Thermal Composite Packages
We know that our customers need options when designing hermetic packages to protect sensitive electronics. Our thermal titanium composite packaging technology with Cu/Mo heat sinks was developed to address the evolving needs of our customers.
These housings use titanium as the primary material. Composite heat-sinks made of molybdenum/copper (Mo/Cu) or copper tungsten (Cu/W) are then integrated into strategic locations of the structure. This combination of titanium and Mo/Cu or Cu/W is ideal for achieving lightweight, low-coefficient of thermal expansion (CTE), and high-thermal-conductivity electronic packages. Electrical feedthru pins can be hermetically sealed directly into the titanium using the Hermetic Solutions Group’s proprietary Kryoflex® ceramic to metal seals. Alternately, hermetic connectors made from explosively bonded dissimilar metals can be laser welded into position using state-of-the-art laser welding technology.
Titanium Composite Technology
Titanium is a good material choice for hermetic housings because it is commercially available, has characteristics that allow for conventional machining and provides low-density attributes. Titanium’s CTE is compatible with direct attachment of aluminum oxide and gallium-arsenide electronic circuitry. Titanium provides 300% more stiffness than aluminum and can be hermetic with walls as thin as .010″. This means an existing aluminum package can be redesigned to be stiffer, lighter, more reliable, and more thermally conductive by integrating the Hermetic Solutions Group’s titanium composite technology. Titanium is compatible with both resistance and laser welding processes for flexibility in connector integration and cover sealing. Titanium is also conducive to metal injection molding, making it a viable option for high-volume manufacturing.
Titanium is well suited for electronic package construction, even though it has low thermal dissipation characteristics. By utilizing our titanium composite packaging technology (incorporating Mo/Cu or Cu/W composite heat-sinks) that characteristic becomes a non-issue. During the initial design phase, the electronic circuitry is mapped against the housing floor where hot spots are readily identified. The Mo/Cu or Cu/W composite heat sinks are then metallurgically bonded only at the locations where the housing comes into contact with the high-power devices. This limited use of the heat sink material minimizes the overall mass of the package.
Composite Metal Connectors for Electronic Packaging
The Hermetic Solutions Group has developed composite metal connectors for years, offering customers an alternative to traditional solder-in connectors and feedthrus. This technology is made possible by a process combination of explosive bonding and laser welding. Explosion bonding is a method of joining dissimilar metals by driving them together with an explosive detonation. The product of this explosive welding procedure is a sheet consisting of atomically bonded layers of different metals. In the case of the titanium composite packaging, the connectors are fabricated from an explosion bonded sheet, where one of the layers within the sheet is titanium and the other layer is a ferrous metal compatible with laser welding. This explosion bonded sheet is then used to fabricate connector shells, containing titanium on one side and a ferrous alloy on the other side. The ferrous side receives a group of feedthru pins that have previously been hermetically sealed into a ferrous insert. This insert is then laser welded to the ferrous portion of the connector shell while the titanium portion is welded to the titanium package. This process allows for a hermetic seal between the connector and the housing without the use of solder.
The titanium composite package is an excellent solution for today’s high-powered airborne electronic packaging demands, which require lightweight, low CTE and high thermal conductivity. Titanium has a low density and, when integrated with Mo/Cu or Cu/W composite heat sinks, yields highly-thermally-conductive housings. The titanium composite material does not require mold tooling or diamond machining, hence, the technology can be incorporated into new designs with very limited nonrecurring tooling making the prototype phase more economical than would be possible with competitive technology.