ConceptLTCC Design Guidelines HTCC Design Guidelines High and Low Temperature Cofired Multilayer Ceramics
The current trend of miniaturization in the electronics and communication sectors is on the rise, creating demands for solutions with increasingly complex requirements. Since possibilities for reducing the size of conventional glass-to-metal seals have been nearly exhausted, it has become necessary to develop new and innovative approaches.
Ceramic-to-metal sealing represents one such approach, and it has the potential for further development. In these seals, various types of electrical feedthroughs are embedded into a special ceramic material, offering totally new possibilities in the encapsulation of complex electronic and optoelectronic systems.
SCHOTT CerTMS® are manufactured using high-temperature, co-fired alumina ceramics. The ceramics are produced by mixing ceramic and glass powders of specific particles sizes, and small quantities of binding agent and solvent to create a homogeneous slurry. This slurry is then cast to form sheets of uniform thickness (about 100 μm - 500 μm). Once dried, these so called Green Sheets can be easily cut, rolled up for transport, and processed further (e.g. screen printing, punching, via filling, etc.).
The next step in the production of SCHOTT CerTMS® involves the definition of the electrical conducting paths. Depending on the design, the sheets are processed to form cavities and vias, which can be filled with a refractory metal paste. These vias create vertical connections for the electrical feedthroughs. The planar electrical lines are defined on the ceramic sheets by screen-printing, again using refractory metal pastes.
Once the various metal structures are defined, the ceramic sheets are stacked in a specific order and laminated. This process connects the individual, basically two dimensional sheets and ends up in a three dimensional structure with hermetic electrical feedthroughs. In data communication, this three dimensional structure often is similar to a "T", which is why the finished ceramic product is also called a T-bar.
The multilayer ceramic is co-fired at temperatures of up to 1,600°C. A final metal coating (e.g. a plated Ni or Ni/Au coating) on the accessible refractory metal structures offers the possibility for high temperature brazing (using e.g. AgCu eutectic) or low temperature soldering (e.g. AuSn eutectic) process steps. By this the ceramic feedthrough component can be combined with an even more complex metal housing, providing an extremely reliable hermetic package with various customized electrical, optical and thermal functionalities.
Advantages of the Technology
Higher performance and increasingly complex designs
SCHOTT CerTMS® components and packages have many advantages. They are ideal for use in complex electronic and optoelectronic systems because of their large number of inputs/outputs. They offer possibilities for extremely reliable hermetic packages enabling them to be used in increasingly complex modules. CerTMS make it easier to miniaturize packages, use standard IC interconnection processes and even integrate impedance matched high frequency feedthroughs for fast data transmission into the system.
SCHOTT CerTMS® are used primarily in hybrid and microelectronic packaging. Please refer to our Opto-electronics Product Division page for more information.
Design guidelines for LTCC and HTCC substrates are available in the downloads below.