Formation of metal interconnects and their resistance-change behavior during tensile stretching for stretchable packaging applications

Abstract

We examined the resistance-change behavior of thin Pt and Au films on the PDMS elastomeric substrate. A maximum Young's modulus of 1.74 MPa was obtained for the PDMS substrate by adjusting the mixing ratio between base polymer and its curing agent to 10:1. Parylene coating on the PDMS surface was effective as an adhesion layer between metal interconnects and PDMS substrate. Without a Parylene coating, the resistance of a 150 nm-thick Pt film increased from 18.7to 3000 with stretching to 20% strain and became open at strains larger than 20%. On the other hand, the resistance of a Pt film, sputtered on a Parylene-treated PDMS, was initially 10.3 before loading, increased to 99.3 at 30% elongation, and then decreased to 23.8 after complete unloading. Thin Au metallization has better resistance properties for stretchable interconnect applications than Pt thin film. The resistance of a 150 nmthick Au film on a Parylene-coated PDMS substrate was 1.3 before loading, increased to 19 at 30% elongation, and then returned to 1.3 after complete unloading.

Study on circuit modeling of stretchable serpentine interconnects

“…Peel tests of rubber on copper samples indicate that the rupture of long fibrils in substrate will lead to interface failure 15 . Resistance characterization of stretchable interconnects shows that variation of structural parameters of serpentine interconnect due to strain would affect the electrical reliability of the flexible system significantly 16,17 . Most of current studies focus on the fabrication process and analysis of mechanical or electrical performance of serpentine interconnects.…”