PCB V-Cut Panelisation: Standards, Tolerances and Design Rules

What V-Cut Does

V-cut scoring is the fastest and cheapest way to separate rectangular boards from a panel. Two rotating blades cut a shallow V shaped groove into both faces of the panel along the line where the boards must separate, leaving a controlled web of material in the middle that holds the panel together through assembly and breaks cleanly at depanelisation. Because the blades run in a straight line, the method only works for straight, full length separations, and because they cut from both sides, it requires the board to be flat and of uniform thickness. Within those limits it is far quicker than routing, it produces no dust, and it leaves an edge that is clean enough for most products.

Scoring Geometry and the Remaining Web

Three parameters define the score. The blade angle is normally 30 or 45 degrees, with 45 degrees being the common standard because it leaves a wider opening for the same depth and reduces the risk of the blade touching the copper. The scoring depth, expressed as the remaining web thickness at the centre, is what holds the panel together; a common specification leaves about one third of the board thickness, which for a 1.6 mm board is roughly 0.5 mm. The score line position determines the finished board size, and it is measured from the board edge rather than from the panel. Deeper scoring makes separation easier but weakens the panel through assembly, and shallower scoring risks a ragged break with fibres torn from the edge. The balance is normally set by the fabricator and stated in the drawing.

The Standards That Apply

International standards cover the geometry and the resulting edge quality rather than a single process recipe. The usual requirements are that the remaining web thickness is within a stated range, that the score line is straight and free of offset between the two faces, that the V groove does not cut into the copper, the solder mask or the plating, and that the separated edge does not show delamination or torn fibres beyond the acceptance limit. Typical production tolerances are about plus or minus 0.1 mm on the score line position relative to the board edge, around 0.1 mm on the remaining web, and about 0.1 mm on the depth matching between the top and the bottom score. A misaligned pair of scores leaves a step on the edge and is the most common V-cut defect.

Design Rules for a V-Cut Panel

Keep the score line straight and running the full length of the panel, because a partial score cannot be produced. Leave enough clearance between the score and any component: a common rule is 1 mm or more from the board edge to the nearest pad, and more where a component body overhangs. Keep the score clear of the copper layer by at least 0.3 to 0.5 mm so that the blade and the resulting edge do not expose circuitry, and keep it clear of plated edges and castellations entirely, because scoring through plating damages it. Provide panel rails wide enough for the assembly conveyor, typically 5 mm or more, and remember that a rail with components is not a rail. Keep the score lines parallel to each other where possible, since an odd angle forces a separate pass. Where the board is thinner than about 0.8 mm or thicker than about 2.4 mm, or where there are components close to the edge, the method becomes a poor fit and routing or stamp hole separation is better.

V-Cut Compared With the Alternatives

Routing cuts any shape and any angle and can leave a clean edge with a specified radius, at the cost of a slower process and a router bit that wears. Stamp hole separation uses a row of small drilled holes with a breakaway web, which suits small boards and panels where components sit close to the edge, and it leaves a rougher edge that usually has to be smoothed. Laser cutting handles fine geometry and unusual materials but leaves a charred or tapered edge and is expensive at volume. V-cut wins on speed and cost for rectangular boards with straight separation lines and normal edge clearance, and it loses as soon as the shape becomes irregular or the edge becomes load bearing.

Depanelisation Matters as Much as the Score

Most V-cut damage happens when the boards are separated rather than when they are scored. Breaking a thick board by hand bends the assembly and can crack components and solder joints, particularly on large ceramic capacitors and on ball grid arrays near the score line. A depanelisation fixture that supports the assembly on both sides of the score and applies a controlled bending moment along the line separates the boards with far less stress. For thick boards and for assemblies with large components, a cutting tool or a router is preferable to breaking. The rule is simple: the closer the components are to the score, the more controlled the separation has to be.

Cost Factors

Scoring is an inexpensive step, priced mainly by the length of the score line and the number of passes. A panel with parallel scores in one direction needs one pass; a mix of vertical and horizontal separations needs two, and the panel has to be handled between them. Very thin or very thick panels may need a different process or may be rejected outright. The dominant cost consequence is not the scoring itself but the panel design: an efficient panel uses the score pattern to maximise board count and rail width at the same time, while a poorly designed panel wastes material and still pays for the scoring.

FAQ

How thick should the remaining web be? About one third of the board thickness is a common specification, so roughly 0.5 mm for a 1.6 mm board, with the exact value agreed with the fabricator and stated in the drawing.

What blade angle is standard? Thirty and forty five degrees are both used, with 45 degrees the more common because it leaves a wider opening for the same depth and reduces the risk of contact with the copper.

Can V-cut be used on a board with castellations? No. Scoring through a plated edge or a castellation damages the plating, so those edges must be routed instead.

How close can a component be to the score line? Keep at least about 1 mm from the board edge to the nearest pad, and more where a component body overhangs, because the separation process stresses the area next to the score.

Is breaking by hand acceptable? Only for thin boards with components well away from the score. A supported fixture or a cutting tool is safer for thick boards and for assemblies with large or brittle components.

Conclusion

V-cut is the cheapest separation method available and the most restrictive: straight lines only, uniform thickness, and a real clearance requirement around the score. Specify the blade angle, the remaining web thickness and the score position tolerance in the drawing, keep copper and components away from the line, and control the separation rather than the breaking. The panel and separation capability of a supplier is part of PCB capabilities, the clearance and panel layout rules belong in PCB design and layout, and the assembly steps that follow are covered by SMT PCB assembly. A prototype PCB assembly run on the real panel confirms the separation does not damage the assemblies in 2026.