scholarly journals Calibration of a Constitutive Model from Tension and Nanoindentation for Lead-Free Solder

Micromachines ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 608 ◽  
Author(s):  
Xu Long ◽  
Xiaodi Zhang ◽  
Wenbin Tang ◽  
Shaobin Wang ◽  
Yihui Feng ◽  
...  

It is challenging to evaluate constitutive behaviour by using conventional uniaxial tests for materials with limited sizes, considering the miniaturization trend of integrated circuits in electronic devices. An instrumented nanoindentation approach is appealing to obtain local properties as the function of penetration depth. In this paper, both conventional tensile and nanoindentation experiments are performed on samples of a lead-free Sn–3.0Ag–0.5Cu (SAC305) solder alloy. In order to align the material behaviour, thermal treatments were performed at different temperatures and durations for all specimens, for both tensile experiments and nanoindentation experiments. Based on the self-similarity of the used Berkovich indenter, a power-law model is adopted to describe the stress–strain relationship by means of analytical dimensionless analysis on the applied load-penetration depth responses from nanoindentation experiments. In light of the significant difference of applied strain rates in the tensile and nanoindentation experiments, two “rate factors” are proposed by multiplying the representative stress and stress exponent in the adopted analytical model, and the corresponding values are determined for the best predictions of nanoindentation responses in the form of an applied load–indentation depth relationship. Eventually, good agreement is achieved when comparing the stress–strain responses measured from tensile experiments and estimated from the applied load–indentation depth responses of nanoindentation experiments. The rate factors ψ σ and ψ n are calibrated to be about 0.52 and 0.10, respectively, which facilitate the conversion of constitutive behaviour from nanoindentation experiments for material sample with a limited size.

Author(s):  
Samaneh Pourolajal ◽  
Gholam Hossein Majzoobi

Determination of dynamic behaviour of materials is a serious challenge in mechanics of materials. In this investigation, a new approach is proposed to obtain stress–strain curves of metals from dynamic indentation test. This approach is based on a combined experiment, simulation, and optimization techniques. In the experiment side, a conical penetrator is shot against the material as the target. The load–indentation depth curve is obtained from the dynamic indentation test. The indentation test is simulated using Ls-dyna and the numerical load–indentation depth is obtained from the simulation. The stress–strain curves are defined by Johnson–Cook material model. From optimization of the difference between the experimental and numerical load–indentation depth curves, the constants of the material model are identified. The material model is validated also by stress–strain curves obtained from quasi-static test conducted using Instron and dynamic tests conducted using Split Hopkinson Bar. The results show a close agreement between the model prediction and the experimental stress–strain curves for different strain rates.


2004 ◽  
Vol 41 (2) ◽  
pp. 351-355 ◽  
Author(s):  
Dieter Stolle ◽  
Peijun Guo ◽  
Gabriel Sedran

This paper analyzes the impact of natural random variation of soil properties on the constitutive modelling of geomaterial behaviour. A theoretical framework for accommodating variation in soil properties is presented. The framework is then used to examine the consequence of parameter variability on stress–strain relations. An important observation is that average soil parameters from a series of tests on small specimens, in which density of the specimens varies randomly, do not necessarily reflect the average constitutive behaviour of soil. Model predictions are shown to be consistent with the experimental data.Key words: random variability, deterministic analysis, soil parameters, constitutive model.


2020 ◽  
Author(s):  
Manoj Kumar Pal ◽  
Gréta Gergely ◽  
Dániel Koncz-Horváth ◽  
Zoltán Gácsi

Abstract The Sn-3.0Ag-0.5Cu solder alloy is a prominent candidate for the Pb-free solder, and SAC305 solder is generally employed in today’s electronic enterprise. In this study, the formation of intermetallic compounds (Cu6Sn5 and Ag3Sn) at the interface, average neighbour’s particle distance, and the morphological mosaic are examined by the addition of SiC and nickel-coated silicon carbide reinforcements within Sn-3.0Ag-0.5Cu solder. Results revealed that the addition of SiC and SiC(Ni) particles are associated with a small change to the average neighbor’s particle distance and a decrease of clustering rate to a certain limit of the Sn-3.0Ag-0.5Cu solder composites. Moreover, the development of the Cu6Sn5 and the structure of the Ag3Sn are improved with the addition of SiC and Ni coated SiC.


2009 ◽  
Vol 01 (03) ◽  
pp. 515-525 ◽  
Author(s):  
T. L. LI ◽  
J. H. LEE ◽  
Y. F. GAO

Frictionless contact between an arbitrarily-shaped rigid indenter and an elastically anisotropic film-on-substrate system can be regarded as being superposed incrementally by a flat-ended punch contact, the shape and size of which are determined by the indenter shape, indentation depth (or applied load) and elastic properties of film and substrate. For typical nanoindentation applications, the indentation modulus can thus be approximated from the response of a circular contact with pressure of the form of [1 - (r/a)2]-1/2, where r is the radial coordinate and a is the contact radius. The surface-displacement Green's function for elastically anisotropic film-on-substrate system is derived in closed-form by using the Stroh formalism and the two-dimensional Fourier transform. The predicted dependence of the effective modulus on the ratio of film thickness to contact radius agrees well with detailed finite element simulations. Implications in evaluating film modulus by nanoindentation technique are also discussed.


