Determination of High and Low Temperature High Strain Rate Mechanical Properties for SAC-R After Exposure to Isothermal Aging of 50°C Up To 8 Months

2021 ◽  
Author(s):  
Pradeep Lall ◽  
Mrinmoy Saha ◽  
Jeff Suhling ◽  
Ken Blecker

Abstract Electronic parts may be subjected to continuous activity at high temperatures as well as high strain-rate loads in the oil exploration industry, military, automotive, avionics, and space applications, and parts may be stored in non-climate-controlled enclosures prior to deployment. Material properties evolve at even moderate temperatures after a long period of storage, according to previous studies on undoped SAC alloys. To reduce the aging effects, a number of alloy formulations have been proposed. Data on the mechanical properties of lead-free solder alloys used for interconnection in electronic packaging at high strain rates and high storage temperatures is very important for design optimization of electronic package sustainability at extreme temperatures, since SAC soldiers have shown degradation of mechanical properties after prolonged exposure to storage temperature. The use of dopants in SAC solder has been proposed as a solution to minimize degradation. In this study, After keeping the samples in storage at 50°C for 1–8 months, a doped SAC solder called SAC-R (Ecolloy) was subjected to high strain rate testing. Uniaxial impact hammer tensile tests were conducted on samples with no aging and samples that had been aged for up to 8 months to assess the mechanical properties of SAC-R at high and low operating temperatures ranging from −65°C to 200°C and the Mechanical properties has been compared with an undoped solder SAC 105. The constants for the Anand Visco-Plasticity model were calculated using the material data for SAC-R. By comparing model predictions of the uniaxial tensile test with experimental results, the model’s ability to reflect material constitutive behavior has been quantified.

Author(s):  
Pradeep Lall ◽  
Mrinmoy Saha ◽  
Jeff Suhling ◽  
Ken Blecker

Abstract Electronic parts in military, automotive, avionics and space applications may be subjected to sustained operation at high temperature in addition to high strain-rate loads. Parts may be stored in non-climate-controlled enclosures prior to deployment. Earlier studies on undoped SAC alloys have shown that the material properties evolve after prolonged period of storage at even modest temperatures. In order to mitigate the aging effects, a number of alloy formulation have been proposed. Data of the mechanical properties of lead-free solder alloys which is used for interconnection in the electronic packaging at high strain rates and at high storage temperature is very essential for design optimization of electronic package sustainability at extreme temperature environment because the SAC solders have shown to have degradation in mechanical properties at prolonged exposure to storage temperature. Industries have come up with a solution to reduce the degradation using dopants in SAC solder. In this study, a doped SAC solder called SAC-R has been subjected to high strain rate testing after extended storage at temperature of 50°C for 1 month, 2 months and 3 months. Samples with no aging and aged samples for up to 3-months have been subjected to uniaxial tensile tests to measure the mechanical properties of SAC-R for High and Low operating temperature ranging from −65°C to +200°C. The material data has been used to compute the constants for the Anand Visco-Plasticity model. The ability of the model to represent the material constitutive behavior has been quantified by comparing the model predictions of the uniaxial tensile test with the experimental data.


Author(s):  
Pradeep Lall ◽  
Vikas Yadav ◽  
Jeff Suhling ◽  
David Locker

Electronics in automotive underhood and downhole drilling applications may be subjected to sustained operation at high temperature in addition to high strain-rate loads. SAC solders used for second level interconnects have been shown to experience degradation in high strain-rate mechanical properties under sustained exposure to high temperatures. Industry search for solutions for resisting the high-temperature degradation of SAC solders has focused on the addition of dopants to the alloy. In this study, a doped SAC solder called SAC-Q solder have been studied. The high strain rate mechanical properties of SAC-Q solder have been studied under elevated temperatures up to 200°C. Samples with thermal aging at 50°C for up to 6-months have been used for measurements in uniaxial tensile tests. Measurements for SAC-Q have been compared to SAC105 and SAC305 for identical test conditions and sample geometry. Data from the SAC-Q measurements has been fit to the Anand Viscoplasticity model. In order to assess the predictive power of the model, the computed Anand parameters have been used to simulate the uniaxial tensile test and the model predictions compared with experimental data. Model predictions show good correlation with experimental measurements. The presented approach extends the Anand Model to include thermal aging effects.


2011 ◽  
Vol 82 (3) ◽  
pp. 280-287 ◽  
Author(s):  
Xuehui Gan ◽  
Jianhua Yan ◽  
Bohong Gu ◽  
Baozhong Sun

The uniaxial tensile properties of 4-step 3D braided E-glass/epoxy composites under quasi-static and high-strain rate loadings have been investigated to evaluate the tensile failure mode at different strain rates. The uniaxial tensile properties at high strain rates from 800/s to 2100/s were tested using the split Hopkinson tension bar (SHTB) technique. The tensile properties at quasi-static strain rate were also tested and compared with those in high strain rates. Z-transform theory is applied to 3D braided composites to characterize the system dynamic behaviors in frequency domain. The frequency responses and the stability of 3D braided composites under quasi-static and high-strain rate compression have been analyzed and discussed in the Z-transform domain. The results indicate that the stress-strain curves are rate sensitive, and tensile modulus, maximum tensile stress and corresponding tensile strain are also sensitive to the strain rate. The tensile modulus, maximum tensile stress of the 3D braided composites are linearly increased with the strain rate. With increasing of the strain rate (from 0.001/s to 2100/s), the tensile failure of the 3D braided composite specimens has a tendency of transition from ductile failure to brittle failure. The magnitude response and phase response is very different in quasi-static loading with that in high-strain rate loading. The 3D braided composite system is more stable at high strain rate than quasi-static loading.


2004 ◽  
Vol 43 (10) ◽  
pp. 7192-7199 ◽  
Author(s):  
Fumikazu Saito ◽  
Kensuke Fujihata ◽  
Takuyasu Hashiguchi ◽  
Toshitika Usui ◽  
Hideki Tamura

Sign in / Sign up

Export Citation Format

Share Document