The production of printed circuit board is very complicated. Here, a four-layer printed board is taken as an example to experience how PCBs are made.
A new raw material is needed here, called a prepreg, which is the adhesive between the core board and the core board (PCB layers>4), as well as the core board and the outer copper foil, and it also serves as an insulation.
The lower copper foil and the two layers of prepreg have been fixed in advance through the alignment hole and the lower iron plate, and then the finished core board is also placed in the alignment hole, and finally the two layers of prepreg, a layer of copper foil and A layer of pressure-bearing aluminum plate covers the core plate.
The PCB boards clamped by the iron plates are placed on the support, and then sent to the vacuum heat press for laminating. The high temperature in the vacuum hot press can melt the epoxy resin in the prepreg and fix the core boards and copper foils together under pressure.
After the lamination is completed, remove the upper iron plate that presses the PCB. Then remove the pressure-bearing aluminum plate. The aluminum plate also plays the responsibility of isolating different PCBs and ensuring the smoothness of the outer copper foil of the PCB. Both sides of the PCB taken out at this time will be covered by a layer of smooth copper foil.
To connect 4 layers of non-contact copper foils in the PCB, first drill through the through-hole through the PCB, and then metalize the hole wall to conduct electricity.
X-ray drilling machine will be used to locate the inner core board. The machine will automatically find and locate the hole position on the core board. Then, PCB will be punched with positioning hole to make sure that the next drilling is right through the center of the hole position.
Place a layer of aluminum plate on the punch machine, and then place the PCB on it. In order to improve efficiency, according to the number of PCB layers, 1 to 3 identical PCB boards are stacked together for perforation. Finally, cover the uppermost PCB with a layer of aluminum plate. The upper and lower layers of aluminum plate are used to prevent the copper foil on the PCB from tearing when the drill bit drills in and out.
In the previous lamination process, the molten epoxy was squeezed out of the PCB, so it needed to be cut off. The profiling milling machine cuts its periphery according to the correct XY coordinates of the PCB.
The above information is provided by PCB manufacturer.
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