Comparison measurements of low resistance and high strength on synthesis graphene conductive ink filled epoxy

Stretchable and conductive materials are expected to be widely used for various electronic equipment in the future especially in the field of automotive safety. Flexibility and expandability are the main features of the Stretchable Conductive Ink (SCI) while maintaining the high conductivity levels and can be applied to electronic circuits in vehicles especially for driver health monitoring systems. The experimental work obtained the suitable formulation of the conductive ink based on the resistivity and elasticity values. Five different percentages of samples, 10 wt.% until 30 wt.% with each sample interval represents 5 wt.%. Samples of 20 wt.%, 25 wt.%, and 30 wt.% did not show significant differences in terms of the average volume of resistivity. Filler loading of 25 wt. %of GNP in the filler loading matrix produced the best results for nanomechanical properties. Low resistance and high elasticity of SCI in the vehicle electronic equipment can monitor more effectively the driver's health as SCI can be stretched according to the shape of the human body. It also has good conductivity to measure the movement of the human pulse and muscles

Measurement Of Optimal Stretchability Graphene Conductive Ink Pattern By Numerical Analysis

This study determines the optimal stretchability performance of graphene conductive patterns by using maximum principal elastic strain and Von Mises stress analysis. It was performed by using experimental and finite element analysis (FEA) modelling approaches. The experimental work was initiated by obtaining the optimal formulation of the conductive ink based on the resistivity values and 20 wt.% of graphene nanoplatelets (GNP) was selected. Then, the Young’s modulus and Hardness values for this formulation were determined to become the input for the FEA modelling. Six different types ofpattern were developed for FEA analysis, which are the straight-line, sine wave, semi-circle, serpentine, zigzag and horseshoe as the straight-line pattern becomes the baseline. The sine wave pattern produced the best results as the percentage different with the baseline pattern in terms of maximum principal elastic strain and Von Mises stress were the largest with the value of 37 times lower. This is due to the fact that the sine wave has more edge and depicts the spring-like behaviour which produces better stretchability. The increased length of the pattern also contributes to stretchability performance. Furthermore, this study shows that the FEA approach can be utilised in investigating the stretchability performance of conductive ink

Transient thermal simulation analysis of die-attach adhesives

This paper discusses the approach of using a three-dimensional finite element analysis (FEA) model for transient thermal analysis of die-attach materials layers with the silicon carbide (SiC) diodes directly attached to the bonded copper. For FEA analysis, six different die-attach materials models were developed: Au/Sn (80/20) braze, nanoscale silver, SAC alloy solder paste, Epo-Tek P1011 epoxy, graphene, and copper. By evaluating the maximum temperature and total heat flux, FEA modeling can be utilized to identify which die-attach materials have more effect on the thermal conductivity of the model. Fourier’s law of heat conduction was implemented to investigate transient thermal characteristics during heating with commercial software code, namely ANSYS. Temperature dependency and thermal material properties, and other thermal parameters boundary conditions were taken into consideration throughout the thermal conductivity procedure. The temperature and total heat flux distribution changes of the die-attach and substrate assemblies were obtained and transient thermal characteristics were analyzed during heating within 1.5 s by using temperature load, 90.3 °C on the dies (diode) surface. Moreover, heat flow was also measured in the model by comparing the thermal resistance discovered in the die-attach materials with a manual calculation. The graphene achieved the best results in terms of the least maximum temperature and total heat flux values, 90.3 °C and 11.04 x 106 W/m2 respectively. As a result, graphene-based die-attach materials produce an efficient heat conductor, which can become beneficial in the future. This is due to the lowest thermal resistance and highest thermal conductivity of graphene die-attach materials

Analyse of strain and stress on different stretchable conductive ink materials by numerical method

This study determines the optimal stretchability performance of different materials on a conductive pattern by using maximum principal elastic strain and Von Mises stress analysis. It was performed by using finite element analysis (FEA) modelling approaches. The FEA modelling was initiated from previous studies of comparative difference in strain and stress caused by stretching the screen printed straight-line pattern (baseline) and curving wave pattern using graphene conductive ink as material. The research is using a sine wave pattern because it has the best results from the previous studies compared to other patterns. Five different FEA modelling conductive materials were developed, which are copper as the baseline, graphene, carbon nanotube (CNT), carbon black, and silver. The maximum principal elastic strain and equal stress (Von Mises stress) obtained by FEA modelling can be used to approximate which material has better elasticity. After 20% elongation, the maximum principal elastic strain of carbon-based conductive ink carbon black and graphene, 14.521 x 10-3 and 14.578 x 10-3, respectively, produced the best results, with percentage difference values of 2.63% and 2.24% from copper (baseline). As compared to the copper (1761.7MPa) conductive ink, the Von Mises stress value for carbon black (241.76 MPa) and graphene (257.34 MPa) is about 7 and 6 times lower stress respectively. There are no significant differences in strain and stress values between graphene and carbon black conductive inks. The findings show that carbon black can be an alternative to graphene as a good conductive ink. Furthermore, this research demonstrates that the FEA method can be used to investigate the stretchability of conductive ink

The Effect Of Curing Time On Electrical Resistivity, Mechanical Characteristics And Microstructure Behavior Of Graphene Conductive Ink

Nowadays graphene conductive ink (CI) are expected to be widely used for various automotive safety electronic equipment in the future. Graphene has a potential advantage such as high electrical conductivity and thermal conductivity and can be applied to electronic circuits in vehicles especially for driver health monitoring systems. To ensure optimal conductivity, graphene need to go through a curing process to minimize porosity between particles and create a smooth conductive track. The effect of curing time on electrical, mechanical, and microstructural properties was investigated. Five samples at 20 wt.% filler loading with curing times varying from 10-50 minutes with each sample interval of 10 minutes was executed using doctor-blading printing method before analysis. Then, the analysis is done by using four-point probe to measure resistance, followed by nanoindentation and scanning electron microscope (SEM) to study elasticity and observe microstructure behaviour respectively with respect to temperature. Sample of 30 minutes curing time gives the lowest result, 24.9046 Ω.cm for volume of resistivity. The sample also has excellent mechanical properties, with high Young's modulus and low hardness, 8.59 GPa and 7.59 MPa respectively. Stretchable conductive ink (SCI) in vehicle electronic equipment with low resistance and high elasticity can monitor the driver's health more refectively because it can be stretched to fit the shape of the human body. It also has good conductivity for measuring human pulse and muscle movement