Currently, the following types of copper-clad laminates are widely used in our country, and their characteristics are as follows: Types of copper-clad laminates, copper-clad laminate knowledge, and 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 multi-layer board base and special material base (ceramic, metal core base, etc.).

If classified according to the resin adhesive 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 fiberglass cloth-based CCLs include epoxy resin (FR-4, FR-5), which is currently the most widely used fiberglass cloth-based type. There are also other special resins (using 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 flame retardant performance classification of CCL, it can be divided into two types of boards: flame retardant type (UL94-VO, UL94-V1 level) and non-flame retardant type (UL94-HB level). In the past year or two, as more attention has been paid to environmental protection issues, a new type of CCL that does not contain bromine 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 (generally the L of the board is above 150°C), and low thermal expansion coefficient CCL (generally used on packaging substrates). ) and other types. With the development and continuous progress of electronic technology, new requirements are constantly put forward for printed board substrate materials, thus promoting the continuous development of copper-clad laminate standards. At present, the main standards for substrate materials are as follows

① National standards: my country’s national standards for substrate materials are GB/T4721-47221992 and GB4723-4725-1992. The copper-clad laminate standard in Taiwan is CNS The standard is based on the Japanese JIs standard and was released in 1983.

② International standards: Japan's JIS standard, American ASTM, NEMA, MIL, IPc, ANSI, UL standards, British Bs standards, German DIN and VDE standards, French NFC and UTE standards, Canada's CSA standards, Australia's AS standards, the former Soviet Union's FOCT standards, international IEC standards, etc.; common suppliers of PCB design materials include: Shengyi\Kingboard\International, etc.

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

Detailed parameters and uses As follows:

94HB: Ordinary cardboard, not fireproof (the lowest grade material, die-punched, cannot be used as a power board)

94V0: Flame-retardant cardboard (die-punched)

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22F: Single-sided semi-glass fiber board (die punching)

CEM-1: Single-sided fiberglass board (must be computer drilled, not die punched)

< p>CEM-3: Double-sided semi-glass fiber board (except for double-sided cardboard, it is the lowest-end material for double-sided panels. Simple double-sided panels can use this material, which is 5~10 yuan/square meter cheaper than FR-4)

FR-4: Double-sided fiberglass board

1. The classification of flame retardant properties can be divided into four types: 94VO-V-1-V-2-94HB

< p>2. Pre-cured sheet: 1080=0.0712mm, 2116=0.1143mm, 7628=0.1778mm

3. FR4 CEM-3 all represent boards, fr4 is fiberglass board, and cem3 is composite substrate

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4. Halogen-free refers to substrates that do not contain halogens (fluorine, bromine, iodine and other elements), because bromine will produce toxic gases when burned, which is environmentally friendly.

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

6. The circuit board must be flame-resistant and cannot burn at a certain temperature, but can only soften. The temperature point at this time is called the glass transition temperature (Tg point). This value is related to the dimensional durability of the PCB board.

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

When the temperature of high Tg printed circuit board rises to a certain threshold, the substrate will change from "glass state" to "rubber state". The temperature at which is called the glass transition temperature (Tg) of the plate. In other words, Tg is the maximum temperature (°C) at which the substrate remains rigid.

That is to say, ordinary PCB substrate materials continue to soften, deform, melt and other phenomena under high temperatures. At the same time, they also show a sharp decline in mechanical and electrical properties. This affects the service life of the product. Generally, the Tg of the board is 130 Above ℃, high Tg is generally greater than 170℃, medium Tg is about greater than 150℃; usually PCB printed boards with Tg ≥ 170℃ are called high Tg printed boards; as the Tg of the substrate increases, the heat resistance of the printed board, Characteristics such as moisture resistance, chemical resistance, and stability resistance will be increased and improved. The higher the TG value, the better the temperature resistance of the board. Especially in lead-free processes, high Tg is widely used; high Tg refers to high heat resistance. With the rapid development of the electronics industry, especially electronic products represented by computers, which are developing towards high functionality and high multi-layering, higher heat resistance of PCB substrate materials is required as a prerequisite. The emergence and development of high-density mounting technologies represented by SMT and CMT have made PCBs increasingly inseparable from the support of high heat resistance of substrates in terms of small apertures, fine wiring, and thinness.

So the difference between general FR-4 and high Tg: at high temperatures, especially when heated after moisture absorption, the mechanical strength, dimensional stability, adhesion, water absorption, and thermal properties of the material There are differences in various conditions such as decomposition and thermal expansion. High Tg products are obviously better than ordinary PCB substrate materials.