How you panel your boards has a real effect on cost, throughput, and yield, and the right strategy isn't the same for a 20-unit prototype run as it is for full production. Get it right at each stage, and you save substrate, machine time, and rework. Here's what changes as you scale.
A panel is an array of printed circuit boards (PCBs) built at the same time. For very small or odd-shaped PCBs, having them in a panel is highly recommended and in some cases necessary. Panelizing your boards streamlines SMT assembly so both prototype and volume builds produce more boards in less time, which means faster turnaround and lower manufacturing cost for you.
The best panelization strategy for a prototype is often different from the best strategy for volume production. Here's how to think about each.
Paneling falls into three tiers, from optional to required:
A panel isn't required when:
In that last case, we'll review the board design and give you feedback before moving ahead.
For prototypes, the number of PCBs per panel depends on board size and the complexity of the packages on it. We prefer to spread prototype quantities across multiple panels whenever possible. This helps improve manufacturability and gives complex builds a better chance of running smoothly with fewer placement or handling issues.
Our panel sizes:
For complex designs, we keep it to six or fewer per panel when any of these apply:
As you move into production, the math shifts. Wasted substrate that barely registers on a prototype run adds up fast at volume, so panelization usually gets re-optimized once the design is finalized to make the most of every array.
Panel size and array also affect pick-and-place efficiency, machine utilization, and overall throughput. An array lets the machines populate multiple units per cycle, so you get more out of every SMT run. Standardizing panel width cuts setup time, because the conveyor rails don't need readjusting between jobs. Mirrored panels, on the other hand, create extra programming work and are best avoided at volume, though they're a non-issue in prototyping, where simpler, lower-volume equipment handles the job.
Scaling also adds requirements to the board itself. Fiducials give machine-vision systems the reference they need for placement accuracy, and tooling holes stabilize the PCB on its carrier if the design requires one. Leave a solder-mask keep-out around each fiducial, typically a 1 mm fiducial with a 2 mm keep-out. Solder mask over a fiducial can keep the vision system from "seeing" it, depending on the color.
At volume, an EMS provider will usually have width preferences and may cap panel size based on its equipment. PCB fabricators build their panels in larger sheets, commonly 12" x 18" or 18" x 24", so design your array to consume most of that area. Your fabricator can advise on the optimum array size for the sheet they'll use, which minimizes wasted substrate. (Our own maximum is 14" x 19".)
Bigger panels can also cost more: they may need board-support tooling or special handling, both of which add non-recurring tooling costs.
Even single boards that aren't paneled sometimes benefit from added rails or a frame. Add them when:
Once production wraps, individual boards have to be separated from the panel, a step called depanelization (or singulation). The two most common methods are V-score and tab routing with mouse bites, and they trade off speed against edge quality:
Both methods add to fabrication cost, so factor depanelization into your panel design from the start.
Panelization is a good example of why we look at the entire build, not just the board. Sourcing, assembly, and the path to volume all shape the right array. And because we're a division of Milwaukee Electronics, that path runs from your first prototype panel all the way to large-scale production, without changing partners along the way.
Scaling a board from prototype to volume? Send us your design, and we'll help you optimize the array for each stage. Request a quote today.