Multilayer Capacitor Ceramic Composition for Low-Temperature Sintering
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Solution Overview
Problem
Existing ceramic materials for capacitors in multilayer technology do not offer optimal properties for improved durability, resistance, and reduced energy losses, particularly in anti-ferroelectric phases, and are limited by high sintering temperatures that restrict compatibility with certain electrode materials.
Innovation Solution
A ceramic material with a composition of Pb(y−1.5a−0.5b+c+0.5d−0.5e−f)CaaAb(Zr1−xTix)(1−c−d−e−f)EcFedNbeWfO3, doped with Ca, A, and E elements, allowing for a Zr-rich PZT phase with controlled grain size and lower sintering temperatures, enabling co-firing with metals like silver and copper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PZT ceramic materials are used for capacitors, then piezoelectric properties are improved, but sintering temperature becomes too high for compatibility with electrode materials
Solution Approach 1:
The patent modifies the chemical composition parameters of PZT by introducing Ca, A (Na, K, or Ag), and E (Cu, Ni, Hf, Si, or Mn) dopants with specific concentration ranges. This changes the material's sintering characteristics, enabling processing at lower temperatures (reduced by at least 50°C compared to conventional PZT) while maintaining desired piezoelectric properties and anti-ferroelectric phase stability.
Solution Approach 2:
The patent creates a composite ceramic system by combining PZT base material with multiple dopant elements (Ca, A, and E). This composite approach allows synergistic effects where Ca stabilizes the anti-ferroelectric phase, A modifies sintering behavior, and E controls grain growth, collectively achieving low-temperature processing compatibility with electrode materials while preserving functional properties.
2Reliability
If high titanium content is used in PZT, then ferroelectric properties are enhanced, but anti-ferroelectric crystal structure is lost
Solution Approach 1:
The patent precisely controls the Ti content parameter within the range 0.05 ≤ x ≤ 0.3 in the composition Pb(y−1.5a−0.5b+c+0.5d−0.5e−f)CaaAb(Zr1−xTix)(1−c−d−e−f)EcFedNbeWfO3, and combines it with Ca doping (0.05 ≤ a ≤ 0.2) to stabilize the anti-ferroelectric orthorhombic phase. This parameter optimization allows incorporating sufficient titanium for desired piezoelectric response while Ca doping prevents excessive tetragonal phase formation, maintaining the required anti-ferroelectric crystal structure.
Solution Approach 2:
Calcium acts as an intermediary element that mediates between the competing requirements of high titanium content (for ferroelectric properties) and anti-ferroelectric phase stability. Ca doping stabilizes the anti-ferroelectric orthorhombic phase even in the presence of significant titanium content, enabling the material to maintain the desired crystal structure while achieving adequate piezoelectric performance through controlled titanium incorporation.
3Manufacturing precision
If conventional sintering temperatures are used, then ceramic density is achieved, but compatibility with silver and copper electrodes is lost
Solution Approach 1:
The patent changes the sintering temperature parameter to a reduced range that is at least 50°C lower than conventional PZT sintering temperatures. This modified temperature parameter enables co-firing with temperature-sensitive electrode materials like silver and copper, achieving adequate ceramic density and mechanical strength while preventing electrode material degradation, oxidation, or excessive diffusion that would occur at conventional high sintering temperatures.
Solution Approach 2:
The dopant elements (Ca, A, and E) create local compositional variations that modify sintering behavior in specific regions of the ceramic. These local compositional adjustments promote grain boundary stabilization and densification at lower temperatures, enabling adequate ceramic density achievement at reduced sintering temperatures that are compatible with electrode materials, without requiring uniform high-temperature processing throughout the entire material.
4Loss of energy
If energy losses are reduced in anti-ferroelectric phases, then capacitor efficiency is improved, but material composition complexity increases
Solution Approach 1:
The patent optimizes the compositional parameters within defined ranges rather than using single fixed values. The multi-element doping system (Ca, A, E) with controlled concentrations (0.05 ≤ a ≤ 0.2, 0 ≤ b,f ≤ 0.12, 0 ≤ c,d,e ≤ 0.12, 0.05 ≤ x ≤ 0.3) enables fine-tuning of the anti-ferroelectric phase properties to minimize energy losses. This parameter optimization approach reduces dielectric losses and improves capacitor efficiency while maintaining manageable composition complexity through systematic doping rather than random element addition.
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 ceramic material exhibits enhanced durability, reduced energy losses, and compatibility with various electrode materials, facilitating low-temperature sintering and improved mechanical robustness in capacitors.
Implementation Method 1
lower sintering temperatures, enabling co-firing with metals like silver and copper
Data Source
AI summary
The present invention relates to a ceramic material for a multilayer capacitor. The ceramic material has a composition according to the following general formula:Pb(y−1.5a−0.5b+c+0.5d−0.5e−f)CaaAb(Zr1−xTix)(1−c−d−e−d)EcFedNbeWfO3,whereA is one or more of the group of Na, K and Ag;E is one or more of the group of Cu, Ni, Hf, Si and Mn; and0<a<0.14,0.05≤x≤0.3,0≤b≤0.12,0<c≤0.12,0≤d≤0.12,0≤e≤0.12,0≤f≤0.12,0.9≤y≤1.5 and0.001<b+c+d+e+fapplies.Further, the invention includes a capacitor comprising the described ceramic material.