Definition and classification of rigid PCB
In general, the definition of a rigid PCB substrate is a copper-clad laminate, which is what we usually say CCL. It is the use of reinforcing materials, impregnated with resin adhesive, by drying, cutting, stacked composite blanks, and then covered with copper foil, with a steel plate as a mold, in the hot press by high-temperature and high-pressure forming processing and made. The general multilayer plate with the semi-cured sheet is the copper-clad laminate in the production process of semi-finished products (mostly glass cloth impregnated with resin, by drying processing).
There are a variety of classification methods for copper-clad laminates.
The general classification method of the reinforcing material according to the plate can be divided into paper, glass fiber cloth, composite base (CEM series), multilayer laminates, special material base (ceramic, metal core base, such as our commonly used aluminum substrate is a special material base) five major categories.
If the resin adhesive used by the plate is classified in different ways, common are paper-based CCI, glass fiber cloth CCL, and other special resins. Paper-based CCI, including phenolic resins, namely XPC, XXXPC, FR-1, FR-2, etc., in addition to epoxy resin (FE-3), polyester resin and other types. Fiberglass cloth CCL, including epoxy (FR-4, FR-5), is the most widely used type of fiberglass cloth today. Other specific resins, these specific resin plates are usually made of glass fiber cloth, polyimide fiber, non-woven fabric, etc. for the addition of materials, such as double maleimide modified triazine resin (BT), polyimide resin (PI), diphenyl ether resin (PPO), maleic anhydride-styrene resin (MS), polyisocyanate resin, Polyolefin resin and so on.
According to the characteristics of the CCL classification of flame retardancy, it can be divided into flame-retardant (UL94-VO, UL94-V1 grade) and non-flame-retardant (UL94-HB) two types of board.
In the past one or two years, with more attention to environmental protection issues, in the flame-retardant CCL and a new type of non-bromine-containing CCL varieties, can be called “Green flame-retardant CCL.”
With the rapid development of electronic products technology, CCL has higher performance requirements. Therefore, from the CCL performance classification, also divided into general performance CCL, low dielectric constant CCL, high heat resistance of CCL (General Board of L at 150 ℃ above), the low thermal expansion coefficient of CCL (generally used to encapsulate the substrate) and other types. With the development of electronic technology and continuous progress, the PCB substrate materials constantly put forward new requirements, thereby promoting the continuous development of copper-clad laminate standards.