Efficient testing process

Assemblies are validated before packing: automated optical inspection and functional testing on fixtures built to specification, with failed units going back through documented rework and retest. This page covers the test stages, where the specification comes from, and the discipline applied to rework.

The test stages

• 3D SPI on solder paste, catching volume and alignment errors before placement.
• AOI after reflow, on every board, against a programmed reference.
• X-ray for BGA, QFN and other joints that cannot be seen optically.
• ICT or functional test on fixtures built to the customer's specification.
• In-production firmware loading and checksum verification where the product needs it.

Fixtures and specification

Functional test is only as good as the specification behind it. Where a customer supplies a test procedure, a fixture is designed and built against it, and the pass and fail limits are agreed before the first production run. For programmes where no specification exists, Kilandu can work with the customer to define a basic power-up and functional test that catches the failure modes the build is most exposed to, rather than shipping untested boards.

Rework and retest discipline

A board that fails is not simply repaired and passed. Rework is performed to documented procedures, the reason for the failure is recorded, and the unit goes back through the same test it failed before it is released. Where a failure repeats across a lot, the cause is investigated at process level - stencil, reflow profile, component lot or placement programme - rather than treated as isolated. That is the difference between a test department and a control loop.

Test coverage and what it costs

Test scope is agreed at quotation, so what is covered is visible before production rather than assumed. A board that needs only power-up verification is quoted that way; a board carrying safety-relevant functions gets the coverage its application demands, and the extra time is priced in rather than discovered later. The stages above run on the same floor as assembly; the service list is on PCBA testing services.