Inspecting electronics orders: what to check before you pay the balance

Electronics fail in ways a photograph cannot show. This page covers what to write into the order, how to sample an incoming lot, and which checks belong at production rather than at shipment.

Electronics inspection is not garment inspection

Apparel inspection is mostly about appearance: stitching, colour, measurement, symmetry. Electronics inspection is mostly about function, and function can fail while the item looks perfect. A board that photographs beautifully can be dead on arrival at your customer.

That changes where you spend attention. Cosmetic defects are cheap to catch and cheap to fix; a wrong chipset, a stale date code or a missing certification is expensive and often unfixable after the goods have shipped. Put your checking effort where the cost of a miss is highest.

It also changes when you inspect. A garment can be inspected at the end. An electronics batch should be checked at production as well, because a fault that shows up at pre-shipment has already been repeated across the whole run.

Write the acceptance criteria before ordering

An inspection without written criteria is an opinion. Before ordering, write what the goods must do, what marks they must carry, and what variation you will accept. The order document and the inspection checklist should be the same document.

For components, specify the condition (original, new-old-stock or reworked), the manufacturer, the part number, the package type, the date code range you will accept and the quantity tolerance. Those five items decide most disputes.

For finished devices, specify the chipset or an acceptable equivalent, the firmware version and update policy, the interfaces and radio bands, the input voltage, the accessories included, the certifications required and the functions that must pass. Then turn that list into the actual test steps the inspector will run.

Sampling a lot without guessing

Do not accept or reject a lot on one unit. Use a sampling plan so that the decision is defined before you see the goods, and so that both sides know what number triggers a rejection. ISO 2859-1 is the standard reference for sampling by attributes.

Fix three things in the contract: the lot size, the inspection level and the acceptance quality limit. Those three numbers determine how many units get checked and how many defects are allowed. Without them, a rejection argument becomes a negotiation about feelings.

Separate critical from major from minor defects and set a different threshold for each. A dead unit is critical and should reject on a single occurrence regardless of the sampling plan; a scuffed housing is minor and should not stop a shipment. Conflating them means either rejecting good lots or shipping bad ones.

Date codes and lot consistency

For components, check whether the shipment matches the date code range you agreed. Mixed date codes inside one order usually mean the counter assembled the quantity from several sources, which is not automatically wrong but does mean the batch is not uniform.

Ask for the reel or carton labelling to match the inner contents. Where the outer label and the inner marking disagree, resolve it before payment rather than after, because that discrepancy is the one most likely to cause a later functional problem.

If uniformity matters for your production, state it in the order. A supplier who knows that mixed lots will be rejected tends to ship uniform lots; a supplier who learns it after the fact does not.

Power-on and burn-in

A device that powers on for ten seconds proves almost nothing. Run the functions the buyer will actually use, in the order they will use them, and leave the unit running long enough for heat-related faults to appear.

Agree the burn-in duration in advance if the product justifies it. Consumer accessories may need only a functional pass; anything with a power supply, a battery or continuous operation should be run for a stated period with the failure criterion written down.

Record what was tested and which unit failed. A supplier facing a claim responds to a list of specific failures with unit identifiers, not to a general statement that the batch was bad.

Where to put the inspection in the timeline

Put one check during production and one before shipment. The production check catches a process that is producing defects in volume while there is still time to correct it; the pre-shipment check catches packing, labelling and quantity errors that appear at the end.

Hold the final payment against the pre-shipment result. If the balance is released before the check, the check becomes advisory. If it is released after, the check has commercial weight.

Keep the inspection record with the order. It is the document that decides a dispute six weeks later, and it costs almost nothing to file.

The AQL sampling method described here follows ISO 2859-1, published by ISO (catalogue entry linked in sources). We have not reproduced the standard's tables; buy the standard for the actual sampling plans. The practical notes on date codes, burn-in and functional checklists are our own working practice. We do not inspect on anyone's behalf.