Electronic Component Outer Electrode Sn-Ni Plating Crack Resistance
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Solution Overview
Problem
Existing electronic components face issues with cracks in the component main body due to thermal contraction of solder fillets, which can lead to electrostatic capacitance drop and electrical characteristic degradation.
Innovation Solution
The electronic component features a configuration with an internal conductor embedded in the component main body, where the outer electrode includes a Sn plating layer and a Sn—Ni layer containing an intermetallic compound, with the Sn—Ni layer having projections for improved solder wettability control, preventing crack formation by managing thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the outer electrode structure is simplified without specialized plating layers, then manufacturing complexity is reduced, but the component main body becomes susceptible to cracks from solder fillet thermal contraction
Solution Approach 1:
The outer electrode uses a composite plating structure with multiple layers (Sn plating layer, Sn-Ni layer with intermetallic compounds, and Ni plating layer) that combines different material properties. The Sn plating layer provides solder wettability, the Sn-Ni layer with intermetallic compounds provides stress absorption and crack resistance, and the Ni plating layer provides barrier functionality. This composite structure resolves the contradiction by maintaining reliability through specialized material composition while keeping the manufacturing process integrated and efficient.
Solution Approach 2:
The invention changes the physical and chemical parameters of the outer electrode surface by controlling the formation of intermetallic compounds in the Sn-Ni layer through specific plating conditions and heat treatment. This parameter change creates a layered structure with different mechanical properties that can absorb thermal stress, thereby improving crack resistance without significantly complicating the manufacturing process.
2Ease of manufacture
If the Sn—Ni layer has a smooth surface, then manufacturing is easier, but solder wettability is insufficient leading to poor solder joint quality
Solution Approach 1:
The Sn plating layer is applied locally on top of the Sn-Ni layer specifically to provide solder wettability where needed, while the Sn-Ni layer with its intermetallic compounds provides the mechanical strength and stress absorption. This local differentiation of material properties resolves the contradiction by assigning specific functions to specific layers: the Sn-Ni layer handles mechanical stress and the Sn plating layer handles solder wettability.
3Reliability
If the outer electrode covering is extended to cover more of the component main body, then crack propagation is suppressed, but the component size and material usage increase
Solution Approach 1:
The outer electrode structure with its specialized plating layers provides a cushioning effect against thermal stress before cracks can form or propagate in the component main body. The intermetallic compounds in the Sn-Ni layer absorb thermal contraction stresses from the solder fillets, preventing stress concentration that would lead to cracking. This beforehand cushioning resolves the contradiction by preventing crack propagation through material design rather than through extended geometric coverage.
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
This configuration effectively suppresses crack formation in the component main body, maintaining stable electrical characteristics and preventing internal electrode shorting, thus enhancing the reliability of electronic components.
Implementation Method 1
at least a portion of an exposed surface of the main surface covering portion is a Sn plating layer, and at least a portion of an exposed surface of the end surface covering portion is a Sn—Ni layer containing an intermetallic compound of Sn and Ni
Implementation Method 2
a surface of the Sn—Ni layer of the exposed surface of the end surface covering portion include a plurality of projections
Data Source
AI summary
An electronic component includes a component main body including an embedded internal conductor and an outer electrode. The component main body includes an end surface on which the internal conductor is exposed, and a main surface that is continuous with the end surface and intersects with the end surface. The outer electrode includes an end surface covering portion connected to the internal conductor by covering at least a portion of the internal conductor exposed on the end surface, and a main surface covering portion that covers at least a portion of the main surface. At least a portion of an exposed surface of the main surface covering portion includes a Sn plating layer, and at least a portion of an exposed surface of the end surface covering portion includes a Sn—Ni layer.