, Print circuit board substrate

China is the world's printed circuit manufacturing country, but it is not a powerful country. There are many technologies lagging behind developed countries such as the United States and Japan. The key to printed circuit boards (PCB) is first of all raw materials -substrates. PCB cannot be manufactured without substrate materials.

PCB substrates include the substrate (covering the copper foil layer), the pre -immersed material (semi -curing tablet), and the copper foil. Many of the main properties of the PCB are determined by the substrate, such as mechanical strength, dielectric performance, size stability, heat heat resistance, heat resistance to resistance Sex and burning resistance. If the PCB made of phenolic paper base covered with poor mechanical strength and low electrical energy capacity can only be used in ordinary consumer electronics equipment or in high -performance high -reliable electronic equipment, PCB must use high -performance epoxy Glass bucket covers copper foil layer pressure plates or polytetrafluoroethylene and liquid crystal polymer substrates. Only doorsteen is good for good genes. Therefore, the substrate should be regarded as the lifeblood of PCB. Now, in terms of output, China is the largest production country in the world of PCB substrate, but some high -performance substrates lack domestic production and depend on imports.

PCB manufacturing technology is not weak in China. With the cleverness and hard work of the Chinese, as long as the corresponding materials and equipment conditions are available, the complex PCB products can be manufactured. At present, domestic enterprises have created a variety of high -performance special PCBs, including buried elements, buried copper blocks, metal base heat dissipation, and high -frequency hybrids, which have reached the international advanced level. However, the new generation of high -performance PCB use high -performance substrates still depend on imported abroad, highlighting high -frequency and high -speed substrates and high thermal substrates. Many domestic PCB manufacturing companies have created a variety of special PCBs, such as "56 GBPS ultra -high -speed printed circuit boards suitable for 5 GBPS", "5 G vehicle Internet of high density interconnection modules", etc., which are identified by experts. The results of the advanced level of PCB products, but the substrate they use is foreign products.

The 5G era is coming. 5G means that the fifth -generation mobile network is not limited to mobile phone communication. From the Internet of Things, smart cities to unmanned cars, it requires 5G. 5G commercial services will begin fixed wireless in 2018, usually high frequency (such as 28 GHz or 39 GHz). The mobile network deployment will gradually begin from 2020. In fact, several communications companies are planning to release 5G networks later this year.

5G is divided into two areas; the market is less than 6GHz at first, and technology less than 6GHz can be compatible with the materials currently used; another field is millimeter wave with a frequency of 28GHz. Because the frequency of millimeter waves is very high, the requirements for materials have changed a lot, and the required material must be low loss. The factors that affect the insertion loss on the micro -band circuit In addition to the insulation, the copper conductor becomes more critical. This is mainly determined by the smoothness of copper, because in an environment with a very high frequency, the skin collection effect will occur, so the roughness of copper foil becomes more important. Different frequencies of electronic devices have different design requirements, and circuits suitable for different frequencies need to be supported by different characteristics. Usually loss increases with the increase in frequency, and according to the type of circuit material, insertion or loss factor will be large or small. For microwave frequencies, the requirements of key parameters of circuit materials (dielectric constant DK) are very different, such as 6GHz for 5G systems and below microwave frequencies, and short -distance returning links for 5G wireless networks to return to the link of 30 GHz With the above millimeter wave frequency, the design requirements are to select the best circuit material for each band to support different frequencies.

When looking for circuit materials for microwave and millimeter -wave power amplifiers suitable for 5G applications, in addition to DK and DF, it is necessary to perform effective thermal management circuit materials, because its own active devices will cause heat increases. The thermal properties of the evaluation material are generally believed that the thermal conductivity of the substrate must be at 0.5 W / m · K parameter thermal conductivity and the temperature coefficient of the dielectric constant (TCDK). Or higher. The TCDK ideal of the substrate is 0 PPM /℃, that is, DK will not change with changes in temperature, but the DK value of the actual substrate will change with the temperature. It is generally considered that the TCDK is not greater than 0.005% /℃. It is very good. Essence For the amplifier and other circuits in the 5G system, the circuit substrate is required to have low DK, DF, and low TCDK values, as well as high heating rates to create high -quality, high -performance, high -frequency power amplifiers.

The new generation of PCB focuses on the field of 5G communication and automotive electronics, making PCB reflect high -frequency and high -speed characteristics and high heat dissipation characteristics. To meet the requirements of high -frequency and high -speed and high heat dissipation performance, in addition to design and manufacturing factors, it is particularly important. Therefore, substrate materials should be regarded as the core technology of PCB, especially high -performance substrates are the lifeblood of high -performance PCB.

