Vacuum laminator parameter control mainly refers to the organic matching of "temperature, pressure, time" during laminating.
Several temperature parameters are important during the laminating process. That is, the melting temperature and solidification temperature of the resin, the set temperature of the heating plate, the actual temperature of the material, and the speed of temperature rise. The melting temperature is the temperature at which the resin begins to melt when the temperature rises to 70℃.
It is precisely because of the further increase in temperature that the resin further melts and begins to flow. During the period of 70-140℃, the resin is in a fluid state, and it is precisely because of the fluidity of the resin that the resin can be filled and wetted.
As the temperature gradually increases, the fluidity of the resin experiences a process of increasing and decreasing, and finally, when the temperature reaches 160-170℃, the flowability of the resin is zero, and this temperature is called the solidification temperature.
To ensure that the resin can be well filled and wetted, it is important to control the temperature rise rate. The temperature rise rate is a specific expression of laminating temperature, that is, when to control the temperature to rise to how much. The control of the temperature rise rate of the vacuum laminator is an important parameter for the laminating quality of multi-layer boards, and the temperature rise rate is generally controlled at 2-4℃/min. The temperature rise rate is closely related to the type, quantity, etc. of PP.
For 7628PP, the temperature rise rate can be faster, which is 2-4℃/min. For 1080 and 2116PP, the temperature rise rate is controlled at 1.5-2℃/min. At the same time, the quantity of PP is more and the temperature rise rate cannot be too fast. Because if the temperature rise rate is too fast, the wetting property of PP is poor, the fluidity of the resin is large, the time is short, and it is easy to cause slide plates, which will affect the laminating quality. The heating plate temperature mainly depends on the heat transfer situation of the steel plate, steel sheet, kraft paper, etc., and is generally 180-200℃.
The size of the pressure for multi-layer board laminating is based on the basic principle of whether the resin can fill the interlayer voids, exhaust interlayer gas and volatiles.
Since the hot press is divided into non-vacuum press and vacuum laminator, there is a pressure increase from the perspective of pressure. There are two-stage pressure, multi-stage pressure and other methods. Generally, non-vacuum presses adopt general pressure and two-stage pressure. Vacuum laminators adopt two-stage pressure and multi-stage pressure. For high-precision and fine multi-layer boards, multi-stage pressure is usually used. The pressure size is generally determined based on the pressure parameters provided by PP suppliers, generally 15-35kg/cm2.
The time parameter mainly controls the timing of laminating pressure, temperature rise, gel time, etc. For two-stage laminating and multi-stage laminating, controlling the timing of the main pressure and determining the moment when the initial pressure is converted to the main pressure is the key to controlling the laminating quality. If the main pressure is applied too early, it will cause too much resin extrusion and flow, resulting in a lack of bonding and thinness of the laminated board, and even defects such as slip plates. If the main pressure is applied too late, it will cause defects such as poor bonding interface, voids, or bubbles.
Therefore, how to determine the laminating soft parameter of "temperature, pressure, time" is the key technology for multi-layer board laminating. Based on years of practice with the vacuum laminator, we believe that the "temperature, pressure, time" parameters of the laminating soft organically match each other. Only based on the initial test pressure can the ideal "temperature, pressure, time" parameters be determined. However, the parameters can be determined according to different PP combinations, different PP suppliers, different PP models, and different characteristics of PP correspond to laminating parameters.