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Advanced Materials Laboratory Photograph of corrosion on the Al portion of a Au/Al wirebond in a microelectronic device.

Corrosion

The primary goal of Sandia National Laboratories' corrosion program is to prevent or mitigate any undesirable effects that this form of metal degradation can have on high-reliability electrical and structural components. The diversity and breadth of our technical expertise and our focus to obtain science-based engineering solutions to corrosion problems and concerns make our program unique. Because of its multidisciplinary nature, the corrosion staff closely interacts with researchers from many of Sandia's technology centers (e.g., materials science, nano-science, computational science, and geochemistry). Sandia has significant expertise in four corrosion-related areas: atmospheric corrosion, aqueous corrosion, electrochemical science, and failure analysis.

Capabilities

Atmospheric Corrosion: In addition to mechanistic information, our experimental activities provide the ability to perform device-level assessments. State-of-the-art, mixed flowing gas systems produce temperature and humidity controlled environments containing ppb levels of contaminants (e.g., H2S, NO2, and Cl2). We can perform accelerated testing in standardized conditions. We have extensive experience with both Cu and Al corrosion, related primarily to corrosion in electronics.

Sandia's vast suite of analytical capabilities is at our disposal, making corrosion product identification possible. In an important application of our atmospheric-corrosion capabilities, we have formulated mathematical models to assess the effects of corrosion on electrical-device performance and system-level reliability.

Aqueous Corrosion: Because aluminum alloys are the dominant structural material used in Sandia-designed hardware, most of our aqueous-related expertise centers around characterizing and controlling its localized corrosion behavior. Conventional electrochemical techniques are routinely used, and we are proficient in applying and evaluating most coating technologies, including chromate conversion, anodized, and other organic coatings (CPCs). Recently, we have gained considerable expertise applying microelectrode-based techniques to understand localized corrosion phenomena.

In addition to aluminum, we have substantial experience characterizing the corrosion behavior of nickel alloys, stainless steels, and titanium alloys. We have implemented an electrochemical-based technology to monitor the corrosion of cement-lined steel pipelines carrying concentrated brine solutions.

Electrochemical Science and Sensors: Corrosion mechanisms and electrochemical processes are addressed with both traditional and nontraditional techniques. Interfacial and surface chemistry is studied using electron and ion spectroscopies in an ultrahigh vacuum environment and with complementary analyses in a contiguous electrochemical chamber. A nontraditional approach being pursued involves corrosion-sensing schemes integrated directly into material systems of interest. For example, this technology is useful for studying atmospheric corrosion, where reactions take place in ultrathin, localized, condensed-water layers on metal surfaces.

Chemistry-specific and spatially sensitive sensors based on potentiometric sensing produced with microelectronic-fabrication methods are being tested. Finally, small length-scale scanning techniques, including electrostatic-force and scanning-Kelvin-probe microscopy, are applied in our laboratories to study corrosion susceptibility and processes (e.g., surface structure and composition).

Microelectrode array used to study atmospheric corrosion and adsorbed-water layer chemistry.

Failure Analysis: Sandia has many years of experience in performing corrosion-related failure analyses of mechanical and electrical components. High-quality optical microscopy, scanning electron microscopy/energy- dispersive spectroscopy, electron microprobe, and other analytical facilities complement our materials understanding and experience. We combine our corrosion knowledge and experience with that of other materials-science disciplines (ceramics, polymers, etc.) to determine the cause of failure. We provide root-cause analysis, remediation, and prevention information to both internal and external customers.

Major Resources

Photograph of a diode showing a copper-sulfide corrosion product layer that grew across the surface (diode length = 4 mm).

Selected Accomplishments

Contacts: Jill Glass, (505) 845-8050, sjglass@sandia.gov

If you require additional information or have comments, please contact your host or send comments to joyluja@sandia.gov.