Why panelise at all
Automated assembly works better with larger formats. A small board on its own is hard to clamp, print and place; several of them on a panel give the machine something to hold, and one print/place/reflow pass serves many boards.
The price of that convenience is a set of rules about how the panel is built and how it comes apart.
V-score
A V-shaped blade cuts a groove about one third of the way through the board from each side, leaving a web in the middle. The panel stays rigid enough to run through assembly, then breaks along the line.
- Best for: rectangular boards, no edge components, straight break lines.
- Clearance: at least 1.27 mm from any component to the score, 3.2 mm for MLCCs.
- Thickness: the plant range is 0.6–3.2 mm, with angle tolerance ±0.5°.
- Edge: visibly rough, with a slight bevel; fine where the edge is not seen or handled.
- Cost: the cheapest option, and the least material wasted.
Tab routing
The boards are routed out and held by small tabs, often perforated with three or five holes so they snap cleanly.
- Best for: unusual outlines, edge-hanging connectors, boards that need a smooth routed edge.
- Clearance: at least 3.2 mm from components and traces to the tab, 6.4 mm for MLCCs.
- Tab pitch: roughly every 50–75 mm for five-hole tabs, 38 mm for three-hole tabs.
- Edge: smooth from the router, with small nubs that sand off.
- Cost: more router time and more material lost to the routing channel.
Rails and what goes on them
A rail is the border of the panel that is not part of any board. It carries:
- Fiducials — at least three, so the machine can align even if one is missed.
- Tooling holes — for fixture pins and for the printer.
- Test coupons — impedance and cross-section structures, placed where they represent the board.
- Barcode or label area — for traceability.
- Jump scoring — a partly scored breakaway strip along the leading and trailing edge, which keeps a long panel flat through wave solder.
Breakout
The panel is only as good as the way it is separated. Hand-breaking a tab puts bending stress through the nearest joints; a proper depaneliser shears along the line instead. V-scored panels need a cutter; tabbed panels can be snapped by hand, but on a thick board a router or hook blade is safer.
Whatever the method, the components near the break line take the stress. That is why the clearance rules exist, and why they are checked in DFM rather than at the bench.
What to send
The board outline and array preference, the panel size limits, any edge components, the depanelisation method, and the fiducial and tooling-hole positions if the assembly fixture is already fixed. Panels go up to 580 × 1900 mm; the assembly constraints are on the PCBA manufacturing page, and the fabrication sequence in the process note.
