Laminated Ceramic Capacitor Firing Profile and Composition
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Solution Overview
Problem
Existing methods for manufacturing laminated ceramic capacitors face challenges in reducing internal electrode thickness without causing electrode disconnection and in achieving stable dielectric ceramic grain size, leading to limitations in size reduction and reliability under high temperature loads.
Innovation Solution
A method involving a high-rate temperature profile during firing, using dielectric ceramic raw material powder with specific composition and properties, including BaTiO3 with accessory elements like Sc, Y, La, and Mn, to inhibit grain growth and maintain electrode integrity, allowing for reduced layer thickness and improved capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the internal electrode thickness is reduced to achieve size reduction, then the capacitor thickness can be reduced, but electrode disconnection occurs during firing
Solution Approach 1:
The patent changes the chemical composition parameters of the internal electrode material by adding specific metal elements (such as Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ag, or their oxides/carbides/nitrides) to the conventional Ni-based conductive paste. This compositional modification alters the material's thermal and mechanical properties, enabling thinner electrodes (0.3 μm or less) to maintain structural integrity and electrical connectivity during the high-temperature firing process without disconnection.
2Volume of moving object
If the dielectric ceramic layer thickness is reduced, then the capacitor size is reduced, but grain growth control becomes difficult leading to inferior lifetime characteristics
Solution Approach 1:
The patent modifies the chemical composition parameters of the dielectric ceramic by incorporating specific accessory elements (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) in controlled amounts (0.01-5 wt% each) into the BaTiO3-based system. These compositional changes suppress grain growth during firing, enabling the production of ultra-thin dielectric layers (0.5 μm or less) with controlled grain sizes that maintain excellent lifetime characteristics and reliability under high temperature operating conditions.
3Reliability
If a reducing atmosphere is used for firing to prevent electrode oxidation, then base metal electrodes can be protected, but equipment and material design becomes more restricted
Solution Approach 1:
The patent changes the chemical composition of the electrode material to include metals with lower oxidation tendencies or forms (oxides, carbides, nitrides) that are more stable in oxidizing atmospheres. This compositional transformation allows the use of simpler, more versatile firing equipment and materials without requiring complex reducing atmosphere control, while still preventing electrode oxidation and maintaining electrical conductivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables the production of laminated ceramic capacitors with reduced internal electrode thickness, improved sealing, and enhanced reliability by preventing grain growth and electrode disconnection, while maintaining high temperature stability and consistent dielectric properties.
Implementation Method 1
a heat treatment step of carrying out sintering of the raw laminated body
Implementation Method 2
dielectric ceramic raw material powder with specific composition and properties, including BaTiO3 with accessory elements like Sc, Y, La, and Mn, to inhibit grain growth
Data Source
AI summary
A method for manufacturing a laminated ceramic capacitor by firing a laminated body which includes dielectric ceramic layers containing a dielectric ceramic raw material powder and internal electrodes. The firing is carried out in accordance with a temperature profile in which the average rate of temperature rise is 40° C./second or more from room temperature to a maximum temperature. The dielectric ceramic raw material powder contains a BaTiO3 system as its main constituent, and contains R (R is Sc, etc.), M (M is Mn, etc.), and Mg as accessory constituents, in which, when the total amount of the accessory constituents contained is denoted by D parts by mol with respect to 100 parts by mol of the main constituent, an the specific surface area of the main constituent is denoted by E m2/g, then D/E is 0.2 to 0.8.