Co-fired ceramic devices are monolithic, ceramic microelectronic devices where the entire ceramic support structure and any conductive, resistive, and dielectric materials are fired in a kiln at the same time. Typical devices include capacitors, inductors, resistors, transformers, and hybrid circuits. The technology is also used for a multi-layer packaging for the electronics industry, such as military electronics, microprocessor and RF applications.
The Co-fired Ceramic Process
Low temperature co-fired ceramic (LTCC) devices are made by processing a number of layers independently and assembling them into a device as a final step. This differs from semiconductor device fabrication where layers are processed serially; each new layer being fabricated on top of previous layers. Co-fired ceramic devices are made by processing a number of layers independently and assembling them into a device as a final step.
When Co-fired Ceramic Began
Co-fired ceramics were first developed in the late ’50s and early ’60s to make more robust capacitors. The technology was later expanded in the ’60s to include multilayer printed circuit board like structures. Co-firing can be divided into low temperature (LTCC) and high temperature (HTCC) applications.
Low Temperature co-fired ceramic is a multilayer capable substrate technology offering excellent microwave performance characteristics. Its low sintering temperature allows co-firing with highly conductive metals such as silver and gold. The multilayer technology allows for the parallel stacking of up to more than twenty layers.
Low temperature co-fired ceramic technology is especially beneficial for RF and high-frequency applications. In RF and wireless applications, LTCC technology is also used to produce multilayer hybrid integrated circuits, which can include resistors, inductors, capacitors, and active components all in the same package.
Low temperature co-firing technology presents advantages compared to other packaging technologies including high temperature co-firing: the ceramic is generally fired below 1,000 °C due to a special composition of the material. This permits the co-firing with highly conductive materials. LTCC also features the ability to embed passive elements, such as resistors, capacitors and inductors.
The excellent mechanical and electrical properties of LTCC substrates, combined with the ability to embed passive components and to apply fine line patterning, offer superior RF performance and device miniaturization for high-frequency applications. Further features like the application of heat sinks, frames and nail head pins by brazing allow for hermetic and highly complex packages.