2021 ◽  
Author(s):  
Mohammad Ashraful Haq ◽  
Mohd Aminul Hoque ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall

Abstract A major problem faced by electronic packaging industries is the poor reliability of lead free solder joints. One of the most common methods utilized to tackle this problem is by doping the alloy with other elements, especially bismuth. Researches have shown Bismuth doped solder joints to mostly fail near the Intermetallic (IMC) layer rather than the bulk of the solder joint as commonly observed in traditional SAC305 solder joints. An understanding of the properties of this IMC layer would thus provide better solutions on improving the reliability of bismuth doped solder joints. In this study, the authors have used three different lead free solders doped with 1%, 2% and 3% bismuth. Joints of these alloys were created on copper substrates. The joints were then polished to clearly expose the IMC layers. These joints were then aged at 125 °C for 0, 1, 2, 5 and 10 days. For each aging condition, the elastic modulus and the hardness of the IMC layers were evaluated using a nanoindenter. The IMC layer thickness and the chemical composition of the IMC layers were also determined for each alloy at every aging condition using Scanning Electron Microscopy (SEM) and EDS. The results from this study will give a better idea on how the percentage of bismuth content in lead free solder affects the IMC layer properties and the overall reliability of the solder joints.


2020 ◽  
Vol 405 ◽  
pp. 115-120
Author(s):  
Ľudovít Parilák ◽  
Peter Burik ◽  
Peter Bella ◽  
Pavel Kejzlar

Cold tube drawing is a metal forming process that enable to manufacturers to produce high precision tubes. The dimensions of the tube are reduced by drawing it through a conical converging die with or without inner tool. There are four types of tube cold drawing process. Their difference relies on the technique used for inner diameter calibration. Therefore, the main objective was determining the difference in development of crystallographic texture and stress-strain state between drawing with the fixed plug and hollow sinking process. The input feedstock (with E235 steel grade) after the recrystallizing anneal was cold drawn (drawing with the fixed plug, hollow sinking) by one drawing passes. Electron BackScatter Diffraction (EBSD) analysis was used to evaluate the changes of grain structure and texture connected with tubes manufacturing. The stress-strain state in the tube material during drawing was calculated using DEFORM-3D software and the crystallographic orientation with respect to the cylindrical reference frame (Z-direction = drawing direction). A significant difference in stress-strain state between drawing with the fixed plug and hollow sinking process was recorded in radial direction.


2015 ◽  
Vol 2015 (1) ◽  
pp. 000787-000792
Author(s):  
E. Misra ◽  
T. Wassick ◽  
I. Melville ◽  
K. Tunga ◽  
D. Questad ◽  
...  

The introduction of low-k & ultra-low-k dielectrics, lead-free (Pb-free) solder interconnects or C4's, and organic flip-chip laminates for integrated circuits have led to some major reliability challenges for the semiconductor industry. These include C4 electromigration (EM) and mechanical failures induced with-in the Si chip due to chip-package interactions (CPI). In 32nm technology, certain novel design changes were evaluated in the last Cu wiring level and the Far Back End of Line levels (FBEOL) to strategically re-distribute the current more uniformly through the Pb-free C4 bumps and therefore improve the C4 EM capabilities of the technology. FBEOL process integration changes, such as increasing the thickness of the hard dielectric (SiNx & SiOx) and reducing the final via diameter, were also evaluated for reducing the mechanical stresses in the weaker BEOL levels and mitigating potential risks for mechanical failures within the Si chip. The supporting white-bump, C4 EM and electrical/mechanical modeling data that demonstrates the benefits of the design and integration changes will be discussed in detail in the paper. Some of the key processing and integration challenges observed due to the design and process updates and the corresponding mitigation steps taken will also be discussed.


2014 ◽  
Vol 2014 (1) ◽  
pp. 000251-000257
Author(s):  
Steven Grabey ◽  
Samson Shahbazi ◽  
Sarah Groman ◽  
Catherine Munoz

An increased interest in low temperature polymer thick film products has become apparent due to the rise of the printed electronics market. The specifications for these products are becoming more demanding with expectations that the low temperature products should perform at a level that is typically reserved for their high temperature counterparts; including solderability with lead free solders, high reliability and strong adhesion. Traditionally, it has only been possible to use leaded solders for soldering to polymer based thick film conductors. Over the last 15 years environmental concerns and legislation have pushed the industry towards a lead free approach. The shift to lead free solders, while beneficial, provides new challenges during processing. The high temperatures required for a lead-free soldering process yield a naturally harsher environment for polymer thick film pastes. In the past these conditions have proven too harsh for the pastes to survive. The polymer thick film discussed in this document aims to address some of these concerns for a highly reliable and easy to process polymer thick film paste. Due to the poor leaching characteristics of polymer thick films, at elevated temperatures, the predecessors of this paste typically soldered at low temperatures with leaded solders. The goal of this paper is to present a low temperature paste that is compatible with a variety of substrates and readily accepts lead-free solder. This paper will discuss a newly formulated low temperature curing (150°C – 200°C) RoHS and REACH compliant paste that shows excellent solderability with SAC305 solder. The paste was evaluated using a dip soldering method at 235°C–250°C on a variety of substrates. The data presented includes solder acceptance, adhesion data, thermal analysis and SEM analysis.


2005 ◽  
Vol 20 (8) ◽  
pp. 2004-2011 ◽  
Author(s):  
Yifang Cao ◽  
Dehua Yang ◽  
Wole Soboyejoy

In this paper, we present a method for determining the initial contact point and nanoindentation load–indentation depth characteristics for soft materials. The method is applied to the prediction of the load–indentation depth characteristics of polydimethylsiloxane. It involves the combined use of Johnson–Kendall–Roberts and Maugis–Dugdale adhesion theories and nonlinear least squares fitting in the determination of the initial contact point, the transition parameter, and the contact radius at zero contact load. The elastic modulus and the work of adhesion are also extracted from the load–indentation depth curves.


Sign in / Sign up

Export Citation Format

Share Document