin copper foil. .

The new generation of PCBs focuses on 5G communications and automotive electronics, and exhibits high-frequency, high-speed characteristics and high heat dissipation characteristics on the PCB. In addition to design and manufacturing factors, PCBs must meet the requirements of high frequency, high speed and high heat dissipation performance. Therefore, the substrate should be regarded as the core technology of the PCB, especially the high-performance substrate is the lifeblood of high-performance PCB.

3 The gap between high-performance substrates

The main requirements for high frequency materials are low dielectric constant (Dk) and low dielectric loss factor (Df). Current mainstream high frequency products are realized by using polytetrafluoroethylene (PTFE) and hydrocarbon resin materials.

Check out product technical information for PCB substrate manufacturers such as CCL, which are internationally advanced CCL manufacturers such as Rogers, Isola, Park Electrochemica, and Tektronix. (Taconic), Tenghui (ventec), Panasonic (Panasonic), etc. For example, Matsushita's ultra-low loss multi-layer substrate MEGTRON7 is a multilayer circuit board material with the lowest industrial transmission loss, meeting the requirements of high-capacity, high-speed transmission of high-end network equipment.

Rogers has a series of high-frequency high-speed and high-heat-conducting substrates. Its CCL is composed of polytetrafluoroolefin (PTFE) resin glass cloth reinforcement, PTFE resin-filled ceramics, PTFE resin-filled ceramic glass cloth reinforcement, modified epoxy. Resin-filled ceramics, hydrocarbon-filled ceramics, hydrocarbon-filled ceramic glass cloth reinforcements, ceramic-filled thermosetting polymers, and polyetheretherketone (PEEK) resin glass cloth reinforcements. In particular, Rogers does not simply provide high-performance substrates, but provides Advanced Connectivity Solutions (ACS), which not only introduces a variety of high-performance CCL and Pp products, but also introduces specific performance and application areas of various products. , as well as a PCB design and processing technology guide. Their new substrate development combined with PCB users is targeted and targeted. These practices of Rogers are also factors in which their substrates are chosen by more PCB manufacturers.

In terms of high thermal conductivity substrates, Tenghui's products are more prominent. For example, metal-based copper clad laminates can be selected from different substrates and insulating layers. The thermal conductivity ranges from 1W/m·K to 10W/m·K. For ceramic multilayer filled high thermal conductivity laminates and prepregs for multilayer PCBs, the thermal conductivity of 2.2 W/m·K is 8 times that of FR-4.

According to Essence Securities. Southern Fortune Network reported: high-frequency substrates are basically occupied by US and Japanese manufacturers, Rogers (55%), Park/Nelco (22%), Isola (9%) and Zhongxing Chemical (5%) occupy the world's major markets Share, where PTFE market share Rogers is above 90%. Whether these percentage values ​​are exact or not, and the engineers who manufacture high-performance PCBs say that the substrate must be called a foreign company's products. At present, the high-frequency high-speed PCB substrates in China are almost all using the specifications of foreign companies.

Look at our leading CCL manufacturing companies in China, such as CPCA's 17th (2017) China Electronic Circuit Industry Rankings, ranking the top five companies in China's CCL production: Guangdong Shengyi Technology, Jinan Guoji Technology, Shandong Jinbao Electronics , South Asia New Materials Technology, Zhejiang Huazheng New Materials. Looking at the websites of these companies, in addition to Shandong Jinbao Electronics' paper-based CCL, the other four have or are introducing high-performance CCL and Pp new substrates.

For example, Guangdong Shengyi Technology Co., Ltd. has the high-speed circuit substrate: S7045G/S7045GB, application fields: communication, server, base station, backplane, line card, high-performance computer, office router, etc.; RF & microwave circuit substrate: S7136H Applications: High-frequency wireless communications, high-speed computers, satellite signal transmission equipment, microstrip and cellular base stations, antennas and power amplifiers. The dielectric properties of these substrates are only close to the low loss range.

