Test & measurement
very obvious solution to this – lasers. Once Amfax had chosen lasers and CAD as
its input for the inspection, the company started designing a machine. Initially this was a prototype test bed
whereby Amfax could take laser scans and check measurements. It became clear at this point that the company was on the right path as it was possible to achieve high resolution scans and apply tolerances easily through maths. Suddenly unambiguous PCB inspection was possible. Amfax realised that each element of a PCBa will require multiple tests to ensure that it is correct. For instance, the company needs to ensure that a component is the correct part, in the correct location, with no rotation and tilt, has the correct amount of solder, no solder bridges etc. On average the company has found that each component has approximately 12-16 individual checks applied depending on type. If any single test fails then the inspection has failed. Not only that but it is possible to tell why and by how much as it is a measured value - data that can be used elsewhere. The technology Amfax use has proven to be
extremely versatile. Originally the company expected that this would be used for SMT devices only but it soon realised that it could complete some tests on devices such as BGAs which give real confidence that a board will work going forward. Amfax has also been able to check through whole components by ensuring they are correctly soldered, the pins are straight and correctly trimmed. The real game changer has been
around solder volumes. Amfax’s machine measures the amount of solder and then calculates the volume. The system collects the data and identifies trends in the manufacturing process. The company has seen an instance at one client whereby they were reducing the amount of solder they were using. Amfax was able to recognise this trend
‘‘
Zero defects is now achievable.
We know what to fix in both our designs and our manufacturing process. Its all down to a3Di.
’’
and show that the solder volumes were reaching dangerously low levels. In essence it was able to predict failures before they happened as the data allowed the company to react in an informed way. Ironically visual inspectors were passing the boards as they were looking at consistency of solder across the board and not solder volumes as they have no way to measure. In their eyes if solder looks the same on all joints then it passes. Opinion rather than fact. Amfax has machines in major aerospace
manufacturing sites in the UK and Far East. The feedback the company has received to date is that the data it produces through measurement allows informed decisions as to what and when to make changes. It has proven to be a tool that can really contribute to improvement. The plan, do, check, act cycle is easy to use as real data and statistical tools can be used to identify trends.
Amfax
www.amfaxa3di.com
Instrumentation Monthly March 2019
53
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