Low temperature co-fired ceramic-metal packaging technology

DETAILED DESCRIPTION We have found that the LTCC-M system has an additional advantage for integrated package components that run hot.
The conductive metal support substrate provides excellent heat sinking.
Thus components that are hot can be either directly mounted onto the metal support board or be mounted to conductive vias in a multilayer ceramic circuit board that lead to the metal support board.
For more complex integration, the LTCC-M technology can be used to provide additional heat sinking by connecting conventional heat sinks, or thermoelectric coolers, to, or through, the support substrate.
The metal support board can act as a heat sink, directly or indirectly, for devices such as semiconductor lasers, or for devices that use very dense circuitry.
The temperature of semiconductor lasers during operation for example must be closely controlled because the wavelength of the emitted light depends on the temperature of the device and its environment.
Another type of device wherein good temperature control is required is for thermal management of flip chip packaging.
Densely packed microcircuitry, and devices such as amplifiers, oscillators and the like which generate large amounts of heat, can also use LTCC-M techniques advantageously.
Similarly, the technique is useful with for packaging power resistors.
A chip for flip chip packaging can be mounted bump side up within a cavity in the ceramic layer and bump bonded to a flex circuit that connects the input/output bumps to metal traces on the top layer of ceramic.
Placing the chip on a metal support board provides the cooling required for high integration chips.
LTCC-M technology non flex package covers can be soldered to the package for applications requiring hermetic seals.
Such covers can also include useful features such as solder re-flow indicators and imbedded trace wiring.