The role of friction coefficient on the stitch bondability in Pd coated Cu and bare Cu wire bonding

2012 ◽  
Author(s):  
A. Rezvani ◽  
C. Nan ◽  
M. Mayer ◽  
I. Qin
Keyword(s):  
Friction Coefficient ◽  
Wire Bonding

Understanding the Role of Ultrasonic Welding in Wire Bonding

2015 ◽  
Vol 2015 (1) ◽  
pp. 000430-000433
Author(s):  
Lee Levine
Keyword(s):  
Ultrasonic Welding ◽  
Wire Bonding ◽  
Ultrasonic Energy ◽  
Weld Formation ◽  
Bonding Parameter ◽  
Key Factor

Wire bonding is the dominant chip interconnection method. Ultrasonic energy is the most important bonding parameter effecting the quality and the reliability of the intermetallic weld. Understanding the mechanism enabling weld formation is a key factor in maintaining the reliability and productivity that wire bonding provides.

A Mechanism of Sliding on the Nanometer-Thick Ag Layers

2005 ◽  
Author(s):  
F. Honda ◽  
M. Goto
Keyword(s):  
Friction Coefficient ◽  
Normal Load ◽  
High Vacuum ◽  
High Energy ◽  
Thin Layers ◽  
Ultra High Vacuum ◽  
Wear And Friction ◽  
Thickness Measurements

Tribological performance of sub-nano to nanometer-thick Ag layers deposited on Si(111) have been examined to understand the role of surface thin layers to the wear and friction characteristics. The slider was made of diamond sphere of 3 mm in radius. Sliding tests were carried out in an ultra-high vacuum environment (lower than 4 × 10−8 Pa) and analyzed in-situ by Auger electron spectroscopy (AES) for the quantitative thickness-measurements, by reflection high-energy electron diffraction (RHEED) to clarify the substrate cleanliness and crystallography of the Ag films, and by scanning probe microscopy (SPM) for the morphology of the deposited/slid film surfaces. As the results, a minimum of the friction coefficient 0.007 was observed from the film thickness range of 1.5–10 nm, and exactly no worn particles were found after 100 cycles of reciprocal sliding. Results have directly indicated that solid Ag(111) sliding planes allowed to reduce the friction coefficient very low without any detectable wear particles, and Ag nanocrystallites in Ag polycrystalline layers increase the size to 20–40 nm order, during sliding. The friction coefficient was slightly dependent to the normal load. Results were discussed on the role of the surface atoms to the friction, and a mechanism of sliding on Ag thin layers.

scholarly journals Rubber Wear and the Role of Transfer Films on Rubber Friction on Hard Rough Substrates

2021 ◽  
Vol 69 (2) ◽  
Author(s):  
A. Tiwari ◽  
N. Miyashita ◽  
B. N. J. Persson
Keyword(s):  
Friction Coefficient ◽  
Sliding Friction ◽  
Present Theory ◽  
Concrete Surface ◽  
Relative Importance ◽  
Rubber Compound ◽  
Transfer Films ◽  
Rubber Compounds ◽  
Rubber Friction

AbstractWe study the influence of rubber transfer films on the sliding friction between rectangular rubber blocks and a concrete surface. We present experimental results for the friction coefficient for a rubber compound sliding on a concrete surface contaminated by another rubber compound, for two different pairs (A, B) and (C, D) of rubber compounds. For the same rubber compounds, we present theory results which illustrate the relative importance of the viscoelastic and adhesive contribution to the sliding friction. We correlate the calculated rubber friction with the nature of the observed transfer films (or wear processes). Graphical Abstract

Insert Damping of Hollow Airfoils

2009 ◽  
Author(s):  
Hans Peter Borufka ◽  
Hernan Victor Arrieta ◽  
Andreas Hartung
Keyword(s):  
Friction Coefficient ◽  
Turbine Blade ◽  
Frictional Contact ◽  
Excitation Amplitude ◽  
Single Element ◽  
Torsion Mode ◽  
Mechanical Damping ◽  
Very High ◽  
Damping Systems

This paper describes a new mechanical damping device for hollow airfoils. The concept combines cooling and damping systems in one single element. Damping is achieved by frictional contact between an insert and specially selected contact locations on internal airfoil surfaces. The mechanical damping system is optimized for the first torsion mode of a shroud-less turbine blade and leads to very high damping effectiveness. In parallel an acceptable damping of the first flap mode was observed. In addition studies indicating the role of main parameters such as friction coefficient, excitation amplitude, geometry and location of damper elements are presented.

