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56 DESIGN007 MAGAZINE I FEBRUARY 2025 Routing boards is like routing wood. We use a spinning cutter on a computerized numeri- cal control (CNC) machine that cuts into the panel following the outline of the board. is is the most cost-effective and efficient way to break apart a panel of PCBs. For smaller production runs where assem- blers work by hand one at a time in a shop, routing individual boards is fine. Assemblers manufacturing at scale are always looking for production efficiency. ey oen prefer to receive the boards in panel form or at least with some real estate around the edges of the boards because they need to clamp the boards into their conveyor system for the automated placement of components. Individual boards do not run through their pick-and-place (P&P) machines effectively. If there is circuitry and assembly near the edges, there is no room to clamp the boards to these conveyors. e assembler can use a jig or fix- ture to hold the board during assembly, and this oen requires multiple manual setups that can slow an automated assembly process. Partial or tab routing is an option. We add a frame around a handful (or more) of boards on the panel and rout around the group. is allows the assembler to clamp onto the frame, cut into it, and have fiducials that allow their vision systems to align to the board registra- tion for automated assembly. V-scoring is another option that allows multi- ple boards to be assembled. Adding a score line along the board outlines allows the boards to be broken or cut apart aer assembly. is doesn't apply to parts that overhang the board edge unless someone adds them aer singulation. Designers should communicate their routing preferences to the manufacturer at the outset and document those requirements in the design notes and fabrication and assembly prints. Laser Depaneling Lasers are accurate, and laser routing is an excellent option when a customer's require- ments are ±1 mil on the board dimension or slot width. is can be expensive and time- consuming, but it's useful with the tight dimen- sional tolerances oen present in smaller, more complex board designs. Verification and Inspection We have now reached the final stages of pro- duction. e boards or panels head to the qual- ity control department. is team is responsi- ble for verifying the boards meet all the print requirements, the IPC class requirements, have the right surface finishes, are the correct dimensions, and comply with any other mate- rial requirements. e shipment includes inspection results (testing and impedance data) and other veri- fication forms. Boards undergo a final visual inspection to confirm: • No copper is exposed • All pads have a surface finish • ere is no dewetting (solder losing sur- face adhesion) • e correct cutouts are added • ere is no damage to the board Once we are certain all the design require- ments and quality standards have been met, it is ready for shipment. e boards are then pack- aged to ensure they don't get damaged, and then head to the customer or assembler. DESIGN007 I encourage you to explore the PCB manufacturing process in greater depth by reading my book, The Printed Circuit Designer's Guide to… Designing for Reality. You can listen to the podcast here. Matt Stevenson is vice president and general manager of ASC Sunstone Circuits. To read past columns, click here.