Microstructure and mechanical behavior of SnBi-xAg and SnBi-xAg@P-Cu solder joints during isothermal aging

2021 ◽  
Vol 127 ◽  
pp. 114388
Author(s):  
Yang Liu ◽  
Boqiao Ren ◽  
Yuxiong Xue ◽  
Min Zhou ◽  
Rongxing Cao ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Isothermal Aging ◽  
Solder Joints

Growth of the nano-phase intermetallic compounds and its effect on mechanical behavior of Au80Sn20/CrMnFeCoNi solder joints during isothermal aging

2020 ◽  
pp. 157823
Author(s):  
Xiao Liu ◽  
Baishan Chen ◽  
Siyuan Wu ◽  
Yunzhu Ma ◽  
Siwei Tang ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Intermetallic Compounds ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Phase Intermetallic

Mechanical Behavior of Sn-3.0Ag-0.5Cu/Cu Solder Joints After Isothermal Aging

2015 ◽  
Vol 45 (1) ◽  
pp. 125-135 ◽  
Author(s):  
Van Luong Nguyen ◽  
Chin-Sung Chung ◽  
Ho-Kyung Kim
Keyword(s):  
Mechanical Behavior ◽  
Isothermal Aging ◽  
Solder Joints

Investigation and Comparison of Aging Effects in SAC305 and Doped SAC+X Solders Exposed to Isothermal Aging

2020 ◽  
Author(s):  
Jing Wu ◽  
Mohammad S. Alam ◽  
KM Rafidh Hassan ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Lead Free ◽  
Aging Effects ◽  
Solid Solution Strengthening ◽  
Solution Strengthening

Abstract Microstructural evolution occurs in lead free Sn-Ag-Cu (SAC) solder joints exposed to isothermal aging. Such changes lead to degradations in the mechanical properties and creep behavior of the solder, and can result in dramatic reductions in the board level reliability of lead-free electronic assemblies subjected to aging. In our recent research, Scanning Electron Microscopy (SEM) has been used to: (1) monitor aging induced microstructural changes occurring within fixed regions in selected lead-free solder joints, (2) create time-lapse imagery of the microstructure evolution, and (3) analyze the microstructural changes quantitatively and correlate to the observed mechanical behavior evolution. This approach has removed the limitations of many prior studies where aged and non-aged microstructures were taken from two different samples and could only be qualitatively compared. In our current study, the microstructural evolutions were observed in SAC305 (96.5Sn-3.0Ag-0.5Cu) and SAC_Q (SAC+Bi) exposed to isothermal conditions at T = 100 °C and 125 °C for several different regions from several different joints. The microstructures in several fixed regions of interest were recorded after predetermined time intervals of aging, which were 1 hour (up to 270 hours) and 250 hours (up to 7000 hours) for the long-term aging samples. The aging induced changes in microstructure have been correlated with the changes in mechanical behavior measured using uniaxial tensile testing. The area and diameter of each IMC particle were tracked during the aging process using the recorded images and imaging processing software. As expected, the analysis of the evolving SAC305 and SAC+X microstructures showed a significant amount of diffusion of silver and bismuth in the beta-tin matrix during aging. In particular, Ag3Sn particles coalesced during aging leading to a decrease in the number of particles. Any bismuth in the SAC+X microstructure was observed to quickly go into solution, resulting in solid solution strengthening. This primary occurred within the beta-Sn dendrites, but also in the Ag3Sn intermetallic rich regions between dendrites. The presence of bismuth in was also found to slow the diffusion process that coarsens the Ag3Sn IMC particles. The combination solid solution strengthening and a lower diffusion rate for Ag lead to reduced aging effects in the SAC+Bi alloy relative to the SAC305 solder alloy. The SAC_Q alloy was found to have significantly better high temperature mechanical properties relative to SAC305 at all prior aging conditions. In particular, the initial modulus and ultimate tensile strength of SAC305 experienced large degradations during high temperature aging, whereas the same properties of SAC_Q changed only slightly. These changes in mechanical behavior correlated well with the observed increases in the average IMC particle diameter and decreases in the number of IMC particles. The microstructural and material property degradations were especially large for SAC305 during the initial 50 hours of aging.

scholarly journals Suppression of the Growth of Intermetallic Compound Layers with the Addition of Graphene Nano-Sheets to an Epoxy Sn–Ag–Cu Solder on a Cu Substrate

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 936 ◽  
Author(s):  
Min-Soo Kang ◽  
Do-Seok Kim ◽  
Young-Eui Shin
Keyword(s):  
Intermetallic Compound ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Solder Paste ◽  
Shear Tests ◽  
Sac305 Solder ◽  
Epoxy Solder ◽  
The Relationship ◽  
Bonding Characteristics ◽  
Preventive Effects

