Principle of CCL Press
CCL press introduction to the principle of pressing copper clad laminate. The adhesive sheet first softens and melts under heat and pressure in the laminator, and the polymer becomes viscous fluid. With the temperature and time gradually increasing, the resin begins to cure, and the viscosity gradually increases. When it reaches the gel point, the viscosity rapidly increases. Dicyandiamide is a latent curing agent. In the presence of accelerator, it starts to slowly react with epoxy resin at 70 ℃, and after reaching 120 ℃, the reaction speed is accelerated. The reaction reached the peak at 150-155 ℃.
In this process, the polymer is gradually cross-linked and solidified, and the polymer is transferred from viscous fluid state to viscoelastic state. When the temperature reaches 175 ℃, the curing reaction is basically completed, the adhesive sheet is firmly bonded with the copper foil, and the product is completely hardened to form a copper clad plate. Therefore, heat must be supplied for copper clad laminate molding to facilitate the curing reaction. At the same time, it must be pressurized. Although the curing process of epoxy glass fiber cloth CCL is an addition polymerization reaction, due to the moisture absorption of dicyandiamide and various factors, there is still more or less some moisture and low molecular substances in the curing process. Therefore, it is necessary to pressurize and remove these moisture and low molecular substances to ensure that the product layers are firmly bonded without holes and air gaps. Pressurization can also increase the resin penetration into the glass fiber gap in the viscous flow state, which is conducive to improving the product density, product surface smoothness and the adhesion between the substrate and copper foil. Since there is little water and low molecular weight on the adhesive sheet, the pressure need not be as large as that of paper-based CCL. There is no need to "bleed" during the lamination pressure rise process. When using the laminating machine to press products, low molecular substances and water vapor are easier to escape under high vacuum, so relatively low laminating forming pressure can be used. After the curing reaction is completed, it must be cooled gradually to take out the product. Therefore, the laminating process includes heating, pressurizing and cooling, that is, the laminating machine should have the functions of heating, pressurizing and cooling.
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