Prepreg/PP Sheet

Description of Prepreg/PP Sheet:

Also known as "PP sheet", it is one of the main insulation materials in the production of multi-layer board. It is mainly composed of resin and reinforcing material. The reinforcing material is divided into several types, such as fiberglass cloth, paper base and composite material. Most of the prepregs (bonded sheets) used in printed boards are made of fiberglass cloth.

Advantages of Prepreg/PP Sheet:

The treated fiberglass cloth Prepreg/PP sheet is impregnated with resin glue, and then heat-treated (pre-baked) to make the resin enter the B stage. The sheet material is called a prepreg, which softens under heat and pressure, and reacts and solidifies after cooling. Since the number of yarn strands of the glass fiber cloth in the warp direction and the weft direction is different, the warp and weft direction of the prepreg should be paid attention to during shearing. Generally, the warp direction (the direction in which the glass fiber cloth is curled) is selected as the short side direction of the production board, and the weft direction the long side direction of the board, in order to ensure the flatness of the board surface, preventing from being distorted after being heated.

The main appearance requirements of the prepreg used in the multilayer board are: the cloth surface should be flat, free of oil, stains, foreign matter or other defects, no cracks and excessive resin powder, but microcracks are allowed. In the design of the pcb, if it is a multi-layer board design, a prepreg must be used. In addition, in the process of multi-layer board copying, it must be polished away to accurately analyze the circuit diagram of the sample board.