To optimize the comprehensive properties of Ni−Si precipitation strengthened phosphor bronze,the impact of the Ni/Si mass ratio and heat treatment process on a Cu−8Sn−0.1P−1Ni−xSi alloy was explored.High resolution fi...To optimize the comprehensive properties of Ni−Si precipitation strengthened phosphor bronze,the impact of the Ni/Si mass ratio and heat treatment process on a Cu−8Sn−0.1P−1Ni−xSi alloy was explored.High resolution field emission scanning electron microscopy and transmission electron microscopy were used for microstructural characterization.The results indicate that the properties are influenced by the Ni/Si mass ratio,attributed to the formation of various second phases.Simultaneously,by influencing the diffusion rate,the microstructures and properties are influenced by the solid solution treatment.The strength is enhanced by precipitated nanoscale particles during the aging process by influencing the motion of dislocations.Ultimately,excellent comprehensive properties,including ultimate tensile strength,yield strength,and elongation of 866 MPa,772 MPa,and 8.7%,respectively,are obtained in the Cu−8Sn−0.1P−1Ni−0.227Si alloy.展开更多
Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is ...Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is critical for a microelectronic interconnection,will go through a phase transition at temperatures between 186 and 189℃.This research conducted an in-situ TEM study of a micro Cu/ENIG/Sn solder joint under isothermal aging test and proposed a model to illustrate the mechanism of the microstructural evolution.The results showed that part of the Sn solder reacted with Cu diffused from the electrode to formη´-Cu_(6)Sn_(5)during the ultrasonic bonding process,while the rest of Sn was left and enriched in a region in the solder joint.But the enriched Sn quickly diffused to both sides when the temperature reached 100℃,reacting with the ENIG coating and Cu to form(Ni_(x)Cu_(1-x))_(3)Sn_(4),AuSn_(4),and Cu_(6)Sn_(5)IMCs.After entering the heat preservation process,the diffusion of Cu from the electrode to the joint became more intense,resulting in the formation of Cu_(3)Sn.The scallop-type Cu_(6)Sn_(5)and the seahorse-type Cu_(3)Sn constituted a typical two-layered structure in the solder joint.Most importantly,the transition betweenηandη’was captured near the phase transition temperature for Cu_(6)Sn_(5)during both the heating and cooling process,which was accompanied by a volume shifting,and the transition process was further studied.This research is expected to serve as a reference for the service of micro Cu/ENIG/Sn solder joints in the electronic industry.展开更多
Kirkendall voids(KVs)at the Cu/Sn interface are a typical failure in integrated circuits,leading to solder joint cracking and electrical disconnection.Although the formation of KVs has been attributed to the differenc...Kirkendall voids(KVs)at the Cu/Sn interface are a typical failure in integrated circuits,leading to solder joint cracking and electrical disconnection.Although the formation of KVs has been attributed to the difference in atomic diffusion rates at the Cu/Sn interface,the role of Cu intrinsic"quality"parameters(crystal defects)in this process remains unclear.This work systematically investigated the effects of Cu crystal defects on KVs:Cu substrates with different lattice defects and grain boundaries were prepared using proprietary electrodeposition additives,and the number of defects was quantitatively characterized by micro-strain,geometric dislocation density,and geometric phase analysis.The thermal aging experiments further showed that the formation of intermetallic compounds and KVs was related to crystal defect energy.When the grain boundary energy was higher than the lattice energy,the additional driving force resulted in short-circuit diffusion,causing local Cu depletion and voids.The lowcrystal-defect samples maintained the local Cu/Sn interdiffusion equilibrium,resulting in fewer voids after 1000 h.This study emphasizes that regulating the crystal defects can reduce KVs and provides a new insight for improving the integrated solder joint's reliability.展开更多
Lithium metal,with its exceptionally high theoretical capacity,emerges as the optimal anode choice for high-energy-density rechargeable batteries.Nevertheless,the practical application of lithium metal batteries(LMBs)...Lithium metal,with its exceptionally high theoretical capacity,emerges as the optimal anode choice for high-energy-density rechargeable batteries.Nevertheless,the practical application of lithium metal batteries(LMBs)is constrained by issues such as lithium dendrite growth and low Coulombic efficiency(CE).Herein,a roll-to-roll approach is adopted to prepare meter-scale,lithiophilic Sn-modified Cu mesh(Sn@Cu mesh)as the current collector for long-cycle lithium metal batteries.The two-dimensional(2D)nucleation mechanism on Sn@Cu mesh electrodes promotes a uniform Li flux,facilitating the deposition of Li metal in a large granular morphology.Simultaneously,experimental and computational analyses revealed that the distribution of the electric field in the Cu mesh skeleton induces Li inward growth,thereby generating a uniform,dense composite Li anode.Moreover,the Sn@Cu mesh-Li symmetrical cell demonstrates stable cycling for over 2000 h with an ultra-low 10 mV voltage polarization.In Li||Cu half-cells,the Sn@Cu mesh electrode demonstrates stable cycling for 100 cycles at a high areal capacity of 5 mAh·cm^(-2),achieving a CE of 99.2%.This study introduces a simple and large-scale approach for the production of lithiophilic three-dimensional(3D)current collectors,providing more possibilities for the scalable application of Li metal batteries.展开更多
基金the support of the National Key Research and Development Program of China(No.2018YFE0306103)the National Natural Science Foundation of China(No.52071050)the Science and Technology Innovation Project of Ningbo,China(No.2021Z032).
