Simulation And Experimental Research On Deformation Characteristics Of Flexible Interconnects

The application of the flexible electronic device greatly expands the application environment of the electronic device,but the effect of large deformation on the performance of the flexible electronic remains to be further studied.In this paper,we study the serpentine interconnects,which are responsible for the main deformation in the flexible and stretchable electronic devices.We use the finite element method to apply different tensile displacements to study the serpentine deformation characteristics and the change of the transmission characteristics under different tensile elongations.The transmission characteristics of serpentine under bending deformation is also studied.The S-parameter in-sampling test was performed on the flexible and stretchable serpentine interconnects with different tensile ratios using a microwave probe station and a vector network analyzer to verify the accuracy of the simulation.By analyzing the variation of the shape of the serpentine line,and using the stretching factor,the RLC parameters of the serpentine line under the stretching condition are calculated and compared with the RLC values extracted from the Q3D simulation.Using the analytically calculated serpentine LC parameters,the transmission delay is calculated and compared with the simulation results.Considering the high-frequency effect of interconnects,a serpentine double-?equivalent circuit model is established to characterize the transmission characteristics of serpentines.The parameters of the circuit model are extracted by quasi-linear function method,and S parameters are compared and verified by ADS.It is found that the serpentine line opens the arc opening to achieve ductility in the stretching process,and the stress and strain concentration on the top of the serpentine arc are observed.With the increase of the elongation,the thickness of PDMS gradually decreases,and the strain at the interface between the base and the serpentine arc is greater.By studying the serpentine transmission characteristics,it is found that the serpentine phenomenon of S-parameter occurs.With the increase of the tensile ratio,the frequency of the S-parameter extremum gradually decreases,the amplitude of the S₁₁ extremum gradually decreases,and that of S₂₁ increases.In time domain,as the stretch rate increases,the serpentine transmission delay increases.These results are in good agreement with the experimentally tested results.After bending simulation of the serpentine line,it is found that as the bending angle increases,the frequency of the S-parameter extremum decrease,and the amplitude of extreme point of S₁₁ gradually decreases,that of S₂₁ gradually decreases as well.After extracting the RLC parameters of the serpentine line after stretching,it is found that when the serpentine is stretched by 40%,the DC resistance of the serpentine line increases by 0.1%,the capacitance increases by 11.1%,and the inductance increases by 14.2%.The tensile factor is introduced to perform the analytical calculations of the capacitance and inductance that changed with tension.The analytically calculated capacitance and the simulation result error is 2.1%.The error between analysis and simulation results of inductance is 3.8%.The time delay is obtained by using the analytically calculated inductance and capacitance and the delay error is 2.5%.A double-?equivalent circuit model is established to characterize the serpentine transmission performance.The circuit parameters are extracted by using the quasi-linear function method.The S-parameters obtained by circuit simulation in ADS are compared with that of Comsol's electromagnetic simulation.The overall trend is consistent.The maximum amplitude difference at the extreme point is 2dB,and the maximum error in the range from1GHz to 10GHz is 1.8dB.Different circuit model parameters can be extracted by analyzing the calculated RLC parameters under different tensile ratios.The circuit model composed of these parameters can be used to characterize the serpentine S-parameters with different elongation rate.By combining the snake-shaped deformation characteristics and electrical characteristics,a reasonable explanation can be given to the mechanism of the change of the serpentine transmission characteristics.The analytical calculation of the serpentine parasitic parameters and the establishment of the equivalent circuit model may lay the foundation for the system design and performance optimization of the ductile flexible electronics.