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Why is the clearance of drillings in the inner layers required to be larger than on the outside?
2019-08-09
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Author:IPCB      Share

If plated-through drillings are desired which are not supposed to be connected to the respective inner layers, appropriate clearances from surrounding copper have to be applied.

Plated-through drillings, which connect to an adjacent copper area due to minor offsets within the inner layers, can cause an electric short if these clearances are insufficient.

Thus the clearances in the inner layers should be approximately 0.7 mm larger than the final drilling diameter (r = 0.35 mm)