Over the past decade, PA&E has provided customers with the hermetic connector and packaging technologies available. With the introduction of its thermal composite packaging, this trend continues. The technology uses titanium as the primary housing material and integrates composite heat-sinks composed of molybdenum/copper (Mo/Cu) or copper tungsten (Cu/W) into strategic locations of the structure for excellent heat dissipation capabilities.
The 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 PA&E’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 Lasag laser welding technology.
Titanium Composite Technology
Titanium is the material of choice for housings because of its commercial availability along with its characteristics that allow for conventional machining and low-density attributes. Titanium’s CTE is compatible with direct attachment of aluminum oxide and gallium-arsenide electronic circuitry. Titanium is 300% stiffer than aluminum and can hermetic with walls as thin as .010″. This means an existing aluminum package can be redesigned to be stiffer, lighter weight, more reliable, and better thermally by integrating PA&E’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 an ideal material for electronic packages, 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
PA&E 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 the best 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. A titanium composite package, complete with cover and integrated hermetic connectors and feedthrus, is now available through PA&E.