ALD-Coated MLCC Powders for Uniform Thin Layers and Higher Capacitance
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Solution Overview
Problem
Conventional methods for producing multi-layer ceramic capacitors (MLCCs) face challenges in achieving uniformity and performance due to the use of larger particle sizes and non-uniform mixing of sintering retardants, leading to imperfections and reduced capacitance.
Innovation Solution
The application of atomic layer deposition (ALD) coatings on metal and ceramic powders to create thinner, more uniform layers, eliminating the need for mixed-in sintering retardants, and enabling better temperature matching and conductivity between metal and dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods use larger particle sizes (200-500 nm) for metal and ceramic layers, then manufacturing is easier, but capacitance per volume and layer thickness are limited
Solution Approach 1:
The patent applies atomic layer deposition (ALD) to deposit metal and ceramic layers at the nanoscale with precise thickness control. This changes the manufacturing parameter from conventional particle-based assembly to atomic-level deposition, enabling layer thicknesses of tens of nanometers with uniformity, thereby increasing capacitance per volume while maintaining manufacturability through controlled deposition processes
2Temperature
If sintering retardants are mixed into metal powders to increase sintering temperature, then metal layer sintering temperature matches dielectric layers, but uniformity deteriorates due to non-uniform mixing
Solution Approach 1:
The patent extracts the sintering retardant function from the metal powder mixture and applies it separately through ALD deposition of ceramic layers. The ceramic layers serve as the sintering retardant barrier, eliminating the need to mix retardants into metal powders. This separation maintains metal powder uniformity while achieving temperature matching through the inherent properties of the deposited ceramic layers
Solution Approach 2:
The ALD-deposited ceramic layers act as an intermediary between the metal layers, providing the sintering retardant function. These ceramic layers are deposited conformally on metal particles, creating a uniform barrier that controls sintering temperature without requiring mixing into the metal powder, thus maintaining both temperature matching and uniformity
3Productivity
If thinner metal layers are deposited to increase layer count and capacitance, then conductivity may deteriorate with voids and discontinuities, but capacitance per volume improves
Solution Approach 1:
The patent replaces conventional mechanical mixing and screening of metal powders with atomic layer deposition (ALD), a chemical vapor deposition process. ALD deposits metal layers atom-by-atom in controlled cycles, ensuring complete coverage and continuity even at tens of nanometers thickness. This substitution of deposition mechanism eliminates voids and discontinuities inherent in mechanical methods, maintaining conductivity while enabling thinner layers for higher capacitance density
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 MLCCs with increased capacitance, improved heat management, and reduced defects, allowing for more layers and better electrical performance.
Implementation Method 1
The invention includes methods of making multi-layer ceramic capacitors (MLCCs) by laminating sheets of dielectric particles with layers of conductive particles, wherein either the dielectric particles or the conductive particles, or both, are coated with material by atomic layer deposition (ALD) methods
Data Source
AI summary
The use of Atomic Layer Deposition (ALD) and Molecular Layer Deposition (MLD) applied to powders and intermediates of the MLCC fabrication process can provide significant advantages. Coating metal particles within a defined range of ALD cycles is shown to provide enhanced oxidation resistance. Surprisingly, a very thin ALD layer was found to substantially increase sintering temperature.