By Professor John H. Marsh, Founder and Chief Technical Officer, Intense Ltd.
There is a large and growing demand for reliable techniques for coding and marking of products. Several techniques have become established over the last 20 years, particularly thermal transfer and ink jet technologies. However, the established technologies have limitations, particularly as security and environmental issues become more important.
Both thermal transfer and ink jet systems mark on the surface of the product. Such marking is easy to remove and relatively easy to alter. Techniques which allow a buried layer to be marked, for example a layer in the middle of a laminated package, are much more secure.
Thermal transfer and ink jet solutions require consumables to be available on the production line. Thermal transfer techniques make use of wax and resin coated ribbons. After printing, most of the coating remains on the ribbon and it is difficult to recycle such materials effectively. Ink jet technology uses inks containing a variety of additives including solvents. Solvents lead to atmospheric contamination and spills are a major contributor to contamination of ground water. As a result, their use is subject to increasing controls and is severely restricted in many regions.
Further drivers behind new technologies are the need for increased speed, a preference for non-contact technologies, and a growing need to mark uneven surfaces, such as labels containing RFID tags.