Ultrasonic Fluxless Soldering of Eutectic SnPb and SnAgCu Alloys: A Feasibility Study

2014 ◽  
Author(s):  
Jing Shi ◽  
Yachao Wang
Keyword(s):  
Feasibility Study ◽  
Focal Point ◽  
Lead Free ◽  
Ultrasonic Power ◽  
Element Analysis ◽  
Chemical Flux ◽  
Soldering Time ◽  
Fluxless Soldering ◽  
Ultrasonic Soldering ◽  
Eutectic Snpb

Compared with the traditional eutectic SnPb soldering, lead-free soldering has been a focal point for electronics packaging research in order for the industry to meet the regulations on environment protection. By eliminating the lead element from soldering process, the concerns on environmental pollution can be significantly reduced. However, the current lead-free soldering processes usually still require the flux chemicals for promoting wetting. The use of flux chemicals is not environmentally friendly. In this study, motivated by the potential benefits of soldering using ultrasonic energy, we carry out a feasibility study of ultrasonic fluxless soldering experiments on both the regular eutectic SnPb soldering alloy, Sn63Pb37 and the popular SnAgCu alloy, SAC305. By developing the appropriate testing conditions, the solder joints are successfully formed using the dipping ultrasonic soldering method regardless if chemical flux is applied. The effects of soldering time, temperature, and ultrasonic power are investigated. The results from SEM observation and EDS element analysis indicate that the use of chemical flux produces thicker intermetallic compound (IMC) layers for Sn63Pb37 alloy, and a longer soldering time leads to thicker IME layers for both solder alloys. However, a higher soldering temperature may not be beneficial to the growth of IME layer in ultrasonic soldering of SAC305 alloy. However, the driving mechanisms behind the phenomena remain to be investigated in the future.

scholarly journals Prediction of Thermal Fatigue Life of Lead-Free BGA Solder Joints by Finite Element Analysis

2001 ◽  
Vol 42 (5) ◽  
pp. 809-813 ◽  
Author(s):  
Young-Eui Shin ◽  
Kyung-Woo Lee ◽  
Kyong-Ho Chang ◽  
Seung-Boo Jung ◽  
Jae Pil Jung
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Lead Free ◽  
Element Analysis ◽  
Thermal Fatigue Life

scholarly journals Adhesion Strength of BNT Films Hydrothermally Deposited on Titanium Substrates

2010 ◽  
Vol 123-125 ◽  
pp. 399-402
Author(s):  
Fang Chao Xu ◽  
Kazuhiro Kusukawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Adhesion Strength ◽  
Pure Titanium ◽  
Tensile Tests ◽  
Film Deposition ◽  
Lead Free ◽  
Element Analysis ◽  
Substrate Strain ◽  
Titanium Substrates

Lead-free piezoelectric (Bi1/2Na1/2)TiO3 (BNT) films were deposited on 1 mm thick pure titanium(Ti) substrates by a hydrothermal method. Tensile tests were performed to quantitatively assess the adhesion strength between BNT films and Ti substrates. Ti substrates were pretreated by chemical polish and mechanical polish respectively prior to BNT film deposition. In the tensile test, the behavior of BNT film exfoliation was investigated by the replica method. The critical Ti substrate strain inducing BNT film exfoliation was determined by the aid of finite element analysis (FEM). In this study, the results revealed that BNT film exfoliations were caused by the strain of Ti substrate, and the mechanical polish pretreatment improved the adhesion of BNT film to Ti substrate.

Design for Desired Mode Shapes: Preliminary Results

1998 ◽  
Author(s):  
Elizabeth K. Lai ◽  
G. K. Ananthasuresh
Keyword(s):  
Finite Element ◽  
Feasibility Study ◽  
Mode Shape ◽  
Longitudinal Axis ◽  
Mode Shapes ◽  
Future Research ◽  
Structural Members ◽  
Element Analysis ◽  
Cross Sectional ◽  
Made In

Abstract This paper is concerned with the shape optimization of structures to attain prescribed normal mode shapes. Optimizing structural members in order to have desired mode shapes, besides the desired natural frequencies, is of interest in some applications at both macro and micro scales. After reviewing the relevant past work on the “inverse mode shape” problem, a feasibility study using the lumped spring-mass models and finite element models of an axially vibrating bar is presented. Based on the observations made in the feasibility study with bars, a meaningful optimization problem is formulated and solved. Using finite element analysis and numerical optimization, a method for designing beam-like structures for prescribed mode shapes is developed. The method is demonstrated with an example of designing the cross-sectional area profile of a beam along its longitudinal axis to get a desired fundamental mode shape. The nonuniqueness of the solution is noted and avenues for future research are identified.

