Multilayer Capacitor Cover Layer for Moisture-Resistant Plating
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Solution Overview
Problem
Multilayer ceramic capacitors face challenges in achieving miniaturization and high capacitance while maintaining reliability, as they are prone to moisture and plating solution permeation, which can lead to physical peeling and damage of insulating layers during manufacturing processes.
Innovation Solution
A multilayer electronic component design featuring a body with dielectric layers and internal electrodes, external electrodes with specific band and corner portions, and a cover layer with a hydrophilic base layer and insulating layer to prevent moisture and plating solution permeation, along with plasma treatment and plating layers to enhance adhesion and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of laminated layers is decreased to achieve miniaturization and high capacitance, then the effective volume fraction increases, but the capacitor becomes more susceptible to moisture and plating solution permeation
Solution Approach 1:
The patent applies composite materials by forming a cover layer comprising an insulating layer and a plating layer on the external electrode. The insulating layer (e.g., glass-based material) provides moisture barrier properties, while the plating layer (e.g., nickel or palladium) provides corrosion resistance and adhesion. This composite structure protects the miniaturized capacitor from moisture and plating solution permeation without increasing the core capacitor volume.
Solution Approach 2:
The patent uses a thin film cover layer structure that conformally coats the external electrode surfaces. This thin film approach provides effective moisture and chemical protection while adding minimal volume, enabling the capacitor to maintain miniaturization while achieving high reliability against environmental degradation.
2Reliability
If an insulating layer is disposed on the external electrode to protect from moisture permeation, then reliability improves, but the insulating layer may be physically peeled off and damaged by polishing or plating processes
Solution Approach 1:
The patent forms a composite cover layer structure with an insulating layer followed by a plating layer. The plating layer (nickel or palladium) serves as a protective intermediate layer that bonds to both the insulating layer and the external electrode, distributing mechanical stresses from polishing and plating processes. This composite structure prevents direct peeling of the insulating layer while maintaining strong adhesion.
Solution Approach 2:
The patent applies beforehand cushioning by forming the plating layer over the insulating layer before final assembly and testing. This plating layer acts as a cushioning protective layer that absorbs mechanical stresses from subsequent polishing and plating operations, preventing direct damage to the insulating layer and eliminating the need for rework.
3Productivity
If the mounting space is significantly reduced to mount more components, then productivity increases, but external moisture and plating solution can easily permeate into the capacitor
Solution Approach 1:
The patent employs composite materials by combining an insulating layer (moisture barrier) with a plating layer (corrosion protection) on the external electrode. This dual-layer composite structure provides comprehensive protection against moisture and plating solution permeation, enabling miniaturized capacitors to be densely mounted without sacrificing reliability.
Solution Approach 2:
The patent applies parameter changes by optimizing the thickness and material composition of the cover layer to provide adequate protection against moisture permeation while minimizing the volume increase. The insulating layer thickness and plating layer thickness are carefully controlled to balance protection effectiveness with miniaturization requirements.
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 design effectively reduces mounting space, improves capacitance per unit volume, and enhances the adhesion between the cover layer and external electrodes, thereby increasing the reliability and moisture resistance of the multilayer ceramic capacitors.
Implementation Method 1
The cover layer comprises a base layer, having hydrophilicity, and an insulating layer disposed on the base layer
Implementation Method 2
performing a plasma treatment on an external surface, on which the external electrode is not formed, among either one of an external surface of the externa electrode and an external surface of the body
Data Source
AI summary
A multilayer electronic component includes: a body including dielectric layers and first and second internal electrodes and having first to sixth surfaces; a first external electrode including a first connection portion on the third surface, a first band portion on the first surface, and a third band portion on the second surface; a second external electrode including a second connection portion on the fourth surface, a second band portion on the first surface, and a fourth band portion on the second surface; a cover layer disposed on the first and second connecting portions and disposed to cover the second surface and the third and fourth band portions; a first plating layer disposed on the first band portion; and a second plating layer disposed on the second band portion. The cover layer includes a base layer, having hydrophilicity, and an insulating layer disposed on the base layer.