How AOI technology can boost productivity as component size shrinks, but count grows
02 December 2019
As component dimensions continue to shrink & PCB population densities climb, automated inspection becomes a necessity, rather than a luxury for most electronics manufacturers. While this is well-recognised, it’s also essential to understand the significant advantages the latest available inspection technologies offer over earlier, less-powerful implementations.
This case study was originally featured in the December 2019 issue of EPDT magazine [read the digital issue]. Sign up to receive your own copy each month.
In this case study, Andy Bonner, Managing Director at production, inspection & test equipment distributor, Cupio tells us how Nordson’s latest-technology automated inspection solutions have boosted productivity for Cupio customer, Bela Electronic Designs.
Bedfordshire-based Bela Electronic Designs offers a complete electronic manufacturing service, providing bespoke electronic engineering solutions to a wide range of customers and industries. The company has enjoyed consistent growth in this role over the last 35 years – and for nearly half that time, it has met this growth’s associated challenges through investment in ever-evolving automated optical inspection (AOI) technology.
Since 2010, it has relied on inspection, test & production solution provider, Cupio for AOI equipment, training and support, with its first Nordson YESTECH BX Benchtop AOI machine purchased in 2010, followed by a second in 2017.
Yet technology has continued to move on, in terms of both the PCBs and components used in electronics manufacturing, and the automated solutions for inspecting them. Accordingly, Bela has now acquired two new machines from Cupio; a Nordson YESTECH FX-940 Ultra 3D AOI and a Nordson DAGE Explorer one for MXI (automatable X-ray inspection).
“Our focus is on high-complexity, low volume projects”, explains Keith Dent, Production Manager at Bela, “A batch size is typically around 20, although it has been as little as just one for a special project. Nevertheless, our output is running at around 100 SMT jobs per month, so we need high efficiency. Our staff are well trained and highly capable, but not particularly large in number. Instead, we rely on automation as much as possible to achieve the productivity we need – and both new machines, in their own ways, are contributing to this strategy.”
Explorer one automated X-ray inspection
Bela had been using X-ray inspection for some time as a tool for resolving areas of doubt on PCBs. However, as it was difficult to justify an outright purchase, its policy had been to hire a machine by the hour to solve any problems that arose. This changed after a visit to Cupio’s stand at the Southern Manufacturing 2019 exhibition, where Dent noticed that the Explorer one’s image quality was superior to that of earlier, larger machines.
He was also aware of its implications; features as small as 2 µm became visible, allowing inspection of a bond in high detail, rather than merely detecting its presence.
Bela took one of the Explorer one systems on trial, to compare against their sub-contract service and to estimate the amount of work that they would have for a system of their own. After completing the trial, which was supported by Nordson and Cupio staff, Bela decided to purchase the Explorer one.
“Our operating experience with the machine made this an extremely easy decision to reach,” commented Dent, “Quite simply, we didn’t know what we had been missing.”
Recent case history shows just why the Explorer one is so valuable to Bela. Its inspection capabilities can resolve issues related to faulty manufacturing, faulty components and faulty design.
Identification of faulty manufacturing
In one example, a customer had asked Bela to populate their PCBs with SMT components, but installed the through-hole parts themselves. This led to some failures, but Bela was able to identify these rapidly with X-ray inspection; some of the holes were not fully filled with solder. For subsequent batches, Bela was asked to perform the entire soldering requirement – and supply a set of X-ray images for ongoing customer assurance.
In general, Bela can use X-ray inspection to identify which pins on a connector have potential weaknesses, and advise operators to take extra care of their soldering accordingly.
Identification of faulty design
Another example called for great accuracy. A new board design had used the wrong footprints for some SMT components – but they weren’t grossly inaccurate. In fact, X-ray inspection showed that the pads aligned just well enough with the chip pins to be useable; this saved the customer the expense of a board re-layout.
A different situation arose when another customer designed a Wi-Fi module for mounting on a mainboard. The module contained a large LGA with an unusual arrangement of pads around its periphery. X-ray inspection revealed soldering problems with these pads; further investigation showed that the problem arose from a different coefficient of expansion between the module and the mainboard. The stresses that this generated during reflow caused lift and breakage of some solder joints. The problem was eliminated by increasing the PCB thickness and reducing the panel size.
Identification of faulty components
X-ray inspection can also identify faulty components. On one occasion, a customer returned several boards from a batch, with a functional fault. Each board held 96 QFNs, and X-ray inspection revealed soldering problems with some of the chips. These were found to have arisen from contamination of the terminations, which compromised their solderability. The visibility afforded by X-ray inspection allowed the faults to be identified far more easily than would otherwise have been possible; it was then a straightforward job to rework the boards with new QFNs of better quality.
Production & ad-hoc use
While the above examples show how Explorer one has resolved different fault scenarios, Bela equally uses it for production, and, increasingly, as an ad-hoc problem-solving and assurance tool. Although not used for routine production, it is regularly employed for new product introduction (NPI) projects, and to bring extra confidence to certain sensitive builds.
On ad hoc use, Dent comments: “Now that we have established the X-ray inspection facility, staff are increasingly using it on an ad-hoc basis to solve problems, or if they’re simply not sure about a certain aspect of a board’s manufacturing quality.
“Also, as customers have become aware that we have the capability, they are asking for X-ray images for extra confidence in their production batches.”
Nordson YESTECH FX-940 Ultra 3D AOI
Bela has replaced one of their BX desktop AOI machines with an FX-940 Ultra 3D AOI, with 2D and 3D imaging technology. With 5-axis 3D viewing, advanced LED lighting and newly available image processing technology, and new software, the machine, in Bela’s opinion, brings additional subtlety to AOI inspection. The 940 Ultra is also able to detect shallow lifted leads and other such defects with its high precision, shadowless, height measurement. Bela originally tested its capabilities at Cupio, by providing three simulated-fault boards for inspection. After the machine found two faults immediately on the blind test, and the third after minimal retuning, Bela made the purchase.
Bela continues with a strategy in which all SMT boards are AOI inspected. In-process verification and post-reflow inspection is performed with the BX machine for the simpler jobs, while the FX-940 performs the same roles for more complex assemblies.
All the automated inspection equipment is integrated into Bela’s production network, and accessible to its Team Viewer software. All machines can be interrogated remotely across the network.
“We are delighted with the benefits we are seeing from automated inspection” comments Dent, “These have been facilitated not just through the quality of the machines and the Nordson group that manufactures them, but also by the level of support we have consistently enjoyed from Cupio, ever since our first BX purchase back in 2010.
“And these benefits are manifold. The fact that we can identify faults so quickly and effectively not only saves us time directly and improves our productivity, but also reduces time in discussion with customers and suppliers, as we can so easily demonstrate the problem and the required solution. Customers are buying into this, as evidenced by their increasing requests for X-ray inspection pictures along with their products.
“Overall, our enhanced inspection capability is generating more work, as it positively impacts our customers’ view of us as a quality supplier, and acts to promote customer assurance.
“Another great point is that, after our initial investment, our staff are making increased use of it, helping maximise our ROI.
“Our experience also underlines the essential necessity of constantly reviewing our automated inspection strategy, and ensuring that we’re always deploying the latest technology. This is critical to ensuring that we can maintain our productivity levels in the face of ever-higher component densities, and more sophisticated customer expectations.”
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