25 years of Ersa Rework
Sustainability in Practice!
A journey through 25 years of Rework Technology
Ersa has been involved in the repair of electronic assemblies for 25 years. Above all, the rework of highly polarized SMT components – also called “rework” – is the focus here. In times of component shortages and interrupted supply chains, it is more important than ever to maintain the value already created.
It all started in 1997 with the IR 500 A, Ersa´s first infrared rework system. It was developed in cooperation with Rewatronik to safely solder and de-solder the “Ball Grid Array” (BGA) components, which were still new at the time. A suitable unit for component placement was quickly designed in a further cooperation with the Swiss placement specialist Essemtec, since fine-pitch components and those with hidden solder joints could not be placed precisely enough manually. “When I joined Ersa in 2000, SMT/BGA repair was still in its infancy,” says Jörg Nolte, Ersa Product Manager Rework. And adds: “But then things moved forward – the spread of BGAs, which were initially difficult to master, increased steadily, and with it the need for qualified rework.”
Today, the BGA belongs to the family of bottom terminated components (BTC), i.e. components with solder connections on the component underside. Initially, BGAs were often the most sensitive components in an assembly: If the thermal balance in the soldering process was not completely balanced, the package would warp and often bridge or other solder defects would occur. The classic case with BGAs is and was excessive stress in the solder joints of the corner balls and the associated microcracks. The re-melting of the BGA with the addition of a little flux remains a tried and tested means of repairing such defects to this day. Today´s BGA descendants are also sensitive to relevant process parameters. For example, “micro lead frame” (MLF) components tend to float when the amount of solder is inaccurately dosed, resulting in open signal contacts.
IR-Technology
Even today, you can find adventurous clips of attempts to swap processors and other components on PCBs with the help of heat guns. The soldering results: More than questionable. Ersa had to invest a lot of time and energy in convincing users from cell phone service centers to the electronics industry to use infrared technology. The medium-wave and thus largely invisible radiant heat of the ceramic heaters was convincing: Unlike quartz heaters, their radiation spectrum is excellently suited to heat metals, plastics, ceramics and epoxy resins of a stationary assembly quickly and homogeneously.
The temperature differences measured over a component (delta T) reached values of only 6 °C and better. It quickly became clear that the sensor-guided process of a medium-wave IR rework system even has advantages over established techniques – the soldering profile follows the specification very precisely due to precise temperature control, and components and assemblies are heated homogeneously and gently.
Lead-free Repair
During the introduction of lead-free solders in 2006, the melting temperatures of the solder alloys (leaded 183 °C, lead-free approx. 217 °C) increased the demands on soldering equipment and rework systems. Higher temperatures produced smaller process windows and many component materials had to be reworked first; precise process control became increasingly important.
The Ersa IR/PL 550 and its bigger brother IR/PL 650 shaped the industrial component repair of this time. As a technical highlight, non-contact temperature measurement using a pyrometer was introduced for the first time. Due to the requirements for the repair of large and high-mass printed PCBs from the IT infrastructure sector, the first large-format rework system, the Ersa IR/PL 650 XL, was developed for an American EMS service provider. Rework has since been further professionalized, although some industries continue to exclude it. Studies such as the ZVEI´s “Guide to Rework of Electronic Assemblies” show that professional rework leads to reliable results if – as in the line process – all important parameters are observed.
Sustainability
Maintaining added value and avoiding unnecessary scrap due to a bridge on a QFP or BGA is the first level of sustainable action. The “right to repair” demanded by the EU Commission forms the basis for avoiding electronic waste and advancing electronics production towards the Circular Economy. In industry and in service centers worldwide, thousands of circuit boards are processed with Ersa rework systems every day and thus saved from partly uncontrolled scrapping. While quite a few suppliers of rework systems have appeared and disappeared over the past 25 years, Ersa has firmly established itself in this field as well. Long-standing customer relationships, exemplary worldwide service and very long spare parts availability, even for products that have already been discontinued, are testimony to this.
Ersa becomes hybrid and automatic
Hybrid technology is making its way into Ersa rework systems with the hand-held HR 100 and the automatic HR 600 rework system. Here, the proven IR heating technology is supported by a convection component in the area of the top emitters. This makes even better use of the thermal energy released by the emitter and heats the target component more quickly. Disadvantages such as the blowing away of the smallest chip components in hot gas systems do not arise because very low air volumes are used.
The HR 600, introduced in 2012, linked the desoldering process, component placement and soldering process for the first time in such a way that the operator of the device hardly influences the subsequent result. Process reliability and repeatability are the focus. The special feature of the HR 600 is its automated component placement. With the help of two cameras, image processing and a high-precision axis system, the target component is automatically positioned precisely on the PCB and then automatically soldered in place.
The new Rework Generation
The Ersa Rework portfolio has meanwhile gained further members: “Starting with the HR 500, today´s product range up to the HR 600 XL covers practically all relevant customer requirements of worldwide markets and industries,” Jörg Nolte summarizes Ersa´s positioning. “The user hardly has to get used to anything when switching from one system to another – everything has the same structure,” says Nolte. Although Ersa had brought the technology in-house relatively late with the first complete in-house development HR 550. Jörg Nolte: “It was a big learning curve for us, but we now have all the engineering expertise and can therefore react much better to market movements.” In the case of the flagship HR 600 XL, functional extensions and optimizations requested by customers were thus quickly implemented – with an extended bottom heater, the system can now process assemblies up to a size of 625 x 1,250 mm, and with large heating heads, components with edge lengths of over 100 mm!
What´s next?
“The development continues. Contrary to all predictions, assemblies still need to be reworked.” Currently, an automatic residual solder removal system for the HR 600 XL is being launched. In the area of sensor technology, the company is working on optimizing non-contact measurement technology. Further topics on the accuracy of the systems, the continuation of the heating technology can also be found on the roadmap, as well as additional automation and the connection of the devices to MES. This makes rework a fully-fledged part of the production process in terms of sustainable production.