South Asia New Materials Technology Co., Ltd. has high-speed circuits and CCL for microwave/radio frequency. Some models are only available but have no specific performance specifications. Zhejiang Huazheng New Materials Co., Ltd. has high-frequency materials, which are applicable to base station antennas, airborne, ground and surface radar systems. These products only see test data. I wonder if the specifications are commercialized and commercialized. These high-speed high-frequency circuit substrates in China have a wide range of applications, listing a lot of uses, but poorly targeted. Usually, it is difficult to cure a disease.

In terms of thermal conductive substrate, Guangdong Shengyi Technology Co., Ltd. has high thermal conductivity FR-4, thermal conductive bonding sheet, thermal conductivity 1.5W/m·K; aluminum-based copper clad laminate, thermal conductivity 2.0W/ m•K. Jinan Guoji Technology Co., Ltd. has aluminum-based copper clad laminates with a thermal conductivity of 2.0W/m•K. Huazheng New Materials Co., Ltd. also has heat-dissipating metal-based copper clad laminates and bonding sheets. The domestic company is still a lot worse than the high thermal conductivity substrate of Tenghui.

For the requirements of high-performance substrates, in addition to the dielectric constant and dielectric loss, there are related indicators such as heat resistance, heat dissipation, thermal expansion coefficient, and water absorption. There are also some high-performance substrate materials, such as substrates for integrated circuit package carrier boards, liquid crystal polymer (LCP) resin substrates for flexible PCBs, HDI laminate bonding sheets, etc. material. Of course, the high performance of the substrate requires matching of the corresponding resin with fillers, glass cloth, copper foil, etc. The material source of these substrates is also worth pondering.

4 grasp the core technology of the industry

I regard PCB substrate technology as the core technology of PCB, especially for the high-performance PCB, which is the core of the new-generation PCB.

The above is a brief comparison of the existing high-performance substrates at home and abroad. I may be ignorant and omit the domestic advanced level of substrate products, or misunderstood and depreciated. Welcome to correct me. At present, the high-performance substrate of foreign companies occupies the vast majority of China's high-end PCBs, which can be perceived by everyone in the industry. This fact is the gap between domestic and international advanced substrates. This is the "key core technology is subject to people's situation" .

China's communications equipment manufacturers Huawei and ZTE are leading the 5G era and have strong advanced technology strength. However, the United States issued a ban on ZTE, which allowed ZTE to squat. It was thought that in the 5G era, the corner road was overtaken, and the result was a rollover. The reason is also very simple: ZTE's communication equipment integrated circuit chips are all from American companies. ZTE does not have its own chips. There are no high-performance chips in China. The lifeblood is in the hands of others. Now that the United States has stuck the chips, there is no ZTE's way of life. Advanced products do not have their own core technology, just as high-rise buildings do not have a solid foundation, and they will overturn when there is a storm.

General Secretary Xi also said at this year's meeting of the two chambers: "Practice repeatedly tells us that the key core technology is whether it can't come, buy it, or can't get it. Only by taking the key core technology in its own hands can we fundamentally Guarantee national economic security, national defense security and other security."

If the United States also comes to the ban on high-performance substrates that are not allowed to export to China, what kind of substrate does our 5G use for high-performance PCBs? In the free world and the market economy environment, this assumption may be completely worrying and alarmist. However, in the current "White House trade blindness" situation, warnings are still needed.

We look at things to tell the dialectic, split into two, bad things will become good things, so that the US imperial sanctions become a powerful force!

Domestic PCB substrate manufacturers are striving to develop and introduce high-performance substrates, which are approaching the international advanced level. The National Electronic Circuit Substrate Engineering Technology Research Center and a number of provincial and municipal-level substrate technology research and development centers have also received government awards or funding, and they believe that they can develop advanced high-performance substrates. Now I hope to realize the localization of high-performance substrates at an early date, master the core technology of the industry, and master the initiative of industrial development to make China's printed circuit industry continue to develop safely.