MLCC Bump Geometry to Block Solder Fillets and Squeak
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Solution Overview
Problem
The transmission of squeaking vibrations from multilayer ceramic capacitors to substrates occurs due to the formation of a solder fillet along the bump side, which reduces the squeak-preventing effect.
Innovation Solution
The multilayer ceramic capacitors are designed with bumps that project beyond their central portions in the lamination direction, preventing solder wetting and reducing vibration transmission to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bump is formed to cover a portion of the outer electrode to suppress squeak, then the squeak preventing effect is improved, but solder forms a fillet along the bump side surface that reaches the capacitor main body, transmitting squeak vibrations to the substrate and reducing the squeak preventing effect
Solution Approach 1:
The bump is designed with an asymmetric cross-sectional shape where the upper portion width is smaller than the lower portion width. This asymmetric geometry prevents solder from forming a continuous fillet along the bump side surface, thereby blocking the transmission path of squeak vibrations from the capacitor main body to the substrate while maintaining the squeak suppressing function.
Solution Approach 2:
The bump serves as an intermediary element between the capacitor main body and the substrate. By positioning the bump between these components and designing its asymmetric shape, it interrupts the direct vibration transmission path that would otherwise exist through a standard solder fillet, thus acting as a mediator to reduce harmful vibration transmission.
2Ease of operation
If solder is used to attach the capacitor to the substrate, then electrical connection and mechanical attachment are achieved, but the solder fillet transmits vibrations from the capacitor inner layer to the substrate
Solution Approach 1:
The asymmetric cross-sectional shape of the bump (narrower upper portion, wider lower portion) modifies how solder interacts with the bump structure. This geometry prevents the formation of a continuous solder fillet that would bridge the bump to the capacitor main body, thereby blocking vibration transmission while preserving the solder's attachment and electrical connection functions.
Solution Approach 2:
The invention converts the potential harm of solder fillet formation into a benefit by using the bump's asymmetric shape to control solder flow. The solder still provides necessary attachment and electrical connection, but its flow is restricted from forming a vibration-transmitting fillet, thus transforming a harmful effect into a controlled, beneficial outcome.
Data Source
AI summary
A multilayer ceramic capacitor includes a multilayer body including a dielectric layer and an inner electrode layer alternately laminated, an outer electrode layer on each of two end surfaces at both ends in a length direction perpendicular to a lamination direction of the multilayer body and covering end surface sides of two main surfaces at both ends in the lamination direction and end surface sides of two side surfaces in the width direction and including a base electrode layer connected to the inner electrode layer, and a bump on each of the two end surface sides to hold therebetween the base electrode layer, covering the main surface side, and including a resin and a metal. In each bump, an end surface-side portion near the end surface on the side where the bump is located, projects more than a central portion of the bump toward an outside in the lamination direction.