A journey through 25 years of reworking technology

It all started in 1997 with the IR 500 A, Ersa’s first infrared rework system. It was developed together with the small company from Odenwald Rewatronik to be able to safely desolder and solder Ball Grid Array (BGA) components, which were still new at the time. Very quickly it became another In collaboration with the Swiss positioning specialist Essemtec, a suitable unit was designed for component placement, as fine-pitched components and components with hidden solder spots cannot be positioned accurately enough by hand. “When I joined Ersa in 2000, SMT / BGA repair was still in its infancy,” says Jörg Nolte, product manager responsible for Ersa’s rework area. He adds: “But then things progressed steadily, because we had the right horse backed – especially the spread of ball grid arrays, which at first were difficult to master, steadily increased and with it the need for work. of qualified follow-up “.

Rework promotes the production of sustainable electronics

Maintaining the added value – Rework promotes the production of sustainable electronics. (Image: Ersa)

Today BGA belongs to the family of Bottom Terminated Components (BTC), i.e. components with solder connections on the underside of the component. In the early years, BGAs were often the most sensitive components of an assembly: if the thermal equilibrium in the soldering process was not fully balanced, the package would deform and, as a result, bridges or other soldering defects would often occur – and therefore frequent failures and need for repairs. The classics with the BGAs are and were excessive tension in the welded connections of the corner spheres and the related microcracks. Recasting the BGA with the addition of some flux remains a proven means of repairing such errors. Even today, the descendants of the BGA are sensitive to the relevant process parameters. Micro lead frame (MLF) components tend to fluctuate if solder quantities are metered inaccurately, causing the signal contacts to open. The list of models and causes of failure could be continued – it is important to establish safe repair processes for all these cases.

IR technology

Even today, you can find adventurous clips on the internet that show how people are trying to swap processors and other components on printed circuit boards with the help of hot air guns. The results of the welding: more than questionable. Ersa has had to invest a lot of time and energy to convince users from mobile phone service centers to the electronics industry of infrared technology in their systems. Established manufacturers of hot gas rework systems have also gone to great lengths to torpedo IR technology. “Presumably the components get too hot, the process cannot be controlled and the reflective surfaces do not overheat, the user would be harmed by the IR radiation!” Nolte remembers the verbal barriers of the early years.

However, the medium-wave and thus largely invisible radiant heat of the ceramic heaters was convincing: unlike quartz heaters, their radiation spectrum is optimally suited for quickly and homogeneously heating metals, plastics, ceramic and epoxy resins in a fixed assembly. The temperature differences measured on one component (Delta T) reached values ​​of just 6 ° C and higher. It quickly became clear to many users that the sensor-driven process of a medium wave IR rework system has advantages over established techniques: the weld profile follows specifications very precisely due to precise temperature control. Components and assemblies are heated evenly and gently. Since no component specific nozzles are required, there is a clear view of the weld spot and the process can be observed using cameras.

Lead-free repair

During the introduction of lead-free solder in 2006, melting temperatures increased of solder alloys (lead 183 ° C, lead free approx. 217 ° C) the requirements for soldering equipment and rework systems. Higher temperatures created smaller process windows and many component materials had to be tightened first. Precise process control has become increasingly important.

Ersa HR 600 XL

Professional large format PCB repairs are performed with Ersa HR 600 XL, the universal hybrid rework platform for processing PCB assemblies up to 625 x 1,250mm. The operating software HRSoft 2 takes care of the creation of the graphic profile and the user guide. (Image: Ersa)

