Different amounts of Fe(0.005,0.01,0.03,0.05,and 0.07 wt%)were added to SAC305 to study the shear behavior damage of Fe-doped SAC solder joints under thermal loading(170℃,holding time of 0,250,500,and 750 h).The resu...Different amounts of Fe(0.005,0.01,0.03,0.05,and 0.07 wt%)were added to SAC305 to study the shear behavior damage of Fe-doped SAC solder joints under thermal loading(170℃,holding time of 0,250,500,and 750 h).The results show that during isothermal aging at 170℃,the average shear force of all solder joints decreases with increasing aging time,while the average fracture energy first increases and then decreases,reaching a maximum at 500 h.Minor Fe doping could both increase shear forces and related fracture energy,with the optimum Fe doping amount being 0.03 wt%within the entire aging range.This is because the doping Fe reduces the undercooling of the SAC305 alloy,resulting in the microstructure refining of solder joints.This in turn causes the microstructure changing from network structure(SAC305 joint:eutectic network+β-Sn)to a single matrix structure(0.03Fe-doped SAC305 joint:β-Sn matrix+small compound particles).Specifically,Fe atoms can replace some Cu in Cu_(6)Sn_(5)(both inside the solder joint and at the interface),and then form(Cu,Fe)_(6)Sn_(5) compounds,resulting in an increase in the elastic modulus and nanohardness of the compounds.Moreover,the growth of Cu_(6)Sn_(5) and Cu_(3)Sn intermetallic compounds(IMC)layer are inhibited by Fe doping even after the aging time prolonging,and Fe aggregates near the interface compound to form FeSn_(2).This study is of great significance for controlling the growth of interfacial compounds,stabilizing the microstructures,and providing strengthening strategy for solder joint alloy design.展开更多
Motivated by the increasing use of Sn-3.0 Ag-0.5 Cu(SAC305)solder in electronics worked in marine atmospheric environment and the uneven distribution of Ag3Sn and Cu6Sn5 intermetallic compounds(IMCs)inβ-Sn matrix,com...Motivated by the increasing use of Sn-3.0 Ag-0.5 Cu(SAC305)solder in electronics worked in marine atmospheric environment and the uneven distribution of Ag3Sn and Cu6Sn5 intermetallic compounds(IMCs)inβ-Sn matrix,comb-like electrodes have been designed for in-situ EIS measurements to study the microstructure induced galvanic corrosion evolution of SAC305 solder in simulated marine atmosphere with high-temperature and high-humidity.Results indicate that in-situ EIS measurement by comb-like electrodes is an effective method for corrosion evolution behavior study of SAC305 solder.Besides,the galvanic effect between Ag3Sn IMCs andβ-Sn matrix can aggravate the corrosion of both as-received and furnace-cooled SAC305 solder as the exposure time proceeds in spite of the presence of corrosion product layer.Pitting corrosion can be preferentially found on furnace-cooled SAC305 with larger Ag3Sn grain size.Moreover,the generated inner stress during phases transformation process with Sn3O(OH)2Cl2 as an intermediate and the possible hydrogen evolution at local acidified sites are supposed to be responsible for the loose,porous,cracked,and non-adherent corrosion product layer.These findings clearly demonstrate the corrosion acceleration behavior and mechanism of SAC305 solder,and provide potential guidelines on maintenance of microelectronic devices for safe operation and longer in-service duration.展开更多
The stable operation of electronic devices in marine atmospheric environment is affected by the corrosion deterioration of solder joints,and the effects by atmosphere temperature and chloride deposition are critical.I...The stable operation of electronic devices in marine atmospheric environment is affected by the corrosion deterioration of solder joints,and the effects by atmosphere temperature and chloride deposition are critical.In this work,NaCl deposition and temperature dependent corrosion of Pb-free SAC305 solder in simulated marine atmosphere has been investigated.The results indicate that higher NaCl deposition prolongs the surface wetting time and leads to the final thicker saturated electrolyte film for further corrosion.Higher temperature accelerates the evaporation and contributes to the final thinner saturated NaCl electrolyte film.Besides,the corrosion control process varies under the initially covered thicker NaCl electrolyte layer and under the final saturated much thinner NaCl electrolyte film as the evaporation proceeds.Moreover,the ready oxygen availability through the final thinner saturated NaCl electrolyte film facilitates the formation of corrosion product layer mainly of electrochemically stable SnO2,but higher temperature leads to the final corrosion product layer with smaller crystal size and large cracks.The findings clearly demonstrate the effects of NaCl deposition and temperature on corrosion evolution of SAC305 solder joints and are critical to the daily maintenance of electronic devices for longer service life in marine atmosphere.展开更多
