Wave Soldering
29.08.2022
Having started in the bath and bedroom of the family home almost 35 years ago, VOIGT electronic is a modern EMS service provider today with great passion and know-how for electronics manufacturing. The product spectrum ranges from components for biogas systems to medical technology. By investing in a VERSAFLOW ONE from Ersa which was introduced in 2021, VOIGT have now modernized their THT production and created additional capacities.
No, the foundation of VOIGT electronic GmbH on April 1, 1989 was not an April Fool’s joke, but the starting signal of a success story the kind of which is more commonly known from the USA. However, the origin of this story lies in the former GDR – in the city of Erfurt to be precise. After a marathon of nine months with the authorities, Matthias Voigt finally held the business license in his hands and started his company to produce printed circuit boards.
From the beginnings in the living rooms of the parents’ house with self-made production equipment – for example, a converted hanging file cabinet was used to expose the photoresist for the printed circuit board – VOIGT electronic developed into a modern EMS service provider that is passionate about electronics. The company has never specialized in one industry but has remained broadly positioned until today. The family-owned business manufactures components for measuring instruments, communication, and industrial electronics – as well as for railroad and traffic technology, which is used worldwide. The secret of success: VOIGT live for electronics. This means that they put themselves in the customer’s shoes to understand and optimally manufacture his product. If necessary, products are optimized in terms of production technology and top quality is ensured. Of course, these processes happen in close cooperation with the customer.
With the advent of SMD technology in the 1980s, the development in electronics has changed rapidly. Mixed assembly with THT components and SMDs on both sides is increasing steadily and has become state of the art. The classic soldering process for thru-hole components is the wave process.
However, VOIGT has now reached certain limits with this process. The portfolio includes products that are well-suited for wave soldering, for example assemblies with a large share of THTs on four-layer printed circuit boards. These are mainly long-running products that have been manufactured for many years. Nevertheless, many new customer projects are ill-suited for the wave soldering process – here, VOIGT is dealing with electronic assemblies for measurement technology or test systems, consisting of multilayers with up to 16 or 18 layers assembled with a large variance of bottom-terminated components. This means that all connections are located on the underside of the board. The Erfurt-based company also has many small production lots in its order book: in addition to batches of up to 1,000 units, it also produces prototypes and lots of 20 to 25 assemblies per series. Up to twelve product changes per day have to be handled. VOIGT therefore started a project to evaluate and replace the existing wave soldering system. Here, it was also a matter of assessing whether wave soldering still fitted the product spectrum or if it could possibly be replaced by a selective soldering process.
The advantages of the selective soldering process are, on the one hand, the elimination of solder masks. During wave soldering, these solder masks protect SMD components located on the underside of the PCB from being re-melted and washed away in the solder wave. They are needed even for very small production lots. They must be made specifically for each product and are, of course, a time and cost factor. It is a constant balancing act – if you order too few masks, waiting times occur because the masks are not cleaned quickly enough after a soldering process and it takes too long until they are ready to be used again. You also don’t want to have too many masks for cost reasons.
Another advantage is the flexibility in the selective soldering process: The individual components of a board can be soldered with their individual parameters, whereas with wave soldering one is forced to make compromises. Heating and wetting time in the solder wave can only be set for the entire assembly. Consequently, it is necessary to find the best average value in order to protect sensitive components and still achieve sufficient wetting of the component pins with high heat requirements so that a reliable solder connection is produced. Moreover, since the printed circuit board is only wetted with flux and solder in the spots where the connections to be soldered are located, there is less residue on the board in the selective soldering process. This significantly reduces the cleaning effort and has a positive effect on economic efficiency.
The respective advantages of wave or selective soldering processes are to be found in the amount of THT components in the assemblies to be processed. For mixed assemblies with SMD and THT components, the classic wave soldering system has an advantage if the SMDs are only on the top side of the PCB. In this case, the wave soldering process is very economical because no solder masks are required for processing. If, on the other hand, the underside of the PCB is also fitted with SMDs, with a low proportion of THT components at the same time, selective soldering has an advantage. The economic efficiency is significantly higher simply because solder masks are no longer required.
