MLCC Oxide Layer Structure to Prevent Solder Wetting and Cracking
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Solution Overview
Problem
The challenge is to reduce the height of multilayer ceramic capacitors while maintaining their bending strength and preventing solder from wetting onto the element body during mounting, as existing configurations lead to decreased rupture strength and solder-related obstacles in proper mounting.
Innovation Solution
A ceramic electronic component with an element body, external electrodes, and an oxide layer is designed, where the oxide layer has a thinner portion on the top face spaced from the end faces, and the external electrodes are formed to cover the end faces, with a plating layer on the base layer, preventing solder from reaching the top surface during mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the height of the multilayer ceramic capacitor is reduced by making the element body thinner, then the mounting density is increased, but the rupture strength (bending strength) drops and the capacitor often cracks during mounting
Solution Approach 1:
The patent applies preliminary action by forming a protruding portion on the element body before mounting occurs. This protruding portion prevents solder from wetting up onto the element body during the mounting process, thereby preventing cracks before they can occur. The structure is prepared in advance to counteract the potential harmful effect of solder wetting that would compromise the already-thinned element body's strength.
2Reliability
If the terminal electrode extends to the edge electrode portion, then the electrical connection is improved, but the solder moves onto the element body over the edge electrode portion creating an obstacle against proper mounting
Solution Approach 1:
The patent applies segmentation by dividing the electrode structure into distinct functional zones: the terminal electrode for electrical connection and the protruding portion as a separate mechanical barrier. This segmentation allows the terminal electrode to extend to the edge for good electrical connection while the protruding portion physically segments the path, preventing solder from reaching the element body and causing mounting obstacles.
Solution Approach 2:
The protruding portion acts as an intermediary element between the terminal electrode and the element body. It mediates the interaction during mounting by providing a physical barrier that stops solder flow, thereby protecting the element body while allowing the terminal electrode to maintain its electrical connection function without interference.
3Length of moving object
If the element body is made thin to reduce height, then the mounting density increases, but the solder wetting onto the element body causes mounting obstacles
Solution Approach 1:
The patent applies preliminary anti-action by creating a protruding portion that acts as a preventive barrier against solder wetting. This protruding structure is formed in advance on the element body, and during mounting, it actively counteracts the solder's tendency to wet up onto the thin element body, thereby preventing the harmful effect before it can occur.
Data Source
AI summary
A ceramic electronic component includes an element body, two external electrodes, and an oxide layer. The element body includes a dielectric and internal electrodes. The external electrodes are respectively formed to cover, at least partially, two end faces of the element body. Each external electrode includes a base layer and a plating layer. The base layer has a lower part formed on a bottom face of the element body and an end part formed on a corresponding one of the end faces of the element body. The plating layer is formed on at least the lower part of the corresponding base layer. The oxide layer is formed on a predetermined area of a top face of the element body. The oxide layer has a thinner portion in an area on the top face of the element body that is spaced from the end faces of the element body.