Sn-Ni-Pd Plated MLCC External Electrode for Thermal Stress Resistance
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Solution Overview
Problem
Multilayer ceramic capacitors (MLCCs) used in high-temperature environments, such as engine bays, face mechanical stress due to temperature changes, leading to solder cracking when mounted with solder, and existing solutions like conductive resin adhesives require optimized plating layers to prevent corrosion and ensure reliability.
Innovation Solution
A multilayer electronic component with a structure featuring a Sn plating layer, a Ni plating layer, and a Pd plating layer, where the Sn layer flattens and conducts for uniform Ni and Pd layer formation, enhancing electrical connectivity and corrosion resistance while allowing for mounting with conductive resin adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solder bonding method is used to mount the MLCC on the substrate, then strong electrical connectivity is achieved, but mechanical stress from thermal expansion causes solder cracking and reduces reliability
Solution Approach 1:
The patent changes the material parameters of the plating layer by introducing a multi-layer structure (Sn-Ni-Pd) with specific thickness ratios. The Sn layer (5-20 μm) provides ductility to absorb thermal stress, while the Ni and Pd layers provide corrosion resistance. This parameter change allows the plating layer to withstand thermal expansion stress without cracking, resolving the contradiction between reliability and strength.
Solution Approach 2:
The patent applies a composite plating layer structure combining three different metals (Sn, Ni, Pd) with complementary properties. The Sn layer provides stress absorption, Ni provides barrier properties, and Pd provides corrosion resistance. This composite structure enables the external electrode to simultaneously achieve strong bonding, stress resistance, and corrosion protection, resolving the reliability-strength contradiction.
2Reliability
If a conductive resin adhesive is used instead of solder, then thermal stress and solder cracking are prevented, but the plating layer structure must be optimized and manufacturing complexity increases
Solution Approach 1:
The patent segments the plating layer into three distinct functional layers (Sn, Ni, Pd) with specific thickness requirements. This segmentation allows each layer to perform its specific function optimally while providing clear manufacturing guidelines. The Sn layer (5-20 μm) bonds with conductive resin, Ni layer (1-5 μm) provides intermediate protection, and Pd layer (0.1-1 μm) provides final corrosion protection, reducing overall structural complexity through functional division.
Solution Approach 2:
The patent applies local quality by giving each plating layer specific properties tailored to its function. The Sn layer has high ductility for stress absorption and adhesive bonding, Ni has barrier properties for intermediate protection, and Pd has excellent corrosion resistance for the outer surface. This localized optimization of material properties simplifies the overall design by assigning specific roles to each layer.
3Reliability
If the Pd plating layer is made thicker to prevent corrosion, then corrosion resistance improves, but hydrogen absorption increases causing volume expansion and plating break
Solution Approach 1:
The patent optimizes the Pd layer thickness parameter to a specific range (0.1-1 μm) that balances corrosion protection with hydrogen absorption prevention. This parameter optimization ensures sufficient corrosion resistance while maintaining plating layer integrity, resolving the contradiction between these two requirements.
Solution Approach 2:
The Ni layer acts as an intermediary barrier between the Sn layer and the Pd layer. It provides an additional protection layer that helps prevent hydrogen from reaching the Pd layer, thereby reducing hydrogen absorption and volume expansion while maintaining corrosion resistance. This intermediary structure resolves the contradiction between corrosion protection and plating integrity.
4Reliability
If the external electrode structure is optimized for conductive resin adhesive mounting, then reliability in high-temperature environments improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by specifying different thickness ranges for different plating layers based on their functional requirements. The Sn layer (5-20 μm) requires greater thickness for adhesive bonding, Ni layer (1-5 μm) requires moderate thickness for barrier protection, and Pd layer (0.1-1 μm) requires thinner precision for corrosion protection. This localized thickness specification optimizes manufacturing precision requirements for each layer according to its function.
Solution Approach 2:
The patent defines specific thickness parameter ranges for each plating layer that balance performance requirements with manufacturing feasibility. These parameter specifications provide clear manufacturing targets while ensuring reliable performance in high-temperature environments, resolving the contradiction between reliability and manufacturing precision.
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 solution provides improved reliability and reduced manufacturing costs by preventing plating disconnection, corrosion, and hydrogen absorption, ensuring stable electrical connectivity and high capacitance in compact designs suitable for automotive applications.
Implementation Method 1
an Sn plating layer disposed on the electrode layer; an Ni plating layer disposed on the Sn plating layer; and a plating layer including Pd disposed on the Ni plating layer
Data Source
AI summary
A multilayer electronic component includes a body including dielectric layers and internal electrodes alternately disposed with the dielectric layers and an external electrode disposed on the body. The external electrode includes an electrode layer connected to the internal electrode, an Sn plating layer disposed on the electrode layer, an Ni plating layer disposed on the Sn plating layer, and a plating layer including Pd disposed on the Ni plating layer.