Silver, Copper and Aluminium Coatings for Micro-Material Handling Operations

Abstract

Micro-material handling has challenges accompanying it because of adhesive forces, which make the picking and placing of micro-parts difficult. The adhesive forces hinder the picking of a micro-part, and once picked, they pose even a greater challenge when attempts to release a micro-part are made. Van der Waals' forces are part of the adhesive forces and are always present between interacting surfaces in a micro-material handling operation. However, Van der Waals' forces can profitably be manipulated in a micromaterial handling operation. The paper reveals how the Van der Waals' forces can be advantageously used in micro-material handling operations involving silver, copper and aluminium coatings of rms surface roughness values ranging from 0.5 nm to 2.72 nm, which are produced by the electron beam evaporation (e-beam) method. These were found to exert Van der Waals' forces ranging from 17 nN to 314 nN, which can be used for reliable micro-material handling operations. OPSOMMINGDie hantering van materiaal op 'n mikroskaal het uitdagings wat daarmee gepaard gaan as gevolg van kleefkragte. Kleefkragte bemoeilik die optel van 'n mikro-onderdeel en, wanneer dit eers opgetel is, is daar selfs ʼn groter uitdaging wanneer die part geplaas en gelos moet word. Van der Waalskragte vorm deel van die kleefkragte en is altyd teenwoordig tussen opervlaktes wat met mekaar in aanraking kom wanneer mikro-materiale gehanteer word. Van der Waalskragte kan egter voordelig gemanipuleer word in 'n mikromateriaalhanteringsituasie. Hierdie artikel toon hoedat Van der Waalskragte voordelig gebruik kan word wanneer silwer-, koper-en aluminiumbedekkings met 'n wgk oppervlakgrofheid tussen 0.5 nm en 2.72nm, wat deur die elektronstraalverdamping (e-straal) metode geproduseer word, gehanteer moet word. Daar is gevind dat hierdie bedekkings Van der Waalskragte tussen 17nN en 314nN uitoefen. Die Van der Waalskragte kan gebruik word vir betroubare mikro-materiaalhantering.

Atom Probe Analysis of Nanoparticles Through Pick and Coat Sample Preparation

“…This is both owing to the resolution of the SEM, and the motion of the micromanipulator. In order to enable SEM pick-up, the surfaces of the substrate tip (Matope et al, 2013), TEM grid film (Zhou et al, 2009), or NPs (Neouze & Schubert, 2008) may need to be modified. In the present work, such modifications were unnecessary.…”

Transfer of Individual Micro‐ and Nanoparticles for High‐Precision 3D Analysis Using 360° Electron Tomography

“…Relating to this, the “stamping transfer” method can be improved in terms of flexibility and reliability (without the use of adhesive interlayers) by selecting different materials and/or modifying the surface of either the grid and/or the tip. These modifications can be done by, for example, thin‐film coating techniques, plasma activation, or wet chemical treatment . To strengthen the adhesion between particle and tip, the tip can be coated with a material featuring a high Hamaker constant while ensuring a low surface roughness.…”

Humidity influence on the adhesion of SU-8 polymer from MEMS applications

“…Typical value for A for SU-8 and AFM tip typically made of silicon nitride are Aair = 6.5x10 -21 J in the air [16] and Awater = 1.8x10 -21 J in the water [17]. In this case when two surfaces are in contact in a humidity atmosphere the absorbed and condensed water molecules are present between these surfaces separated at a gap with thickness of molecular distance.…”