Polyurethane spray coating of aluminum wire bonds to prevent corrosion and suppress resonant oscillations

TL;DR

This study investigates polyurethane spray coatings on aluminum wire bonds to prevent corrosion and suppress resonant oscillations, aiming to improve durability in particle physics detectors under harsh conditions.

Contribution

It introduces a polyurethane spray coating method for wire bonds and evaluates its effectiveness against corrosion and oscillations in high-radiation, temperature-variable environments.

Findings

Polyurethane coating reduces corrosion after climate chamber exposure.

Coated wire bonds show suppressed resonant oscillations.

Coating maintains performance under simulated detector conditions.

Abstract

Unencapsulated aluminum wedge wire bonds are common in particle physics pixel and strip detectors. Industry-favored bulk encapsulation is eschewed due to the range of operating temperatures and radiation. Wire bond failures are a persistent source of tracking-detector failure. Unencapsulated bonds are vulnerable to condensation-induced corrosion, particularly when halides are present. Oscillations from periodic Lorentz forces are documented as another source of wire bond failure. Spray application of polyurethane coatings, performance of polyurethane-coated wire bonds after climate chamber exposure, and resonant properties of polyurethane-coated wire bonds and their resistance to periodic Lorentz forces are under study for use in a future High Luminosity Large Hadron Collider detector such as the ATLAS Inner Tracker upgrade.