2. The gap between high performance substrate

In order to meet the needs of 5G transmission rates, high -frequency communication, large -scale antenna technology and active antenna technology (AAU) technology will be widely used. Many different types of high -frequency circuits, including power amplifiers (PA), require appropriate circuit materials. The demand for directly promoting the demand for the high -frequency CCL material (PTFE and hydrocarbons) of the base station's radio frequency front -end is 15-20 times. The core requirements of high -frequency materials are low -agency constant (DK) and low -agent electrical loss factor (DF). At present, the mainstream high -frequency products are achieved by using polytefluoroethylene (PTFE) and hydrocarbons. Rogers (55%) Park/Nelco (22%), ISOLA (9%), and ZTE (5%) occupy the major market share, of which Rogers PTFE has a market share of more than 90%[5]. At present, the high -performance copper -covering board (CCL) of companies such as Rogers occupies my country's high -performance PCB market. At present, the current high -frequency and high -speed PCB base materials use the specifications of foreign companies.

2.1 Examples of high -performance substrates abroad

Check some product technical information of PCB substrate manufacturing companies such as copper -covering layer (CCL). The international advanced CCL manufacturers include Roger S, ISOLA, Park ElectroChemica, Taikang Nick (Taconic), Ventec, Panasonic, etc. It is now based on Panasonic, Tenghui, and some typical products of Rogers. For example, Matsushita's ultra-low loss multi-layer board substrate MEGTRON7, model R-5785N (CCL), R-5680 (PP), DK at 1 GHz is 3.37, DF to 0.001, and 12GHz DK is 3.35, DF is 0.002 to 0.002 at 12GHz, 0.002 is 0.002. Essence This is a multi -layer circuit board material with the lowest industrial transmission loss, which meets the requirements of high -end network equipment large capacity and high -speed transmission, and helps improve its signal processing performance.

Panasonic has recently launched an ultra-low transmission loss circuit board material suitable for semiconductor packaging and modules. The product model is R-G545 L/R-G545 E. Pre-immersion R-G540L/R-G540E. The T G230 ℃, CTE (x, Y -A X I s) of R -G545L (x, Y -A X I s) (0.0 0 0 1%/ ℃), CTE (z -a x i s) (0.0022%/ ℃), 12 GHz DK3.5, DF 0.0026,, DK3.5, DF 0.0026,, DK3.5, DF 0.0026,, DK3.5, DF 0.0026,, DK, DF 0.0026,, DK3.5, DF 0.0026,, DK3.5, df 0.0026, The water absorption rate is 0.06%.

Rogers has a series of high -frequency high -speed and high -thermal conductivity substrates. Its CCL composition has polytrafluorothene (PTFE) resin glass cloth enhancement, PTFE resin filling ceramics, PTFE resin filling ceramic glass cloth enhanced classes, modified epoxy epoxy Resin fills ceramics, hydrocarbon -filled ceramic, hydrocarbon resin filling ceramic glass cloth enhanced class, filling ceramic thermal polymer polymer, polyether ether (PEEK) resin glass cloth enhanced class. For example, its antenna -grade glass cloth PTFE substrate AD250CTM is 2.50, DF is 0.0013 at 10GHz, and the cross -layer glass cloth PTFE substrate CUCLAD 217 is 2.17 and DF at 0.0009 at 10 GHz; 3.0, DF is 0.0010; such as antenna -grade hydrocarbons plus ceramics and glass cloth RO4725JXRTM at 10 GHz DK to 2.64, DF to 0.0026, hydrocarbon compound plus ceramic TTM3 at 10 GHz DK is 3.45, DF is 0.0020; At 10 GHz, the DK is 3.3 and DF to 0.0035 at 10 GHz.

In particular, Rogers does not simply provide high -performance substrates, but provides advanced connection solutions (ACS). Not only launch a variety of high -performance CCL and adhesion products, but also have the specific performance and application field introduction of various products, as well as PCB design and processing technical guidelines. Rogers has been closely related to microwave and RF engineers. There is a very good technical service team closely cooperating with PCB manufacturers and partners to provide help related to design and processing technology. A high -efficiency cooperation relationship has been formed between electrical designers, manufacturers and materials suppliers. These measures are also important factor selected by their substrates by more PCB manufacturers. In terms of high -conducting substrate materials, Tenghui's products are relatively prominent. For example, metal -based copper plates can choose different substrates and insulation layers. The heating rate is complete from 1 W/m · K to 10 W/m · K. The thermal conductivity of the model VT-4B7 is 7.0 W/m · k, and the thermal conductivity of the model VT-4B9 is 10.0 W/m · k. In addition, there are high -condition plates and pre -immersed materials suitable for ceramic filling with ceramics. (Model VT-5A2), the heating rate is 2.2 W/M · K is 8 times that of FR-4.

