Abstract: A carrier sub-assembly having improved dimensional stability for applications in electronic and optoelectronic industries is disclosed. The carrier sub-assembly, when housed in an optoelectronic package, for example, includes a metal substrate and an insert which support optoelectronic devices that are optically coupled to one another. The insert allows for the attachment, for example, via laser spot welding, of electronic and optoelectronic devices where direct attachment of a device to the metal substrate is not practical. In one embodiment of the present invention, the carrier sub-assembly includes Kovar™ insert that is attached to copper/tungsten metal substrate in a recess of the metal substrate so that at least a portion of the insert is attached to the metal substrate in three dimensions. A fiber optic assembly is secured to the insert by a Kovar™ clip.

Abstract: The present invention provide a plurality of layered substrates for semiconductor packages. The substrates include, for example, a metal matrix composite layer and at least one carrier layer having a coefficient of thermal expansion and a thermal conductivity greater than the metal matrix composite. In the preferred embodiment, the metal matrix composite includes between approximately 50% to 95% refractory metal with the remainder copper. Suitable carrier layer materials include, for example, copper. So configured, the layered substrates provide improved rigidity and thermal characteristics for matching with ceramic materials.