Effect of Tensile Load on Electrical Resistivity of Stretchable Conductive Ink (SCI)

To date, research has tended to focus on emerging Electrical Conductive Adhesive (ECA) with stretchable and flexible substrate or known as Stretchable Conductive Ink (SCI). SCI is more flexible, stretchable and multi-purpose compare with the traditional printed circuit. Limitation on the chatacreization of SCI performance especially on it electrical performane under tensile stress has motivate this study. The aim of this research is to investigate the conductivity of the conductive ink under tensile stress at different elongation. The conductive ink carbon black was used to print on the thermoplastic polyurethane (TPU) and cure in the oven at 120°C for 30 minutes. The conductive ink was clamp using in-house stretching equipment with different elongation. The resistivity was measured by four-point probe while surface structure was observed by using Axioscope 2 MAT microscope. The result shows that the resistance increased when the elongation increased. For 40mm length of conductive ink, the initial resistance is 0.562 kΩ and its become 1.217 kΩ when stretch until 18% of its initial length. The sheet resistance of the conductive ink also increased due to the defection (porosity) on the surface of conductive ink after stretching. The strain level for 40mm and 60mm also increase form 0.14 to 0.16 that cause incerase in resistance. However, since there are no crack/defection observes at 80mm after maximum elongaton, the resistance start to decrease that cause increase in SCI conductivity

Effect of Line Width and Thickness on Flexible Printed Electronic Circuit Electrical Performance

Flexible and printable electronics is among the rapidly growing field in many applications. Their performances are affected by many factors such as the interaction between the conductive ink circuit and the type of flexible substrate used as the printed board. In this paper, the effect of the conductive ink circuitry line width and thickness to the flexible printed electronic (FPE) electrical performance is investigated. Commercial type carbon based conductive ink and polyethylene terephthalate (PET) flexible substrate were applied to formulate the FPE circuit, using screen printing technique and cured at room temperature, with varying circuitry line width (between 1.00 mm to 3.00 mm) and thickness (between 0.05 mm to 0.25 mm). The final resistivity for all samples were later tested using digital multimeter. Results for the experiments showed that the electrical resistivity of the FPE samples were alost inversely proportional to the dimension of the circuit thickness and width. The results obtained shall be used in the next project stage as benchmarking data to establish design guidelines related to circuitry geometrical parameters to obtain optimum FPE electrical performance in actual application

The effect of different shape pattern of metal interconnects on the electrical and mechanical properties of stretchable conductive circuit

Electrically conductive adhesive (ECA) had been extensively studied to replace the Sn/Pb solder mainly found in printed circuit boards (PCBs) because of their harmful action towards human health and environment. In the production of stretchable PCBs, ECA mainly comprises of metallic filler and polymer matrix should perform good electrical and mechanical properties when straining being loaded. Therefore, determining the optimum shape pattern to be printed will contribute toward the desired traits of stretchable PCBs. In this study, commercial silver ink and thermoplastic polyurethane (TPU) as substrate was used. The ink was printed on the substrate by doctor-blade technique with different shape patterns with varies widths (1mm, 2mm and 3mm): (a) straight, (b) zigzag, (c) square and (d) sinusoidal. Then measurement of sheet resistance by four-point measurement was conducted on unloaded and loaded straining of shape pattern. This study exhibited that 3mm width zig zag shape pattern can elongate the highest straining (5% strained) compare than others patterns. In the meanwhile, straight and square shape pattern did not tolerate to any deformation which when straining at a minimum elongation of 0.1mm, the conductivity already lost. In conclusion, further study purpose, more analysis were suggested like analysis on the silver composition, curing temperature variation as well as the distribution of stress in printed shape pattern by 3D Finite Element Analysis (FEA) can be done for the more reliable study

Mechanical and Electrical Characterization of Nanocomposites Liquid-Solid Conductive Ink on Polyethylene Terephthalate (PET) Substrate

With drastic development of wearable electronics have urged the studies on the conductive ink and flexible substrate. Wearable electronics consist of nanocomposites liquid-solid conductive ink and flexible substrate such as polyethylene terephthalate (PET). They were produced by using stencil printing method. This paper presents the mechanical and electrical characteristics of  conductive ink with unloaded condition. The conductive ink was printed with four patterns, which were straight, curve, square and zig-zag patterns. Then, all four patterns were tested for their surface morphology, surface roughness, sheet resistivity and bulk resistivity. Surface morphology showed that conductive ink with 3 mm width had less granular particle formed than conductive ink with 1 mm width. Surface roughness of conductive ink with 3 mm width was smoother compared to 2 mm width and 1 mm width. Sheet resistivity and bulk resistivity results indicated that resistivity of all four patterns decreased with the increase of the conductive ink width. From the result, it showed that conductive ink with straight pattern has the best performance. Meanwhile, individual result for each pattern had its own function inside the circuit track.

