Kurtz Ersa Magazine

Best Practice: Preh

Avoid assembly errors with optical control

Preh expands Ersa Wave Soldering System with VERSAGUIDE

Climate control, seat adjustment, touch screen – almost all car drivers have had contact with Preh´s innovations. The automotive supplier from Lower Franconia develops and manufactures human machine interfaces (HMI) for passenger cars and commercial vehicles as well as e-mobility control units. To eliminate zero slippage and rework, Preh retrofitted the Ersa POWERFLOW wave soldering system installed in 2019 with the VERSAGUIDE assistance system.

Jakob Preh founded his company in Bad Neustadt an der Saale in 1919 at the beginning of the broadcasting era. As an expert in radio and later television electronics, Preh initially manufactured electrical installation parts and developed radio receivers. This was followed in the late eighties by the production of electronic heating and air-conditioning control systems – the company´s entry into the automotive industry. In 100 years, Preh grew into a global automotive supplier, today employing around 7,000 people at ten locations (sales 2019: over 1.5 billion Euro).

The Preh corporate claim “Passion for Excellence” implies continuous optimization of all process steps. Example: A complete control system was subsequently added to the Ersa POWERFLOW wave soldering system – consisting of four placement workstations including VERSAGUIDE assistance system, a PCB buffer and a lifting or lowering station. After the soldering process, a VERSAEYE module takes care of the automatic optical inspection (AOI).

Easy operation of the VERSAGUIDE through step-by-step instructions
Easy operation of the VERSAGUIDE through step-by-step instructions

As part of a zero-defect strategy, Preh decided to use VERSAGUIDE to eliminate rework already during assembly. Background: In the automotive sector, only 100% intact parts may be installed to ensure the functional reliability of the components used later. Rework is usually ruled out for the high-mass components often used at Preh, since not enough thermal energy can be introduced into the PCB. VERSAGUIDE supports and controls manual PCB assembly, so that assembly errors and costs for costly rework are avoided. The system is mounted above the assembly workstation – and, as with Preh, can be easily retrofitted.

Functions of the Ersa VERSAGUIDE

  • Check for correct components
  • Color check
  • Assembly process
  • Structure check
  • Checking of strings for barcodes
  • Recording oft he work result

Image recognition prevents assembly errors

Via image recognition, the inspection criteria can be set and monitored. Features such as character strings, patterns, colors and textures are reliably detected, and individual components can be read into the software as an image. For error-free inspection, the camera must capture all components to be assembled and the complete PCB. VERSAGUIDE then guides the user through the individual work steps. The main view is divided into three parts: “Work instruction” shows the correctly assembled PCB. Depending on the complexity, you can insert explanations or work with intermediate results. The camera live image shows the initially empty PCB. By means of an anchor point this is fixed by software. This way, an x/y offset or a rotation can be corrected. Red frames indicate where the next action will take place. VERSAGUIDE also recognizes a wrongly placed component. Which components follow in which order is shown in the third view area below the live view. Individual “checkpoints” result step by step in the finished PCB.

Modular control center center console from Preh for BMW; Source: Preh GmbH
Modular control center center console from Preh for BMW; Source: Preh GmbH

Traceability from start to finish

This is how the Preh line works: The PCB is booked into the system at the placement workstation. VERSAGUIDE points to the start of the assembly process and provides step-by-step support for assembly and inspection.


As soon as the board is ready for soldering, VERSAGUIDE sends a signal via the IO cables to the outside, whereupon a release button is activated. After pressing this button, the PCB is transported to the POWERFLOW where it is soldered. Finally, the PCBs are transported to the VERSAEYE module for inspection and documentation of the soldering quality. If the solder joints meet the defined criteria, the software reports its okay. With the products previously inspected at VERSAGUIDE plus recorded DMC, the AOI result is added in the guidance computer.

Good business relationship at short distance

The automotive supplier has been relying on Ersa soldering equipment since 2005 – the 120 km between the two headquarters are quickly bridged. In addition to the extended wave soldering system, several HOTFLOW (reflow soldering systems), VERSAFLOW (selective machines) and i-CON soldering stations are in use at the Bad Neustadt plant. “Whether it´s PCB layout, traceability or PCB transport – Ersa is our No.1 contact for the entire soldering process,” says Justin Oppelt, Department Manager Electronics Manufacturing at Preh.

Headquarters of Preh GmbH in Bad Neustadt an der Saale; Source: Preh GmbH
Headquarters of Preh GmbH in Bad Neustadt an der Saale; Source: Preh GmbH

Preh GmbH at a glance:

  • Founded in 1919 by Jakob Preh
  • 7,000 employees worldwide, 2,000 of them at the headquarters in Neustadt an der Saale (Germany)
  • Innovation leader in the fields of human machine interfaces (HMI) for passenger cars and commercial vehicles as well as components for e-mobility applications
  • Annual sales in 2019: € 1,5 billion
  • Locations in Germany, USA, Mexico, Sweden, Portugal, Romania, China

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