The process is based on photochemical metallisation of silver compounds. Several methods are said to be available to transfer these silver compounds on to plastic foil or glass, with paths as small as 1µm. By irradiating these with UV light, the silver compounds are transformed into electrically conductive metallic silver. This basic principle allows conductive paths to be created individually.
“There are three possibilities,” said Peter William de Oliveira, head of optical materials, “depending on the requirements. Writing conductive paths using UV lasers is particularly suitable for initial prototype manufacture and testing the design. However, for mass production, this method is too time consuming.”
Photomasks can also be used for structuring. “For a semi continuous process,” he continued, “these are particularly suitable for applying the conductive paths on glass.”
The researchers are currently developing the third method, which uses transparent stamps. “These stamps push out the silver compound mechanically; conductive paths then only occur where there is still silver compound,” de Oliveira explained. Since the stamps are made of soft plastic, they can be arranged on a roll and INM researchers are now working on embedding the UV source directly.
