Evolution of Anand Parameters With Elevated Temperature Aging for SAC Leadfree Alloys

2019 ◽  
Author(s):  
Pradeep Lall ◽  
Vikas Yadav ◽  
Jeff Suhling ◽  
David Locker
Keyword(s):  
Thermal Aging ◽  
High Strain ◽  
Lead Free ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
High Strain Rates ◽  
Free Solder ◽  
Sac Solder

Abstract Electronic components in downhole oil drilling and gas industry applications, automotive and avionics may exposed to high temperatures (> 150°C) and high strain rates (1–100 per sec) during storage, operation and handling which can contribute to the failures of electronics devices. Temperatures in these applications can exceed 200°C, which is closed to melting point for SAC alloys. The microstructure for lead free solder alloys constantly evolves when subjected to thermal aging for sustained periods with accompanying degradation in mechanical properties of solder alloys. In this paper, evolution of microstructure and Anand parameters for unaged and aged SAC (SAC105 and SAC-Q) lead free solder alloys at high strain rates has been investigated induced due to thermal aging. The microstructure of the SAC solder is studied using scanning electron microscopy (SEM) for different strain rate and elevating temperature. The thermal aged leadfree SAC solder alloys specimen has been tested at high strain rates (10–75 per sec) at elevated temperatures of (25°C–200°C). The SAC leadfree solder samples were subjected to isothermal aging at 50°C up to 1-year before testing. To describe the material constitutive behavior, Anand Viscoplastic model has been used. Effect of thermal aging on Anand parameters has been investigated. In order to verify the accuracy of the model, the computed Anand parameters have been used to simulate the uniaxial tensile test. FEA based method has been used to simulate the drop events using Anand constitutive model. Hysteresis loop and Plastic work density has been computed from FEA.

Evolution of Anand Parameters With Elevated Temperature Aging for SnAgCu Lead-free Alloys

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Pradeep Lall ◽  
Vikas Yadav ◽  
Jeff Suhling ◽  
David Locker
Keyword(s):  
Constitutive Model ◽  
Thermal Aging ◽  
High Strain ◽  
Lead Free ◽  
Constitutive Behavior ◽  
Strain Rates ◽  
Lead Free Solder ◽  
High Strain Rates ◽  
Shock Event ◽  
Free Solder

Abstract Electronic components in downhole oil drilling and gas industry applications, automotive, and avionics may be exposed to high temperatures (>150 °C) and high strain rates (1–100 per sec) during storage, operation, and handling, which can contribute to the failures of electronic devices. Temperatures in these applications can exceed 200 °C, which is close to melting point for SnAgCu (SAC) alloys. Prior studies at low strain rates have shown property evolution even under moderate exposure to high temperature. In this paper, the evolution of Anand parameters for unaged and aged SAC (SAC105 and SAC-Q) lead-free solder alloys at high strain rates has been investigated induced under sustained periods of thermal aging. The thermal aged lead-free SAC solder alloys specimen has been tested at high strain rates (10–75 per sec) at elevated temperatures of (25 °C–200 °C). The SAC lead-free solder samples were subjected to isothermal aging at 50 °C up to 1-year before testing. To describe the material constitutive behavior, the Anand Viscoplastic model has been used. The effect of thermal aging on Anand parameters also has been investigated. In order to verify the accuracy of the model, the computed Anand parameters have been used to simulate the uni-axial tensile test. The material constitutive behavior has been implemented in a finite element framework to simulate the drop events using the Anand constitutive model and determine the plastic work per shock event. The plastic work per shock event is a measure of the damage progression in the solder interconnects. The constitutive model has been used to simulate the shock event of a ball-grid array package on printed circuit board assembly.

Understanding the impact response of lead-free solder at high strain rates

2020 ◽  
Vol 172 ◽  
pp. 105416
Author(s):  
Xu Long ◽  
Junmeng Xu ◽  
Shaobin Wang ◽  
Wenbin Tang ◽  
Chao Chang
Keyword(s):  
High Strain ◽  
Impact Response ◽  
Lead Free ◽  
Strain Rates ◽  
Lead Free Solder ◽  
High Strain Rates ◽  
Free Solder ◽  
The Impact

Nanoindentation Characterization of Lead-free Solders and Intermetallic Compounds under Thermal Aging

2010 ◽  
Vol 2010 (1) ◽  
pp. 000314-000318
Author(s):  
Tong Jiang ◽  
Fubin Song ◽  
Chaoran Yang ◽  
S. W. Ricky Lee
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Solder Joints ◽  
Lead Free ◽  
Small Range ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Aging Test ◽  
Free Solder ◽  
Lead Free Solders

The enforcement of environmental legislation is pushing electronic products to take lead-free solder alloys as the substitute of traditional lead-tin solder alloys. Applications of such alloys require a better understanding of their mechanical behaviors. The mechanical properties of the lead-free solders and IMC layers are affected by the thermal aging. The lead-free solder joints on the pads subject to thermal aging test lead to IMC growth and cause corresponding reliability concerns. In this paper, the mechanical properties of the lead-free solders and IMCs were characterized by nanoindentation. Both the Sn-rich phase and Ag3Sn + β-Sn phase in the lead-free solder joint exhibit strain rate depended and aging soften effect. When lead-free solder joints were subject to thermal aging, Young's modulus of the (Cu, Ni)6Sn5 IMC and Cu6Sn5 IMC changed in very small range. While the hardness value decreased with the increasing of the thermal aging time.

