V-Cut Scoring Depth and Panel Separation Control
V-cut scoring leaves a groove on both faces of the panel and a web of material between them. The panel separates along that web, and the thickness of the web decides how it behaves both during assembly and at separation.
How the Web Thickness Is Specified
The remaining web is the panel thickness minus the two groove depths. It is usually specified as a fraction of the thickness or as an absolute figure, and the two give different results on different boards.
The specification should state which one applies. Our scoring notes describe the alternatives.
What the Depth Does to Separation
A thin web separates easily and leaves a small nib. A thick web requires more force, and the force is applied to a board that is already populated.
The force is what damages components, so the web thickness and the components near the edge are related. Our strain notes describe the measurement.
Board Strength During Assembly
A web that is too thin lets the board move in the conveyor and flex during printing, which changes the print gap. The panel has to be stiff enough to carry itself through the line.
The compromise is between the assembly and the separation. Our board support notes describe the deflection that results.
Measuring the Groove
The groove depth is measured on a section or with a depth gauge on the panel edge, and the web is calculated from it. The measurement should be taken at several points because the blade wears across its length.
The wear is the reason the depth drifts during a run. Our fabrication notes list the points to confirm.
Edge Quality After Separation
A scored edge carries the nib left by the web and a rough line where the material broke. The nib is part of the board outline and it should be within the tolerance the drawing states.
Our outline tolerance notes describe the figure.
Where Scoring Is Not Suitable
Scoring requires a straight line across the full panel and it cannot follow a contour. A board with a rounded or a complex outline is routed instead.
The choice is made at panelization. Our panelization notes describe the arrangement.
Verification
The verification is a web thickness measured at several points along the score, a separation force checked against the specification, and an edge inspected for the nib and for delamination after separation.
Our quality notes describe how the records are kept.
Process Control and Verification
Reviewing the design before the data is released is cheaper than correcting it after the panel is in the tank, because every step downstream inherits the decision made at the front end. Documenting the assumption is part of the design work, and a short note on the drawing prevents a question that would otherwise arrive a day later and cost a day of schedule.
The process window is set by the narrowest step in the flow, so an improvement anywhere else shows up as margin rather than as yield until that step is addressed. A short note on the drawing about handling, storage or packaging is often worth more than an extra decimal place on a tolerance.
Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance. A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used.
Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design. The measurements that matter are the repeatable ones: conductor width and spacing, annular ring, finished hole size, plating thickness and surface finish are all verifiable on a coupon that travels with the panel.
Checks Before Release
The checks that matter are the ones performed on the product rather than on a sample kept for the purpose, because a coupon that travels with the panel is the only evidence about that panel. Where a requirement can be measured, it should be measured at the point of manufacture and recorded against the board or the lot it applies to.
A parameter that is set once and never re verified drifts, and the drift is usually discovered by a defect rather than by the record. The tooling, the material and the profile form one system, and a change to any of them should be assessed against the other two before it is released.
Where the process window is narrow, the measurement resolution has to be better than the window, or the data cannot distinguish a good part from a marginal one. A record that identifies the operator, the date and the settings is worth more than a record that identifies only the result.
The acceptance criteria should be written before the work starts, so that the decision is made by the specification rather than by the person inspecting.
FAQ
Can a scored panel be separated by hand? It can where the web is thin and the board is supported, and the force is inconsistent which is why a fixture is preferred.
Does scoring damage the laminate? It cuts into it deliberately. The concern is the delamination that appears if the groove penetrates too close to the inner layers.
What does gopcb provide for scored panels? We provide a web thickness stated as an absolute figure on the drawing, a depth measured at several points along each score, a separation force checked against the specification, and an edge inspected for the residual nib and for delamination after separation.