Behavior of Lead-Free Solder Under Thermomechanical Loading

2004 ◽  
Vol 126 (3) ◽  
pp. 367-373 ◽  
Author(s):  
Y. Wei ◽  
C. L. Chow ◽  
K. J. Lau ◽  
P. Vianco ◽  
H. E. Fang
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Base Alloy ◽  
Back Stress ◽  
General Purpose ◽  
Lead Free ◽  
Element Analysis ◽  
Different Temperatures ◽  
Free Solder

This paper presents an investigation of lead-free Sn-Ag base alloy, 95.5Sn-3.9Ag-0.6Cu, both experimentally and analytically. Experimentally, the deformation behavior of the material was measured for different temperatures (25°C and 1000°C) over a range of strain rates (10−5 to 10−3/s) under isothermal and thermomechanical conditions. Development of a unified viscoplastic constitutive model followed, taking into account the effects of the measured strain rate and temperature changes. The temperature rate effects are considered in the evolution equation of back stress. In order to include material degradation in the solder, the theory of damage mechanics is applied by introducing two damage variables in the viscoplastic constitutive model. Finally, the constitutive model is coded into a general-purpose finite element computer program (ABAQUS) through its user-defined material subroutine (UMAT). The damage-coupled finite element analysis (FEA) is then employed to monitor the condition of failure of a notched component. The predicted and measured maximum loads have been compared and found to be satisfactory. In addition, the calculated damage distribution contours enable the identification of potential failure site for failure analysis.

Effects of Dwell-Time and Ramp-Rate on The Thermal-Fatigue Life of SnAgCu Joints

2005 ◽  
Author(s):  
Walter Dauksher ◽  
John Lau
Keyword(s):  
Finite Element Analysis ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Dwell Time ◽  
Cost Effective ◽  
Lead Free ◽  
Ramp Rate ◽  
Element Analysis ◽  
Thermal Environments ◽  
Thermal Fatigue Life

Finite element analysis examines lead-free part-on-board accelerated thermal environments comprised of ramp and dwell times lasting between 5 and 15 minutes. The accumulated creep strain energy density is determined for each environment and used to evaluate cost-effective accelerated test environments.

scholarly journals Finite element analysis of lead-free surface mount devices

2008 ◽  
Vol 43 (1) ◽  
pp. 212-220 ◽  
Author(s):  
Pradeep Hegde ◽  
Andrew R. Ochana ◽  
David. C. Whalley ◽  
Vadim. V. Silberschmidt
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Free Surface ◽  
Lead Free ◽  
Element Analysis ◽  
Surface Mount

Experimental and Numerical Evaluation of SnAgCu and SnPb Solders Using a MicroBGA Under Accelerated Temperature Cycling Conditions

2004 ◽  
Author(s):  
Bryan Rodgers ◽  
Jeff Punch ◽  
Claire Ryan ◽  
Finbarr Waldron ◽  
Liam Floyd
Keyword(s):  
Fatigue Life ◽  
Large Scale ◽  
Temperature Cycling ◽  
Lead Free ◽  
Model Parameters ◽  
Lead Free Solder ◽  
Element Analysis ◽  
Snagcu Solder ◽  
Numerical Predictions ◽  
Free Solder

A comparative evaluation of the leading lead-free solder candidate (95.5Sn3.8Ag0.7Cu) and traditional tin-lead solder (63Sn37Pb) under thermal cycling conditions was carried out. A test vehicle consisting of four daisy chained 10×10 array 0.8mm pitch plastic micro ball grid arrays (microBGA) mounted on an 8-layer FR4 printed wiring board was designed. The board finish was organic solder preservative (OSP) for the lead-free devices and hot air solder levelled (HASL) in the case of the eutectic devices. An event detector was used to monitor the continuity of each daisy chain during accelerated temperature cycling, where the test vehicles were cycled with a ramp rate of approximately 3°C per minute from −40°C to 125°C, with 10-minute dwells and a total cycle time of 2 hours 10 minutes. Results to date plotted using a Weibull distribution indicate that the SnAgCu solder is more reliable under these conditions. Experiments were also carried out on large-scale lead-free solder specimens to determine the parameters required for the Anand viscoplasticity model. The Anand model was then implemented in finite element analysis using ANSYS®, where the submodelling technique was employed to determine the viscoplastic work per thermal cycle for each solder joint along the package diagonal. Schubert’s fatigue life model was used to predict the number of cycles to failure of each joint, although it should be noted that the necessary model parameters for the may need to be calibrated. Results indicate that the joint under the die edge is likely to fail first and that the SnAgCu solder is more fatigue resistant. The numerical predictions underestimate the fatigue life in both cases.

Sign in / Sign up

Export Citation Format

Share Document