is typically created using screen or ink jet
printing at present. Advantages of screen printing
include easy and economical turn-round of small quantities, low cost of equipment and ability to deposit thick films in one pass. Ink jet has advantages of deposition on very uneven surfaces to a wide choice of thicknesses and formulations and relative lack of ink wastage.
However, as processes are scaled up and costs have to come down, we see printed electronics increasingly being made with traditional high speed printing technology, particularly as suitably thin, high integrity inks become available such as the new silver conductive inks for gravure
and flexo printing. Thin inks can be applied at high speed with gravure or flexo and they do not crack with age or flexing.
Fortunately, at UHF
, conductance and definition of the antenna
pattern are relatively undemanding. Indeed, Avery Dennison
, an RFID
leader in the USA, and Omron
, Japan's largest producer of RFID labels, both moved to gravure for UHF RFID label antennas recently. At a recent event, the PLGA gave Avery Dennison two awards for its gravure printed RFID labels.
Let us look at the competition between gravure and flexo for conventional printing because it has lessons for printed electronics as companies such as PolyIC
develop printed RFID transistor
circuits with both to find the best way forward. To understand the flexo vs gravure arguments, we attended the Packaging
and Label Gravure Association conference in Miami March 1-2.
According to statistics cited by the PLGA and the conference speakers, having lost share some years ago, gravure is now in rapid growth, flexo in slow growth and other printing technologies are in decline. The reasons for this include the quality and reproducibility of gravure printing. Brands are paranoid about getting printers in different countries to reproduce their logo, candy package etc exactly the same in colour, registration etc. Flexo grew to 30% or so but is being beaten back - though gravure is thought to be still a bit
behind flexo. Gravure is used for packaging of cigarettes, alcohol, food etc, magazines, lottery tickets, medicines, catalogues, newspapers, PVC flooring, wallpaper, laminates and postage stamps - though not exclusively. It is good for shelf impact and economic for long runs, bad for short runs and short lead times and the finest definition can sometimes be a problem.
Unfortunately the conventional printing market is shifting to shorter runs. Gravure has responded with fast changeover presses, laser engraved cylinders, plastic cylinder bases, lightweight sleeves, faster engraving heads, automated workflow, register scan present etc. but it has not marketed these benefits as aggressively as the flexo proponents have done. In addition, it is in a poor position in the increasingly popular sub category of flexible packaging. We note that printed electronics is increasingly requiring finer definition and flexible films as substrates.
The European Rotogravure Association (ERA) presented in the main session. It started in 1956 and has 130 member companies involved in publication, packaging and decorative gravure and allied equipment. It has carried out many surveys such as getting brand managers to say what type of person is equivalent to the different printing options they contemplate (gravure is a conservative man in a pin stripe suit and flexo is a guy propping up the bar) and what type of car (gravure is a Mercedes
). George Battrick of ERA claimed that standard flexo is about two thirds of gravure price but high quality flexo is approaching the quality of gravure but also approaching the price of gravure. We would note that flexo is surely better with uneven and flexible surfaces as needed for printed electronics, but the many flexible packages with gravure at this event shows how gravure can cope in these situations too. ERA said that the brands used to respond to the environmental movement but it now prioritises visual impact and is prepared to pay for it. IDTechEx sees something of this with RFID tags as well.