Temperature stable dielectrics with low dielectric losses and high dielectric constant over 75 are key components of capacitors used in high frequency (up to 1GHz) applications such as consumer electronics, cellular phones, filters and so on. The vast majority of such capacitors are made with silver-palladium internal electrodes. With palladium prices exceeding 800 USD per troy ounce (January 2011), it is essential to reduce the palladium content in the electrodes from the traditional 30% down to at least 10%. This requires dielectric materials to be compatible with high silver content electrodes and to be able to sinter at, or below 1000 °C. Moreover, recently adopted Restriction of Hazardous Substances (RoHS) regulations restrict the use of lead, cadmium and four other hazardous materials in manufacturing various types of electronic components, significantly reducing the selection of available dielectric materials on the market. This paper describes two newly developed RoHS compliant very low fired high-K COG dielectrics with dielectric constant over 80 and compares them with two traditional low and very low fired, RoHS and non-RoHS compliant high-K COG dielectrics. Two new RoHS compliant air fired COG dielectric compositions compatible with 90%Ag-10%Pd internal electrodes and having dielectric constant over 80 were developed by MRA Laboratories, Inc.. Comprehensive evaluation of their basic dielectric properties vs. properties of two commercially available analogs revealed that the new materials exhibit comparable dielectric performances at MHz and GHz frequencies, but offer significant advantages in terms of RoHS compatibility, sintering temperature and dielectric reliability. Moreover, the combination of reviewed high temperature properties suggests that these two materials may be used for high temperature applications up to 200°C and beyond, depending on flexibility of electrical circuit board design.
Two novel very low fired high-K COG dielectrics for high frequency capacitor applications
2011
14 Seiten, 4 Bilder, 4 Tabellen, 9 Quellen
Conference paper
English
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