Currently,wire bonding is the most popular first-level interconnection technology used between the die and package terminals,but even with its long-term and excessive usage,the mechanism of wire bonding has not been c...Currently,wire bonding is the most popular first-level interconnection technology used between the die and package terminals,but even with its long-term and excessive usage,the mechanism of wire bonding has not been completely evaluated.Therefore,fundamental research is still needed.In this study,the mechanism of microweld formation and breakage during Cu-Cu wire bonding was investigated by using molecular dynamics simulation.The contact model for the nanoindentation process between the wire and substrate was developed to simulate the contact process of the Cu wire and Cu substrate.Elastic contact and plastic instability were investigated through the loading and unloading processes.Moreover,the evolution of the indentation morphology and distributions of the atomic stress were also investigated.It was shown that the loading and unloading curves do not coincide,and the unloading curve exhibited hysteresis.For the substrate,in the loading process,the main force changed from attractive to repulsive.The maximum von Mises stress increased and shifted from the center toward the edge of the contact area.During the unloading process,the main force changed from repulsive to attractive.The Mises stress reduced first and then increased.Stress concentration occurs around dislocations in the middle area of the Cu wire.展开更多
Cu wires(CuWs)are widely used as electric transmission lines.However,their limited thermal and chemical stabilities become challenges under the high-power and harsh environment.Graphene is regarded as an ideal protect...Cu wires(CuWs)are widely used as electric transmission lines.However,their limited thermal and chemical stabilities become challenges under the high-power and harsh environment.Graphene is regarded as an ideal protective barrier for CuW benefiting from its impermeability to all atoms and molecules.Particularly,the excellent hydrophobicity of vertical graphene(VG)will strengthen its protective capability as a corrosion and oxidation barrier.Herein,VG is directly synthesized on CuW by plasmaenhanced chemical vapor deposition method.The hydrophobic VG coating with a high water contact angle can effectively exclude the corrosive liquid and moisture from CuW surface and prevent their further penetration.Consequently,the electrochemical corrosion rate of VG-CuW is reduced by~13,8,and 2 times,compared with bare CuW,VG-CuW with hydrophilic treatment,and CuW coated with thick horizontal graphene layers,respectively.Negligible oxidation occurs on VGCuW after the long-time exposure to humid air at~200℃ along with the largely enhanced tolerance under high-current operating condition.This study reveals the impressive potentials of hydrophobic VG as a robust corrosion and oxidation barrier for metal wires used in high-power cables and electronic devices in harsh environment.展开更多
基金the National Key R&D Program of China(Grant No.2019YFB1704600)the Hubei Provincial Natural Science Foundation of China(Grant No.2020CFA032).
文摘Currently,wire bonding is the most popular first-level interconnection technology used between the die and package terminals,but even with its long-term and excessive usage,the mechanism of wire bonding has not been completely evaluated.Therefore,fundamental research is still needed.In this study,the mechanism of microweld formation and breakage during Cu-Cu wire bonding was investigated by using molecular dynamics simulation.The contact model for the nanoindentation process between the wire and substrate was developed to simulate the contact process of the Cu wire and Cu substrate.Elastic contact and plastic instability were investigated through the loading and unloading processes.Moreover,the evolution of the indentation morphology and distributions of the atomic stress were also investigated.It was shown that the loading and unloading curves do not coincide,and the unloading curve exhibited hysteresis.For the substrate,in the loading process,the main force changed from attractive to repulsive.The maximum von Mises stress increased and shifted from the center toward the edge of the contact area.During the unloading process,the main force changed from repulsive to attractive.The Mises stress reduced first and then increased.Stress concentration occurs around dislocations in the middle area of the Cu wire.
基金supported by the National Key Basic Research Program of China(No.2016YFA0200103)the National Natural Science Foundation of China(Nos.51520105003,51432002,and U1904193)+2 种基金Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXTD-202001)Beijing Municipal Science&Technology Commission(Nos.Z201100008720006,Z181100004818001,and Z191100000819007)Beijing Nova Program of Science and Technology(No.Z191100001119067).
文摘Cu wires(CuWs)are widely used as electric transmission lines.However,their limited thermal and chemical stabilities become challenges under the high-power and harsh environment.Graphene is regarded as an ideal protective barrier for CuW benefiting from its impermeability to all atoms and molecules.Particularly,the excellent hydrophobicity of vertical graphene(VG)will strengthen its protective capability as a corrosion and oxidation barrier.Herein,VG is directly synthesized on CuW by plasmaenhanced chemical vapor deposition method.The hydrophobic VG coating with a high water contact angle can effectively exclude the corrosive liquid and moisture from CuW surface and prevent their further penetration.Consequently,the electrochemical corrosion rate of VG-CuW is reduced by~13,8,and 2 times,compared with bare CuW,VG-CuW with hydrophilic treatment,and CuW coated with thick horizontal graphene layers,respectively.Negligible oxidation occurs on VGCuW after the long-time exposure to humid air at~200℃ along with the largely enhanced tolerance under high-current operating condition.This study reveals the impressive potentials of hydrophobic VG as a robust corrosion and oxidation barrier for metal wires used in high-power cables and electronic devices in harsh environment.
