Series Ceramic Capacitor Layout to Prevent Simultaneous Short Circuits
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Solution Overview
Problem
Existing capacitor arrangements on wiring boards fail to prevent simultaneous short circuits in monolithic ceramic capacitors connected in series due to shared stress application, leading to potential large current flow between different DC potentials.
Innovation Solution
Arrange monolithic ceramic capacitors on the wiring board such that their mounting directions form an angle of 45±5 degrees relative to each other to differ the direction of stress application, reducing the likelihood of cracks and subsequent short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monolithic ceramic capacitors are connected in series between different DC potentials, then insulation is maintained and large current flow is prevented when one capacitor short circuits, but all capacitors may be cracked simultaneously due to shared stress application
Solution Approach 1:
The patent applies asymmetry by arranging capacitors with different mounting directions (first direction vs. second direction) relative to the stress application direction. This asymmetric arrangement ensures that when stress is applied to the wiring board, each capacitor experiences stress in different directions, preventing simultaneous cracking while maintaining the series connection for insulation protection.
2Area of stationary object
If monolithic ceramic capacitors are mounted at a short distance from each other, then space is saved on the wiring board, but the same stress is applied to each capacitor causing all to crack simultaneously
Solution Approach 1:
The patent uses asymmetry in mounting directions to differentiate the stress experience of each capacitor. Even when capacitors are mounted close together to save space, their different orientations ensure that stress applied to the board does not affect all capacitors equally, thus preventing simultaneous failure while maintaining compact arrangement.
3Object-generated harmful factors
If capacitor arrangement angles are changed to reduce vibration, then noise is alleviated, but simultaneous short circuit due to stress-induced cracking is not prevented
Solution Approach 1:
The patent extends the angle adjustment concept from vibration reduction to stress distribution. By setting specific angle relationships between capacitor mounting directions, the patent simultaneously achieves vibration noise reduction and prevents stress-induced simultaneous cracking, addressing both harmful effects through asymmetric arrangement.
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
Prevents simultaneous short circuits and large current flow by minimizing stress alignment on individual capacitors, ensuring continued operation even if one capacitor fails.
Implementation Method 1
when an audio-frequency range voltage superimposed on a direct current (DC) voltage is applied to a monolithic ceramic capacitor used in a switching circuit, an inverse piezoelectric effect corresponding to an alternating current (AC) component of the electric field occurs. Then, a body of the monolithic ceramic capacitor resonates at a natural frequency thereof and vibrates
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
A wiring board (1) includes a substrate (10) and a plurality of monolithic ceramic capacitors (C1,C2) connected in series on the substrate (10). The plurality of monolithic ceramic capacitors (C1,C2) includes a first monolithic ceramic capacitor (C1) oriented in a first direction; and a second monolithic ceramic capacitor (C2) oriented in a second direction. The second direction is at an angle of 45±5 degrees relative to the first direction.