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Co-fired ceramic devices are monolithic, ceramic microelectronic devices where the entire The technology is also used for robust assembly and packaging of electronic Co-firing can be divided into low temperature (LTCC) and high temperature (HTCC) 3 Comparison; 4 See also; 5 References; 6 External links . LTCC technology has been used in multilayer circuits for decades. Automotive and There can be many causes for a circuit build to not meet specifications. Many times, the circuit Details about these components are summarized in Table 1. The demand to meet advanced substrate requirements in terms of electrical, co -fired ceramics (LTCC) is an advanced substrate technology for the robust . at a pressure of 20 MPa and fired at a peak temperature of about °C for 30 min.
LTCC also maintains stable properties over a wide range of frequencies, temperatures and environments.
These factors explain why LTCC has long been popular in demanding military and automotive applications where stability and reliability are key design criteria.
Many designers of emerging complex multilayer circuits are recognizing LTCC as a key to solving the challenges of high-frequency, high component density applications. Low loss LTCC compared with other materials. Click here to enlarge image A low loss LTCC materials system has advantages over alternative materials for high-frequency, high component density applications. Obviously, low loss LTCC will have a lower loss tangent than alternate materials.
Figure 4a compares low loss LTCC with other materials that have low loss tangent values at high frequencies.
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Note also that at high frequencies, circuit elements are packaged closer together. Preventing thermal and mechanical failure of these high component density modules becomes much more of a challenge, so properties like thermal conductivity become more significant. Figure 4b compares typical values of thermal conductivity of various materials. These values can be further improved by addition of thermal vias to the design, enabling higher package density.
Another often overlooked advantage is that the thick film compositions conductor, resistor, etc. This is especially important to packaging engineers, since thermal mismatch between different thick film materials can result in significant dimensional variation of key features on finished parts. Attempts to optimize thick film materials of various types from various manufacturers often lead to limited process capabilities that are next to impossible to control.
LTCC materials systems with strong research and development foundations demonstrate suitable process repeatability without forcing the packaging engineer to perform constant qualification and optimization. Low loss LTCC materials are now being qualified for use with next-generation microwave applications. As operating frequencies of applications increase, a stable, reliable process becomes critically important.
Dimensional tolerances of embedded components, especially filters, become tighter as features approach the quarter-wavelength of the signal. One factor holding low loss LTCC back from reaching this potential is the lack of design infrastructure.
Silicon and gallium arsenide technologies have well-developed libraries of component models in various EDA packages for designers to use. The reason that low loss LTCC does not yet have this level of design infrastructure is that for simple, low frequency, low component density applications, these models are unnecessary. Coupling between signal lines, effects of quarter-wave resonance effects, and dielectric loss were generally minor considerations that could largely be ignored.
For modern microwave designs, however, these factors cannot be ignored.
To make the design process as efficient as possible, a library of passive circuit components was developed and made available to designers, LTCC fabricators and packaging engineers. Summary of design kit components. Click here to enlarge image Components in the design kit include inductors, capacitors, couplers, filters, resonators, transmission lines, discontinuities and a balun.
Details about these components are summarized in Table 1. Each component design is based on a simulated model developed using commercially available electromagnetic simulation tools. Mechanical layouts were generated based on these models and parts were manufactured. S-parameter files included in the design kit reflect verified test data taken from these manufactured parts. Some components were not verified experimentally, due to limitations in the test fixture and equipment.
These models are still useful, because the designs were based on electromagnetic simulations.
GreenTape™ 9K7 Low Temperature Co-fired Ceramic Material System | DuPont | DuPont USA
The design kit consists of 47 different fixed artwork designs, most of which have been verified by measurement. These library elements can be used now by designers and packaging engineers to verify and qualify low loss LTCC materials.
In their current form, the library elements cannot be easily dropped into a microwave design, because these models reflect specific, measured components in a specific layer stackup. They also include ground-signal-ground probe pads as part of the model. Most components are not de-embedded; they include probe pad ports as part of the component. Finally, library elements reflect fixed artwork without parameters that can be used to scale the individual component to a specific application.
More Proposed Solutions Designers generally use models with selectable parameters that can be modified based on the individual application. For complex, high component density circuits, nearly infinite number of parameter combinations can be possible. To move LTCC materials from the realm of specialty applications to the realm of high-volume wireless markets, a similar level of commitment is required.
This must be a shared commitment between LTCC materials suppliers, packaging engineers and electronic designers. Materials suppliers provide leadership and expertise regarding LTCC's capabilities and processing guidelines, but must work with microwave designers and packaging engineers regarding circuit applications and design. One of the main purposes of introducing this design kit is to facilitate stronger interaction between materials suppliers, packaging engineers and microwave designers.
The focus of this interaction is to determine what basic structures need to be modeled in LTCC and the details of the parameters that can be varied in the geometries of these structures. The payoff to designers in this type of collaboration is to obtain models of LTCC structures that can be quickly integrated into circuits and are critical to meeting specification on the first design build.
The benefit to packaging engineers is more efficient processing of LTCC designs, because circuit models are verified according to established design rules. History[ edit ] Co-fired ceramics were first developed in the late '50s and early '60s to make more robust capacitors.
In RF and wireless applications, LTCC technology is also used to produce multilayer hybrid integrated circuitswhich can include resistors, inductors, capacitors, and active components in the same package. In detail, these applications comprise mobile telecommunication devices 0. Inductors[ edit ] Inductors are formed by printing conductor windings on ferrite ceramic tape.
Depending on the desired inductance and current carrying capabilities a partial winding to several windings may be printed on each layer. Under certain circumstances, a non-ferrite ceramic may be used.
DuPont Low Temperature Co-Fired Ceramic (LTCC) Material Systems
This is most common for hybrid circuits where capacitors, inductors, and resistors will all be present and for high operating frequency applications where the hysteresis loop of the ferrite becomes an issue. Resistors[ edit ] Resistors may be embedded components or 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. With this procedure, the need for additional discrete resistors can be reduced, thereby allowing a further miniaturization of the printed circuit boards.