How to improve the quality of multi-layer board lamination?
D. Organic matching of lamination parameters control of multi-layer board lamination parameters mainly refers to the organic matching of lamination “temperature, pressure, and time”.
1. There are several temperature parameters in the temperature and lamination process that are more important. That is, the melting temperature of the resin, the curing temperature of the resin, the set temperature of the hot plate, the actual temperature of the material, and the rate of temperature increase. The melting temperature is when the temperature rises to 70°C, the resin starts to melt. It is because of the further increase in temperature that the resin further melts and starts to flow. During the period of temperature 70-140℃, the resin is easy to fluid. It is because of the fluidity of the resin that the filling and wetting of the resin can be ensured.
As the temperature gradually increases, the fluidity of the resin goes from small to large, then to small, and finally when the temperature reaches 160-170°C, the fluidity of the resin is 0, and the temperature at this time is called the curing temperature. In order to make the resin better fill and wet, it is very important to control the heating rate. The heating rate is the embodiment of the lamination temperature, that is, to control when the temperature rises and how high. The control of the heating rate is an important parameter for the quality of multilayer laminates, and the heating rate is generally controlled at 2-4°C/MIN. The heating rate is closely related to the different types and quantities of PP. For 7628PP, the heating rate can be faster, that is, 2-4℃/min. For 1080 and 2116PP, the heating rate can be controlled at 1.5-2℃/MIN. At the same time, the number of PP is large, and the heating rate cannot be too fast, because the heating rate is too fast, PP wettability of the resin is poor, the resin has high fluidity, and the time is short. It is easy to cause slippage and affect the quality of the laminate. The temperature of the hot plate mainly depends on the heat transfer of the steel plate, steel plate, corrugated paper, etc., generally 180-200°C.
2. The pressure and the pressure of the multilayer laminate are based on whether the resin can fill the voids between the layers and exhaust the interlayer gas and volatiles as the basic principle. Since the hot press is divided into a non-vacuum press and a vacuum hot press, there is a period of pressurization from the pressure. There are several ways of two-stage pressurization and multi-stage pressurization. Generally, non-vacuum presses use general pressurization and two-stage pressurization. The vacuum machine adopts two-stage pressurization and multi-stage pressurization. Multi-stage compression is usually used for high, fine multilayer PCB boards. The pressure is generally determined according to the pressure parameters provided by the PP supplier, generally 15-35kg/cm2.
3. Time and time parameters are mainly the control of the timing of lamination and press, the control of the timing of temperature rise, and the gel time. For two-stage lamination and multi-stage lamination, controlling the timing of the main pressure and determining the transition time from the initial pressure to the main pressure is the key to controlling the quality of the lamination. If the main pressure is applied too early, the resin will be extruded, too much glue will flow out, and the laminate will lack glue, the board will be thin, and even slippery. If the main pressure is applied too late, it will cause defects such as weak, void, or air bubbles in the lamination bonding interface.
Therefore, how to determine the lamination temperature, pressure, and time software parameters is the key technology for multilayer laminate processing. According to many years of practical experience in lamination, it is believed that the “temperature, pressure, and time” of the lamination software parameters are organically matched, and only the pressure is tested first. On the good basis, the most ideal “temperature, pressure, time” software parameters can be determined. But the “temperature, pressure, time” parameters can be determined according to different PP combination structures, different PP suppliers, different PP models, and different characteristics of the PP itself to determine the corresponding lamination parameters.
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