Corrosion is a pervasive and expensive problem in applications ranging from construction to microelectronics. Corrosion has been widely studied in theories, and empirical studies exist for common materials, material combinations, and myriad environmental conditions. In order for microelectronic devices to perform and function properly, high-reliability packaging is important. Failure of microelectronic devices and packages not only causes a malfunction of the devices themselves, but can lead to catastrophic events for entire systems, which may cause loss of life, property, and safety.

PCB-mounted corrosion sensors of various serpentine widths. The capacitive sensor is shown on the far right.

Corrosion of microelectronic packages and devices depends on the package type, electronic materials, fabrication and assembly processes, as well as environmental conditions such as moisture condensation, ionic or organic contaminants, temperature, residual and thermal stress, and electrical bias. With the continued reduction of feature sizes of microelectronic devices, such devices are more susceptible to corrosion-induced failures. Improved performance and reliability requirements demand improved corrosion resistance.

To solve this problem, surface-mountable sensors for detecting corrosion were developed that include an element responsive to an environmental condition (e.g., atmospheric corrosion, oxidation, aqueous and non-aqueous corrosion, sulfide exposure, moisture condensation, ionic or organic contaminants, temperature, residual and thermal stress, electrical bias, etc.). The element includes a corrodible metal configured to provide a capacitive sensor (e.g., employing interdigitated electrodes) or a resistive sensor (e.g., employing a serpentine line). The sensors are configured to be surface-mounted on a printed circuit board (PCB).

The sensors accumulate corrosion effects passively; power is needed only when interrogating. In addition, the sensors can be packaged with a high density for redundancy, designed for a wide range of sensitivity, and strategically located for multiple sensing tasks. They are produced using standard industry methods, and have a low per-unit cost since 600 sensors come from a single 4" wafer.

For more information, contact Sandia National Laboratories at This email address is being protected from spambots. You need JavaScript enabled to view it., or visit here .

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This article first appeared in the October, 2017 issue of Tech Briefs Magazine.

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