Light Sintering of Metal Foil Coated Ceramic Capacitors
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Solution Overview
Problem
Existing capacitor technologies face challenges in forming capacitors with high dielectric constant ceramics and conductive metals due to high sintering temperatures, which often lead to material incompatibilities and limitations in functionality and miniaturization, especially in multi-layered ceramic capacitors.
Innovation Solution
A method involving a metal foil coated with a ceramic precursor containing a susceptor and a high dielectric constant oxide, sintered using high intensity, high pulse frequency light energy to form capacitors without compromising the ceramic or conductive layers, allowing for additional functionality and terminations without a co-sintering stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature sintering is used to achieve adequate ceramic density, then dielectric density and capacitance are improved, but metal conductor compatibility deteriorates due to oxidation and material degradation
Solution Approach 1:
The sintering process is segmented into multiple stages with different atmospheres and temperature profiles. The ceramic is sintered first in a reducing atmosphere at high temperature to achieve density, then the metal conductor paste is applied and sintered in a separate lower-temperature step in an oxidizing or neutral atmosphere, preventing metal oxidation while maintaining ceramic integrity.
Solution Approach 2:
The ceramic body is pre-sintered to achieve adequate density and structural integrity before applying the metal conductor paste. This preliminary action ensures the ceramic can withstand subsequent processing without degradation, and allows the metal paste to be applied to a stable substrate that won't undergo further high-temperature changes.
2Ease of manufacture
If traditional co-sintering is used for multi-layered ceramic capacitors, then manufacturing process is simplified, but additional functionality (resistance, inductance) cannot be incorporated due to material incompatibility
Solution Approach 1:
The invention enables a single capacitor component to perform multiple functions by incorporating different material layers with distinct properties. Conductive pastes create electrical connections, resistive pastes create bleeding resistors, and inductive pastes create inductors, all within the same MLCC structure through sequential application and sintering.
Solution Approach 2:
The sintering parameters are changed between processing steps to accommodate different material requirements. The first sintering cycle uses high temperature in a reducing atmosphere for ceramic densification, while subsequent cycles use lower temperatures in oxidizing or neutral atmospheres for metal and functional paste sintering, enabling versatile functionality integration.
3Reliability
If base metal conductors are used to reduce cost, then material cost is reduced, but sintering atmosphere control complexity increases due to oxidation prevention requirements
Solution Approach 1:
The sintering process is segmented so that base metal conductors are applied after the ceramic is already sintered. This allows the ceramic to be processed in a reducing atmosphere for density, while the base metal paste is subsequently sintered in a simpler oxidizing or neutral atmosphere at lower temperature, reducing oxidation risk and atmosphere control complexity.
Solution Approach 2:
The ceramic body is pre-sintered to establish a stable, non-reactive substrate before applying base metal conductor pastes. This preliminary ceramic sintering creates a protective environment that reduces the stringency of atmosphere control requirements for subsequent metal sintering, enabling cost-effective base metal usage.
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 enables the formation of capacitors with high density ceramic dielectrics and conductive layers that are otherwise incompatible, providing enhanced capacitance and functionality while avoiding the limitations of traditional sintering processes, such as reduced voltage handling and material costs.
Implementation Method 1
sintered using high intensity, high pulse frequency light energy
Implementation Method 2
ceramic precursor containing a susceptor and a high dielectric constant oxide
Data Source
AI summary
An method of forming a metal foil coated ceramic and a metal foil capacitor is provided in a method of making a metal foil coated ceramic comprising providing a metal foil; applying a ceramic precursor to the metal foil wherein the ceramic precursor comprises at least one susceptor and a high dielectric constant oxide and an organic binder, and sintering the ceramic precursor with a high intensity, high pulse frequency light energy to form the metal foil ceramic.