Somat, Widiyuta Wisesa (2016)
Exploring and Characterizing of the Mechanical Stability and Electrical Contact Resistance of Hook and Loop Nanowire-Fasteners.
Technische Universität Darmstadt
Bachelorarbeit, Bibliographie

Kurzbeschreibung (Abstract)

Surface mount devices (SMDs) have been an everyday staple in today’s electronic industry. It is an important component in various fields of application due to its ease and lower cost of manufacture. The widely used surface mount technologies however rely heavily on high temperature bonding which uses a lot of energy and is environmentally harmful. Recent developments in nanotechnology make it possible to use biomimetic surface bonding by utilizing Van-der-Waals force under room temperature, but these methods deliver either a strong normal adhesion, or a good electrical conductivity, and therefore it does not gain a lot of adoption in the SMDs industry.

By using ion track etch method, radiating a polycarbonate film with heavy ions and etching it with alkali solutions, a porous template for growing large array of nanowires/-tubes can be made. Forests of metallic nanowires can be grown in this template through electrodeposition with a specific electrolyte, i.e. copper sulphate for copper nanowires. Metallic nanowire-fasteners open up new possibilities in providing a strong normal adhesion and good conductivity simultaneously, with gold nanowire-fasteners able to withstand up to 5 N/cm² tensile stress and with an electrical resistance as low as 2 Ohms. As such, similar metals are expected to likewise be applicable in surface bonding.

An experiment is conducted to examine whether copper nanowires, which are grown on borosilicate wafer through ion track etch method can be used as a nanowire-fastener and can provide a stable mechanical connection as a surface bonding method. Experiment setups and a nanowire chip design for measuring the electrical resistance and tensile strength are established in the course of the study. A mounting is also designed to facilitate fixation of the nanowire-fasteners to a tensile testing machine. The copper nanowires manufactured for this experiment are 10 µm high and have 100 nm diameter, with wire density of 3*10^8 wires per cm².

This study has shown that copper nanowire-fasteners are able to administer a strong adhesion between surface under a high preload, withstanding up to 235 N/cm² tensile stress under a 31,25 kN/cm² preload. A proportional relation between preload and maximum tensile stress is also observed, the copper nanowire-fasteners can hold a higher tensile stress when they are pressed together with a higher preload. However under low to medium preload (50 to 200 N/cm²) gold nanowire-fasteners can provide much stronger adhesion.

Based on the result of the tensile test, copper nanowire-fasteners are a stable surface mount technology under a specific situation. Another matter of importance is that the proposed tensile test setup can provide a more accurate reading of the tensile strength of copper nanowires than previously used methods.

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