Thin-Film Ceramic Capacitor With Mixed Phase Dielectric
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Solution Overview
Problem
Ferroelectric materials like PZT and BT-based dielectric materials exhibit significant temperature-dependent dielectric properties, leading to unstable electrical performance in capacitors, and paraelectric materials like BST have low dielectric constants, limiting the manufacturing of high-capacitance capacitors.
Innovation Solution
A thin-film ceramic capacitor is designed with a dielectric layer comprising a mixed phase of perovskite and pyrochlore phases, where the pyrochlore phase is strategically positioned at interfaces between dielectric and electrode layers, stabilizing capacitance across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ferroelectric materials (PZT, BT) are used in dielectric layers, then high permittivity and low dielectric loss are achieved, but temperature-dependent dielectric properties cause unstable electrical performance
Solution Approach 1:
The dielectric layer is formed as a composite material containing both perovskite phase (ferroelectric) and pyrochlore phase (paraelectric) regions. The perovskite phase provides high permittivity while the pyrochlore phase provides temperature stability. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both high capacitance and temperature stability.
Solution Approach 2:
The invention creates local regions with different phases within the dielectric layer. Perovskite phase regions are distributed throughout to provide high permittivity, while pyrochlore phase regions are specifically positioned at interfaces between dielectric and electrode layers to provide temperature stability. This local differentiation allows each region to contribute its optimal property to the overall capacitor performance.
2Reliability
If paraelectric material (BST) is used in dielectric layers, then temperature stability is improved, but low dielectric constant limits capacitance
Solution Approach 1:
The dielectric layer combines paraelectric pyrochlore phase regions (for temperature stability) with ferroelectric perovskite phase regions (for high permittivity). This composite approach allows the capacitor to achieve both temperature stability from the pyrochlore phase and high capacitance from the perovskite phase, resolving the contradiction between these two requirements.
Solution Approach 2:
Pyrochlore phase regions are strategically positioned at interfaces between dielectric and electrode layers where temperature stability is most needed, while perovskite phase regions are distributed throughout the bulk to maximize permittivity. This spatial differentiation allows each phase to optimize its function without compromising the other.
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 capacitor achieves high capacitance with reduced temperature coefficient of capacitance, ensuring stable electrical performance across a wide temperature range.
Implementation Method 1
a perovskite phase (23a) having ferroelectric properties and a pyrochlore phase (23b) having paraelectric properties
Implementation Method 2
a perovskite phase (23a) having ferroelectric properties and a pyrochlore phase (23b) having paraelectric properties
Data Source
AI summary
A thin-film ceramic capacitor includes: a body in which a plurality of dielectric layers and first and second electrode layers are alternately disposed on a substrate; and first and second electrode pads disposed on an external surface of the body. The dielectric layer contains a mixed phase of a perovskite phase having ferroelectric properties and a pyrochlore phase having paraelectric properties, the pyrochlore phase being disposed on interfaces between the dielectric layers and the first and second electrode layers in lower portions of the dielectric layers.