Electronics Production | June 21, 2012

Case Study: Yestech's AOI system at TT Electronics Wales

TT electronics integrated manufacturing services (IMS) specialises in the production of low volume, high mix electronics built for the aerospace, defence, medical, industrial and rail industries.
These applications typically call for complex, densely-packed, advanced technology Printed Circuit Card Assemblies (PCB) for which Automated Optical Inspection (AOI) is an absolute necessity to ensure a robust quality product.

Advances in PCB technology and reduction in component sizes have required TT electronics to upgrade to the latest Yestech AOI platform. Backed by local training and support from YesTech europe, this has improved productivity and quality both by faster online throughput and by easier, faster offline programming and changeover between products

TT electronics integrated manufacturing services (IMS) specialises in the production of low volume, high mix electronics built for the aerospace, defence, medical, industrial and rail industries. Such customers and their target environments naturally demand consistently high quality from their suppliers’ products, while typically calling for these as relatively low volumes of densely-packed, complex and sometimes large boards and assemblies.

Unlike large-volume manufacturers, TT electronics’ service is optimised to be the right fit for these customers’ specialised requirements, in terms of delivery, flexibility and innovation as well as quality and responsiveness. The Company’s business has grown from their ability to meet these challenges on a global basis.

Automated optical inspection (AOI) plays a key role in TT electronics’ business model, as it is one of the key elements they require to achieve the quality, coverage and throughput they need in their low volume, high mix environment. With today’s package densities, component sizes and throughput requirements, manual inspection is no longer fast or reliable enough, and, increasingly, not even possible.

By contrast, AOI with its rapid programming, inspection reliability and fast throughput provides a viable solution, and in fact TT electronics has been using this technology for over ten years in both its Rogerstone, Wales and Perry, Ohio factories.

TT electronics has recently undertaken a development and upgrade programme, focusing their attention on their key markets and emerging needs. As well as this, the company has always embraced the steady advances in component and PCB technology. Among other developments, this meant that the existing AOI equipment was no longer able to handle the demands made of it. With TT handling 0201 devices, component sizes were becoming too small for the cameras’ resolution, throughput was not fast enough and the false failure rate was too high, due to aging algorithms.

TT electronics invited the existing AOI equipment supplier to offer a replacement, but they were unable to supply a comparable solution. Accordingly, TT decided to evaluate a number of other AOI suppliers to identify the best available answer for their particular requirements. YesTech europe was chosen after an exercise which included paper evaluations and equipment trials. Their evaluation system proved easy to program, and the evaluation boards ran through inspection quickly and easily on a short production run. The system’s pricing was attractive as well. TT electronics therefore asked YesTech europe to supply two Nordson Yestech FX in-line AOI systems for the Rogerstone plant, and another for the Perry, Ohio site. YesTech europe ensured TT’s uninterrupted production by loaning a benchtop machine during the transition. In all, up to about 300 inspection programs had to be transferred to the new AOI installation – this task is now nearing completion.

The benefits of the new installation quickly became apparent. The throughput rate has substantially improved, even though the number of checks has been considerably increased. The FX’s camera and optical capabilities have particularly impressed TT electronics. The machine’s OCR, pattern matching, accuracy of component value capture and recognition of manufacturers’ logos contribute to efficiency in fault capture as well as reducing the number of false fails. Checking of component orientation is also an improvement from the previous system. Inspecting large boards such as backplanes for 19” rack applications becomes more efficient, as the entire board can be captured in a single image. By contrast, the earlier system had to generate a single picture from eight separate images.

Alongside the improved optical resolution and accuracy, TT electronics also considers the reduction in false failure rate to be of critical importance. Previously, they were experiencing levels of around 3 per board; the Yestech system has now reduced these to a level that complies with TT’s manufacturing environment, with a related increase in productivity.

Inspection at Rogerstone takes place within a cellular architecture, in which output from four production lines can be directed through either of the two Yestech AOI cells. 100% inspection has become more easily manageable since the FX machines’ arrival, assisted by strategic use of holding areas to organise assemblies before and after inspection.

However, it’s not just about online throughput. TT has found that Yestech’s offline capabilities have made an equal improvement to productivity. The FX machines can be programmed offline, avoiding loss of production time. This offline capability can be taken further, because a captured image can be transferred to an ordinary office PC where the inspection program can be configured. The complete package can then be transferred back to an online FX system, where it is ready to use subject to final checking.