文摘To optimize the comprehensive properties of Ni−Si precipitation strengthened phosphor bronze,the impact of the Ni/Si mass ratio and heat treatment process on a Cu−8Sn−0.1P−1Ni−xSi alloy was explored.High resolution field emission scanning electron microscopy and transmission electron microscopy were used for microstructural characterization.The results indicate that the properties are influenced by the Ni/Si mass ratio,attributed to the formation of various second phases.Simultaneously,by influencing the diffusion rate,the microstructures and properties are influenced by the solid solution treatment.The strength is enhanced by precipitated nanoscale particles during the aging process by influencing the motion of dislocations.Ultimately,excellent comprehensive properties,including ultimate tensile strength,yield strength,and elongation of 866 MPa,772 MPa,and 8.7%,respectively,are obtained in the Cu−8Sn−0.1P−1Ni−0.227Si alloy.
基金supported by the opening fund of National Key Research and Development Program of China(No.2020YFE0205300)Key Laboratory of Science and Technology on Silicon Devices,Chinese Academy of Sciences(No.KLSDTJJ2022-5)+1 种基金Chongqing Natural Science Foundation of China(No.cstc2021jcyj-msxmX1002)the Fundamental Research Funds for the Central Universities(No.AUGA5710051221).
文摘Sn/ENIG has recently been used in flexible interconnects to form a more stable micron-sized metallurgical joint,due to high power capability which causes solder joints to heat up to 200℃.However,Cu_(6)Sn_(5)which is critical for a microelectronic interconnection,will go through a phase transition at temperatures between 186 and 189℃.This research conducted an in-situ TEM study of a micro Cu/ENIG/Sn solder joint under isothermal aging test and proposed a model to illustrate the mechanism of the microstructural evolution.The results showed that part of the Sn solder reacted with Cu diffused from the electrode to formη´-Cu_(6)Sn_(5)during the ultrasonic bonding process,while the rest of Sn was left and enriched in a region in the solder joint.But the enriched Sn quickly diffused to both sides when the temperature reached 100℃,reacting with the ENIG coating and Cu to form(Ni_(x)Cu_(1-x))_(3)Sn_(4),AuSn_(4),and Cu_(6)Sn_(5)IMCs.After entering the heat preservation process,the diffusion of Cu from the electrode to the joint became more intense,resulting in the formation of Cu_(3)Sn.The scallop-type Cu_(6)Sn_(5)and the seahorse-type Cu_(3)Sn constituted a typical two-layered structure in the solder joint.Most importantly,the transition betweenηandη’was captured near the phase transition temperature for Cu_(6)Sn_(5)during both the heating and cooling process,which was accompanied by a volume shifting,and the transition process was further studied.This research is expected to serve as a reference for the service of micro Cu/ENIG/Sn solder joints in the electronic industry.
基金financially supported by the National Natural Science Foundation of China(Nos.62274172 and 62304143)High-level Talent Innovation and Entrepreneurship Plan of Shenzhen Key Technology Research and Development Team Funding Application(No.JSGGKQTD20221101115650008)+2 种基金Shenzhen-Hong Kong-Macao Science and Technology Plan Project(Category C)(No.SGDX20220530111004028)Macao Science and Technology Development Fund(FDCT)for funding(No.0013/2024/RIB1)the Multi-Year Research Grant(MYRG)from University of Macao(Nos.MYRG-GRG2023-00140-IAPME-UMDF and MYRG-GRG2024-00206-IAPME)
文摘Kirkendall voids(KVs)at the Cu/Sn interface are a typical failure in integrated circuits,leading to solder joint cracking and electrical disconnection.Although the formation of KVs has been attributed to the difference in atomic diffusion rates at the Cu/Sn interface,the role of Cu intrinsic"quality"parameters(crystal defects)in this process remains unclear.This work systematically investigated the effects of Cu crystal defects on KVs:Cu substrates with different lattice defects and grain boundaries were prepared using proprietary electrodeposition additives,and the number of defects was quantitatively characterized by micro-strain,geometric dislocation density,and geometric phase analysis.The thermal aging experiments further showed that the formation of intermetallic compounds and KVs was related to crystal defect energy.When the grain boundary energy was higher than the lattice energy,the additional driving force resulted in short-circuit diffusion,causing local Cu depletion and voids.The lowcrystal-defect samples maintained the local Cu/Sn interdiffusion equilibrium,resulting in fewer voids after 1000 h.This study emphasizes that regulating the crystal defects can reduce KVs and provides a new insight for improving the integrated solder joint's reliability.
基金supported by the Key Research and Development Program of Hubei Province,China(No.2023BAB108)the Natural Science Foundation of Hubei Province,China(No.2022CFB096)the National Natural Science Foundation of China(Nos.22279093 and 22075216)。
文摘Lithium metal,with its exceptionally high theoretical capacity,emerges as the optimal anode choice for high-energy-density rechargeable batteries.Nevertheless,the practical application of lithium metal batteries(LMBs)is constrained by issues such as lithium dendrite growth and low Coulombic efficiency(CE).Herein,a roll-to-roll approach is adopted to prepare meter-scale,lithiophilic Sn-modified Cu mesh(Sn@Cu mesh)as the current collector for long-cycle lithium metal batteries.The two-dimensional(2D)nucleation mechanism on Sn@Cu mesh electrodes promotes a uniform Li flux,facilitating the deposition of Li metal in a large granular morphology.Simultaneously,experimental and computational analyses revealed that the distribution of the electric field in the Cu mesh skeleton induces Li inward growth,thereby generating a uniform,dense composite Li anode.Moreover,the Sn@Cu mesh-Li symmetrical cell demonstrates stable cycling for over 2000 h with an ultra-low 10 mV voltage polarization.In Li||Cu half-cells,the Sn@Cu mesh electrode demonstrates stable cycling for 100 cycles at a high areal capacity of 5 mAh·cm^(-2),achieving a CE of 99.2%.This study introduces a simple and large-scale approach for the production of lithiophilic three-dimensional(3D)current collectors,providing more possibilities for the scalable application of Li metal batteries.
