Multi-functional 0–3 composite polyimide films for microsystem applications

Abstract

The development of smart functional thin film composite polymer materials has been extensively investigated over the past decade. However, the polymers poor thermal properties have negatively impacted the manufacturing complexity resulting in limited success in microsystem applications. This paper investigates the development of MEMS compatible flexible multi-functional 0-3 composite materials consisting of a high temperature polyimide (PI) matrix with lead zirconate titanate (PZT) and silver (Ag) nanoparticles. Microfabrication manufacturing methods were investigated to deposit the thin film composites and they were characterized with varying concentrations of nanoparticles. Piezoelectric composites with room temperature d33,f values up to 23 pC N-1 were demonstrated. In addition, Ag-PI composites demonstrated electrical conductivity values of 11 S m-1 at room temperature. The composites maintain relatively high mechanical flexibility and temperature properties from the PI matrix. Integration of the nanoparticles in the films were validated through X-ray diffraction and scanning electron microscopy images. The PZT-PI composites demonstrated an increase in piezoelectric values under elevated temperatures up to 300°C. Capacitor and energy harvesting devices consisting of three layers of composite films (Ag-PI/PZT-PI/Ag-PI) were microfabricated to validate the materials functionality and integration into microsystem-based devices. These novel flexible high temperature films could have wide use in next generation electronics.

Guar gum assisted synthesis of high‐quality silver nanoplates and their polyimide matrix nanocomposites for electromagnetic interference shielding applications

“…On the contrary same wt% loading of silver nanoparticles (with an average diameter of 100 nm) was reported to impart a maximum conductivity of only about 0.05 S/cm to PI films. 49 This markedly enhanced conductivity achieved in the present study may be attributed to the high purity and extended 2D morphology of the synthesized nanoplates. Conducting property of the composite material was further enhanced with gradual loading of the AgNPls-000 reaching as high as 5.5 ± 0.38 S/cm at 12.0 wt% of the filler.…”

Enhancing Manufacturability of SU-8 Piezoelectric Composite Films for Microsystem Applications

“…Agglomeration of piezoelectric particles in a composite film can lead to reduced performance [ 31 , 51 ]. Images of films developed with and without thinner are illustrated in Figure 2 .…”

“…Composites with an 0–3 structure, where particles are dispersed randomly throughout the matrix, are common due to manufacturing benefits, but often have problems with particle orientation [ 1 , 30 ]. Integration of 0–3 composites is challenging for MEMS applications that require patterning at the micro-scale; using non-photodefinable materials often leads to complex etching methods being needed for each composite material [ 31 ]. Using photoresist or photodefinable polymers as the matrix for the composites provides patternability, which is desired for MEMS integration.…”