Avoidance of assembly errors through visual inspection

Whether for climate control, seat adjustment or operating the touchscreen – nearly every car driver has come into contact with the innovative developments of Preh. The automotive supplier from Bad Neustadt an der Saale/Germany develops and manufactures in particular human machine interfaces (HMI) for passenger cars and commercial vehicles as well as e-mobility control units. To guarantee zero defects and avoid any rework, Preh GmbH retrofitted its Ersa POWERFLOW wave soldering system installed in 2019 with the VERSAGUIDE assistance system.

In 1919, when the great age of radio began, Jakob Preh, who gave the company its name, founded his company in Bad Neustadt a. d. Saale in Lower Franconia. As an expert in radio and later also television electronics, Preh initially manufactured electrical installation parts in a former tavern and was one of the first German manufacturers to develop the Preh Funk radio receiver. In the late eighties, the company entered the automotive industry with the production of electronic heating and air conditioning control systems. In its hundred-year history, Preh GmbH has grown into a globally active automotive supplier and today employs around 7,000 people at ten locations. In its anniversary year 2019, the Preh Group achieved record sales of over 1.5 billion Euros.

The company slogan is “Passion for Excellence”. This striving for excellence requires, among other things, continuous optimization of all process steps. Consequently, the Ersa POWERFLOW wave soldering system, which has been in operation at Preh since January 2019, was retrofitted with a complete control system.

The extension contains four placement workstations incl. VERSAGUIDE assistance system, a PCB buffer to realize machine-compatible cycle times, as well as a lifting and lowering station, so that the entire process can be carried out in a round trip and each carrier is returned to its workstation. Following the soldering process, a VERSAEYE automatic optical inspection (AOI) module was integrated to check for the presence of solder and the formation of a meniscus.

In the course of a targeted zero-defect strategy, the automotive supplier Preh decided to use VERSAGUIDE as part of its process to avoid rework as early as the first process step, i.e. assembly. Due to constantly repeated work steps during assembly, it cannot be prevented that mistakes are made or components are completely omitted.
Particularly in the automotive sector, the elimination of assembly errors has high priority because of the stringent requirements that have to be met. To ensure the functional reliability of the components that will be later in use, any reworking of a faulty assembly is ruled out from the outset. For this reason, only 100% fully intact components may be used right from the start.

Apart from these requirements, it is also a major challenge from a purely technical point of view to correct such errors in the downstream process. In the case of high-mass components, which are frequently used by Preh, rework is usually ruled out, since not enough thermal energy can be transferred into the PCB. Full wetting of the missing solder joint cannot be guaranteed, and cold solder joints may subsequently occur.

With the Ersa VERSAGUIDE for support and control during manual PCB assembly, mounting errors and costs for extensive rework can be avoided. The system is mounted above the assembly workstation. Retrofitting is therefore possible without any problems, as in the case of Preh GmbH. As standard, the camera is located directly above the PCB to be assembled and has thus the best view of the work steps.