Multilayer Ceramic Capacitor Mounting Surface for Stronger Solder Bonding
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Solution Overview
Problem
Multilayer ceramic capacitors experience poor bonding strength to circuit boards due to stress concentration at the interface between terminal electrodes and solder, leading to delamination, especially at the corners of terminal electrodes with small areas.
Innovation Solution
The multilayer ceramic capacitor design includes recessed regions on the mounting surface where terminal electrodes are not arranged, with specific dimensions and arrangements to enhance bonding strength by allowing solder to flow and solidify in these areas, increasing contact area and reducing stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If terminal electrodes are arranged on a flat mounting surface, then the capacitor structure is simple, but bonding strength to circuit board is poor due to stress concentration at interface
Solution Approach 1:
The mounting surface is divided into different regions with different heights: a first region at the corner with a first height, a second region adjacent to the first region with a second height lower than the first height, and a third region with a third height lower than the second height. This local quality variation creates a stepped structure that distributes stress more effectively at the solder interface, improving bonding strength without requiring overall structural complexity
Solution Approach 2:
The invention transitions from a two-dimensional flat mounting surface to a three-dimensional stepped structure by creating regions with different heights in the vertical dimension. This dimensional change allows the solder to form a more distributed bonding interface, reducing stress concentration at the corner regions while maintaining electrical connectivity
2Volume of moving object
If terminal electrodes have small area, then capacitor size is reduced, but stress concentration at interface increases causing delamination
Solution Approach 1:
The stepped structure creates local quality variations at the mounting surface, with the first region at the corner having the greatest height to provide enhanced stress distribution, the second region having intermediate height, and the third region having the lowest height. This allows small terminal electrodes to maintain reliability through geometric optimization rather than size increase
Solution Approach 2:
The stepped structure with multiple height levels creates curved transition surfaces between regions, which helps distribute stress more evenly compared to sharp corners. The curved surfaces of the stepped structure reduce stress concentration points while maintaining compact capacitor dimensions
Data Source
AI summary
A multilayer ceramic capacitor includes a cuboid element body having a multilayer unit alternately laminating ceramic layers and internal electrodes composed primarily of metal, a pair of covering portions arranged at both ends of the multilayer unit in the laminating direction and covering surfaces of the multilayer unit, and margin portions covering at least some of the end portions of the ceramic layers and the internal electrodes in the multilayer unit, and connecting the pair of covering portions to each other; and a plurality of terminal electrodes electrically connected to the internal electrodes, and arranged in a spaced-apart manner on a mounting surface, which is one of the surfaces forming the surfaces of the element body, facing the circuit board during circuit board mounting, wherein the plurality of terminal electrodes are arranged in m units in a first direction on the mounting surface and n units in a second direction perpendicular to the first direction (where m is a natural number equal to or greater than 2 and n is a natural number), a region in which the terminal electrodes are not arranged on the mounting surface has a mounting surface side intersection portion in which a first straight line and a second straight line intersect, and a mounting surface side non-intersection portion in which the first straight line and the second straight line do not intersect, when the first straight line is drawn to extend in the first direction without touching any of the terminal electrodes and the second straight line is drawn to extend in the second direction without touching any of the terminal electrodes, and the element body satisfies T1<T2, where T1 is a dimension in the laminating direction of the element body, as measured with reference to a mounting surface side intersection portion, and T2 is a dimension in the laminating direction of the element body, as measured with reference to a mounting surface side non-intersection portion.