C. Treatment Process of Inner Core Board When laminating a multi-layer board, it is necessary to treat the inner core board. The treatment process for the inner core board includes the black oxidation treatment process and the brown treatment process. The oxidation treatment process involves forming a black oxide film on the inner layer of the copper foil, with a thickness ranging from 0.25-4.50mg/cm2. The brown process (horizontal browning) involves forming an organic film on the inner copper foil. The treatment process for the PCB inner layer board serves the following functions:

1. Increase the specific surface area of contact between the inner copper foil and the resin to enhance bonding.
2. Enhance the effective wettability of the molten resin to the copper foil, allowing the resin to flow and extend into the oxide film and show strong grip after curing.
3. Prevent the decomposition of the curing agent dicyandiamide in the liquid resin at high temperatures and the influence of moisture on the copper surface.
4. Improve the acid resistance of the multi-layer board and prevent the formation of pink circles during the wet process.
   D. Organic Matching of Lamination Parameters:
   Controlling the lamination parameters of a multi-layer board mainly involves the organic matching of “temperature, pressure, and time” during lamination. There are several important temperature parameters in the lamination process, including the melting temperature of the resin, the curing temperature of the resin, the set temperature of the hot plate, the actual material temperature, and the rate of temperature increase. The melting temperature refers to when the resin begins to melt at 70°C, which allows it to flow and fill voids. The curing temperature is reached at 160-170°C, where the resin no longer has fluidity. Controlling the heating rate is crucial for proper resin filling and wetting. Typically, the heating rate is controlled at 2-4°C/MIN. Additionally, the temperature of the hot plate is generally around 180-200°C. The lamination pressure is determined based on the ability of the resin to fill voids and exhaust gas and volatiles between layers, typically ranging from 15-35kg/cm2. Time parameters involve the timing of lamination and pressure, the timing of heating, and the gelation time, which are crucial for controlling the quality of the lamination.