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Mainboard classification

Shenzhen Inno Circuit Co.,Ltd | Updated: Jun 01, 2018

Mainboard classification

 At present, many types of copper-clad laminates used in China are of the following types. Their characteristics are as follows: The type of copper-clad laminates, the knowledge of copper-clad laminates, and the classification methods of copper-clad laminates are various.

According to the different reinforcing materials of the board, it can be divided into: paper base, glass fiber cloth base, composite base (CEM series), multi-layer base board and special material base (ceramic, metal core base (common aluminum base), etc. ) Five categories.

According to the different types of resin adhesive used in the board, common paper-based CCIs include: phenolic resins (XPc, XxxPC, FR-1, FR-2, etc.), epoxy (FE-3), and polyester. Resin and other types. The common glass fiber cloth-based CCL has epoxy resin (FR-4, FR-5), which is currently the most widely used type of glass fiber cloth base. In addition, there are other special resins (glass fiber cloth, polyamide fibers, non-woven fabrics, etc. as additional materials): Bismaleimide modified triazine resin (BT), polyimide resin (PI) Diphenylene ether resin (PPO), maleic anhydride imine-styrene resin (MS), polycyanate resin, polyolefin resin, etc.

According to the classification of fire retardant performance of CCL, it can be divided into two types of flame-retardant (UL94-V0, UL94-V1) and non-flame-retardant (UL94-HB) boards.

In the past year or two, with the increasing emphasis on environmental protection issues, a new type of CCL that does not contain bromine has been identified in the flame-retardant CCL, which can be referred to as “green type flame retardant cCL”. With the rapid development of electronic product technology, there are higher performance requirements for cCL. Therefore, from the performance classification of CCL, it is divided into general performance CCL, low dielectric constant CCL, high heat resistance CCL (L of general board is above 150°C), low thermal expansion coefficient CCL (usually used on package substrates ) And other types. With the development and continuous advancement of electronic technology, new requirements have been continuously put forward for printed circuit board substrate materials, thereby promoting the continuous development of copper clad board standards.

At present, the main criteria for substrate materials are as follows:

1 National standards: China's national standards for substrate materials are GB/T 4721-47221992 and GB 4723-4725-1992. The copper-clad plate standard in China's Taiwan region is the CNS standard, which is based on the Japanese JIs standard. It was established in 1983. release.

2 International Standards: Japanese JIS Standards, American ASTM, NEMA, MIL, IPc, ANSI, UL Standards, British Bs Standards, German DIN, VDE Standards, French NFC, UTE Standards, Canadian CSA Standards, Australian AS standards, FOCT standards of the former Soviet Union, international IEC standards, etc.; suppliers of PCB design materials, common and frequently used ones are: Health Benefits, Jianye International, etc.

PCB circuit board sheet introduction: According to the brand quality level from bottom to top divided as follows: 94HB-94VO-CEM-1-CEM-3-FR-4

Detailed parameters and uses are as follows:

94HB: plain cardboard, not fireproof (lowest material, die punching, cannot be used as a power strip)

94V0: flame-retardant cardboard (die punching)

22F: Single Half Fiberglass Plate (Die Punching)

CEM-1: single-sided glass fiber board (must be drilled by computer, can not be punched)

CEM-3: double-sided half glass fiber board (in addition to double-sided cardboard is the lowest end of the double-sided material, a simple double-sided board can use this material, will be cheaper than the FR-4 5 ~ 10 yuan / square meter)

FR-4: Double-sided Fiberglass Board

1. Classification of flame retardancy characteristics can be divided into 94VO-V-1 -V-2 -94HB four kinds

2. Prepreg: 1080=0.0712mm, 2116=0.1143mm, 7628=0.1778mm

3. FR4 CEM-3 is for sheet metal, fr4 is fiberglass, cem3 is composite substrate

4. Halogen-free refers to a substrate that does not contain halogens (such as bromobromoiodide), because bromine generates toxic gases when burned, and environmental protection is required.

5. Tg is the glass transition temperature, the melting point.

6. The circuit board must be flammable, 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), and this value is related to the dimensional durability of the PCB board.

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

High Tg printed circuit board When the temperature rises to a certain threshold, the substrate will change from "glassy state" to "rubbery state", and the temperature at this time is called the glass transition temperature (Tg) of the plate. That is, Tg is the maximum temperature (° C.) at which the substrate maintains rigidity. In other words, ordinary PCB substrate materials continue to produce softening, deformation, melting and other phenomena at high temperatures, while also showing a sharp decline in mechanical and electrical properties. This affects the service life of the products. Generally, the Tg plate is 130. Above °C, high Tg is generally greater than 170 °C, medium Tg is greater than 150 °C; PCBs with Tg ≥ 170 °C are generally referred to as high Tg printed boards; the Tg of the substrate is increased, and the heat resistance of the printed board is increased. Moisture resistance, chemical resistance, stability and other characteristics will be improved and improved. The higher the TG value, the better the temperature resistance of the plate, especially in the lead-free process, high Tg applications are more; high Tg refers to high heat resistance. With the rapid development of the electronics industry, electronic products represented by computers, in particular, are moving towards higher functionality and higher levels of multi-layered development, and the higher heat resistance of PCB substrates is a prerequisite. The emergence and development of high-density mounting technologies represented by SMT and CMT have made it possible for PCBs to be inseparable from the substrate's high heat resistance in terms of small aperture, fine line, and thin profile.

Therefore, the difference between the general FR-4 and high Tg: At the same time under high temperature, especially after heat absorption, the mechanical strength, dimensional stability, adhesion, water absorption, thermal decomposition, thermal expansion and other There are differences in the situation, high Tg products are obviously better than ordinary PCB substrate materials.