For electronic warfare systems, implantable medical devices, down-hole oil logging tools, and other applications that require components to operate reliably in harsh and mission-critical environments, reliable hermetic packaging and components provide a critical defense against failures that can quickly lead to catastrophic results. To respond efficiently to those reliability challenges, manufacturers should look to a comprehensive approach to hermetic packaging — one able to combine the optimal blend of techniques and technologies required to meet each application’s unique requirements.
Hermetic Packaging Considerations:
- Every mission-critical application needs reliable connector options. For harsh environments, reliability depends on the availability of rugged hermetic seals, regardless of whether the connector is a standard or custom configuration.
- To secure sensitive electronics within a hermetic package, engineers need flexible attachment options for solder and preform geometries. Selecting the optimum alloy and shape for these preforms requires a careful understanding of the associated physical and chemical requirements.
- Applications increasingly need diverse thermal management solutions. High temperatures can degrade device performance and reliability. Manufacturers need to apply manufacturing methods and materials able to protect the system from temperature stress.
- Manufacturers may need getters to mitigate damage from outgassing in many designs. Inside a sealed package, the release of moisture, hydrogen or other volatile gases commonly associated with electronic devices can cause serious performance and/or reliability issues in systems operating in harsh environments. Placed within the package, getters can absorb these materials before they impact the packaged electronic systems.
- Finally, manufacturers need robust package lidding and sealing options able to maintain a hermetic seal in the face of mechanical, chemical or thermal stress found in the target application.
- To address these challenges, manufacturers should consider a diverse range materials and methods best able to meet each application’s unique requirements.
Multiple materials are available to address specific packaging priorities including:
- Kovar. Kovar is common in the industry. It is an iron-nickel alloy that is heavy, somewhat expensive and has low thermal conductivity. It does however offer a coefficient of thermal expansion (CTE) similar to hard glass — it expands and contracts at about the same rate and is often matched with borosilicate glass.
- Aluminum. Aluminum is lightweight and possesses high rates of thermal expansion, low density and low strength, and offers good thermal conductivity.
- Titanium. Titanium is strong and light with a low CTE but poor thermal conductivity and is typically required for implantable packages.
- Titanium composite. A titanium composite exhibits all the good characteristics of titanium. It can be used with integrated copper-molybdenum (CuMo) heatsinks for greatly improved thermal conductivity.