Ni-Pt Inner Electrode Structure for Thin-Layer Ceramic Capacitors
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Solution Overview
Problem
Existing multilayer ceramic capacitors face a decrease in dielectric breakdown voltage due to increased strain and electric field concentration caused by thickness reduction, and the use of glass in cover layers can lead to moisture resistance issues.
Innovation Solution
A multilayer ceramic capacitor design featuring inner electrode layers with alternating Ni and Ni-Pt solid solutions, where one layer is coupled to the cathode, enhancing the dielectric breakdown voltage and improving high-temperature loading life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the dielectric ceramic layer is reduced to achieve size reduction, then the capacitance density is improved, but the dielectric breakdown voltage decreases due to increased strain and electric field concentration
Solution Approach 1:
The patent changes the chemical composition parameters of the inner electrode layers by introducing Ni-Pt solid solutions with specific atomic ratios (Pt/(Ni+Pt) between 0.02-0.25). This compositional parameter change modifies the electrode's interaction with the dielectric, reducing electric field concentration and preventing breakdown while maintaining high capacitance density in thin-layer structures.
Solution Approach 2:
The patent uses composite inner electrode structures combining Ni and Pt in specific ratios to create Ni-Pt solid solutions. This composite material approach leverages the beneficial properties of both metals: Ni provides cost-effectiveness and conductivity, while Pt enhances resistance to electric field concentration and breakdown, enabling thin dielectric layers to maintain high reliability.
2Reliability
If glass particles are increased in the cover layer to suppress strain from electrostrictive effect, then the dielectric breakdown voltage is improved, but moisture resistance deteriorates due to glass melting
Solution Approach 1:
The patent extracts the strain suppression function from the cover layer glass and relocates it to the inner electrode layers. By equipping the inner electrodes with Ni-Pt solid solutions, the patent eliminates the need for excessive glass in the cover layer, thereby preserving moisture resistance while still suppressing electric field concentration and preventing breakdown through the electrode material's inherent properties.
Solution Approach 2:
The Ni-Pt solid solution in the inner electrode acts as an intermediary that mediates between the electrical stress and the dielectric. It absorbs and distributes the electrostrictive strain internally within the electrode structure, preventing strain transmission to the cover layer glass and eliminating the trade-off between breakdown voltage and moisture resistance.
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 design improves dielectric breakdown voltage and high-temperature loading life by reducing electric field concentration and preventing glass-related moisture resistance issues.
Implementation Method 1
Ni included in one of the first inner electrode layers and the second inner electrode layers forms a solid solution with Pt
Implementation Method 2
When a voltage is applied to the multilayer ceramic capacitor, an electrostrictive effect occurs such that the effective dielectric portion extends in the stacking direction
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body and an outer electrode. The multilayer body includes dielectric layers and inner electrode layers alternately stacked with the dielectric layers. Ni in one of first and second inner electrode layers forms a solid solution with Pt, and Ni in the other of the first and second inner electrode layers forms no solid solution with Pt. The one of the first and second inner electrode layers in which Ni forms a solid solution with Pt are coupled to a cathode when the multilayer ceramic capacitor is mounted.