Adhesive reliably bonds RFID chips and antennas

The global RFID market is rapidly growing. IDTechEx expect it to triple to $23.4m (USD) by the year 2020. Tag manufacturers, who sold nearly six billion units in 2013 alone, focus on cost-efficient production. Already today, one flip-chip system bonds up to 20,000 chips to antenna substrates per hour. At the same time, the trend towards miniaturisation is ever-increasing in the field of RFID labels. Their chips are often just 400x400µm in size, which further boost the requirements imposed on the adhesive used. The surfaces for contacting and fixing are shrinking, and the adhesive must be precisely applied in minute quantities.

For this chip attach process, DELO's DELOMONOPOX AC245 adhesive is based on an epoxy resin and provides the utmost reliability thanks to optimised filler content. To verify the reliability, DELO subjected the bonded labels to the special 85/85 test where specimens are stored at +85°C and 85% relative humidity. The tag sensitivity remains at 85% of the initial value even after 1,000 hours under these conditions. It is suitable for the commonly used antenna substrates PET/aluminium, PET/copper or paper-based structures, and for both HF and UHF tags.

Many of today’s labels require no more than 0.02mg of adhesive. Therefore, most RFID manufacturers rely on adhesive jetting to achieve an efficient production process. Such minute quantities of DELO’s RFID adhesive can be dispensed through jet valves. The results achieved during a processing time of several days are both reproducible and precise. Thus, DELO’s adhesive combines high reliability and excellent processing properties. In production, this long processing time offers the advantage of shortening the cleaning intervals of the valves to minimise machine downtimes and ensure that less adhesive is wasted. When a thermode is used, the adhesive takes just 8s to cure at 180°C, ensuring high production output.