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If you want to be well placed for the future, you have to live a digital and connected life. This applies to virtually all sectors in the professional environment—but it plays a central role in the electronics industry. Without a doubt, the machinery is an important resource. They must be able to think for themselves and optimize processes. Yet, the people behind the machines are important, too. Without them, the factories would fall silent. That is why it is vital that the systems are easy to operate. The use of an automated X-ray inspection (AXI) system by Goepel electronic in Limtronik GmbH’s smart factory demonstrates how intelligent machines can be operated in a simple way to make good use of this interconnectedness.
Based in Limburg, Germany, EMS firm Limtronik has a total of three SMD assembly lines, one of which is a prototyping line. The two main lines are each equipped with powerful pick-and-place machines capable of handling up to 10 feeder modules, and a solder paste inspection (SPI) and an automatic optical inspection (AOI) machines. As is typical among EMS providers, product diversity varies greatly: individual assemblies and prototypes are every bit as much a part of day-to-day business as high-volume production runs. The complexity of the assemblies is likewise vastly different.
Assembly Testing and QA Using Automated X-ray
Outstanding quality is vital to be able to survive the fierce competition between contract manufacturers. Customers from the security technology, automotive, and medical technology sectors require almost 100% test coverage. Thanks to inspection systems in the assembly line and electrical testing in the test bay (in-circuit test, function test and JTAG/boundary scan), Limtronik is well positioned. To check the quality of solder joints especially in BGAs and QFNs, Limtronik installed Goepel electronic’s X Line·3D Series 100 AXI system in 2010 to achieve full-surface 3D X-ray imaging within the cycle time. After several years in continuous operation, it was replaced by a new model from the Series 300.
Figure 1: Verification station for viewing detected faults: BGA with void.
Face-to-face assemblies are common, that is, assemblies in which BGAs are populated congruently on both the top and underside. Reliable quality control is only possible with 3D X-ray. Superpositions of BGA and SMD capacitors, likewise, pose a major challenge since they have a high density and complicate the evaluation of the X-ray images. However, layered reconstruction of the solder joints offered by X Line·3D provides reliable analysis in a very short time. A 4-way panel of an assembly with multiple BGAs and a size of 216 mm x 164 mm, for example, needs on average just 26 seconds for the full 3D X-ray inspection.
Software and Smart Operation
It is not just adhering to cycle times that is important in production. A low level of programming complexity and simple operation are valued in particular by contract manufacturers with frequently changing assemblies with varying lot sizes. Thanks to a complete offline programming concept with the programming software PILOT AXI, test programs can be created and optimized remotely. A test procedure wizard guides the user through creating the program, from importing the CAD data to debugging the test program, helping with quick parametrization of the test functions. The machine software PILOT Inspect makes handling the X-ray system even more convenient for the operator. The app-style touch-control operating concept clearly displays the most important information and allows even new operators to get to grips with the system quickly, thanks to integrated information messages, images and videos. The inspection system can also be controlled and operated remotely using a tablet.
"Even at my workstation in the office, I have all the information that I would have otherwise only had at the machine itself," says Manuel Sehr, AOI/AXI technician at Limtronik. "I can monitor and control the system, thus enabling me to avoid downtimes and diagnose problems remotely. I can even chat with the system operator from the comfort of my office. It may sound trivial, but it helps clear up questions and problems quickly."
Figure 2: Andreas Türk from Goepel electronic (left) with Limtronik AOI/AXI technician Manuel Sehr at the X Line·3D.
Limtronik Smart Factory
The terms "Industry 4.0" and smart factory have been circulating for many years in the electronics industry. There is barely a company in existence that doesn’t adorn itself with these particular feathers. Although it is only applied to machine labelling in some areas, Limtronik is one of the most cutting-edge EMS companies in the country and is a pioneer of smart manufacturing.
Concrete implementation is based on the interconnectedness of all elements and on creating added value by leveraging useful information from a large data pool. Gerd Ohl, director at Limtronik, refers to it as “turning big data into smart data”. It’s not simply a matter of collecting data—it’s more about data mining. This is understood to mean using statistical methods to obtain empirical relationships from a database—recognizing patterns and trends and prompting machines to take action as required. A project such as this is implemented in collaboration with partners from research and IT fields. All the data—from the assembly process or the manufacturing execution system (MES), for example—is relayed to the project partners, validated and verified. The X Line·3D also plays a role in this. In addition to the full results of an inspection, machine statuses and operating times are also relayed. Among other things, this is intended to enable better planning and integration of future maintenance cycles.
To read the full version of this article, which appeared in the July 2018 issue of SMT007 Magazine, click here.