Medium to High Strain-Rate Characterization of Lead Free Solder Alloys Through Metal Cutting Experiments

2019 ◽  
Author(s):  
Yuvraj Singh ◽  
Anirudh Udupa ◽  
Srinivasan Chandrasekar ◽  
Ganesh Subbarayan
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Metal Cutting ◽  
High Strain ◽  
Lead Free ◽  
Strain Rates ◽  
Lead Free Solder ◽  
Orthogonal Metal Cutting ◽  
Free Solder

Abstract Studies on medium to high strain-rate characterization (≥ 0.1s−1) of lead-free solder are relatively few, primarily due to the lack of available methods for testing. Prior work in literature uses Split Hopkinson Bar (SPHB) experiments for high strain-rate characterization (≥ 300s−1) [1,2], while a modified micro-scale tester is used for medium strain-rate characterization (0.005s−1 to 300s−1) [3] and an impact hammer test setup for testing in a strain-rate regime from 1s−1 to 100s−1 [4]. However, there is still limited data in strain-rate regimes of relevance, specifically for drop shock applications. In this paper, we present orthogonal metal cutting as a novel method to characterize lead-free solder alloys. Experiments are carried out using a wedgelike tool that cuts through a work piece at a fixed depth and rake angle while maintaining a constant cutting velocity. These experiments are conducted at room temperature on Sn1.0Ag0.5Cu bulk test specimens with strain-rates varying from 0.32 to 48s−1. The range of strain-rates is only limited by the ball screw driven slide allowing higher strain-rates if needed. The strains and strain-rates are captured through Particle Image Velocimetry (PIV) using sequential images taken from a high-speed camera just ahead of the cutting tool. The PIV enables non-contact recording of high strain-rate deformations, while the dynamometer on the cutting head allows one to capture the forces exerted during the cutting process. Results for the stress-strain response obtained through the experiments are compared to prior work for validation. Orthogonal metal cutting is shown to be a potentially attractive method for characterization of solder at higher strain-rates.

High Strain Rate Mechanical Properties of SAC-Q Solder for Extreme Temperatures After Exposure to Isothermal Aging Up to 90 Days

2021 ◽  
Author(s):  
Pradeep Lall ◽  
Vishal Mehta ◽  
Jeffrey C. Suhling ◽  
Ken Blecker
Keyword(s):  
Mechanical Properties ◽  
Oil And Gas ◽  
High Strain ◽  
Strain Rates ◽  
Solder Alloys ◽  
Aerospace Medical ◽  
Free Solder ◽  
Electronic Parts ◽  
Sac Solder ◽  
Temperature Storage

Abstract In many industries, such as automotive, oil and gas, aerospace, medical technologies, electronic parts can often be exposed to high strain loads during shocks, vibrations and drop-impact conditions. Such electronic parts can often be subjected to extreme low and high temperatures ranging from -65oC to 200oC. Also, these electronic devices can be subjected to strain rates of 1 to 100 per second in the critical environment. Recently, many doped SAC solder alloys are being introduced in the electronic component e.g. SAC-Q, SAC-R, Innolot, etc. SAC-Q is made with addition of Bi in Sn-Ag-Cu are composition. Mechanical characteristic results and data for lead-free solder alloys are extremely important for optimizing electronic package reliability, at high temperature storage and elevated strain rates. Furthermore, the mechanical properties of solder alloys can be changed significantly due to a thermal aging, which is causing modification of microstructure. Data for the SAC-Q solder alloy with a high temp aging and testing at extreme low to high operating temperatures are not available.

Effect of Mechanical Cycling at Elevated Temperatures on The Constitutive Properties and Microstructure of Lead Free Solder Alloys

2021 ◽  
Author(s):  
Mohd Aminul Hoque ◽  
Mohammad Ashraful Haq ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
High Temperature ◽  
Hysteresis Loop ◽  
Lead Free ◽  
Uniaxial Tensile ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Plastic Strain Range ◽  
Mechanical Cycling ◽  
Free Solder ◽  
Fixed Region

Abstract Solder joints in electronic packages often experience fatigue failures due to cyclic mechanical stresses and strains in fluctuating temperature environments. These stresses and strains are induced by mismatches in coefficients of thermal expansion, and lead to damage accumulation that contributes to crack initiation, crack propagation, and eventually to failure. In this study, we have tried to compare the effects of elevated mechanical cycling on SAC305 and SAC+Bi (SAC_Q). Initially, small uniaxial cylindrical samples of both alloys were prepared and reflowed in a reflow oven. These samples were then mechanically cycled for various durations at testing temperatures of 100 °C. The measured cyclic stress-strain curves were used to characterize the evolution of the hysteresis loop properties (peak stress, hysteresis loop area, and plastic strain range) with high temperature mechanical cycling. In addition, uniaxial tensile tests and creep tests were also conducted on specimens that had been previously mechanically cycled for various durations (e.g 0, 50, 100, 200, and 300 cycles) at an elevated temperature. This allowed us to study the evolution of the constitutive behavior of the solder alloys that occurred during the high temperature mechanical cycling due to the fatigue damage that builds up in the specimens. The reductions in the properties that occur during high temperature mechanical cycling were also correlated with the corresponding changes in the microstructure of the specimens. Rectangular cross-sectioned samples of the two lead free solder alloys were polished and selected regions indented to track the changes in the microstructure of a fixed region with mechanical cycling at T = 100 °C. Using the results of this study, we are working to develop better fatigue criteria for lead free solders which are subjected to variable temperature applications.

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