PCB Back Drilling: define the stub, protect the connection

Start with the signal path and identify unused barrel segments that matter to the channel. Some designs can reduce the problem by changing routing layers or selecting another via construction.

For the retained through-via architecture, create a controlled map of the locations needing removal. A blanket note on every via can add work and can conflict with connections that the circuit still requires.

For the multilayer PCB, show the physical layer sequence and name the copper connection that must remain intact. State the entry side independently for every backdrill depth family.

Layer numbering should agree across the drawing, fabrication outputs and any signal-integrity review. When a stackup revision moves the protected layer, the drilling plan must be reviewed again.

Along the board thickness, the process must approach the unwanted barrel without reaching protected copper. Across the board, the larger removal tool needs clearance and registration control around the original hole.

The online workbench helps expose an inconsistent axial budget. It does not model the conical drill tip or radial tolerances, and it cannot replace the fabrication engineering review.

Include the required residual-stub definition and the agreed verification method in the request. Inspection should address the features that matter to the design, with sampling and reporting specified in advance.

Ask the quote to separate the drilling scope, additional inspection and any qualification work. We can review the submitted construction and open requirements before confirming price, schedule and exceptions.