LTCC multi layer ceramic circuits
Electronic circuits are often exposed to special loads. LTCC multi-layer ceramic technology offers unique solutions for demanding applications in harsh environments.
Micro-Hybrid offers the complete spectrum for the development and manufacture of extremely reliable and miniaturized circuits, from electronic design and the production of LTCC substrates to assembly.
Functionality of a LTCC circuit
Low temperature cofired ceramics are multilayer circuits consisting of individual ceramic layers. Conductive tracks, resistors as well as capacitive and inductive functionalities can be generated by printing the individual ceramic layers. For the production of multilayer circuits, the ceramic carriers must be pressed and finally sintered at 850 to 900 °C. The ceramic carriers must be printed on the ceramic layers to produce capacitive and inductive functionalities.
Applications of ceramic substrate technologies
When is LTCC the optimal substrate technology for a circuit? Many applications place special demands on electronic circuits and components. LTCC is used when the following is required:
- Ideal heat conduction in a wide temperature range (-100 °C ... + 200 °C)
- High frequency stability
- Long-lasting hermeticity
- Long-term stability (> 20 years)
- High dielectric strength & mechanical strength
- Resistance to plasma or ion bombardment
- High degree of miniaturization - 3-D functions such as cavities, stepped bonding planes, channels and membranes
Compared to conventional circuit carriers such as FR4, LTCC technology can meet precisely these requirements. Typical areas of application include medical technology, automotive industry, high-frequency technology, space technology and communications technology.
Typical structure of an LTCC circuit
We at Micro-Hybdrid deliberately do not give any fixed design rules for the construction of a ceramic circuit. Depending on the specific requirements, our development professionals can design the appropriate circuit for our customers. Here we describe the basic features of such electronics.
- Material systems DuPont 951 + 9K7 - low coefficient of thermal expansion, 5.8 ppm/K (DuPont 951), 4.4 ppm/K (DuPont 9K7)
- Compatibility with various precious metal pastes (for very reliable conductors)
- Thickness of a single layer: 40 μm -200 μm
- Number of layers 3...40
- Panel size : 6" x 6" (unsintered state)
LTCC substrate manufacturing process
For the production of LTCC we use prefabricated green foils. Depending on the given design, holes are punched at given positions and filled with a metal paste. These so-called vias form the vertical contact in the multilayer structure. The metal pastes are then screen printed onto the green foil to form the planar electrical conductor paths.
After the metal structures have been applied, the green foils are pressed together in a specified sequence and sintered between 850 °C - 900 °C. The green foils are then pressed onto each other and sintered between 850°C - 900 °C. Sensitive structures or surface components can also be applied or fitted. Subsequently, the LTCC substrates are separated and tested for their functionality.
We will be happy to advise you on your development project and the optimum substrate and packaging technologies.