Eutectic Barrier
Metallic alloy bonding creates a gas-tight junction between the lid and the base of a microelectronic package. Gold tin hermetic sealing employs a specific eutectic composition to prevent the ingress of moisture or contaminants into the sensor cavity.
Processing Protocol
Soldering occurs at approximately 280 degrees Celsius where the alloy transitions from solid to liquid. This relatively low temperature protects the sensitive electronics inside while providing a high strength bond.
Moisture Resistance
Long term reliability of a sensor depends on maintaining a dry internal environment. Gold tin hermetic sealing offers superior protection against hydrogen and water vapor compared to epoxy seals. The metal interface does not outgas, ensuring that the internal vacuum or inert gas atmosphere remains stable over decades.
This stability is required for resonant sensors where changes in gas pressure would alter the damping and the frequency of the device.
Lifecycle Performance
Fatigue resistance of the 80/20 gold tin alloy ensures that the seal remains intact during repeated thermal cycling. Engineers verify the quality of the seal using helium leak detection and gross leak testing in a fluorocarbon bath. These inspections confirm that the leak rate stays below the thresholds established by military and industrial standards.
The resulting bond provides both electrical grounding for the lid and a physical shield against electromagnetic interference.
