What is a semi-cured sheet? It is "PP sheet", one of the main materials in the production of multilayer ...
What is a semi-cured sheet? It is "PP sheet", one of the main materials in the production of multilayer board. It is mainly composed of resin and reinforcing materials. Reinforcing materials are divided into glass fiber cloth, paper base, composite materials and other types, while the semi-cured sheet (adhesive sheet) used in the production of multilayer printed board is mostly made of glass fiber cloth as reinforcing material.
The thin sheet material made of processed glass fiber cloth, impregnated with resin glue solution, and then heat treated (pre-baked) is called semi-cured sheet. It will soften under heating and pressure, and solidify after cooling. Due to the difference in the number of strands of glass fiber cloth per unit length in warp and weft, attention should be paid to the warp and weft of the semi-cured sheet when cutting. Generally, warp (the direction of glass fiber cloth crimp) is selected as the direction of short side of production board, while weft is the direction of long side of production board, so as to ensure the flatness of the board surface and prevent distortion of the board after being heated.
The main appearance requirements of the semi-cured sheet for multilayer board are: the cloth surface should be smooth, free from grease, stains, foreign impurities or other defects, free from breakage and excessive resin powder, but micro cracks are allowed. In PCB design, semi-cured sheet must be used if the design is multilayer. In addition, in the process of multi-layer copying board , it must be polished off in order to accurately analyze the circuit diagram of the sample.
The semi-cured sheet belongs to the raw material. It is a semi-finished product.