Study On Fabricating Printed Conductive Patterns Based On Polyimide Substrate

Printed Electronics（PE）,which is an emerging field of additive manufacturing technology,has emerged as one of the key technologies for electronics and has been concerned by more and more researchers in recent years.Due to the characteristics of additive manufacturing,PE have proceeded rapidly significant potentials for low-cost and large-area electronics manufacturing process,high material utilization rate,less waste product and increased flexibility for hybrid design,in comparison with traditional etching–based process.At the same time,PE has a variety of applications,Radio Frequency Identification Tags（RFID）,thin-film flexible solar cells,sensors and transparent conductive films etc.Meanwhile,various printing technology,such as gravure,offset printing,flexography printing,screen printing,ink-jet printing and so on,has received adequate attention and development in recent years.With the rise of flexible electronic devices and packaging markets,printed electronics technology will be concerned and developed in the future.In this thesis,we research about the development status of printed electronic technology,functional conductive ink and conductive materials at home and abroad now.In combination with the characteristics of printing technology and polyimide（PI）films,three kinds of whole printed conductive pattern manufacturing process are carried out,and the key parameters and principle of the processes are studied.In the first progress,silver ion based catalytic ink is utilized as a seeded layer for electroless copper metallization in room temperature by using the principle of electroless deposition.Through optimization of Ag⁺ink composition and printing process parameters,the pattern definition and continuity of electroless plated copper have been improved.The copper pattern conductivity reached 8.01×10^-6Ω·cm.In the second progress,we demonstrate a simple,one step and heating-free approach to produce the silver conductive patterns which is based on ion exchange self-metallization on polyimide（PI）films by using low end color inkjet printer.The silver ion ink and reducing agent ink which filled in different color cartridge of color inkjet printer were printed on the alkaline treated polyimide film in proper order.Due to the reaction of silver ion exchange and chemical reducing,silver particles were synthesized on the polyimide film.The resulting resistivity of the printed silver patterns reached 5.56×10^-6Ω·cm.In the third progress,a silver-capsuled toner has been facilely developed for electrophotographic patterning of copper layers on flexible substrates,with high performance across manufacturing scalability,printing resolution and speed,and production affordability to end users.The obtained copper tracks have electrical conductivity of 6.8×10^-4Ω·cm.The advantages of the three processes are simple,low cost and no heat treatment process.The traditional process of printed electrics,printing nano-metal particles and sintering under high temperature,was developed.In the first process,the ionic ink was used to overcome problems of blocking the nozzle by nano-metal particles and the heat treatment.At the same time,adding the chemical copper plating process is a good way to reduce the production costs;In the second process,the color inkjet printer was used to achieve one-step to making conductive lines;In the third process,the laser printer was used to achieve the high-speed printing in printed electronics process and expand the option of printing technology.These three processes all have broad application prospects in the manufacture of flexible circuit boards,flexible devices and sensors and other fields.