Measurement of the Conductivity of Screen Printing Films at Microwave Frequency Employing Resonant Method
- PDF / 1,072,237 Bytes
- 7 Pages / 593.972 x 792 pts Page_size
- 112 Downloads / 182 Views
https://doi.org/10.1007/s11664-020-08594-w Ó 2020 The Minerals, Metals & Materials Society
ORIGINAL RESEARCH ARTICLE
Measurement of the Conductivity of Screen Printing Films at Microwave Frequency Employing Resonant Method HUATING TU
,1 JIYONG HU
,1,3 and XIN DING2
1.—Shanghai Collaborative Innovation Center for High Performance Fiber Composites, Donghua University, No. 2999, North Renmin Road, Songjiang District, Shanghai 201620, China. 2.—Key Laboratory of Textile Science and Technology, Ministry of Education, Donghua University, Shanghai 201620, China. 3.—e-mail: [email protected]
The conductivity of screen printing films at microwave frequency is one of the most important properties of conductive ink when applied in printed electronics. However, the existing methods of conductivity characterization at microwave frequency focus on homogeneous metal films or semiconductors, which are not suitable for conductive composite materials with poor thickness uniformity, like screen printing films. In this research, by applying a classic stripline ring resonator, a rigorous electromagnetic model was set up, and the conductivity of the screen printing film was able to be deduced by comparison between the measurement and simulation results. As a result, the equivalent conductivity of the film is 2 9 106 S/m at 1–3 GHz, which is a little higher than its average direct current conductivity of 1.82 9 106 S/m. This method has been proved to be feasible in measuring the conductivity of screen printing films at microwave frequency. Furthermore, it has great potential in the characterization of other printed conductive composite materials on rough surfaces, like textiles. Key words: Conductivity, films, ring resonator, Q factor, loss, microwave frequency
INTRODUCTION Conductive ink has been widely used in screen printing flexible antennae, sensors, and wearable electronics.1–3 The conductivity of conductive ink film is one of the most important properties to evaluate the performance of conductive ink. For simple circuit structures or low operating frequency, the conductivity of screen printing films has usually been characterized in direct current (DC) by measuring the sheet resistance with a fourpoint probe4,5 or the resistivity with a multimeter.6–8 However, for sensors or filters working at microwave frequency, the electric properties of the film cannot be simply described by DC conductivity,9 since the electrical transmission properties of
(Received July 27, 2020; accepted October 24, 2020)
conductive particles are influenced by the skin effect10 and the polarization effect.11 Until now, conventional methods to measure the conductivity of materials at microwave frequencies are time-domain spectroscopy,12–14 the transmission/reflection method,15–17 and the resonant technique.18 However, the spectroscopy technique is mainly applied in nanometer-thick gold films in the far-infrared frequency band.12 For the transmission/reflection method, the material under test is placed as a part of the transmission line, and the conduct
Data Loading...
