Laminated Ceramic Capacitor High-Temperature Reliability
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Solution Overview
Problem
Laminated ceramic capacitors used in high-temperature environments, such as those mounted on vehicles, face challenges in maintaining high-temperature load reliability beyond the conventional limit of 175°C, as existing dielectric ceramic compositions do not demonstrate sufficient reliability at temperatures of 200°C or higher.
Innovation Solution
A laminated ceramic capacitor with a dielectric ceramic composition comprising Ba, Re (where Re is La, Ce, Pr, or Sm), Ti, Zr, M (M is Mg, Al, Mn, or V), and Si, with specific molar ratios forming perovskite compounds, enhancing high-temperature load reliability by meeting specific conditions for element amounts and ratios, thereby improving the capacitor's performance at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric ceramic compositions are used, then the capacitor can operate at standard temperatures, but the high-temperature load reliability deteriorates at temperatures of 200°C or higher
Solution Approach 1:
The patent modifies the dielectric ceramic composition by changing the chemical parameters - specifically incorporating Ba, Re (La, Ce, Pr, or Sm), Ti, Zr, M (Mg, Al, Mn, or V), and Si in controlled molar ratios to form perovskite compounds. This compositional parameter change enables the capacitor to maintain reliability at temperatures of 200°C or higher, extending the operating temperature limit beyond conventional 175°C capacitors
Solution Approach 2:
The invention uses a composite dielectric ceramic material system combining multiple elements (Ba, Re, Ti, Zr, M, Si) in specific proportions to create a perovskite-based composite structure. This composite material approach provides both the required dielectric constant of 70 or more and the enhanced high-temperature stability with MTTF of 100 hours or more at 200°C
2Reliability
If the dielectric constant is increased to improve capacitance, then the capacitance value improves, but the high-temperature load reliability may deteriorate
Solution Approach 1:
The patent achieves the dual objective by precisely controlling the molar ratio parameters of the dielectric ceramic composition. By adjusting the amounts of Ba, Re, Ti, Zr, M, and Si within specific ranges and forming perovskite compounds, the invention simultaneously achieves a dielectric constant of 70 or more (improving capacitance) and MTTF of 100 hours or more at 200°C (ensuring high-temperature reliability)
Data Source
AI summary
A ceramic capacitor having dielectric ceramic layers that include Ba, Re (Re is at least one of La, Ce, Pr, Nd, and Sm), Ti, Zr, M (M is at least one of Mg, Al, Mn, and V), Si, and optionally Sr, where at least some of the Ba, Re, Ti, and Zr and optionally Sr are in the form of a perovskite compound. Respective amounts, expressed as parts by mol, of the elements of the dielectric ceramic layers satisfy, with respect to a total of 100 of the Ti amount and the Zr amount, 0≦a≦20.0 where a is the Sr amount; 0.5≦b≦10.0 where b is the Re amount; 46≦c≦90 where c is the Zr amount; 0.5≦d≦10.0 where d is the M amount; 0.5≦e≦5.0 where e is the Si amount; and 0.990≦m≦1.050 where m is a ratio of a total of the Ba amount, the Sr amount, and the Re amount, to the total of the Ti amount and the Zr amount.