1. CNC drilling
Most double-sided flexible printed circuit boards still use CNC drilling machines for drilling holes. The CNC drilling machine used for flexible printed circuit boards is basically the same as that for rigid printed circuit boards, but the drilling conditions are different. Due to the thinness of flexible printed circuit boards, multiple overlapping pieces can be drilled. If the drilling conditions are good, overlapping drilling of 10 to 15 pieces can be achieved. The support plate and cover plate can be made of paper-based phenolic laminates, glass fiber cloth epoxy laminates, or aluminum plates with a thickness of 0.2 to 0.4 millimeters. There are drill bits specifically designed for flexible printed circuit boards on the market, as well as drill bits and milling cutters used for rigid printed circuit boards for shape processing.
The processing conditions for drilling, milling, and reinforcing plates are basically the same. However, due to the soft adhesive used in flexible printed circuit board materials, it is easy to adhere to the drill bit, so it is necessary to frequently check the status of the drill bit and increase the drill bit speed appropriately. Extra caution is required for drilling holes in multi-layer flexible printed circuit boards or multi-layer rigid flexible printed circuit boards