Low temperature co-fired ceramic

Low temperature co-fired ceramic (LTCC) is a well-established multi-layer technology which has been in use for many years in the microelectronics packaging industry. Each of the layers are processed in parallel and only brought together in an accurately aligned stack immediately prior to firing. This is the key differentiator to serially produced multi-layer structures such as thick film hybrid interconnect and components such as ceramic capacitors.LTCC 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 in the same package. LTCC hybrids have a smaller initial ("non recurring") cost as compared with ICs, making them an attractive alternative to ASICs for small scale integration devices.

This technology presents advantages compared to other packaging technologies such as HTCC: the ceramic is generally fired below 1000°C due to a special composition of the material. This permits the co-firing with highly conductive materials (silver, copper and gold). LTCC also features the ability to embed passive elements, such as resistors, capacitors and inductors into the ceramic package minimising the size of the completed module.

Printed resistances: In addition to embedded components, resistors may be added to the top layer post firing. Using screen printing, a resistor paste is printed onto the LTCC surface, from which resistances needed in the circuit are generated. When fired, these resistors deviate from their design value (±25%) and therefore require adjustment to meet the final tolerance . With Laser trimming one can achieve these resistances with different cut forms to the exact resistance value (±1%) desired. With this procedure, the need for additional discrete resistors can be reduced, thereby allowing a further miniaturization of the printed circuit boards.

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