Corrosion Resistance of Copper-Coated Contacts

ISRN Corrosion, 2013

Hydrogen sulphide (H 2 S) is considered one of the most corrosive atmospheric pollutants. It is a weak, diprotic, reducing acid, readily soluble in water and dispersed into the air by winds when emitted from natural, industrial, and anthropogenic sources. It is a pollutant with a high level of toxicity impairing human health and the environment quality. It attacks copper forming thin films of metallic sulphides or dendrite whiskers, which are cathodic to the metal substrate, enhancing corrosion. H 2 S is actively involved in microbially influenced corrosion (MIC) which develops in water, involving sulphur based bacteria, in oxidizing and reducing chemical reactions. H 2 S is found in concentrated geothermal brines, in the atmosphere of geothermal fields, and in municipal sewage systems. Other active atmospheric pollutants include SO X , NO X , and CO. This investigation reports on the effects of H 2 S on copper in microelectronic components of equipment and devices, with the formation of nonconductive films that lead to electrical failures.

Microelectronics Reliability, 2020

Microelectronic reliability requirements are tightening to a standard of near zero ppb defects due to the evolution of self-driving cars and wearable electronics. The successful transition from gold (Au) to copper (Cu) in wire-bonding introduces corrosion related reliability concerns to wire-bonded devices in integrated circuit (IC) packaging. This report studies the effect of bimetallic contact, Cu wire vs. aluminum (Al) bond pad, on the corrosion failure of Al bond pads when exposed to low ppm levels of chloride (Cl −) contamination. Real time corrosion screening was carried out on simulating Cu/Al micro patterns for time-dependent observation of corrosion progression in 5-20 ppm Cl − solutions at pH 5. Al in Cu/Al bimetallic couple corroded at accelerated rate compared to Al without bimetallic contact. Cathodic hydrogen evolution was found to be the key factor driving this aggressive Al bond pad corrosion under the influence of the peripheral Cu/Al bimetallic contact in acidic chloride solution. Chemically modifying the surface of Cu wires to prevent this H 2 evolution reaction resulted in the inhibition of Al bond pad corrosion.

Revista de Metalurgia, 2007

Samples of electrolytic tin and nickel have been exposed for 1 to 12 m in indoor environment, inside a box (rain sheltered cabinet), placed in tropical humid marine-urban climate, as a part of Gulf of Mexico. The corrosion aggressiveness of box has been classified as a very high corrosive, based on the monitored chlorides and SO 2 deposition rates, and the Temperature/Relative Humidity air daily complex. The annual mass increasing of nickel is approximately twice higher than its values of mass loss (C). The relation between nickel mass loss or increasing and time of wetness (t) of metal surface is linear and does not obey the power equation C = A t n , which has be found for tin. The SEM images reveal a localized corrosion on nickel and tin surfaces. XRD detects the formation of SnCl 2 .H 2 O as a corrosion product. Within the time on the tin surface appear black spots, considered as organic material.

Materials and Corrosion, 2013

This paper presents an investigation on the corrosion performance of Ni/Au, NiP/ Au, Ni/NiP/Au and Ni/NiPd/Au electrical connector coating systems. The coating systems were exposed to 10 days Class III mixed flowing gas and were subsequently examined by X-ray diffraction, focused ion beam microscopy, scanning electron microscopy and energy dispersive spectroscopy to evaluate the performance of each coating system. The Ni/Au coating system showed the worst performance followed by NiP/Au and Ni/NiP/Au. The Ni/NiPd/Au coated connector materials exhibited the least surface corrosion and this was attributed to a number of factors including a thicker coating system, more compact gold layer with fewer defects and a reduction in the electrochemical potential difference between layers reducing the local cell effect.

Anti-corrosion Methods and Materials, 2011

Purpose -The electronics industry has grown over the past 50 years, mostly in developed countries, contributing to their economic progress. Particularly in the Baja California State located in the northwest of Mexico, these companies have prospered in the industrial parks of Mexicali considered as an arid zone and Ensenada, a port and city on the Pacific Ocean considered as a marine region. In both environments, during winter and summer, the climate impacts on indoor conditions, affecting humidity and temperature, and generating corrosion which decreases the yields of the electronic devices and industrial machines. The purpose of this paper is to investigate the effects of corrosion on electronic devices in these arid and marine environments. Design/methodology/approach -The paper determines the corrosivity levels inside industrial plants of desertic and coast regions in Mexico, to evaluate the deterioration of electronic metals. Findings -Relative humidity, temperature, time of wetness, are recorded and related to the corrosion process in arid and marine environments. Research limitations/implications -Some missing information about air pollution in Ensenada from some Environmental Monitoring Stations was a limitation, and the need to use complex atmospheric techniques. Originality/value -The paper shows that it is very important to control metallic corrosion generated by climate factors and air pollution in indoor industrial plants: the corrosion of electronic devices and equipments depletes their yield and can lead to loss-making failures.

