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Successful Completion of EU-funded Clean4Yield Project

Dr. Schenk is one of the 15 partners in this prestigious project

Ultra-fast Dr. Schenk TDI cameras as used in the Clean4Yield project

Dr. Schenk's ultra-fast TDI cameras with CMOS technology are used in all Dr. Schenk AOI systems

After three years of researching contamination prevention and defect control  to increase the yield of large-scale roll-to-roll production of OPV (organic photovoltaics) and OLEDs (organic light emitting diodes), EU-funded project Clean4Yield has been successfully completed. Dr. Schenk is one of the 15 partners in this prestigious project, contributing over 30 years of optical inspection expertise embodied in three Dr. Schenk systems used for defect detection and layer thickness monitoring.

The challenge Clean4Yield set out to solve was how to inspect, clean and possibly repair the extremely thin nano-scale layers used in OPV, OLED and high-end barrier film production. When the fine layer structures are damaged, for example by particle contamination or coating defects, the functionality of the entire product is at risk. Tiny particles in the conductive layers can lead to a short circuit and the failure of an entire module.

Since OLED and OPV are manufactured in a roll-to-roll process, it is essential to produce them economically. This requires optimization of the production process along with efficient but gentle cleaning of the foils on which the organic modules are placed. Product optimization can be achieved by detecting defects early in the production process. The defective material can thus be excluded from further costly processing. Depending on the kind of defect, the isolated material can be repaired using a laser to target the defect and thus remove the danger of short-circuiting an entire module.

Dr. Schenk provided one particle counter (PAC) and two automatic optical inspection solutions (AOI) to Clean4Yield. The PAC is able to detect extremely small particles on very thin films. It detects, distinguishes and categorizes particles down to 0.5 µm on films of 100 µm thickness and can even determine whether a particle is located on the front or back of the film. The two AOI are equipped with new QUAD_LINE illumination units, featuring four different wavelengths. These solutions were used to monitor changes in the thickness of the coating layers, returning information for the complete width of the inspected film. The data collected by the inspection solutions is complemented by data from a ellipsometer. The latter is commonly used to monitor layer thickness variations but delivers only point-by-point results. The Clean4Yield project showed that Dr. Schenk’s AOI can not only deliver the information that the layer thickness is changing – they can also determine whether the layer thickness is increasing or decreasing. This information is crucial for process optimization where the goal is to use only as much of the costly coating material as necessary to ensure the product function but not exceed that amount.  

All three systems were optimized during the Clean4Yield project. Both products, PAC and AOI, are available as turn-key solutions for manufacturers all over the world.