Multilayer Electronic Component Alloy Layers to Suppress Sintering Cracks
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Solution Overview
Problem
The rapid diffusion of copper into nickel during the sintering process in multilayer ceramic capacitors leads to volume expansion of internal electrodes, increasing the risk of cracking, especially when miniaturization and high capacitance are desired.
Innovation Solution
Incorporating alloy layers composed of copper, nickel, and aluminum with a specific molar content ratio (Cu > Ni > Al) to improve the connection between internal and external electrodes, thereby reducing the diffusion rate disparity and suppressing crack formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu and Ni are used to form an alloy layer during sintering, then electrical connection between internal and external electrodes is improved, but Cu diffuses rapidly into Ni causing volume expansion and radiating cracks
Solution Approach 1:
An Al alloy layer is introduced as an intermediary barrier between the Cu external electrode and the Ni internal electrode. This intermediate layer prevents direct diffusion between Cu and Ni, eliminating the volume expansion and radiating cracks that would otherwise occur during sintering, while still allowing electrical connection to be established.
Solution Approach 2:
A composite electrode structure is formed using multiple materials (Al, Cu, Ni) in specific layers. The external electrode comprises a Cu-rich alloy layer and an Al-rich alloy layer, creating a composite structure that combines the electrical conductivity of Cu with the diffusion barrier properties of Al, while the internal electrode uses Ni with controlled Cu diffusion.
2Volume of moving object
If the dielectric layer and internal electrode are thinned to achieve miniaturization, then device size is reduced, but stress increases making the structure more vulnerable to radiating cracks
Solution Approach 1:
The Al-rich alloy layer acts as a stress buffer and intermediary protective layer between the thinned dielectric layer and the electrode structures. This intermediate layer absorbs and distributes mechanical stress, preventing stress concentration that would lead to radiating cracks in the thinned structure.
Solution Approach 2:
The composition and thickness parameters of the alloy layers are specifically optimized to compensate for the reduced dimensions. By adjusting the Al content and layer thickness, the mechanical strength and crack resistance are enhanced to offset the vulnerabilities introduced by thinning the dielectric and internal electrodes.
3Quantity of substance
If high capacitance is achieved through miniaturization, then device capacity increases, but the structure becomes more susceptible to moisture penetration and connection failure
Solution Approach 1:
A composite electrode structure with multiple alloy layers (Cu-rich and Al-rich) is implemented to provide both high capacitance performance and superior moisture resistance. The layered composite structure creates multiple barriers to moisture penetration while maintaining the electrical properties needed for high capacitance in a miniaturized form factor.
Solution Approach 2:
The Al-rich alloy layer serves as an intermediary protective barrier that prevents moisture from reaching the internal electrode and dielectric interface. This intermediate protective layer secures the electrical connection and prevents corrosion, enabling the miniaturized high-capacitance device to maintain reliability in humid environments.
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
The alloy layers enhance the connection between electrodes and reduce crack occurrence, ensuring reliability and moisture resistance in miniaturized, high-capacitance multilayer ceramic capacitors.
Implementation Method 1
Ni of an internal electrode and Cu of an external electrode may be mutually diffused during a sintering process to form a Ni—Cu alloy layer
Implementation Method 2
a rate at which Cu diffuses into Ni is even faster than a rate at which Ni diffuses into Cu
Implementation Method 3
Ni of an internal electrode and Cu of an external electrode may be mutually diffused during a sintering process
Data Source
AI summary
A multilayer electronic component includes: a body including a dielectric layer and first and second internal electrodes alternately disposed in a first direction with the dielectric layer interposed therebetween, a first external electrode and including a first alloy layer connected to the first internal electrode; and a second external electrode and including a second alloy layer connected to the second internal electrode, wherein the first and second alloy layers include alloys including Cu, Ni and Al, and a molar content of Ni included in the first alloy layer is greater than a molar content of Al, and a molar content of Cu is greater than the molar content of Ni.