Ceramic Component Lead Terminal Coating for Crack Resistance
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Solution Overview
Problem
Ceramic electronic components with lead terminals experience cracks due to shrinkage stress during solder solidification, leading to mechanical weakness, especially when the ceramic element body is small.
Innovation Solution
A ceramic electronic component with a lead terminal joined to a terminal electrode using a solder fillet, where a coating layer with a copper-tin alloy, preferably Cu6Sn5, is formed on the lead terminal to improve solder wettability and reduce the fillet angle, enhancing mechanical strength and preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the lead terminal is joined by solder to the terminal electrode, then the lead terminal is connected to the ceramic element body, but cracks are likely to occur inside the element body due to shrinkage stress during solder solidification
Solution Approach 1:
The invention changes the material parameters of the lead terminal by forming a coating layer with specific composition (Cu6Sn5 intermetallic compound) on the lead terminal surface. This coating layer has optimized physical and chemical properties that improve solder wettability and reduce the contact angle, thereby reducing shrinkage stress during solidification and preventing cracks while maintaining joining strength
Solution Approach 2:
The invention creates a composite structure consisting of the lead terminal base material (copper or copper alloy) combined with a coating layer (Cu6Sn5 intermetallic compound). This composite structure combines the high conductivity and ductility of copper with the excellent solder wettability and low contact angle properties of the Cu6Sn5 coating, achieving both strong joining and crack resistance
2Volume of moving object
If the size of the ceramic element body is reduced, then the component becomes more compact, but the mechanical strength of the joined structure is insufficient
Solution Approach 1:
By changing the surface material parameters of the lead terminal through the Cu6Sn5 coating layer, the invention achieves significantly improved solder wettability and reduced contact angle. This allows for stronger bonding in smaller components where the joining area is limited, compensating for the reduced size effect and maintaining sufficient mechanical strength even in compact ceramic electronic components
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 ensures a strong and crack-resistant ceramic electronic component by optimizing solder wettability and fillet geometry, improving both joining strength and heat resistance at the solder interface.
Implementation Method 1
the coating layer is formed of a metal component having a contact angle of the solder smaller than that with the lead terminal
Data Source
AI summary
A ceramic electronic component of the present invention includes: a ceramic element body; a terminal electrode formed on from an end surface to a side surface of the ceramic element body; and a lead terminal joined to the terminal electrode by a solder. A fillet of the solder is formed between the terminal electrode of a side surface at the ceramic element body and the lead terminal, and a coating layer is formed on a surface of the lead terminal that is in contact with the solder. The coating layer is formed of a metal component having a contact angle with the solder smaller than that of the lead terminal.