Including V-Score Groove Width in Copper Setback Reviews

A V-score centerline is not the complete region removed by the scoring blade. The groove has a finite width at the surface, determined by its depth and included angle. Copper placed safely away from the line can still approach the cut face when the full geometry and registration allowance are considered.

Draw the groove cross-section

For an ideal symmetric V-groove, surface half-width equals groove depth multiplied by the tangent of half the included angle. This geometric estimate helps identify the cut envelope, but the actual blade tip, wear and process tolerances must come from the fabricator. Top and bottom grooves may also be misaligned.

Eurocircuits publishes copper-to-edge guidance that distinguishes scoring from routing. Treat those values as that supplier’s guidance rather than universal limits. The relevant review combines the proposed scoring process with the finished board requirement.

Check copper at the relevant height

Outer copper is close to the widest part of the groove. Inner copper encounters a different cross-section depending on its depth in the stack. The centerline clearance alone therefore does not describe every layer’s remaining dielectric margin. Show the groove and copper layers together in a sectional sketch. Identify the least favorable combination of depth and lateral offset before choosing the inspection locations.

• Obtain included angle, groove-depth tolerance and positional tolerance.
• Confirm the minimum residual web between opposing grooves.
• Check copper on both board faces and affected inner layers.
• Include final edge condition after separation when that surface is functional.

Avoid solving one geometry problem with another

A deeper groove may make separation easier but widen the surface opening and reduce panel stiffness. A narrower groove angle changes the geometry but may require a different tool or process. Review the actual supplier proposal before adjusting copper setbacks or residual web requirements.

For example, a power plane near a scored edge may require local pullback while a neighboring signal layer already has sufficient margin. Apply the change to the affected layers and verify it in the manufacturing data. Connect this check with residual-web verification and panel drawing approval. A complete scoring detail controls where material is removed, what remains between boards and how copper stays protected throughout separation.