Development of an automated digital radiography system for the inspection of plastic electronics
Plastic electronics is a relatively young technology to be used in consumer electronics products. Nevertheless, the plastic electronics global market is forecast to grow as much as £143bn by 2027. Plastic electronics are mostly printed or sprayed on, rather than etched using expensive photolithography systems. Therefore this technology offers a number of advantages over existing printed circuit board manufacture techniques, including low cost and physical flexibility. However, numerous types of defects can arise during manufacture which are specific to plastic electronics and are discovered only after production, leading to high product waste and correspondingly high prices, which threatens the market promise. Specifically, organic light emitting diodes (OLEDs) used in digital displays need to be checked for quality. The OLED inkjet printing process can result in defective pixels, resulting from cracks, chips, pin holes and misaligned layers.
The goal of PlastronicsSpec was to perform rapid, online, high-resolution and 100 per cent volumetric inspection by digital, real-time radiographic imaging. Emphasis was on the development of an in-line automated digital radiography inspection system with high throughput and advanced image pattern recognition links. The PlastronicsSpec project developed a system able to perform rapid and high-resolution inspection of printed plastic flat panels or reel-to-reel flexible electronics sheet using real-time digital radiographic imaging. This enables the automatic detection and instant rejection of defective products with minimum wastage and the elimination of human error in data interpretation.
The main features of the PlastronicsSpec system are:
- a microfocus X-ray source and a 2D flat panel digital detector which generates radiographs with up to 1.2μm resolution at high magnification
- prototype can accommodate a 600mm2D flat OLED panel and can be adapted to handle roll-to-roll flexible electronic samples
- novel multimode signal processing options have been used to detect the smallest possible image differences. Various image-filtering techniques have been integrated to achieve optimum pattern recognition and accurately size defects. The software allows automatic sentencing of parts as good or bad.
By assuring defect-free products, the PlastronicsSpec project provided an enabling technology for the achievement of a mass market in plastic electronics products.
This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement No 286531.