The effects of Mn addition(0.005,0.01,0.03,0.05,and 0.07 wt.%)on microstructure,shear mechanical behavior,and interfacial thermal stabilities of SAC305 joints were investigated under isothermal aging temperatures of 1...The effects of Mn addition(0.005,0.01,0.03,0.05,and 0.07 wt.%)on microstructure,shear mechanical behavior,and interfacial thermal stabilities of SAC305 joints were investigated under isothermal aging temperatures of 170 C with different aging time(0,250,500,and 750 h).It is found that Mn addition can increase fracture energy of joints without decreasing the shear strength.And the microstructures have transformed from the eutectic net-like structure in SAC305 solder joints into the structures based onβ-Sn matrix with intermetallic compounds(IMCs)distributed.By doping 0.07 wt.%Mn,the Cu_(6)Sn_(5) growth along the SAC305/Cu interface during thermal aging can be inhibited to some extent.During isothermal aging at 170°C,the maximum shear force of solder joint decreases continuously with aging time increasing,while the fracture energy rises first and then decreases,reaching the maximum at 500 h compared by that with the microstructure homogenization.Cu_(3)Sn growth between Cu_(3)Sn_(5)/Cu interface has been retarded most at the aging time of 250 h with 0.07 wt.%Mn-doped joints.With the aging time prolonging,the inhibition effect of Mn on CusSn IMC layer becomes worse.The strengthening effect of Mn can be explained by precipitation strengthening,and its mechanical behavior can be predicted by particle strengthening model proposed by Orowan.展开更多
As electronic devices continue to become lighter and thinner,they require much smaller solder joints and fine-pitch interconnections for microelectronic packaging.Pb-free solders incorporated with nano-sized particles...As electronic devices continue to become lighter and thinner,they require much smaller solder joints and fine-pitch interconnections for microelectronic packaging.Pb-free solders incorporated with nano-sized particles have been identified as potential Pb-free nanocomposite solders that could provide higher microstructure stability and better mechanical properties than the conventional solders.The present study investigates the effects of NiO addition on the mechanical properties and microstructure of the Sn-3.0Ag-0.5Cu(SAC305)solder alloy.In this study,three different solder alloys were prepared by reflow soldering.Sn-3.0Ag-0.5Cu(SAC 305)solder alloys were doped with different percentage of NiO(nickel oxide)nanoparticles content;i.e.0.01 wt%,0.05 wt%,and 0.15 wt%in producing nanocomposite solder paste.Morphology refinement of SAC305-NiO nanocomposite solder contributed to the enhancement of mechanical properties in the field of microelectronic industries.ECM(electrochemical migration)of SAC-NiO nanocomposites solder pastes was measured using a WDT(water drop test).Effects of electrochemical migration of its surface morphology were investigated using OM(optical microscopy).展开更多
基金supported by the Yunnan Fundamental Research Projects(No.202301BC070001-001)funded by the Yunnan Provincial Department of Science and Technologythe Yunnan Provincial Science and Technology Plan Project(No.202005AF150045)+1 种基金the Jiangsu Province Industry-University-Research Cooperation Project(No.BY2022832)funded by the Jiangsu Provincial Department of Science and Technologythe National Natural Science Foundation of China(No.52275339).
文摘Different amounts of Fe(0.005,0.01,0.03,0.05,and 0.07 wt%)were added to SAC305 to study the shear behavior damage of Fe-doped SAC solder joints under thermal loading(170℃,holding time of 0,250,500,and 750 h).The results show that during isothermal aging at 170℃,the average shear force of all solder joints decreases with increasing aging time,while the average fracture energy first increases and then decreases,reaching a maximum at 500 h.Minor Fe doping could both increase shear forces and related fracture energy,with the optimum Fe doping amount being 0.03 wt%within the entire aging range.This is because the doping Fe reduces the undercooling of the SAC305 alloy,resulting in the microstructure refining of solder joints.This in turn causes the microstructure changing from network structure(SAC305 joint:eutectic network+β-Sn)to a single matrix structure(0.03Fe-doped SAC305 joint:β-Sn matrix+small compound particles).Specifically,Fe atoms can replace some Cu in Cu_(6)Sn_(5)(both inside the solder joint and at the interface),and then form(Cu,Fe)_(6)Sn_(5) compounds,resulting in an increase in the elastic modulus and nanohardness of the compounds.Moreover,the growth of Cu_(6)Sn_(5) and Cu_(3)Sn intermetallic compounds(IMC)layer are inhibited by Fe doping even after the aging time prolonging,and Fe aggregates near the interface compound to form FeSn_(2).This study is of great significance for controlling the growth of interfacial compounds,stabilizing the microstructures,and providing strengthening strategy for solder joint alloy design.
