Research On NFC Antenna Fabricating Technology Based On Printed Electronics

With the rapid development of the information technology, more and more ordinary people have started using smartphones. Those smartphones embedded with the Near Field Communication(NFC) system especially are changing people’s daily life gradually. Transit cards, debit or credit cards, key fobs and many other cards that utilize Radio Frequency RFID technology can all be replaced with smartphones that support NFC features. In order to massively promote the NFC system, solutions to reduce its manufacturing cost are in demand. The traditional NFC antenna manufacturing techniques, such as etching, and conductive ink printing, require complicated process, expensive equipments, and cause waste in resources, and pollutions. Hence, this paper proposed “additive process” method based on the printed electronics techniques. This method is easy to process, environmentally friendly, and low in cost. It is expected that this technique can replace the current traditional antenna manufacture methods.Printed electronics technique’s main feature is superposition. Functional electronic inks(metal conductive ink, semiconductive ink, media ink etc.) are deposited on the organic or inorganic substrate by common printing equipments to create electronic circuits and devices. The main research contents of this paper are:1. Research on the theory of NFC antenna, and analyze the effects of the antenna thickness h on resistance, inductance, and impedance. Compare the advantages and drawbacks of etching, gravure printing, silk-screen printing, ink-jet printing, and direct laser writing methods, and proved that the technique proposed in this paper has its advantages over others.2. State the reasons of using polyimide as antenna printing substrate material, and introduce several substrate surface modification methods. Research on technique that uses alkaline potassium permanganate in surface modification, and show that the PI thin-film surface roughness can be raised by using alkaline potassium permanganate solutions, and the hydrophobic substrate surface can be altered to be hydrophilic by introducing carboxyl and Hydroxyl through hydrolysis. Discuss the preparation techniques of precursor ink that is suitable for printing, and prepare ink that meets the viscosity, surface tension, and pH value requirements.3. Research on the best performance of antenna device printed with ink-jet lithography, and verify that the resolution of the printing is 127 μm, and the optimal printing distance is 2 mm. Discussed the patterns of the change in antenna width after metallization, and give a guideline on antenna width design. Research on the changes in line-width and the copper layer patterns under 30° and 45° angle between the lines and injector operating direction. Research on two-step copper-plating technique, and reduce the resistivity of the copper-plated layer to 2.8×10-8 Ω·m. Verify the 40-50℃, 3 min one-step copper-plating technique. Analyze the effects of additives in the second-step plating solutions on the consistency of the copper layer, and verify the amount of added 2-MBT to the second-step plating solutions. At last, give solutions to the instability of the second-step plating solutions during electroplating.