Ni-Cr Internal Electrode Interface for Moisture-Resistant MLCCs
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving both smaller size and improved moisture resistance reliability, as increasing the thickness of cover layers or external electrodes to enhance moisture resistance often results in reduced capacitance and potential structural instability.
Innovation Solution
Incorporating a nickel-chromium alloy region in the internal electrodes, with specific lengths and compositions, to enhance moisture resistance and structural stability without increasing the capacitor's size, by forming an alloy region that includes nickel, chromium, and potentially other metals like copper, tungsten, or molybdenum, which improves insulation resistance and reduces hydrogen infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of cover layer or external electrode is increased to improve moisture resistance, then moisture resistance reliability is improved, but capacitance is reduced and size increases
Solution Approach 1:
The patent applies local quality by forming an alloy region with specific composition (Ni-Cr alloy) only at the contact portion of the internal electrode where it interfaces with the external electrode. This localized treatment provides enhanced moisture resistance and structural stability at the critical interface region without requiring thickening of the entire cover layer or external electrode, thereby maintaining capacitance while improving moisture resistance reliability
Solution Approach 2:
The patent uses composite materials by creating a Ni-Cr alloy region that combines nickel and chromium in specific proportions (Ni: 70-90 at%, Cr: 10-30 at%). This composite alloy structure provides both the electrical conductivity needed for electrode function and the corrosion/moisture resistance required for reliability, eliminating the need to increase external electrode thickness
2Reliability
If the thickness of cover layer or external electrode is increased to improve moisture resistance, then moisture resistance reliability is improved, but the size of capacitor increases
Solution Approach 1:
The alloy region is formed only at the specific contact portion between internal and external electrodes, providing localized protection against moisture infiltration. This targeted approach enhances reliability without increasing the overall dimensions of the capacitor body, cover layers, or external electrodes
Solution Approach 2:
The patent extracts the moisture protection function from the bulk external electrode structure and concentrates it in a specialized alloy region at the critical interface. This separation allows the main electrode structure to remain thin and compact while the extracted protection function is implemented locally where moisture infiltration is most likely to occur
3Quantity of substance
If the internal electrode structure is made thinner to reduce capacitor size, then capacitance density is improved, but structural stability is reduced
Solution Approach 1:
The patent applies local quality by reinforcing only the contact portion of the internal electrode with a Ni-Cr alloy region, while the rest of the internal electrode can maintain a thinner profile to achieve high capacitance density. The alloy region provides localized structural support and crack prevention at the stress-prone interface without requiring the entire internal electrode to be thicker
Solution Approach 2:
The Ni-Cr alloy region creates a composite structure where the alloyed zone provides enhanced mechanical strength and crack resistance, while the non-alloyed portions of the internal electrode maintain thin dimensions for high capacitance density. This composite approach allows the internal electrode to be both thin and structurally stable
Data Source
AI summary
A multilayer capacitor includes a body including a dielectric layer and a plurality of internal electrodes stacked on one another with the dielectric layer interposed therebetween, and external electrodes disposed externally on the body, and each connected to the plurality of internal electrodes, wherein at least one of the plurality of internal electrodes includes an alloy region formed in a region in contact with a corresponding external electrode of the external electrodes, and the alloy region includes a nickel (Ni)-chromium (Cr) alloy.