基金financially supported by the National Natural Science Foundation of China(No.51601057)。
文摘Motivated by the increasing use of Sn-3.0 Ag-0.5 Cu(SAC305)solder in electronics worked in marine atmospheric environment and the uneven distribution of Ag3Sn and Cu6Sn5 intermetallic compounds(IMCs)inβ-Sn matrix,comb-like electrodes have been designed for in-situ EIS measurements to study the microstructure induced galvanic corrosion evolution of SAC305 solder in simulated marine atmosphere with high-temperature and high-humidity.Results indicate that in-situ EIS measurement by comb-like electrodes is an effective method for corrosion evolution behavior study of SAC305 solder.Besides,the galvanic effect between Ag3Sn IMCs andβ-Sn matrix can aggravate the corrosion of both as-received and furnace-cooled SAC305 solder as the exposure time proceeds in spite of the presence of corrosion product layer.Pitting corrosion can be preferentially found on furnace-cooled SAC305 with larger Ag3Sn grain size.Moreover,the generated inner stress during phases transformation process with Sn3O(OH)2Cl2 as an intermediate and the possible hydrogen evolution at local acidified sites are supposed to be responsible for the loose,porous,cracked,and non-adherent corrosion product layer.These findings clearly demonstrate the corrosion acceleration behavior and mechanism of SAC305 solder,and provide potential guidelines on maintenance of microelectronic devices for safe operation and longer in-service duration.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51601057 and 51701038)and the Marine Science Special Project of Hebei Normal University of Science&Technology(No.2018HY004),and the authors acknowledge the assistance.
文摘The stable operation of electronic devices in marine atmospheric environment is affected by the corrosion deterioration of solder joints,and the effects by atmosphere temperature and chloride deposition are critical.In this work,NaCl deposition and temperature dependent corrosion of Pb-free SAC305 solder in simulated marine atmosphere has been investigated.The results indicate that higher NaCl deposition prolongs the surface wetting time and leads to the final thicker saturated electrolyte film for further corrosion.Higher temperature accelerates the evaporation and contributes to the final thinner saturated NaCl electrolyte film.Besides,the corrosion control process varies under the initially covered thicker NaCl electrolyte layer and under the final saturated much thinner NaCl electrolyte film as the evaporation proceeds.Moreover,the ready oxygen availability through the final thinner saturated NaCl electrolyte film facilitates the formation of corrosion product layer mainly of electrochemically stable SnO2,but higher temperature leads to the final corrosion product layer with smaller crystal size and large cracks.The findings clearly demonstrate the effects of NaCl deposition and temperature on corrosion evolution of SAC305 solder joints and are critical to the daily maintenance of electronic devices for longer service life in marine atmosphere.
基金support received from Yunnan Fundamental Research Projects(Grant No.202101BC070001-007)the Jiangsu Province Industry-University-Research Cooperation Project(No.BY2022832)the National Natural Science Foundation of China(No.52275339).
文摘The effects of Mn addition(0.005,0.01,0.03,0.05,and 0.07 wt.%)on microstructure,shear mechanical behavior,and interfacial thermal stabilities of SAC305 joints were investigated under isothermal aging temperatures of 170 C with different aging time(0,250,500,and 750 h).It is found that Mn addition can increase fracture energy of joints without decreasing the shear strength.And the microstructures have transformed from the eutectic net-like structure in SAC305 solder joints into the structures based onβ-Sn matrix with intermetallic compounds(IMCs)distributed.By doping 0.07 wt.%Mn,the Cu_(6)Sn_(5) growth along the SAC305/Cu interface during thermal aging can be inhibited to some extent.During isothermal aging at 170°C,the maximum shear force of solder joint decreases continuously with aging time increasing,while the fracture energy rises first and then decreases,reaching the maximum at 500 h compared by that with the microstructure homogenization.Cu_(3)Sn growth between Cu_(3)Sn_(5)/Cu interface has been retarded most at the aging time of 250 h with 0.07 wt.%Mn-doped joints.With the aging time prolonging,the inhibition effect of Mn on CusSn IMC layer becomes worse.The strengthening effect of Mn can be explained by precipitation strengthening,and its mechanical behavior can be predicted by particle strengthening model proposed by Orowan.
文摘As electronic devices continue to become lighter and thinner,they require much smaller solder joints and fine-pitch interconnections for microelectronic packaging.Pb-free solders incorporated with nano-sized particles have been identified as potential Pb-free nanocomposite solders that could provide higher microstructure stability and better mechanical properties than the conventional solders.The present study investigates the effects of NiO addition on the mechanical properties and microstructure of the Sn-3.0Ag-0.5Cu(SAC305)solder alloy.In this study,three different solder alloys were prepared by reflow soldering.Sn-3.0Ag-0.5Cu(SAC 305)solder alloys were doped with different percentage of NiO(nickel oxide)nanoparticles content;i.e.0.01 wt%,0.05 wt%,and 0.15 wt%in producing nanocomposite solder paste.Morphology refinement of SAC305-NiO nanocomposite solder contributed to the enhancement of mechanical properties in the field of microelectronic industries.ECM(electrochemical migration)of SAC-NiO nanocomposites solder pastes was measured using a WDT(water drop test).Effects of electrochemical migration of its surface morphology were investigated using OM(optical microscopy).
