Paper over wet etching for RFID antennas

The manufacturing of RFID antennas through the process of etching is now being challenged by a patented technology.

Walki-4E is a way of producing flexible circuit boards efficiently and sustainably. This is possible through a dry production process, involving no liquid chemicals and using paper as the substrate. It also allows for computer to antenna production and accurate laser cutting of the circuit board patterns.

Walki, a producer of technical laminates, looked for ways to simplify the manufacturing process, while making use of its knowledge in lamination.

“We think that Walki-4E technology is the first feasible alternative to etching and that it will bring new dimensions of cost efficiency and sustainability to the industry,” said Sami Liponkoski, business line manager at Walki.

In brief, the idea is to make a special laminate of aluminium and paper substrate, where the aluminium foil is cut in patterns using a laser.

Computer to antenna production and laser cutting of the flexible board patterns allow for a speedy production process and high accuracy. For example, the laser cuts with an accuracy of 20 microns while a human hair has the thickness of 100-120 microns.

The technology can be used for any production of flexible circuits boards, ranging from RFID antennas to boards for radiators and flexible displays. The first product to be launched using the technology is Walki-Pantenna, a UHF RFID antenna.

The four E’s of Walki-4E stand for efficiency, exactness, economy and ecology. Compared with etching, the technology eliminates a whole step from the tag production process or from the converter’s process, thus combining efficiency and economy.

“Since paper is used as a substrate, the RFID manufacturers can leave out the insertion of the PET inlay into paper, a necessary step when the antenna has been produced by etching. Moreover, the computer to antenna production method speeds up design and development, an advantage especially when it comes to producing short series, involving a fewer number of antennas,” Liponkoski said.

Cost efficiency comes hand-in-hand with environmental benefits. The dry process does not involve any chemicals, thus resulting in process residue that is easily recyclable. The absence of liquid chemicals also leaves the RFID manufacturers with a product, the ready antenna, that is 100% recyclable.

“Since the antenna is free from plastics, made of paper and aluminium only, it is easily recycled in a fibre recycling process, where metal detectors sort out the aluminium,” said Liponkoski.

The precision of the laser cutting of the patterns allows for smaller chips, greater repeatability in the production process and higher accuracy of the antenna.

“This does not only overcome certain accuracy problems that etching brings, but also gives new possibilities for developing the antennas and the chips,” Liponkoski said.

Digitalisation of the production process - ie, computer to antenna production - brings efficiency and allows for an endless number of variations in the patterns.

“Our vision is that the antenna production eventually will be completely digital. Laser cutting can speed up the production process by 10 times and, taking into account the development that laser technology undergoes every year, the possibilities of producing flexible circuit boards with lasers are almost limitless.

“We are now in the ramp-up phase for our production line in Pietarsaari, Finland, and we are looking forward to introduction in the market. There is a lot of interest in our product and we strongly believe it has the capacity to change the industry,” Liponkoski said.