MLCC External Electrode Layers for Crack Suppression and Hydrogen Blocking
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Solution Overview
Problem
Multilayer ceramic capacitors (MLCCs) face challenges in maintaining high-temperature reliability due to hydrogen penetration during plating, which causes reliability degradation, and are prone to mounting cracks and flex cracks during reflow heat treatment and substrate stress, necessitating improved physical and electrical connectivity between electrode layers.
Innovation Solution
A multilayer electronic component design featuring a two-layer external electrode structure with base electrode layers made of glass and Ni, intermediate electrode layers containing an Sn and Ni alloy, and conductive resin layers with a resin and metal, enhancing bonding strength and preventing hydrogen penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional single-layer external electrode structure is used, then the manufacturing process is simple, but mounting cracks and flex cracks occur during reflow heat treatment and substrate stress
Solution Approach 1:
The external electrode is divided into three distinct layers: a base electrode layer (Ni) directly contacting the internal electrode, an intermediate electrode layer (Sn-Ni alloy) providing transition and protection, and a conductive resin layer (silver-filled epoxy) providing mechanical strength and electrical connectivity. This segmentation allows each layer to perform its specific function, preventing cracks while maintaining manufacturability
Solution Approach 2:
The patent employs composite material structures at multiple levels: the intermediate electrode layer uses Sn-Ni alloy combining the low melting point and wetting properties of Sn with the hardness and oxidation resistance of Ni; the conductive resin layer combines epoxy resin matrix with silver particles for both mechanical strength and electrical conductivity. These composite structures enhance overall reliability without significantly complicating the manufacturing process
2Reliability
If plating process is performed to form external electrodes, then electrical conductivity is improved, but hydrogen penetration occurs causing reliability degradation at high temperatures
Solution Approach 1:
The intermediate electrode layer acts as a mediator between the base electrode layer and the conductive resin layer, and crucially, as a barrier against hydrogen penetration. The Sn-Ni alloy layer with its specific composition (Sn: 70-95 wt%, Ni: 5-30 wt%) provides hydrogen blocking properties while maintaining electrical conductivity and mechanical bonding, thus protecting the internal electrode from hydrogen-induced degradation at high temperatures
3Volume of moving object
If dielectric and internal electrode layers are reduced in thickness for miniaturization, then compactness is improved, but physical and electrical connectivity between electrodes deteriorates
Solution Approach 1:
The conductive resin layer uses a composite of epoxy resin and silver particles (silver content: 60-80 wt%) to achieve high electrical conductivity despite the reduced thickness of connected layers. The silver particles form conductive pathways that maintain electrical connectivity even when the dielectric and internal electrode layers are thinned for miniaturization
Solution Approach 2:
The patent optimizes the thickness and composition parameters of the external electrode layers to compensate for the reduced thickness of internal layers. The base electrode layer thickness is controlled at 1-10 μm, intermediate electrode layer at 5-20 μm, and conductive resin layer at 10-50 μm, with specific material compositions that ensure adequate electrical and mechanical connectivity in miniaturized structures
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 suppresses mounting and flex cracks, improves electrical connectivity, and maintains high-temperature reliability by preventing hydrogen ingress, thereby ensuring excellent reliability even at reduced thicknesses of dielectric and internal electrode layers.
Implementation Method 1
forming an Sn plating layer on the base electrode layer... to prevent hydrogen generated during plating from penetrating into a body
Implementation Method 2
performing a curing heat treatment on the paste-applied body to form an intermediate electrode layer and a conductive resin layer
Implementation Method 3
performing a sintering operation to form a base electrode layer of an external electrode
Data Source
AI summary
A multilayer electronic component includes a body including first and second surfaces opposing each other in the first direction, and third and fourth surfaces connected to the first and second surfaces and opposing each other in a second direction, a first external electrode including a first base electrode layer including glass and Ni and disposed on the third surface, a first intermediate electrode layer including an alloy containing Sn and Ni and disposed on the first base electrode layer, and a first conductive resin layer including a resin and a metal and disposed on the first intermediate electrode layer and extending to the first and second surfaces, a second external electrode including a second base electrode layer disposed on the fourth surface, a second intermediate electrode layer disposed on the second base electrode layer, and a second conductive resin layer disposed on the second intermediate electrode layer.