“Of course, quality is a decisive criterion. But in this case, output was almost more of a priority for us. At the end of the day, I have to produce a certain number of assemblies, otherwise I won’t make my delivery times,” production manager Frank Koppetsch describes the requirements. “In addition, we are currently experiencing a growth boost,” adds Managing Director Sabine Voigt. “The new soldering system should make our production future-proof and provide a backup for further growth.”
VOIGT electronic has been operating an ECOSELECT 4 from Ersa for three years. Therefore, it was a logical step to contact the Wertheim-based soldering specialist again for the new production system. “We attach great importance to long-term partnerships. On the supplier side, this means we need partners who not only supply the equipment, but also take us along technologically to be equipped for the future. That’s what we get with Ersa,” says company founder Matthias Voigt.
This machine project was a classic win-win situation for VOIGT electronic and Ersa: The VERSAFLOW ONE was introduced to the market at Productronica 2021. This compact selective soldering system is the new Ersa entry model into high-end selective soldering. VOIGT electronic became one of the beta testers of the VERSAFLOW ONE. This gave VOIGT the opportunity to evaluate the process for the upcoming investment not only based on a test assembly, but to solder entire production lots with the machine. Under real conditions, they thus found out whether the existing wave soldering machine could really be replaced by a selective soldering system.
VERSAFLOW ONE is available in four versions. Thanks to these fixed configurations, the VERSAFLOW ONE is available within two to four weeks only. The core processes of fluxing – heating – soldering have been adopted from the premium models VERSAFLOW 3/45 and VERSAFLOW 4/55. This means that VERSAFLOW ONE as well features solder level monitoring with automatic solder wire feeder, solder wave height monitoring or regular automatic nozzle activation. This also includes the three-part pin-and-chain conveyor with 3 mm edge support and automatic width adjustment, which can be quickly adapted to different PCB sizes. The soldering module is available with one or two solder pots – special feature here: X-variability. In the maximum expansion stage, the system has two soldering modules.
The VERSAFLOW ONE has also achieved an energy saving of 10% in preheating. The glass cover was replaced by a grid through which the heat reaches the assemblies directly without any absorption loss. By changing the distance, it was possible to reduce the number of IR heaters while maintaining the performance of the heating system.
“Our team got to know the system extremely quickly,” production manager Koppetsch reports his experiences. All Ersa selective soldering systems have a similar operating concept, which is extremely intuitive and user-friendly. In addition, VOIGT already benefitted from the knowledge gained from operating the existing ECOSELECT 4, because like all Ersa systems, the VERSAFLOW ONE is controlled with the ERSASOFT 5 operating software. The integrated CAD Assistant 4 editor makes the creation of soldering programs very fast and easy. Of course, the programs for a product can be saved and are thus quickly available when needed again. Both features are enormously important in companies with frequent product changes.
The soldering quality and throughput of the VERSAFLOW ONE were convincing, but also the ease of maintenance and the low nitrogen consumption. “From our point of view, you need a nitrogen tunnel to operate a wave soldering system properly,” explains Frank Koppetsch. “Since we generate our own nitrogen, we would have had to invest in a larger plant when buying a new wave soldering machine. For the nitrogen coverage of the solder bath in the VERSAFLOW ONE, the consumption is only 2 m3/h. We can cover that very well with our existing nitrogen generator.” Thus, VOIGT electronic decided to keep the VERSAFLOW ONE as a replacement for their wave soldering system after the test phase.
“We are now even more flexible in production and have the desired capacity buffer. Maintenance is much easier and faster than with our old wave soldering system. We are now excellently positioned for the future in this area, especially since our ECOSELECT 4 can be expanded into a VERSAFLOW system if required,” summarizes Frank Koppetsch.
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