Reducing AOI False Calls Without Losing Real Defects An automated optical inspection machine that flags every board is not a better inspector, it is a machine that will soon be disabled by the line. False calls cost rework labour, hide the real defects in a long queue of images and,…

V-Cut Scoring Depth and Panel Separation Control V-cut scoring leaves a groove on both faces of the panel and a web of material between them. The panel separates along that web, and the thickness of the web decides how it behaves both during assembly and at separation. How the Web…

Solder Mask Colour and Its Effect on Optical Inspection Solder mask colour is usually chosen for appearance, and it has a measurable effect on how well an inspection system can see the board. The effect is not about quality and it is about contrast. How Colour Changes Contrast An inspection…

Component Coplanarity for Fine Pitch Packages Every package that is soldered with leads or bumps depends on those terminations reaching the pad at the same time and with the same pressure. Coplanarity is the measure of how well they do that: the deviation of the seating plane from a perfect…

Fixture Probe: Design Rules and Process Limits In-circuit test finds assembly defects by touching every accessible node of a board at once. The fixture that does the touching is a block of probes arranged to match the board, and its quality decides whether the test detects real defects or produces…

Depanelization Stress Control in PCB Assembly Separating a board from its panel is the last mechanical operation before test and enclosure, and it is also where a surprising share of latent damage is created. The cut itself looks clean, but the force that produces it travels through the laminate and…

Assembly Tooling Investment Planning Tooling for an assembly line is capital that is committed before the first board is built, and the decision is usually made on the price of the tool rather than on the cost of not having it. The better question is what the tooling allows the…

Legend Ink Selection and Silkscreen Quality Control The legend is the printed information layer that tells an assembler where a component goes, which way round it fits and what the board is. It is not a structural layer and it is often treated as an afterthought, yet a legend that…

Tape and Reel Splice Quality and Feeder Performance A splice joins two reels so that a feeder can continue without the line stopping. The splice has to pass through the same path as the rest of the tape, and a splice that is thicker or weaker than the tape will…

Cost of Poor Quality in Assembly The cost of poor quality is the total of everything spent because the process did not produce the right result first time: rework, scrap, inspection added to catch defects, warranty and the engineering time spent investigating. It is usually much larger than the accounts…