External Electrode Hydrophobic Coating for Solderable Ceramic Chips
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Solution Overview
Problem
Ceramic electronic devices face electrical breakdown due to dew condensation under high-temperature and high-humidity conditions, and existing water repellent coatings on external electrodes need to be removed before mounting, which can lead to mounting failures.
Innovation Solution
A ceramic electronic device with a multilayer chip structure and external electrodes, where a water repellent agent is applied with varying thicknesses on different faces, ensuring adequate water repellency on exposed surfaces without interfering with solder bonding, thus preventing electrical breakdown and mounting failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform thick water repellent coating is applied on all external electrode surfaces to maximize water protection, then water repellency is improved, but solder bonding ability deteriorates
Solution Approach 1:
The water repellent coating is applied with non-uniform thickness across different surfaces. The side faces receive a thicker coating for maximum water protection, while the end faces receive a thinner coating that preserves solder bonding capability. This resolves the contradiction by providing sufficient water repellency where needed while maintaining manufacturing ease for soldering.
2Reliability
If the water repellent agent is removed before mounting to ensure good solder bonding, then mounting reliability is improved, but water protection capability deteriorates
Solution Approach 1:
By applying the water repellent agent with differentiated thicknesses, the end faces maintain a thin coating that does not interfere with solder bonding, eliminating the need for removal before mounting. Meanwhile, the side faces retain a thick coating for effective water protection, thus improving both mounting reliability and water protection capability simultaneously.
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 effectively suppresses water adhesion and migration on external electrodes, preventing electrical breakdown and ensuring reliable solder bonding, even without removing the water repellent agent before mounting, thereby enhancing the reliability of ceramic electronic devices in harsh conditions.
Implementation Method 1
a water repellent agent formed on a surface of the external electrodes
Data Source
AI summary
A ceramic electronic device includes, a multilayer chip in which each of a plurality of dielectric layers and each of a plurality of internal electrode layers are alternately stacked, external electrodes provided on the first end face and the second end face, and a water repellent agent formed on a surface of the external electrodes. A thickness A (>0) of the water repellent agent on at least one of four faces of the external electrodes that cover an upper face in a stacking direction, a lower face in the stacking direction, and two side faces of the multilayer chip is larger than a thickness B (>0) of the water repellent agent on faces of the external electrodes that cover the first end face and the second end face.