Full 3D SPI and component inspection at Variosystems around the world
From our original base in Steinach, Switzerland, not far from Lake Constance, we have expanded to become a multinational company with production sites around the world, from China and Sri Lanka in Asia to the USA and Mexico in North America. In order to meet the high quality standards that are expected by customers everywhere, Variosystems has entered into a strategic partnership with the German company PARMI Co, Ltd. PARMI supplies all Variosystems sites with state-of-the art inspection machinery.
Made in Switzerland
As a full-service EMS (Electronic Manufacturing Services) partner, our mission is to support our customers from product conceptualisation and development through to the actual electronics manufacturing and aftersales. We aim to provide an individualised service. We do this while maintaining the highest standards of quality and productivity. We manufacture electronic assemblies for prototypes as well as large series for a wide range of applications such as industrial, aviation, medicine etc.
Because we are a Swiss company, expectations are obviously going to be high that we will deliver top quality. The challenge, however, is to meet this demand when we are in global competition with locations that have much more advantageous cost structures. Our answer to this challenge was the expansion and globalisation of Variosystems. Right from the start, we committed ourselves to installing and using state-of-the-art equipment that meets the highest specifications at all of our production sites, i.e. identical machinery at each plant. This enables us to determine the most appropriate production location in consultation with the individual customer. Due to the further expansion and the demand for delivery of consistently high quality, worldwide and independent of location, it became necessary to modernise and standardise our optical inspection systems for solder paste and components. With these expectations foremost in our mind, a whole range of requirements in terms of SPI (Solder Paste Inspection) and AOI (Automated Optical Inspection) immediately had to be catered for.
Fault detection and inspection speed
100% reliability in the detection of faults has to be the top priority for both the SPI and the AOI. At the same time, these systems should not be permitted to become a bottleneck in the entire production line with its high-speed pick-and-place machines. In our case, the networking of the systems enables worldwide access to central databases. Once a product has been defined, the relevant parameters and programmes can be downloaded at any of our locations.
Another challenge for the AOI arose due to the wide variety of assemblies and components. As an EMS provider, we not only have to deal with miniature-scale designs; there will continue to be mixed assemblies with connectors and pins as well as special designs, all of which have to be inspected. The heights of the structures to be inspected range from 0.1 millimetres (01005) to several centimetres.
The evaluation of an SPI and AOI that would best meet our requirements turned out to be a special challenge in its own right. We wanted to source the two systems from a machine supplier who could guarantee optimal harmonised networking of both systems. At the end of the evaluation phase, we decided on the systems offered by PARMI. In contrast to conventional light fringe projection or even moiré technology, PARMI uses laser triangulation in both its SPI and its AOI. This technology enables us to conduct SPI with resolutions of 10 µm in the x/y plane and to detect ultra-fine (0.1 µm) irregularities in paste printing. Through data feedback to the printer, the position is corrected accordingly. In addition, the SPI takes on the control of the stencil cleaning cycle.
In the case of the AOI, we were impressed by its ability to inspect the smallest components right down to high (press-fit) pins with regard to position, height and alignment. With increasingly fine structures, it was also especially important to us that, in addition to the primary component inspection, the AOI could to check whether there were foreign bodies such as components, solder beads or fibres on the PCB. In this regard, it became apparent that competitor systems were unable to detect these either with any degree of reliability or without additional inspection time. Last but not least – especially for small series – the time and effort that went into programming these systems was considerable, which obviously increased the inspection costs. With the PARMI machines, the auto-teaching function by means of AI algorithms reduces the programming effort by up to 80%. What really impressed us was that the reliability that comes from using AI not only recognises the structures, but also the type of components according to polarity control and/or text identification.
Networked monitoring of quality and quantity
As a globally active company, we not only face local competition but also have to think beyond national borders. In an internationally competitive environment, it is not enough to exploit the cost advantages of other locations if the same level of productivity and quality of the products cannot be not guaranteed. To evaluate this, we utilise the extensive statistical process evaluation tools. We use these to evaluate the production ratios of the individual machines at the various locations worldwide and compare them in order to implement suitable corrective measures as and when necessary.
Return on Investment
Cost-benefit analysis obviously precedes every investment decision, and scrutiny is often even more intense in the case of quality control machines. At Variosystems, we came to the conclusion that complementary SPI and AOI systems would create the prerequisite to guarantee the same quality standards at all locations as well as to compare SMD (Surface Mount Device) productivity between sites. We are convinced that our choice of PARMI as strategic partner sets us up optimally for the challenges ahead.