Mounting Substrate Slit Layout for MLCC Bending Stress Relief
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Solution Overview
Problem
Multilayer ceramic capacitors on mounting boards are prone to failure due to mechanical stress when the board is bent, leading to potential short circuits and increased board size and cost when multiple capacitors are used to mitigate this issue.
Innovation Solution
Incorporating a slit in the first wiring pattern with specific dimensions relative to the land, such as a longer length in the second direction and shorter distance to the land, reduces mechanical stress on the capacitors by dispersing board distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multilayer ceramic capacitor is mounted on a land connected to a solid wiring pattern, then voltage stability is improved, but mechanical stress increases causing breakage risk
Solution Approach 1:
The solid wiring pattern is segmented by introducing slits that divide it into multiple regions. This segmentation allows the wiring pattern to flex locally under mechanical stress while maintaining electrical connectivity, thereby reducing stress concentration on the capacitor while preserving voltage stability.
Solution Approach 2:
The physical structure of the wiring pattern is changed by introducing slits with specific dimensions and orientations. These parameter changes (slit length, width, spacing, and orientation relative to the capacitor) transform the rigid solid wiring into a semi-flexible structure that can accommodate board bending without transmitting excessive stress to the capacitor.
2Reliability
If multiple multilayer ceramic capacitors are arranged to prevent failure, then reliability improves, but board size and cost increase
Solution Approach 1:
The mechanical stress factor is extracted and isolated from the capacitor mounting structure by introducing slits in the wiring pattern. This allows a single capacitor to be adequately protected without needing multiple capacitors, thereby preventing failure while maintaining compact board size.
3Power
If the wiring pattern is made solid for large current handling, then current capacity improves, but mechanical flexibility decreases
Solution Approach 1:
The solid wiring pattern is segmented by slits that maintain overall electrical conductivity while allowing local flexibility. The slit configuration is designed to preserve current handling capacity by maintaining adequate conductive path width while introducing flexibility through the segmented structure.
Solution Approach 2:
Different regions of the wiring pattern have different properties: areas near the capacitor have slits to provide flexibility and stress relief, while other areas maintain solid structure for optimal current handling. This local differentiation allows simultaneous optimization of both current capacity and mechanical flexibility.
Data Source
AI summary
A mounting substrate includes two wiring patterns and corresponding two lands for mounting a component. A direction connecting centers of two lands in a plan view is a first direction thereto. A slit is provided within a first wiring pattern adjacent to a first land. A length of the slit is greater than a length of a first land in a second direction. A length of the slit is greater than a length of the first land in the first direction. A distance between an end part of the slit and an end part of the first wiring pattern adjacent the first land is less than the length of the first land. The length of a linear end part of the first wiring pattern is equal to or greater than the length of the first land and is in contact with the first land.