Blind or Buried Vias

Designs that use blind or buried vias (vias that do not penetrate through the PCB) need supplementary drilling operations before proceeding. Unfortunately, they are also quite a bit more difficult to activate and through plate since each must be processed singly.

• Fully disassemble the drilled stack.
• Reassemble a substack consisting of the backing sheet, one of the copperclad substrates that need additional drilling, and the entry foil that carries the drillmaster.
• Re-pin with the dowels and tape as before.
• Playing close attention to the drillmaster symbols representing the holes needed by the included substrate, drill the substack.
• Disassemble the substack and repeat steps 2 through 4 for each layer that needs further drilling.
• Inspect each layer after it is drilled and remove any debris that might be blocking the holes.
• If all of the holes are drilled to your satisfaction, the individual layers are now ready for activation.