How to make an interstitial via hole
Dear Sir or Madam,
I would like to make interstitial via holes on a multi-layer substrate but I cannot understand how to do that. Could you please tell me web-site or give me documents? I would like to know how to make an interstital via between the following patterns; L1 - L2, L2 - L3, L1 - L3, L1 - L2 - L3.