Corrosion Study and Intermetallics Formation in Gold and Copper Wire Bonding in Microelectronics Packaging

Goh, C.S.; Chong, Wee Ling; Lee, Teck Kheng; Breach, C.D.

doi:10.3390/cryst3030391

Cited by 58 publications

(35 citation statements)

References 15 publications

(19 reference statements)

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“…Otherwise, it was proved experimentally that thin Al pad (≈ 1 µm thickness) can prevent gold and copper corrosion, because intermetallics formation rate in Au-Al system is much more higher than intermetallics formation rate in Cu-Al system, so it is possible to use Cu instead of Au for wire bonding in microelectronics packaging, and Cu has higher electric conductivity, higher thermal conduction, and lower material cost than Au [2]. It was founded experimentally, that copper electric corrosion is higher than aluminium electric corrosion in approximately two times at temperatures less than 40 о С [3,4], so thin Al layer can prevent copper electric corrosion.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic Diffusivities Ratio Analysis in the Al-Cu System

Yarmolenko

2020

Phys. Chem. Solid St.

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Copper and aluminium electric corrosion rates are investigated experimentally at room temperature and at temperature 100oC. It is founded that copper corrosion is higher than aluminium corrosion, and ratio of electric corrosion rates, kCu/kAl , decreases with temperature increasing. It is calculated that copper corrosion rate is approximately equal to aluminium corrosion at temperature about 300oC due to Cu2+ ions are less mobile than Cu+ ions. It is obvious physically: the higher temperature is, the grater atoms’ displacements in crystal lattice, Cu atoms can diffuse without two electrons, and Cu2+ ions more strongly interact with crystal lattice than Cu+ ions. A theoretical method to calculate intrinsic diffusivities ratio in double multiphase systems is proposed. The method involves the Kirkendall plane displacement and the general phases thickness only. Intrinsic diffusivities ratios in the Al-Cu system are calculated using literature experimental data. Diffusion activation energies and pre-exponential coefficients for the Cu-Al system are calculated combining literature experimental results. Analysis of literature data shows that the Kirkendall shift changes sign at temperature about 460oC in the Cu-Al system because of intrinsic diffusivities ratio, DCu*/DAl*, dependence from temperature. Such result agrees with copper and aluminium electric corrosion rates investigation.

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Section: Introductionmentioning

confidence: 99%

Intrinsic Diffusivities Ratio Analysis in the Al-Cu System

Yarmolenko

2020

Phys. Chem. Solid St.

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“…As a result of its excellent electrical conductivity, chemical stability, and corrosion resistance, gold is widely used as an electronic sliding contact material for high precision inertial devices, satellite slip ring brushes, robots, etc. [ 1 , 2 , 3 , 4 , 5 ]. However, the low intrinsic hardness, easy deformation, and poor elasticity of pure gold limits its application in circumstances necessitating high mechanical strength requirements [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Parallel Micro-Gap Resistance Welding of an AuNi9 Microwire and Au Microlayer

Zhang

Wang

et al. 2021

Micromachines

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Welding between an AuNi9 microwire and Au microlayer is of great importance for fabricating electrical contact structures for high precision inertial devices, satellite slip ring brushes, robots, etc. In this paper, the achievement of parallel micro-gap resistance welding (PMRW) with 200-μm AuNi9 microwires on a 3-μm Au layer was presented. The study on the orthogonal design of the experiment was carried out. The effect of the process parameters (welding current, welding time, and welding pressure) was discussed in reference to the morphologies and tensile force of the joint using range analysis. It is shown that too much or too little heat input will decrease the welding performance. A group of optimized process parameters (0.275 kA welding current, 3 ms welding time, and 28.7 N welding pressure) was obtained. During the welding process, the dynamic resistance of the whole welding system was measured, which can reflect the welding quality. Finite element simulation is utilized to calculate the welding temperature. The highest temperature was located in the center area of the AuNi9 microwire, reaching 1397.2 °C, which is higher than the melting point of AuNi9. By contrast, the highest temperature for the pad was 826.47 °C (lower than the melting point of Au). Hence, under optimized process parameters, a transient interfacial reaction between the liquid AuNi9 microwire and solid Au pad occurred, and the strength of the welded joint reached 5.54 N.

