Generally, PCB substrate materials can be divided into two categories: rigid substrate materials and flexible substrate materials. Copper clad laminate is an important material for rigid substrates. It is made of reinforced material (Reinforeing Material), impregnated with resin adhesives, through drying, cutting and stacking, then coated with copper foil, using steel plate as a die, and processed by high temperature and high pressure forming in a hot press. Generally, the semi-cured sheet for multilayer board is the semi-finished product of copper clad board in the process of manufacture (mostly glass cloth impregnated with resin, dried and processed).
There are many classification methods for 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), laminated multilayer board base and special material base (ceramics, metal core base, etc.). Common paper-based CCI is classified according to the different resin adhesives used in the board. There are: phenolic resin (XPc, XxPC, FR-1, FR-2, etc.), epoxy resin (FE-3), polyester resin and other types. The common glass fiber cloth CCL is epoxy resin (FR-4, FR-5), which is the most widely used type of glass fiber cloth. In addition, there are other special resins (glass fiber cloth, polyamide fiber, non-woven fabric, etc.): bismaleimide modified triazine resin (BT), polyimide resin (PI), diphenyl ether resin (PPO), maleic anhydride imide-styrene resin (MS), polycyanate resin, polyolefin resin and so on.
According to the flame retardancy of CCL, it can be divided into two types: flame retardant (UL94-VO, UL94-V1) and non-flame retardant (UL94-HB). In the past 12 years, with more attention paid to environmental protection, a new type of CCL without bromine was separated in flame retardant CCL, which can be called "green flame retardant cCL". With the rapid development of electronic products 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 (general plate L is above 150 C), low thermal expansion coefficient CCL (commonly used on packaging substrates) and other types.
With the development of electronic technology and continuous progress, new requirements for PCB substrate materials are constantly put forward, so as to promote the continuous development of copper clad foil standards. At present, the main standards of substrate materials are as follows.
(1) At present, the national standards for substrate materials in China are GB/T4721-4722 1992 and GB 4723-4725-1992. The copper clad foil standard in Taiwan, China is CNS standard, which is based on the Japanese JIs standard. It was issued in 1983.
(2) The main standards of other countries are: JIS standards of Japan, ASTM, NEMA, MIL, IPc, ANSI and UL standards of the United States, Bs standards of the United Kingdom, DIN and VDE standards of Germany, NFC and UTE standards of France, CSA standards of Canada, AS standards of Australia, FOCT standards of the former Soviet Union, international IEC standards, etc.