MLCC External Electrode Ni-Cu Layer Against Hydrogen Penetration
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Solution Overview
Problem
The penetration of hydrogen gas and plating solution during the nickel and/or tin plating process in multilayer ceramic capacitors (MLCCs) deteriorates insulation resistance and reliability, and the occurrence of radial cracks and reduced flexural strength are issues in miniaturized electronic components.
Innovation Solution
The use of external electrodes with a Ni-Cu alloy composition, where the Cu content is 70-90 mol% of the total Ni and Cu content, prevents hydrogen gas penetration and suppresses radial cracks, while maintaining a thin dielectric and internal electrode thickness to enhance reliability and flexural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nickel and/or tin plating is performed on external electrodes to facilitate mounting, then ease of manufacture is improved, but hydrogen gas generated during plating penetrates into internal electrodes deteriorating insulation resistance and reliability
Solution Approach 1:
A Cu-rich barrier layer (with Cu content of 70-90 mol%) is introduced as an intermediary between the Ni plating layer and the internal electrodes. This barrier layer prevents hydrogen gas generated during Ni plating from penetrating into the internal electrodes, while still allowing the plating process to proceed for mounting facilitation.
Solution Approach 2:
The external electrode structure uses a composite material approach with multiple layers: a Ni-Cu alloy layer (70-90 mol% Cu) combined with Ni plating layer. This composite structure provides both the mounting facilitation of Ni plating and the hydrogen barrier properties of the Cu-rich layer.
2Ease of manufacture
If plating process is performed to improve ease of manufacture, then ease of manufacture is improved, but radial cracks occur and reliability deteriorates
Solution Approach 1:
The Cu-rich barrier layer acts as a mediator that prevents the formation and propagation of radial cracks by blocking the path of crack propagation from the external electrode into the internal electrodes, thereby maintaining flexural strength while still enabling plating for mounting.
Solution Approach 2:
The Ni-Cu alloy layer with high Cu content is applied beforehand to cushion and absorb the stress and hydrogen gas generation during subsequent Ni plating, preventing radial cracks from forming in the first place while still allowing the plating process to proceed.
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 Ni-Cu alloy composition effectively prevents hydrogen gas penetration, improves insulation resistance, and enhances flexural strength, thereby maintaining the reliability and capacitance of the multilayer ceramic capacitors.
Implementation Method 1
a second electrode layer disposed on the first electrode layer and including an Ni-Cu alloy... prevents penetration of hydrogen gas generated during plating
Implementation Method 2
The plating process is generally performed as electronic deposition or electroplating
Data Source
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AI summary
A multilayer electronic component includes a body including a dielectric layer and internal electrodes stacked in a first direction with the dielectric layer interposed therebetween and external electrodes including a first electrode layer connected to the internal electrodes and including Ni, and a second electrode layer disposed on the first electrode layer and including an Ni-Cu alloy. A Cu content of the second electrode layer is 70 mol to 90 mol compared to 100 mol of the total content of Ni and Cu of the second electrode layer.