How to store prototype and pilot PCBs without mixing up revisions
· PCBRacks.com engineering team
A production lot might be five hundred identical boards. A pilot build is more like nine boards across four revisions, two of them reworked, and one of them the only example of a change the customer has already seen. They all look alike, and engineers pick them up far more often than anyone handles production boards.
That mix leads to two kinds of loss: handling damage, and boards nobody can identify anymore. You'll find out about the second one when the customer asks which unit they tested.
Give each revision its own slots
Put revision A in slots 1 to 5, leave slot 6 empty, and start revision B at slot 7. When someone asks whether the board on the bench has the reworked regulator, the rack answers, and nobody has to rely on memory. Number the slots and write the revision map on the rack label. Labeling and tracing boards in a rack has a numbering scheme you can copy.
Keep the golden sample apart
Every pilot has one board that can't be replaced: the only unit with the modification, or the one the customer signed off. Don't keep it in the rack with the working stock, and don't keep it in a drawer. Give it its own labeled rack in a known place, where everyone on the team knows it's kept.
Cut down the handling
Engineers pick pilot boards up to look at them, probe them and show them to someone. Each pickup is a chance to flex the board, touch a pad, or carry it across the room without grounding. Keep a small slotted rack on the bench itself, so boards go back into a slot instead of lying on the mat or on a pile of paper, and carry them between areas in the rack, not loose.
Watch the floor-life clock
Prototype builds run long. Boards get built, wait three weeks for firmware, then go back for rework. If they carry moisture-sensitive parts, all of that time counts against floor life, and the rework reflow is where an over-exposed part can delaminate or crack. Floor life runs from when the parts' bag was opened or from the last reflow, so write the last reflow date on the rack and check it before rework. If they're past it, bake the assembly per J-STD-033 at a temperature every part on the board can take.
When the product moves to production
With nine boards, it's tempting to improvise with a tote or a foam block. An improvised setup tends to follow the product into production, where it ends up holding a hundred boards. When the product heads for production, size proper racks for it, and don't let the tote make the trip.
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