Capacitive coupling of discrete micro-sized gaps for RF applications

This paper investigates the performance of a passive thin metallic object containing micro-sized gaps exposed to a plane wave excitation. This work has potential applications for emerging antenna fabrication techniques where the conducting sections are made from discrete metallic sections. This includes antennas composed from nanomaterials and conventional inkjet printed antennas. Electromagnetic simulations showed metallic sections separated by a micro-sized gap were found to capacitively couple. The coupling can be enhanced by reducing the size of the gap, increasing the width of the metallic object or by filling the gap with a permittivity greater than unity. It should be noted that the DC value of parallel plate capacitor is not strictly valid at radiofrequencies – however, this paper shows that the DC value of capacitance is a reasonable approximation and is useful to understand the behavior

Modern Microelectronic Technologies in Fabrication of RFID Tags

This paper presents fabrication of RFID tags, especially antennas for HF band (13.56 MHz), on cheap flexible substrates. The physicochemical, geometrical, DC and AC electrical properties as well as long-term stability (under thermal, moisture-thermal and mechanical exposures) have been characterized for several low-temperature polymer thick-film conductive films made on various paper or foil substrates. Resistance measurement during curing has been used for investigation of polymerization velocity, which is very important for increase of process capacity

The Effect Of Temperature On The Electrical Conductivity And Microstructure Behaviour Of Silver Particles

Silver conductive ink has been used in the electronics industry due to their potential advantages such as high electrical conductivity and thermal conductivity. However, silver needs to undergo a curing process to reduce the porosity between particles as well as to have a smooth conductive track to ensure maximum conductivity. Therefore, the effect of temperature on the electrical conductivity and microstructure were explored. The printing of silver conductive paste was executed on a polymer substrate through screen printing before analysis. Next, an electrical analysis was done to measure the conductivity by using a 4-point probes instrument, followed with microstructure and mechanical analysis which were carried out to observe the structure behaviour and hardness of silver respectively with respect to temperature. The study found that the electrical conductivity of silver increases when temperature elevated. Besides that, the microstructure of silver has a larger size with the increase in temperature, correspondingly cause the silver to have less hardness. In conclusion, temperature plays significant roles in increasing the electrical conductivity of silver

Deposition of High Conductivity Low Silver Content Materials by Screen Printing

A comprehensive experimental investigation has been carried out into the role of film thickness variation and silver material formulation on printing capability in the screen printing process. A full factorial experiment was carried out where two formulations of silver materials were printed through a range of screens to a polyester substrate under a set of standard conditions. The materials represented a novel low silver content (45%–49%) polymer material and traditional high silver content (65%–69%) paste. The resultant prints were characterised topologically and electrically. The study shows that more cost effective use of the silver in the ink was obtained with the low silver polymer materials, but that the electrical performance was more strongly affected by the mesh being used (and hence film thickness). Thus, while optimum silver use could be obtained using materials with a lower silver content, this came with the consequence of reduced process robustness

Resistivity Characterization For Carbon Based Conductive Nanocomposite On Polyethylene Terephthalate And Thermoplastic Polyurethane Substrates

Nanotechnology has gained a lot of focus in recent years due to its application in multidisciplinary fields such as chemistry, electronics energy, and biology. Wearable electronic consists of nanocomposites liquid-solid conductive ink and flexible substrate. This study characterizes the electrical characteristic of the conductive ink with unloaded condition. The conductive ink was printed with four patterns; straight, curve, square and zig-zag patterns. Sheet and bulk resistivity results indicated the decrement of resistivity of all four patterns with the increase of the conductive ink width. From the result, it showed that the resistivity inside the conductive ink increased such as constriction resistance, tunnelling resistance and the number of squares of the meandering trace as compared to similar lengths of a straight-line trace. Size of the particle also affected the contact area and electrical flow between the conductive ink particles. Meanwhile, individual results for each pattern had its own function inside the circuit trac

High electrical conductivity waterborne inks for textile printing

Printing of conductive inks is an attractive means of manufacturing of electronic components on flexible substrates including textiles. The textiles thus produced are often referred to as “e-textiles.” When high electrical conductivity is required, inks are preferably made from metal nanoparticles such as silver. However, such inks are expensive and generally not known to withstand severe washing and wearing to which textiles are normally subjected during the end use. In the present study, which forms a part of a larger study by the authors, waterborne dispersions of conductive grades of carbon black were converted into finished inks followed by washing and creasing tests to ascertain the durability of these inks. We found that not only were the inks stable after letdown with different binders, but they possessed high electrical conductivity despite the fact that the final pigment loading in all of the formulated inks was significantly less than the pigment loading that is generally found in commercial conductive inks. In addition, the electrical conductivity after washing and creasing tests of the formulated inks was found to be significantly greater than that of the tested commercial conductive inks. This shows that using large surface area, highly conductive grades of carbon black pigments in relatively small amounts in inks for textile printing is beneficial in achieving some of the critically required characteristics, particularly those pertaining to durability of the ink film