Thursday, March 12, 2009

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.

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