2.2 Domestic high -performance substrate example

The leading domestic CCL manufacturing companies, such as the top domestic CCL output ranking in 2017: Guangdong Shengyi Technology, Jinan Guoji Technology, Shandong Jinbao Electronics, South Asia New Materials Technology, Zhejiang Huazheng New Materials, DVD, V2V and other brands. Except for the bronze plate of the paper base of Shandong Jinbao Electronics, the new substrate of CCL and adhesive slices (PP) of high -performance CCL and adhesion (PP) is now available as follows:

2.2.1 high -frequency high -speed substrate aspect

Guangdong Shengyi Technology Company's high -speed circuit substrate: S7045G/S7045GB, 1 GHz DK is 4.4, DF is 0.010, 5 GHz DK is 4.5, DF is 0.015, high TG halogen, lower Z -axis CTE. Application fields: communication, server, base station, backplate, wire card, high -performance computer, office router, etc. RF and microwave circuit substrates: S7136H, 10 GHz DK is 3.42 and DF to 0.0030, which belongs to electronic -grade glass fiber cloth to enhance the four -axis aircraft ceramic filler and hydrocarbon composite media. Stable dielectric energy at different frequencies, low swelling factor of Z axis, and excellent size stability. Application areas: high -frequency wireless communication, high -speed computer, satellite signal transmission equipment, microstructure and cellular base stations, antenna and power amplifiers. The dielectric performance of these substrates is close to the low -loss range. Although its application areas are wide, the depth is not clear.

South Asia New Materials Technology Company has high -speed circuit (very low loss) CCL: NY6300, 1 GHz DK is 3.7, DF to 0.002, and 10 GHz DK is 3.6 and DF to 0.004. In addition, the microwave/radio frequency electronic glass cloth enhances the polytefluoroethylene group CCL. Only the model (NYHP-220D, 255D, 265D) is found, but there is no specific performance specification value.

Zhejiang Huazheng New Materials Company has H5300 and H5220, which is suitable for the base station antenna, airborne, ground and water surface radar system. When these products only see the test data of 10GHz, the DK is 3.0, 2.2, and the DF is 0.0020, 0.0009. I wonder if the specifications of the commercialization and commercialization are?

2.2.2 High -thermal conductivity aspect

Guangdong Shengyi Technology Co., Ltd. has high heat conductors FR-4, heat-conducting adhesion (ST115, ST115B), and armal conductivity 1.5 W/m · K. Excellent heat dissipation is 3 to 4 times that of ordinary RF-4. In addition, it has excellent heat resistance and insulation reliability and relatively excellent processing and low Z axis thermal expansion coefficient. (Application field: automotive electronic equipment, high brightness LED, power circuit, DC rectifier). There are aluminum -based copper plate SAR15 and SAR20, the insulation layer is a glue film, and the thermal conductivity is 1.5 W/M • K, 2.0 W/m • K. Halogless high CTI products, excellent heat dissipation, excellent peeling strength, excellent heat resistance and insulation reliability, excellent processing. (Application field: medium -power LED lighting, LED TV, power circuit).

Jinan Guoji Technology Company has aluminum -based copper plates. The distinction of thermal conductivity includes ≤1.0 W/(M • K), 1.0 to 1.5 w/(m • k), greater than 1.5 ≤ 2.0 w/(m • k), etc. Series. Suitable for LED lighting, LED TV, power amplifier, switch, automotive electronics equipment, input and output amplifier, DC/AC converter, rectifier, high -power transistor and other industries.

Huazheng New Materials Co., Ltd. also has cooling metal -based copper plates and adhesive slices, and its heating rate is not prominent and no longer described it. In addition, look at the products that are slightly famous in China to produce special substrate companies, such as Changzhou Chaoshun Electronic Technology Co., Ltd., which specializes in the production of metal-based copper plates, which believes that the aluminum-based copper plate CCAF-06, which is close to the international advanced level, The thermal conductivity is 2.5 ~ 2.8 w/m · k. Taizhou Wangling Insulation Material Factory, which specializes in the production of polytetrafluoroethylene substrates, is covered with a copper foil plate F4B255 for the polytetrafluoroethylene glass cloth. At 10 GHz, the DK is 2.55, and the DF is 0.0015. This product's dielectric constant and medium loss is that the PTFE resin factors are indeed low, but there is still a gap in comprehensive indicators such as TCDK values.

For the requirements of high -performance substrates, in addition to theaters of dielectric constant and medium loss, there are also related indicators such as heat resistance, heat dissipation, thermal expansion coefficient, and water absorption. High -performance substrates are also reflected in the type of resin and filler, woven glass cloth structure, and low roughness of copper foil. Other high -performance substrate materials, such as substrates for integrated circuit packaging boards, deflection PCB liquid crystal polymer (LCP) resin substrates, etc., have not yet seen domestic similar commercial substrates.

3. End language

Printing circuit boards are products that set up conductive circuits on the insulation substrate. Many important performances determine the inherent characteristics of substrate materials, so they regard PCB substrate technology as the core technology of PCB. Especially for high -performance PCB, the core position of high performance substrates is the lifeblood of the new generation of PCB.