Precise and Clean Connections Soldering Under High Vacuum

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Clean, oxide-free solder joints and consistent results can be achieved under high vacuum conditions. This is precisely where the vacuum soldering process from iew comes in: The systems work with precisely coordinated vacuum technology from Pfeiffer Vacuum+Fab Solutions and enable stable processes with minimal energy consumption and low maintenance requirements.

For the development of a new generation of vacuum soldering systems, iew needed a reliable high-vacuum solution that is both technically robust and economically efficient. Together with Pfeiffer Vacuum + Fab Solutions, a system concept was developed, consisting of a combination of a turbomolecular vacuum pump and a backing pump. This ensures an ultimate vacuum of up to 8×10⁻⁶ hPa (mbar). As a result, reproducible solder joints are achieved even with temperature-sensitive materials because oxidation is prevented under these nearly gas-free conditions, heat transfer is precisely controlled, and the components are evenly bonded with the solder alloy. At the same time, the oil-free vacuum pumps reduce maintenance efforts and prevent contamination in the process chamber—a crucial factor for the high quality of the manufactured components.

Where Precision Meets Innovation

Originating from a thesis on induction heating, the company was founded in 1996 by Dipl.-Ing. Martin Schweikhart as Ingenieurbüro Schweikhart. Just a year later, it was renamed iew induktive Erwärmungsanlagen GmbH. With around 20 employees, iew now serves customers worldwide.
 In addition to individually configurable induction heating systems, iew's vacuum soldering systems make up an increasingly significant portion of revenue. The company is the only provider globally offering both technologies from a single source—which is an advantage for many customers who require both processes for their production.
 The systems are used in applications such as soldering high-performance diamond tools, shrinking, annealing, and hardening metals, as well as in testing technology and research. In the vacuum soldering business area, approximately 80 percent of applications are in tool technology. Manufacturers of measuring probes and companies in the medical technology sector also show significant interest in the soldering technology.

Vacuum Soldering Under Optimal Conditions

The vacuum soldering process begins with the preparation of the components to be joined, which may consist of hard metal, polycrystalline diamond, or ceramics, depending on the application. After applying the solder paste, the workpieces are positioned in a quartz glass vacuum chamber. The chamber is then evacuated until a pressure of about 5×10⁻⁴ hPa (mbar) is reached. This removes oxygen, nitrogen, and moisture from the process chamber—crucial to prevent oxidation and contamination at the solder joints.

During the soldering process, infrared heaters provide precise heating of the components. Initially, they are uniformly preheated to avoid any stress in the material. Once the soldering temperature is reached, the vacuum pumps lower the pressure further to about 5×10⁻⁵ hPa (mbar). This high vacuum level minimizes heat conduction through residual gases and ensures uniform melting of the solder alloy at typically around 700 to 900 °C (approx. 1290 to 1650 °F).

After the soldering process is completed, the vacuum level is further increased—to about 8 to 9×10⁻⁶ hPa (mbar). In this nearly gas-free environment, the workpieces can cool down slowly and controlled, without oxygen or nitrogen reacting with the surface. Only when the temperature has dropped to about 150 °C (approx. 302 °F) is ambient air gradually allowed back in to ensure a gentle pressure equalization.

The interplay of precise temperature control and stable high-vacuum conditions guarantees reproducible results, dense and clean solder joints, and consistently high product quality. The robust systems are designed for continuous industrial operation and impress with their long lifespan and minimal maintenance requirements.

Tailored Vacuum Technology Instead of Off-the-Shelf Solutions

In 2016, iew began developing the first prototypes for vacuum soldering systems, which were later to be available in two versions—a compact variant for smaller batch sizes and a larger system for industrial mass production. The aim was to create a reliable and resource-efficient alternative to conventional systems, which often operated with oil diffusion pumps. During startup, the oil had to be brought to operating temperature, and there was always a risk that oil vapors would enter the vacuum chamber, contaminating sensitive surfaces. Additionally, maintenance and cleaning were correspondingly labor-intensive.

In response to these issues, a compact high-vacuum solution was developed with the support of Pfeiffer Vacuum + Fab Solutions, which operates without diffusion pumps and works significantly more efficiently. The jointly realized system architecture combines turbomolecular vacuum pumps with dry or oil-lubricated backing pumps—depending on the process requirements. This combination ensures stable pressure conditions down to the range of 8×10⁻⁶ hPa (mbar) and enables clean, reproducible soldering with minimal energy and maintenance effort.

In the smaller system variant, a Hi-Pace turbopump and an oil-free Hi-Scroll series scroll vacuum pump are used, complemented by precise vacuum gauges, dust separators, and robust valves. For higher throughput, the larger system utilizes a HiPace turbopump in conjunction with an oil-lubricated DuoVane rotary vane vacuum pump. All components are perfectly coordinated and designed for operation under continuously varying thermal loads with occasional dirt ingress—a prerequisite for high process stability in daily use.

Simon Riefling, responsible for international sales at iew, emphasizes: "We chose the vacuum solutions from Pfeiffer Vacuum + Fab Solutions in 2018 because the company stands for top quality and excellent service. As a German manufacturer with strong high-tech expertise, Pfeiffer is a market leader, whose products we regularly see at universities, colleges, and in renowned companies. For us, Pfeiffer embodies maximum reliability, which is why we use their vacuum pumps in our vacuum soldering systems; we want to ensure the best possible quality for our customers." The installed vacuum solutions are characterized by easy maintenance and long service life. The turbopumps, for example, are designed for a maintenance-free runtime of up to five years.

*Head of Marketing, Busch Austria GmbH