A Method for Making Elastic Metal Interconnects
- PDF / 1,715,046 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 89 Downloads / 215 Views
H6.12.1
A Method for Making Elastic Metal Interconnects Joyelle Jones1, Stéphanie Périchon Lacour1, Sigurd Wagner1, Zhigang Suo2 Departments of 1Electrical and 2Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08540 Abstract Stretchable, elastic metal interconnects are a key to the fabrication of 3-D conformal circuits and electrotextiles. The basic concept for reversibly stretchable, elastic metallization is a corrugated stripe of thin-film metal that is expanded by stretching. The maximum elongation is reached when the stripe is stretched flat. We prepared wavy metal stripes by evaporating gold onto pre-stretched strips of the elastomer, poly-dimethyl siloxane (PDMS). We experimented with gold metal line width and thickness and substrate elongation. We measured the film structure, amplitude, and wavelength, as well as electrical resistance in relaxed and various stretched states. So far we have reached elastic strains of 15% while maintaining the initial resistance and 80% with a rise in the resistance. We discovered a rich macroscopic and microscopic film morphology. Presented are the fabrication, electro-mechanical performance, and data on the film structure of these wavy metal interconnects. Introduction Our goal is to construct metal lines with morphology and electrical characteristics most conducive to reversible stretching. This poses a challenge because free standing metal films fracture when strained by more than 1% to 2%.1 The basic concept of stretchable metallization is a corrugated stripe of thin-film metal that is expanded reversibly by stretching. Very recently, three approaches have been demonstrated to fabricate such metallization by deposition of thin films on elastomeric substrates. (1) A film deposited with built-in stress on a flat substrate can be made to buckle to a wave, which then can be stretched.2 (2) When a film is deposited onto a wavy substrate surface it becomes a wave. (3) The substrate is stretched prior to deposition of the film, which upon release relaxes to a wave. In this presentation we focus on the universally applicable technique (3), which recently has been demonstrated for an organic conductor.3 This paper is a record of experimental procedures and observations. As will be seen below, we have discovered a variety of mechanical and electrical phenomena. These remain to be interpreted theoretically. Sample preparation Substrates of 1-mm thick poly-dimethyl siloxane (PDMS) (Sylgard 184® from Dow Corning) were prepared by first mixing the silicone gel with cross linker in a 10:1 weight ratio, and then curing the mixture at 60oC for at least 12 hours. Three parameters were independently varied in order to obtain a wavy metal with morphology and electrical characteristics most conducive to stretching: metal line width, metal line thickness, and added strain. Figure 1 outlines the fabrication steps, which include preparing the PDMS membrane, pre-stretching it, electron beam evaporation of the metal onto the pre-stretched PDMS, and releasing the metal/PDMS
Data Loading...