2015 IEEE 65th Electronic Components and Technology Conference (ECTC), 2015

Copper aluminum interconnects are being used in automotive applications for deployment underhood, on-engine and on-transmission. Electronics is widely used for enabling safety function including lane departure warning systems, collision avoidance systems, antilock braking systems, and vehicle stability systems. Models for copper interconnect degradation are needed for life prediction modeling to ensure 10-year, 100,000 mile reliability for electronics in automotive applications. Small concentrations of chloride ions may diffuse towards the bond pad interface under temperature, humidity, and electrical bias. The chloride ions may act as a catalyst breaking down the passivation layer of aluminum pad and accelerate the micro-galvanic corrosion at the copperaluminum leading to the failure of the wirebond. Models for prediction of the diffusion of the chloride ions and the corrosion of the copper-aluminum interface have been difficult to develop, because of the small scale of the interface and the lack of appropriate electro-chemical properties for the Cu-Al system and the Electronic Molding Compounds under conditions relevant to operation. In this effort, a multiphysics model for electrolytic corrosion in the presence of chloride has been presented. The contaminant diffusion along with the corrosion kinetics has been modeled. In addition, contaminated samples with known concentration of KCl contaminant have been subjected to the temperature humidity conditions of 130°C/100RH. The resistance of the Cu-Al interconnects in the PARR test have been monitored periodically using resistance spectroscopy. The diffusion coefficients of chloride ion has been measured in the electronic molding compound at various temperatures using two methods including diffusion cell and inductively coupled plasma (ICPMS). Moisture ingress into the EMC has been quantified through measurements of the weight gain in the EMC as a function of time. Tafel parameters including the open circuit potential and the slope of the polarization curve has been measured for both copper, aluminum under different concentrations of the ionic species and pH values in the EMC. The measurements have been incorporated into the COMSOL model to predict the corrosion current at the Cu-Al bond pad. The model predictions have been correlated with experimental data.

Tribology International, 1997

Optics and Lasers in Engineering, 2006

Materials used in electrical contact applications are usually constituted of multilayered compounds (e.g.: copper alloy electroplated with a nickel layer and finally by a gold layer). After the electro-deposition, micro-channels and pores within the gold layer allow undesirable corrosion of the underlying protection. In order to modify the gold-coating microstructure, a laser surface treatment was applied. The laser treatment suppressing porosity and smoothing the surface sealed the original open structure as a low roughness allows a good electrical contact. Corrosion tests were carried out in humid synthetic air containing three polluting gases. SEM characterization of cross-sections was performed to estimate the gold melting depth and to observe the modifications of gold structure obtained after laser treatment. The effects of the laser treatment were studied according to different surface parameters (roughness of the substrate and thickness of the gold layer) and different laser parameters (laser wavelength, laser fluence, pulse duration and number of pulses). A thermokinetic model was used to understand the heating and melting mechanism of the multilayered coating to optimize the process in terms of laser wavelength, energy and time of interaction. r

IMAPS symposia and conferences, 2015

Reliability of electronic devices used in extreme and harsh conditions such as in automotive applications is often associated with prevention of corrosion at the interfaces of dissimilar interconnect metals and of metal (Al or Cu) bonding pads. Packaging materials, especially molding compounds, contain several ionic components and can uptake certain level of moisture to provide electrolytic conditions to initiate corrosion processes. Probability of occurrence of corrosion in devices with high voltage applications is of special interest as many analog devices operates at higher voltages and with new CuWB packages there is a higher susceptibility of corrosive failures. This paper examines the impact of voltage on the mold compound compatibility with CuWB packages up to 65 V. Bias HAST reliability evaluation of various mold compounds at different voltages will be described. Corrosion of bonding pad (Al) and at the Al-Cu intermetallic compound interface was observed in the presence of certain ions present in mold compounds. Even though current mold compounds are "green", the allowable amounts of halide ions can far exceed the ppm limit to prevent CuWB corrosive failures. Bromide ions are known to be very corrosive to metals. Br ions are still present in some mold compounds. The impact of the Br ion on CuWB reliability will be described. Additive impact of Br ions in presence of Cl will be examined. Another corrosive component present in many mold compounds, sulfur compounds, also can be corrosive under certain reliability stress conditions. Difference in corrosion behavior of Cu and Pd-Cu wirebonded packages due to sulfur compounds will be presented. Corrosive impact of high levels of Cl on the Al pad corrosion leading thick aluminum oxide growth and reliability failures will be discussed.

2006