Laminated Ceramic Capacitor External Electrodes Bonding
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Solution Overview
Problem
Multilayer ceramic capacitors with external electrodes face challenges in achieving sufficient equivalent series resistance (ESR) without using expensive metals or complex structures, which can lead to inadequate bonding and reduced electrostatic capacitance due to issues with weather resistance and bonding strength, especially under thermal and mechanical stress.
Innovation Solution
The use of external electrodes with resistive layers containing a complex oxide that generates an intermetallic compound with Ni or Ni alloy, along with a glass component and a metal that forms a solid solution or compound with Ni or Ni alloy, provides sufficient bonding and weather resistance, while maintaining stable ESR through controlled composition and printing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive layer containing a complex oxide (e.g., In-Sn complex oxide) and glass component is used to increase resistance, then sufficient ESR can be obtained without expensive metals or three-layer structure, but weather resistance and bonding strength with internal electrode become insufficient
Solution Approach 1:
The patent uses a composite material system consisting of complex oxide particles (In-Sn), glass particles, and metal particles (Ni, Cu, or their alloys). This composite structure combines the high resistance of complex oxide with the bonding capability of metal particles that form solid solutions with internal electrode Ni, achieving both sufficient ESR and strong bonding strength simultaneously.
Solution Approach 2:
The patent optimizes the particle size parameters of complex oxide (0.3-2.0 μm), glass (0.5-2.5 μm), and metal particles (0.2-1.5 μm), as well as their compositional ratios, to achieve the balance between resistance and bonding strength. The specific particle size ranges ensure proper sintering behavior and interface formation.
2Reliability
If Ag is added to control resistance of external electrodes, then ESR can be adjusted, but bonding properties with internal electrode decrease due to lack of solid solution region with Ni
Solution Approach 1:
The patent replaces expensive Ag with cheaper metal particles (Ni, Cu, or their alloys) that can form solid solutions with internal electrode Ni. These metals provide both resistance control through the conductive network and strong bonding through solid solution formation, eliminating the need for Ag while maintaining or improving performance.
3Reliability
If external electrodes use a three-layer structure with thick film thickness to achieve sufficient resistance, then ESR can be controlled, but component size reduction is inhibited
Solution Approach 1:
The patent creates local conductive pathways within the external electrode by incorporating metal particles (Ni, Cu, or their alloys) that form solid solutions with internal electrode Ni. This localized solid solution formation at the interface provides sufficient bonding and resistance control without requiring thick film layers, enabling miniaturization.
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 solution achieves stronger bonding and increased weather resistance, ensuring stable ESR and electrostatic capacitance, even under thermal shock and bending conditions, by using Ni or Cu as the reacting metal and In-Sn complex oxide, and controlling the glass component's softening point for resistance stability.
Implementation Method 1
a complex oxide which generates an intermetallic compound with Ni or a Ni alloy
Implementation Method 2
a metal which forms a solid solution or a compound with Ni or a Ni alloy
Implementation Method 3
a glass component, and metal which forms a solid solution or a compound with Ni or a Ni alloy
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An object of the invention is to provide a multilayer ceramic capacitor including external electrodes which also have a function of resistive element, wherein the external electrodes may achieve strong bonding with internal electrodes containing Ni or a Ni alloy. External electrodes (6,7) include a resistive electrode layers (8) contacting a ceramic laminate (3) and internal electrodes (4,5). The resistive electrode layers (8) contains a complex oxide which reacts with Ni or a Ni alloy contained in the internal electrodes (4,5) in a proportion of 26 to 79% by weight, a glass component in a proportion of 20 to 56% by weight, and metal which reacts with Ni or a Ni alloy in a proportion of 1 to 18% by weight.