MLCC Mounting Structure With Pad Layout for Acoustic Noise Reduction
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Solution Overview
Problem
Multilayer ceramic capacitors generate acoustic noise due to piezoelectric vibrations, which can be unpleasant and interfere with device functionality, especially in quiet operating environments and voice circuit devices.
Innovation Solution
A multilayer ceramic capacitor mounted structure is designed with specific electrode pad placement and insulating layers to minimize the attachment area based on the ceramic body's expansion and contraction direction, reducing acoustic noise by controlling the conductive bonding member's position and extent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the multilayer ceramic capacitor is mounted with large electrode pads and extensive conductive bonding members, then the electrical connection and mechanical stability are improved, but the acoustic noise increases due to greater vibration transmission
Solution Approach 1:
The patent applies local quality by creating an insulating layer with non-uniform thickness: a first insulating layer with greater thickness at positions corresponding to internal electrodes, and a second insulating layer with lesser thickness at other positions. This localized variation in insulating layer thickness provides differential vibration damping exactly where needed (at internal electrode locations) while maintaining adequate electrical connection elsewhere, thus reducing acoustic noise without compromising overall mechanical stability.
Solution Approach 2:
The insulating layer acts as an intermediary substance between the internal electrodes and the external environment. By positioning the insulating layer at specific locations corresponding to internal electrodes, it serves as a mediator that absorbs and dampens vibrations generated by the piezoelectric effect, thereby reducing the transmission of acoustic noise to the substrate while still allowing the capacitor to function electrically.
2Reliability
If the conductive bonding member is extended to cover the entire external electrode, then the electrical conductivity and mechanical strength are improved, but the acoustic noise increases due to increased attachment area
Solution Approach 1:
The patent implements local quality by making the insulating layer thickness position-dependent: thicker regions are placed at locations corresponding to internal electrodes where vibration occurs, while thinner regions are placed at other locations. This localized differentiation allows the structure to provide enhanced vibration damping precisely where needed without unnecessarily increasing the overall attachment area, thus maintaining electrical conductivity while reducing acoustic noise.
Solution Approach 2:
The patent applies partial action by providing the insulating layer only at specific positions corresponding to internal electrodes, rather than uniformly across the entire external electrode. This selective placement of the insulating layer (partial action) is sufficient to dampen the vibrations generated by internal electrodes, achieving acoustic noise reduction without the need for extensive coverage that would increase attachment area and potentially worsen noise.
3Object-generated harmful factors
If the insulating layer is applied uniformly across the entire external electrode, then the vibration damping is improved, but the electrical connection and mechanical stability are compromised
Solution Approach 1:
The patent resolves this contradiction by applying the insulating layer with locally varied thickness rather than uniform thickness. The first insulating layer with greater thickness is positioned at locations corresponding to internal electrodes to provide vibration damping, while the second insulating layer with lesser thickness is positioned at other locations to maintain electrical connection. This local quality approach ensures vibration damping is provided where needed without compromising overall electrical connectivity.
Solution Approach 2:
The patent uses partial action by applying the insulating layer selectively only at positions corresponding to internal electrodes, rather than uniformly across the entire external electrode. This partial application is sufficient to dampen vibrations from the internal electrodes (the source of noise) while leaving other areas with adequate electrical connection properties, thus achieving noise reduction without compromising electrical connectivity.
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
This configuration effectively reduces acoustic noise by limiting the area of attachment to the substrate, minimizing vibrations and noise generation, thereby enhancing the operational quietness and performance of electronic devices.
Implementation Method 1
the dielectric layers are piezoelectric, and thus when a DC or AC voltage is applied to the multilayer ceramic capacitor, a piezoelectric phenomenon occurs between the internal electrodes, thereby generating periodic vibrations while expanding and contracting a volume of ceramic bodies thereof depending on a frequency
Implementation Method 2
a first insulating layer having a greater thickness at positions corresponding to internal electrodes than at other positions, and a second insulating layer having a lesser thickness at positions corresponding to the internal electrodes than at other positions
Data Source
AI summary
A multilayer ceramic capacitor mounted structure relates to a structure in which a multilayer ceramic capacitor is mounted on a circuit board through electrode pads. The multilayer ceramic capacitor may include: a ceramic body including a plurality of dielectric layers stacked with a length, a width, and a thickness of a preset size; external electrodes spaced apart from each other along a longitudinal direction of the ceramic body, each of the external electrodes being disposed on at least opposite sides in a width direction of the ceramic body; and a plurality of internal electrodes alternately stacked with the dielectric layers therebetween and respectively connected to the external electrodes in the ceramic body, and edges of the external electrodes may be aligned with outer edges of the electrode pads or positioned at least more outwardly than the outer edges of the electrode pads, at opposite ends along the longitudinal direction of the ceramic body.