Meaning
Protective packaging covers establish the primary barrier against environmental contamination for sensitive microelectronic circuits. Using a kovar lid allows manufacturers to achieve a highly reliable hermetic seal on ceramic packages.
Thermal Matching
Thermal expansion compatibility is essential to prevent mechanical stress at the joint between the cover and the substrate. Because the kovar lid expands and contracts at almost the same rate as the ceramic package, the risk of micro-cracking during thermal cycling is minimized. This expansion matching prevents moisture from entering the package and causing internal corrosion.
Engineers select this alloy for applications that experience temperature swings.
Package Hermeticity
Sealing integrity is verified through fine and gross leak testing. If a kovar lid is poorly welded, it creates a leak path that allows atmospheric gases to enter the cavity. This leakage degrades the internal vacuum or inert gas atmosphere, which can lead to component failure.
Testing protocols ensure that every sealed package conforms to industrial hermeticity standards.
Warranty Protection
Supply contracts for high-reliability components often mandate the use of specific packaging materials. A distributor who sells oscillators with a kovar lid can offer a longer warranty period due to the protection provided by this alloy. This contract clause reduces the distributor’s long-term liability and reassures the buyer of the component’s durability.
If the manufacturer substitutes a cheaper material, they are liable for subsequent field failures.