This study investigated the suppression of the growth of the intermetallic compound (IMC) layer that forms between epoxy solder joints and the substrate in electronic packaging by adding graphene nano-sheets (GNSs) to 96.5Sn–3.0Ag–0.5Cu (wt %, SAC305) solder whose bonding characteristics had been strengthened with a polymer. IMC growth was induced in isothermal aging tests at 150 °C, 125 °C and 85 °C for 504 h (21 days). Activation energies were calculated based on the IMC layer thickness, temperature, and time. The activation energy required for the formation of IMCs was 45.5 KJ/mol for the plain epoxy solder, 52.8 KJ/mol for the 0.01%-GNS solder, 62.5 KJ/mol for the 0.05%-GNS solder, and 68.7 KJ/mol for the 0.1%-GNS solder. Thus, the preventive effects were higher for increasing concentrations of GNS in the epoxy solder. In addition, shear tests were employed on the solder joints to analyze the relationship between the addition of GNSs and the bonding characteristics of the solder joints. It was found that the addition of GNSs to epoxy solder weakened the bonding characteristics of the solder, but not critically so because the shear force was higher than for normal solder (i.e., without the addition of epoxy). Thus, the addition of a small amount of GNSs to epoxy solder can suppress the formation of an IMC layer during isothermal aging without significantly weakening the bonding characteristics of the epoxy solder paste.

scholarly journals Comprehensive Properties of a Novel Quaternary Sn-Bi-Sb-Ag Solder: Wettability, Interfacial Structure and Mechanical Properties

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 791 ◽  
Author(s):  
Kaipeng Wang ◽  
Fengjiang Wang ◽  
Ying Huang ◽  
Kai Qi
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Low Temperature ◽  
Strain Rate ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Solder Matrix ◽  
Interfacial Structure ◽  
Solder Alloys ◽  
Cu Substrate

Sn-58Bi eutectic solder is the most recommended low temperature Pb-free solder but is also limited from the interfacial embrittlement of Bi segregation. Since the quaternary Sn-38Bi-1.5Sb-0.7Ag solder provides a similar melting point as Sn-58Bi eutectic, this paper systematically investigated the properties of this solder from wettability, bulk tensile properties, interfacial microstructure in solder joints with a Cu substrate, interfacial evolution in joints during isothermal aging and the shear strength on ball solder joints with effect of aging conditions. The results were also compared with Sn-58Bi solder. The wettability of solder alloys was evaluated with wetting balance testing, and the quaternary Sn-38Bi-1.5Sb-0.7Ag solder had a better wettability than Sn-58Bi solder on the wetting time. Tensile tests on bulk solder alloys indicated that the quaternary Sn-38Bi-1.5Sb-0.7Ag solder had a higher tensile strength and similar elongation compared with Sn-58Bi solder due to the finely distributed SnSb and Ag3Sn intermetallics in the solder matrix. The tensile strength of solder decreased with a decrease in the strain rate and with an increase in temperature, while the elongation of solder was independent of the temperature and strain rate. When soldering with a Cu substrate, a thin Cu6Sn5 intermetallic compound (IMC) is produced at the interface in the solder joint. Measurement on IMC thickness showed that the quaternary Sn-38Bi-1.5Sb-0.7Ag had a lower IMC growth rate during the following isothermal aging. Ball shear test on solder joints illustrated that the quaternary Sn-38Bi-1.5Sb-0.7Ag solder joints had higher shear strength than Sn-58Bi solder joints. Compared with the serious deterioration on shear strength of Sn-58Bi joints from isothermal aging, the quaternary Sn-38Bi-1.5Sb-0.7Ag solder joints presented a superior high temperature stability. Therefore, the quaternary Sn-38Bi-1.5Sb-0.7Ag solder provides better performances and the possibility to replace Sn-58Bi solder to realize low temperature soldering.

scholarly journals Dynamic Observation of Interfacial IMC Evolution and Fracture Mechanism of Sn2.5Ag0.7Cu0.1RE/Cu Lead-Free Solder Joints during Isothermal Aging

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 831 ◽  
Author(s):  
Di Zhao ◽  
Keke Zhang ◽  
Ning Ma ◽  
Shijie Li ◽  
Chenxiang Yin ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fracture Mechanism ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Diffusion Mechanism ◽  
Bulk Diffusion ◽  
Cu Substrate ◽  
Dynamic Observation ◽  
Free Solder ◽  
The Relationship

Dynamic observation of the microstructure evolution of Sn2.5Ag0.7Cu0.1RE/Cu solder joints and the relationship between the interfacial intermetallic compound (IMC) and the mechanical properties of the solder joints were investigated during isothermal aging. The results showed that the original single scallop-type Cu6Sn5 IMC gradually evolved into a planar double-layer IMC consisting of Cu6Sn5 and Cu3Sn IMCs with isothermal aging. In particular, the Cu3Sn IMC grew towards the Cu substrate and the solder seam sides; growth toward the Cu substrate side was dominant during the isothermal aging process. The growth of Cu3Sn IMC depended on the accumulated time at a certain temperature, where the growth rate of Cu3Sn was higher than that of Cu6Sn5. Additionally, the growth of the interfacial IMC was mainly controlled by bulk diffusion mechanism, where the activation energies of Cu6Sn5 and Cu3Sn were 74.7 and 86.6 kJ/mol, respectively. The growth rate of Cu3Sn was slightly faster than that of Cu6Sn5 during isothermal aging. With increasing isothermal aging time, the shear strength of the solder joints decreased and showed a linear relationship with the thickness of Cu3Sn. The fracture mechanism of the solder joints changed from ductile fracture to brittle fracture, and the fracture pathway transferred from the solder seam to the interfacial IMC layer.

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