The Ersa IR / PL 550 and its big brother IR / PL 650 shaped the industrial assembly repair of that time. As a technical highlight, non-contact temperature measurement using a pyrometer was first introduced in these systems. Due to the requirements for the repair of large and large printed circuit boards in the IT infrastructure industry, the first large format rework system, Ersa IR / PL 650 XL, was created for an American EMS service provider. Since then, rework has been further professionalized, although some sectors continue to exclude it. Investigations like this ZVEI “Guidelines for Rework Electronic Assemblies” (published in 2017).that professional reworking leads to reliable results if, as in the line process, all important parameters are met. “Often it is not the lack of confidence in the technical process, but the release effort associated with the repair that justifies this reluctance,” says Jörg Nolte. At this point, deeper cooperation between users, device manufacturers and institutions is desirable.

sustainability

Maintaining added value and avoiding unnecessary waste due to bridging an MFF or BGA is the first level of sustainable action. The “right to repair” required by the EU Commission forms the basis for avoiding electronic waste and also for advancing electronics production on the path of consumer protection resources and towards a circular economy. In industry and service centers, thousands of printed circuits are processed every day with Ersa’s reworking systems and therefore protected from partly uncontrolled scrapping.

Exact positioning of components

Exact positioning of components from chip components to BGAs with an edge length of approximately 100mm: Left: Metallic BGA above the light dome to detect component connections Right: when manipulating above the board (Image: Ersa)

Ersa becomes hybrid and automatic

Hybrid technology is making its way into Ersa’s rework systems with the HR 100 manual rework system and the HR 600 automatic rework system. The proven IR heating technology is supported by a convection component in the upper heater area. This means that the heat energy released by the radiator is used even better and the target component is heated more quickly. The disadvantages, as is known for hot gas systems, eg. the blowing of the smaller components of the chip, does not occur, however, as very small amounts of air are used.

The HR 600 presented in 2012 also takes into account an important customer request: more automation! For the first time, the desoldering process, component placement and soldering process are linked in such a way that the device operator has almost no influence on the subsequent result. Process safety and repeatability are the focus of attention. The particularity of the HR 600, whose revised version is still one of the most popular repair systems today, lies in the automated positioning of components. With the help of two cameras, image processing and a high-precision axis system, the target component is automatically and precisely positioned on the printed circuit board and thus also automatically welded.

Process monitoring with RPC camera during welding.

Process monitoring with RPC camera during welding (Image: Ersa)

The new generation of rework systems

“Starting with the HR 500, the current product range up to the HR 600 XL covers virtually all the needs of relevant customers in global markets and industries”, summarizes the positioning of the Ersa brand Jörg Nolte. The youngest convince Systems both in terms of technology and in terms of the need for a uniform software platform. “The user does not have to get used to switching from one system to another: everything is structured in the same way”, Nolte emphasizes. With the first HR 550 developed entirely in-house, Ersa introduced the technology in-house relatively late. Jörg Nolte: “Of course it was a big learning curve for us, but now we have the entire engineering experience and therefore we can react much better to market movements. This is a decisive factor today, especially in software technology. “With the flagship of the product line, the HR 600 XL, the functional extensions and optimizations requested by customers can be implemented quickly and with high quality: with a lower heater extended, the system can now accommodate assemblies up to a size of 625 x 1,250mm, with large heating head components with edge lengths of over 100mm!

And what’s next?

When asked if everything is over after 25 years, Jörg Nolte smiles and explains: “In principle, yes. But development goes on. And this is just as good. Because contrary to all forecasts, the assemblies will have to be reworked in the near future ”. An automatic residual solder removal for the HR 600 XL is currently being launched on the market. In the field of sensors, work is underway to optimize non-contact measurement technology.

Additional topics on systems accuracy, continuation of heating technology can also be found in the roadmap, as well as additional automation and linking devices to Manufacturing Execution Systems (MES). This makes rework a full-fledged part of the manufacturing process in terms of sustainable production. Yes, the currently widely misused term artificial intelligence has also already been discussed. And, of course, the machining of new component shapes must be taken into account, as well as the manufacturing costs of the devices. When asked what he likes best about Ersa’s 25 years of rework systems, Nolte replies: “It’s a great feeling we’re providing our customers with useful tools!”

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