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“…The mass conservation law gives: , (1) so three phases general thickness is approximately greater in two times than initial Cu cover thickness. Otherwise, it was proved experimentally that thin Al pad (≈1 µm thickness) can prevent gold and copper corrosion, because intermetallics formation rate in Au-Al system is much more higher than intermetallics formation rate in Cu-Al system, so it is possible to use Cu instead of Au for wire bonding in microelectronics packaging, and Cu has higher electric conductivity, higher thermal conduction, and lower material cost than Au [2]. Corrosion and intermetallics rate formation in gold and copper wire bonding in microelectronics packaging were investigated in [2] at temperatures T1=175 о С, T2=200 о С, and T3=225 о С during 120, 240, 360, and 480 h. The authors have reported that crosssectional analysis of the Cu ball on Al pad confirmed that corrosion occurred at temperatures about T=200 о С primarily beneath the Cu balls and did not initiate from the Al pad, formation of CuCl2 didn't allow self-passivation of Cu to occur, so rate of copper corrosion increased, and the rate of Cu-Al intermetallics formation was found to be three to five times slower than Au-Al intermetallics formation at all three annealing temperatures.…”

Section: Introductionmentioning

confidence: 99%

Copper, Iron, and Aluminium Electrochemical Corrosion Rates and Intrinsic Diffusivitives Dependence on Temperature Investigations

Mv¹

2021

Preprint

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Our investigations show that electrochemical corrosion of copper is faster than electrochemical corrosion of aluminium at temperatures below 100oC. Literature data analysis shows that the Al atoms diffuse faster than the Cu atoms at temperatures higher than 475oC, Al rich intermetallic compounds (IMCs) are formed faster in the Cu-Al system, and the Kirkendall plane shifts toward Al side. Electrochemical corrosion occurs due to electric current and due to diffusion. An electronic devise working time, for example, depends on initial copper cover thickness on aluminium wire, connected to the electronic devise, temperature, and volume and dislocation pipe diffusion coefficients, so copper, iron, and aluminium electrochemical corrosion rates are investigated experimentally at room temperature and at temperature 100oC. Intrinsic diffusivities ratios of copper and aluminium at different temperatures and diffusion activation energies in the Cu-Al system are calculated by proposed here methods using literature experimental data. Dislocation pipe and volume diffusion activation energies of pure iron are calculated separately by earlier proposed method using literature experimental data. Aluminium dissolved into NaCl solution as the Al3+ ions at room temperature and at temperature 100oC, iron dissolved into NaCl solution as the Fe2+ (not Fe3+) ions at room temperature and at temperature 100oC, copper dissolved into NaCl solution as the Cu+ ions at room temperature and as the Cu+ and the Cu2+ ions at temperature 100oC. It is founded experimentally that copper corrosion is higher than aluminium corrosion, and ratio of electrochemical corrosion rates, kCu/kAl>1, decreases with temperature increasing, although iron electrochemical corrosion rate doesn’t depend on temperature below 100oC. It is obvious, because melting point of iron is more higher then melting point of copper or aluminium. It is calculated that copper electrochemical corrosion rate is approximately equal to aluminium electrochemical corrosion at temperature about 300oC, so copper can dissolve into NaCl solution mostly as the Cu2+ ions at temperature about 300oC. Ratio of intrinsic diffusivities, DCu/DAl <1, increases with temperature increasing, and intrinsic diffusivity of aluminium could be approximately equal to intrinsic diffusivity of copper at temperature about 460oC.

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Corrosion Study and Intermetallics Formation in Gold and Copper Wire Bonding in Microelectronics Packaging

Cited by 58 publications

References 15 publications

Intrinsic Diffusivities Ratio Analysis in the Al-Cu System

Intrinsic Diffusivities Ratio Analysis in the Al-Cu System

Ultrafast Parallel Micro-Gap Resistance Welding of an AuNi9 Microwire and Au Microlayer

Copper, Iron, and Aluminium Electrochemical Corrosion Rates and Intrinsic Diffusivitives Dependence on Temperature Investigations

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