Effect of Surface Profile Structure on Stability of Friction and Wear

2004 ◽  
Author(s):  
A. Titov ◽  
R. Dubrovsky
Keyword(s):  
Friction Coefficient ◽  
Wear Rate ◽  
Testing Machine ◽  
Surface Profile ◽  
Friction Testing ◽  
Test Parameters ◽  
Texture Parameters ◽  
Wear Friction ◽  
Profile Characteristics

This paper describes the role of surface texture parameters of bodies in contact on friction coefficient and wear rate. Experiments are done on wear friction testing machine that allows dynamically tracking friction coefficient and wear rate of surfaces in contact under heavy-duty boundary lubrication conditions. Experiments based on conforming steel 4340 -bronze SAE 40 friction couple showed the role of profile characteristics of bodies in contact such as skewness and bearing length ratio. Experimental results demonstrated that for surfaces with similar roughness, waviness and profile parameters, a surface with skewness higher than −1.3 invokes instability in test parameters causing fast climb of friction coefficient and increased mass loss.

scholarly journals Tribological Behavior of Polymers and Polymer Composites

2020 ◽  
Author(s):  
Lorena Deleanu ◽  
Mihail Botan ◽  
Constantin Georgescu
Keyword(s):  
Friction Coefficient ◽  
Tribological Behavior ◽  
Glass Beads ◽  
Linear Wear ◽  
Neat Polymer ◽  
Linear Wear Rate ◽  
Test Parameters ◽  
Order Of Magnitude ◽  
Contact Durability

This chapter means to explain the tribological behavior of polymer-based materials, to support a beneficial introducing of those materials in actual applications based on test campaigns and their results. Generally, the designers have to take into consideration a set of tribological parameters, not only one, including friction coefficient, wear, temperature in contact, contact durability related to application. Adding materials in polymers could improve especially wear with more than one order of magnitude, but when harder fillers are added (as glass beads, short fibers, minerals) the friction coefficient is slightly increased as compared to neat polymer. In this chapter, there are presented several research studies done by the authors, from which there is point out the importance of composite formulation based on experimental results. For instance, for PBT sliding on steel there was obtained a friction coefficient between 0.15 and 0.3, but for the composite with PBT + micro glass beads, the value of friction coefficient was greater. Adding a polymer playing the role of a solid lubricant (PTFE) in these composites and also only in PBT, decreased the friction coefficient till a maximum value of 0.25. The wear parameter, linear wear rate of the block (from block-on-ring tester) was reduced from 4.5 μm/(N⋅km) till bellow 1 μm/(N⋅km) for a dry sliding regime of 2.5…5 N, for all tested sliding velocities, for the composite PBT + 10% glass beads +10% PTFE, the most promising composite from this family of materials. This study emphasis the importance of polymer composite recipe and the test parameters. Also there are presented failure mechanisms within the tribolayer of polymer-based materials and their counterparts.

What drives orogeny in the Andes?

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 617-620 ◽  
Author(s):  
S.V. Sobolev ◽  
A.Y. Babeyko
Keyword(s):  
Friction Coefficient ◽  
Crustal Structure ◽  
South American ◽  
The South ◽  
Nazca Plate ◽  
South American Plate ◽  
The Andes ◽  
Continental Lower Crust ◽  
Sediment Cover

Abstract The Andes, the world's second highest orogenic belt, were generated by the Cenozoic tectonic shortening of the South American plate margin overriding the subducting Nazca plate. We use a coupled thermomechanical numerical modeling technique to identify factors controlling the intensity of the tectonic shortening. From the modeling, we infer that the most important factor was accelerated westward drift of the South American plate; changes in the subduction rate were less important. Other important factors are crustal structure of the overriding plate and shear coupling at the plates' interface. The model with a thick (40–45 km at 30 Ma) South American crust and relatively high friction coefficient (0.05) at the Nazca–South American interface generates >300 km of tectonic shortening during 30–35 m.y. and replicates the crustal structure and evolution of the high central Andes. The model with an initially thinner (<40 km) continental crust and lower friction coefficient (<0.015) results in <40 km of South American plate shortening, replicating the situation in the southern Andes. Our modeling also demonstrates the important role of the processes leading to mechanical weakening of the overriding plate during tectonic shortening, such as lithospheric delamination, triggered by the gabbro-eclogite transformation in the thickened continental lower crust, and mechanical failure of the sediment cover at the shield margin.

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