Metal Powder with Complex Metal Compound for Capacitor Sintering
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Solution Overview
Problem
Current methods for producing metal powders for multilayer ceramic capacitors face challenges in achieving uniform dispersion of complex metal compounds, leading to inadequate sintering inhibition and reduced capacitance due to differences in sintering shrinkage behavior between electrode and dielectric layers, and involve high-cost, hazardous organic solvents and high-temperature processes.
Innovation Solution
A method involving separate steps for coprecipitating a metal powder with a complex metal compound, adjusting the pH to 5 or less, and using specific reductants and metal elements to ensure uniform distribution of the complex oxide, which inhibits sintering and improves dispersibility, while avoiding the use of metal alkoxides and reducing the risk of explosions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal powders are used for conductive pastes in multilayer ceramic capacitors, then the electrode layers can be formed, but the sintering shrinkage behavior differs from dielectric layers causing cracking and reduced coverage
Solution Approach 1:
The patent applies composite materials by incorporating fine dielectric particles (such as barium titanate, strontium titanate, or calcium titanate with particle sizes of 0.1-10 μm) into the metal powder composition. This creates a composite structure where dielectric particles are dispersed within the metal powder matrix, allowing the electrode layer to exhibit sintering shrinkage behavior that matches the dielectric layers, thereby preventing cracking and improving coverage while maintaining electrical conductivity.
2Reliability
If fine dielectric particles are incorporated into electrode layers to inhibit sintering, then sintering inhibition is achieved, but uniform dispersion of dielectric particles in metal powder is difficult to achieve
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size of dielectric particles to be in the range of 0.1-10 μm, which is larger than ultra-fine particles but smaller than conventional particles. This specific size range, combined with controlling the weight ratio of dielectric particles to metal powder to be 1-50 parts, optimizes both the dispersion uniformity and the sintering inhibition effect. The controlled parameters ensure that dielectric particles are uniformly distributed throughout the metal powder without agglomeration.
3Productivity
If conventional production methods are used, then metal powder can be produced, but complex metal compounds are not uniformly dispersed leading to inadequate sintering inhibition
Solution Approach 1:
The patent applies preliminary action by pre-mixing fine dielectric particles with metal powder before the sintering process. This pre-dispersion step ensures that dielectric particles are uniformly distributed throughout the metal powder matrix prior to sintering, creating a homogeneous composite structure that provides consistent sintering inhibition throughout the electrode layer, preventing localized sintering variations and ensuring uniform electrical properties.
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
This approach results in a metal powder with enhanced sintering inhibition, improved dispersibility, and reduced delamination of capacitors, achieving high coverage and maintaining the electrical characteristics of multilayer ceramic capacitors with a more uniform and stable complex metal compound distribution.
Implementation Method 1
a first step including preparing a first solution that contains at least one first metal element serving as an element of the metal and at least one group 4 element different from the first metal element, the first solution being adjusted to have a pH of 5 or less, mixing the first solution with a reductant solution to coprecipitate the metal and a metal compound
Implementation Method 2
mixing the first solution with a reductant solution to coprecipitate the metal and a metal compound
Implementation Method 3
A first effect is one in which the fine dielectric particles inhibit contact between metal particles, necking between the metal particles, and sintering of the electrodes
Implementation Method 4
A second effect is one in which the fine dielectric particles are deposited at the triple point of the metal particles (crystals) during the sintering of a metal powder, pin the metal particles, and inhibit the sintering of the electrodes
Data Source
AI summary
A method for producing a metal powder that includes a first step of uniformly arranging a metal compound on a metal particle, and a second step of converting the metal compound uniformly arranged on the metal particle into a complex metal compound. In the first step, a solution that contains at least one metal element and at least one group 4 element different from the metal element is prepared, the solution being adjusted to have a pH of 5 or less. The prepared solution is mixed with a reductant solution to coprecipitate the metal and the metal compound, thereby producing a slurry that contains a metal powder containing the metal combined with the metal compound. In the second step, a solution or a powder containing at least one second metal element is added to the slurry to convert the metal compound into the complex metal compound.