At present, there are several types of copper clad plates widely used in China, and their characteristics are as follows: there are many types of copper clad plates, knowledge of copper clad plates, and classification methods of copper clad foil plates.

 

Generally, according to the different reinforcement materials of the board, it can be divided into five categories: paper base, glass fiber cloth base, composite base (CEM Series), laminated multilayer board base and special material base (ceramic, metal core base (common aluminum base plate), etc.).

 

If classified according to different resin adhesives used in the board, common paper-based CCIS include phenolic resin (XPC, xxxpc, FR-1, FR-2, etc.), epoxy resin (Fe-3), polyester resin, etc. Common glass fiber cloth base CCL includes epoxy resin (FR-4, FR-5), which is the most widely used type of glass fiber cloth base at present. In addition, there are other special resins (glass fiber cloth, polyimide fiber, non-woven fabric, etc. are added): bismaleimide modified triazine resin (BT), polyimide resin (PI), diphenylene ether resin (PPO), maleic anhydride imide styrene resin (MS), cyanate resin, polyolefin resin, etc.

 

According to the fire-retardant performance classification of CCL, it can be divided into two types of boards: flame retardant (ul94-v0, ul94-v1) and non flame retardant (ul94-hb).

 

In recent oneortwo years, with more attention to environmental protection issues, a new type of CCL without bromine was separated from the flame retardant CCL, which can be called "green flame retardant CCL". With the rapid development of electronic product technology, there are higher performance requirements for CCL. Therefore, according to the performance classification of CCL, it can be divided into general performance CCL, low dielectric constant CCL, high heat resistance CCl (the L of general plate is above 150 ℃), low thermal expansion coefficient CCl (generally used on packaging substrate), etc. With the development and progress of electronic technology, new requirements are put forward for PCB substrate materials, which promotes the continuous development of copper clad laminate standards.

 

At present, the main standards of substrate materials are as follows:

① National standards: China's national standards for substrate materials include GB / t4721-47221992 and gb4723-4725-1992. The standards for copper clad laminates in Taiwan, China are CNS standards, which were formulated based on Japanese JIS standards and issued in 1983.

② International standards: Japanese JIS standards, American ASTM, NEMA, mil, IPC, ANSI, UL standards, British BS standards, German DIN and VDE standards, French NFC and ute standards, Canadian CSA standards, Australian as standards, former Soviet FOCT standards, international IEC standards, etc; Suppliers of PCB design materials commonly used include: Shengyi, Jiantao, international, etc.

 

Introduction to PCB board: it is divided into 94hb － 94vo － CEM-1 － CEM-3 － FR-4 according to the brand quality level from bottom to top

 

Detailed parameters and uses are as follows:

94hb: ordinary paperboard, not fireproof (the lowest grade material, die punching, can not be used as power board)

94v0: flame retardant paperboard (die punching)

22F: single side half fiberglass board (die punching)

CEM-1: single side fiberglass board (computer drilling is required, and die punching is not allowed)

CEM-3: double sided half fiberglass board (except for double-sided paperboard, it is the lowest end material of double-sided board. This material can be used for simple double-sided board, which is 5~10 yuan / m2 cheaper than FR-4)

Fr-4: double sided fiberglass board

1. the classification of flame retardant characteristics can be divided into four types: 94vo-v-1-v-2-94hb

2. semi cured sheet: 1080=0.0712mm, 2116=0.1143mm, 7628=0.1778mm

3. FR4 CEM-3 refers to plate, FR4 refers to fiberglass board, and cem3 refers to composite substrate

4. halogen free refers to the base material that does not contain halogen (fluorine, bromine, iodine and other elements), because bromine will produce toxic gas during combustion, which is required by environmental protection.

5. TG is the glass transition temperature, i.e. the melting point.

6. the circuit board must be fire-resistant. It cannot burn at a certain temperature and can only be softened. The temperature point at this time is called the glass transition temperature (TG point), which is related to the dimensional durability of PCB.

What is high Tg? PCB circuit board and advantages of using high Tg PCB:

When the temperature of high Tg printed circuit board rises to a certain threshold value, the substrate will change from "glass state" to "rubber state". The temperature at this time is called the glass transition temperature (TG) of the board. That is, TG is the maximum temperature (℃) at which the substrate remains rigid 。 In other words, common PCB substrate materials constantly produce softening, deformation, melting and other phenomena under high temperature, and also show a sharp decline in mechanical and electrical properties, which will affect the service life of the product. Generally, the TG plate is more than 130 ℃, the high Tg is generally more than 170 ℃, and the medium TG is about more than 150 ℃; Generally, PCB printed boards with TG ≥ 170 ℃ are called high Tg printed boards; The Tg of the substrate is improved, and the heat resistance, moisture resistance, chemical resistance, stability and other characteristics of the printed board will be improved. The higher the TG value is, the better the temperature resistance of the plate is. Especially in the lead-free process, high Tg is widely used; High Tg means high heat resistance. With the rapid development of the electronic industry, especially the electronic products represented by computers, which are developing towards high functionality and high multilayer, higher heat resistance of PCB substrate materials is required as a prerequisite. With the emergence and development of high-density installation technology represented by SMT and CMT, PCB is increasingly inseparable from the support of high heat resistance of the substrate in terms of small aperture, fine wiring and thin.

 

Therefore, the difference between general FR-4 and high Tg: at the same high temperature, especially after moisture absorption and heating, the mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, thermal expansion and other conditions of the material are different. High Tg products are obviously better than ordinary PCB substrate materials.