In TT electronics’ view, Yestech offers an enormous advantage compared with other systems where programming is concerned. This is because Yestech’s image technology lends itself to easier programming than that required for rules-based systems. As a result, Yestech AOI programs can be configured by technicians or operators on the job, rather than requiring the services of highly expensive specialist software engineers.

The programming load is further lightened, because TT can usually avoid the ‘back to basics’ approach of programming from Gerber files. Instead, they use their Siplace files, which have already been verified. They can feed these files through a third-party converter which outputs Yestech-compatible instructions. In TT electronics’ view, the Yestech software environment is easy for operators and engineers to engage with and use, as it is based on a Windows platform.

Deploying new programs as well as developing them is rapid, allowing a reduced product changeover time for Yestech systems. This is important to TT’s throughput because of their high mix, low volume environment, which calls for frequent product changes.

TT electronics is also benefiting from other features specific to the FX systems. They include bar code reading capability as standard, which TT is using both for product traceability and for data logging. To accommodate this, bar code labels are applied to the products before they go through the SMT line. The company regards these developments in traceability and data logging as essential to meeting the expectations of their customers.

Laser height checking of onboard components is a relatively recent AOI feature, and TT appreciates the FX systems’ inclusion of this as well. Because TT is involved in manufacturing large-area PCB board assemblies, they also value the FX’s PCB support system. Operators implement this by adjusting a set of pistons which ensure that incoming PCBs are correctly supported, avoiding sag and consequential misalignment problems. The piston settings can then be stored as part of a recipe for later recall.

Of course the success of any project depends on more than just the underlying hardware. Bob Hannah, Operations Director at TT electronics IMS, noted this when he commented on the quality of the relationship that TT electronics has enjoyed with YesTech europe. “The success of AOI as part of our quality infrastructure depends on our staff’s skill in operating the equipment and making the most of its many features. We are delighted with the quality of AOI training and support, and the untiring commitment, which we have received from YesTech europe throughout TT’s learning curve. As a result, we now have operators who are confident and effective in performing AOI inspection, and a near 100% uptime for our AOI facility.”

Although TT chose the Yestech equipment on the basis of its specifications, evaluation performance and discussions with YesTech europe, they were encouraged by the experience of their Perry, Ohio plant which has four Nordson Yestech FX AOI systems. This relationship extends back over several years, since TT’s original purchase of a YTV1000 machine.

Mark Sowa, VP of Manufacturing at the Perry plant, comments on the relationship between TT electronics and Nordson Yestech: “Throughout our relationship, we have always found Nordson Yestech to be a supportive company who are ready to listen and responsive to our needs. This support is part of a company culture which extends from the top downwards. They are also generous in providing training, and very fast in shipping parts out if we ever need them. One aspect of our relationship stems from our co-operation with them during the development of their bar code reading capability.” Mark’s comments extended to more technical considerations as well: “Perry is a high mix operation, and we have by now built up around 3000 Yestech programs – yet they and the machines are maintained by just one full-time and one part-time technician. Like Rogerstone, we really appreciate how the machines can be programmed by technicians, avoiding the need for expensive IT expertise. We see this as a major advantage compared to other systems.”

The AOI installation at Rogerstone has proved to be reliable, with no problems reported to date. However it’s the reduction in false fails and associated improvements in quality, throughput and reliability that really impresses the team at Rogerstone. An environment with too many false fails inevitably leads to complacency, which adversely affects reliability and quality. By contrast, bringing these down to an acceptable level improves throughput as an immediate consequence, but it also improves quality and reliability as operators have fewer issues to resolve on each board. Accordingly, TT is steadily increasing the number of boards it processes through AOI.

The implications of this for customer relations are clear to the inspectors as well as to the senior management. “The Yestech equipment is much simpler and more user friendly” comments Kim Hanney, Team Leader at Rogerstone, “Also, we trust that it will perform as it’s supposed to. We have faith in the machines, and more confidence in the quality that we can bring to our customer shipments. We feel that Yestech’s AOI helps us to deserve our customers’ trust, and that they should have full confidence in us.”
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