PCB News - Introduction to common plates and parameters of circuit boards

Introduction to common plates and parameters of circuit boards
PCB circuit board board introduction: according to the brand quality level from bottom to high as follows: 94HB－94VO－22F－CEM-1－CEM-3－FR-4
The detailed parameters and uses are as follows:
94HB: ordinary cardboard, not fireproof (the lowest grade material, die punching, can not be used as a power supply board)
94V0: Flame Retardant Cardboard (Die Punching)
22F: Single-sided half glass fiber board (die punching)
CEM-1: Single-sided fiberglass board (computer drilling is necessary, not die punching)
CEM-3: Double-sided semi-glass fiber board (except for double-sided cardboard, it is the lowest-end material of double-sided board. Simple double-sided board can use this material, which is 5~10 yuan/square meter cheaper than FR-4)
FR-4: Double-sided fiberglass board
The grades of flame retardant properties can be divided into four types: 94VO-V-1 -V-2 -94HB
Semi-cured film: 1080=0.0712mm, 2116=0.1143mm, 7628=0.1778mm
FR4 and CEM-3 are all plates, fr4 is glass fiber board, cem3 is composite substrate
Halogen-free refers to the base material that does not contain halogen (fluorine, bromine, iodine and other elements), because bromine will produce toxic gas when burned, which is environmentally friendly.
Tg is the glass transition temperature, or melting point.
The circuit board must be flame-resistant, cannot burn at a certain temperature, but 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 circuit board and the advantages of using high Tg PCB
When the temperature of the high Tg printed circuit board rises to a certain threshold, the substrate will change from the "glass state" to the "rubber state". The temperature at this time is called the glass transition temperature (Tg) of the board. That is, Tg is the highest temperature (°C) at which the base material maintains rigidity. That is to say, ordinary PCB substrate materials will continue to soften, deform, and melt at high temperatures. At the same time, they will also show a sharp decline in mechanical and electrical characteristics. This will affect the service life of the product. Generally, the Tg plate is 130 degree Celsius above, high Tg is generally greater than 170 degree Celsius, medium Tg is greater than 150 degree Celsius; usually Tg ≥ 170 degree Celsius PCB printed board, called high Tg printed board; substrate Tg increased, printed board heat resistance, Features such as moisture resistance, chemical resistance, and stability will be improved and improved. The higher the TG value, the better the temperature resistance of the board. Especially in the lead-free process, high Tg is used more; high Tg refers to high heat resistance. With the rapid development of the electronic industry, especially the electronic products represented by computers, the development of high functionality and high multilayers requires higher heat resistance of PCB substrate materials as a prerequisite. The emergence and development of high-density mounting technologies represented by SMT and CMT have made PCBs more and more inseparable from the support of high heat resistance of substrates in terms of small aperture, fine wiring, and thinning.
Therefore, the difference between general FR-4 and high Tg: at the same high temperature, especially when heated after moisture absorption, the mechanical strength, dimensional stability, adhesiveness, water absorption, thermal decomposition, thermal expansion, etc. of the material There are differences in this situation. High Tg products are obviously better than ordinary PCB substrate materials.
PCB board knowledge and standards At present, there are several types of copper clad laminates that are widely used in our country, and their characteristics are as follows: the types of copper clad laminates, the knowledge of copper clad laminates, and the classification methods of copper clad laminates. Generally, according to the different reinforcing materials of the board, it can be divided into five categories: paper base, glass fiber cloth base, composite base (CEM series), multi-layer laminate base and special material base (ceramic, metal core base, etc.). If classified according to the different resin adhesives used in the board, the common paper-based CCI. There are: phenolic resin (XPc, XxxPC, FR-1, FR-2, etc.), epoxy resin (FE-3), polyester resin and other types. Common glass fiber cloth base 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 (with glass fiber cloth, polyamide fiber, non-woven fabric, 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 CCL's flame-retardant performance, it can be divided into two types: flame-retardant (UL94-VO, UL94-V1) and non-flame-retardant (UL94-HB). In the past one or two years, as more attention has been paid to environmental protection issues, a new type of non-bromine-free CCL has been divided into 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, from the performance classification of CCL, it is divided into general performance CCL, low dielectric constant CCL, high heat resistance CCL (normal board L is above 150 degree Celsius), low thermal expansion coefficient CCL (usually used on package substrates) ) And other types. With the development and continuous progress of electronic technology, new requirements are constantly being put forward for printed circuit board substrate materials, thereby promoting the continuous development of copper clad laminate standards. At present, the main standards of substrate materials are as follows.
1. National standards: my country's national standards for substrate materials include GB/T4721-47221992 and GB4723-4725-1992. The copper clad laminate standard in Taiwan, China is the CNS standard, which is based on the Japanese JIs standard and was formulated in 1983 release. gfgfgfggdgeeeejhjj
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, and Australian standards AS standards, FOCT standards of the former Soviet Union, international IEC standards, etc.; suppliers of PCB design materials, common and commonly used ones include: Shengyi \ Jiantao \ International, etc.