Influence of Fractal Form on Electromagnetic Characteristics of Flexible Chip’s ⊔-shaped Interconnect Structures

Fractal meander-shaped flexible interconnect structure is an important aspect of flexible chip or flexible printed circuit. However, current studies about fractal meander-shaped flexible interconnect structures mainly focus on its manufacturing materials and mechanical properties, researches on high frequency electromagnetic characteristics of these structures are relatively less. However, with the reduction of flexible chip size and the increase of working frequency of 5G communication technology, high frequency transmission characteristics of interconnects become an important influence factor to flexible devices. Among them, curved line and fractal orders are two no negligible factors, the electromagnetic characteristics of the flexible interconnect structure with different numbers of curved units and different fractal orders are analyzed at high-frequencies in this paper to investigate the transmission properties of fractal meander-shaped interconnect structures for flexible chip applications. Fractal ⊔-shaped design is adopted in these interconnect structures, which increases the stretchable length of line per unit area and improves the ductility of interconnects. Then, structures with different fractal orders, and structures with different unit numbers at same line length are simulated respectively. Simulation results show that the variation of fractal orders and the number of ⊔ units have different effects on the return loss of interconnect structures at different frequencies. In addition, it can be found from the results that the increase of fractal orders enlarges the insertion loss in the whole range of 0.01-30 GHz, and the effects of fractal orders on the insertion loss is more obvious as frequency increases; the number of ⊔ units mainly affects the insertion loss in the higher frequency band of 30-40 GHz.