Stacked Ceramic Capacitor Mounting Structure for Acoustic Noise Reduction
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Solution Overview
Problem
Miniaturization and thinning of laminated capacitors lead to significant electric-field-induced strain, causing acoustic noise when mounted on circuit substrates due to transmitted vibrations, which is difficult to suppress, especially in high-dielectric-constant materials like barium titanate.
Innovation Solution
A mounting structure and method involving a first ceramic electronic component with a low strain amount and a second component with a higher strain amount, stacked and connected via outer electrodes, where the first component is connected to the circuit substrate, effectively absorbing the larger strain of the second component to reduce vibration and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If miniaturization and thinning of laminated capacitors are pursued, then capacitance density is improved, but electric-field-induced strain increases causing acoustic noise
Solution Approach 1:
The invention divides a single high-capacitance component into multiple stacked ceramic electronic components with lower individual capacitances. By segmenting the total capacitance requirement across multiple components (e.g., two 10μF components instead of one 20μF component), the electric-field-induced strain in each component is reduced, thereby suppressing acoustic noise while maintaining the required total capacitance.
Solution Approach 2:
The invention changes the electrical parameters by distributing the voltage application across multiple components with different capacitance values. By configuring components with specific capacitance ratios (e.g., C1:C2 = 1:2 or 1:3) and connecting them in series, the voltage distribution across each component is optimized to minimize strain and acoustic noise generation.
2Quantity of substance
If high-dielectric-constant materials like barium titanate are used, then capacitance is improved, but electric-field-induced strain occurs causing acoustic noise
Solution Approach 1:
The invention segments the high-capacitance requirement into multiple components using high-dielectric-constant materials. By dividing the total capacitance into smaller units (e.g., multiple 10μF components to achieve 20μF total), each component experiences reduced electric field strength, which suppresses the piezoelectric effect and acoustic noise while maintaining the use of high-performance dielectric materials.
Solution Approach 2:
The invention employs composite mounting structures combining multiple ceramic electronic components with different capacitance values. By creating a stacked configuration of components with varying dielectric properties and capacitance ratios, the system achieves high total capacitance while the individual component strains are minimized through proper voltage distribution.
3Device complexity
If a single ceramic electronic component is mounted on a circuit substrate, then device complexity is reduced, but acoustic noise is generated due to strain transmission
Solution Approach 1:
The invention segments the mounting structure into multiple stacked ceramic electronic components connected in series. This segmentation allows the total capacitance to be distributed across components with lower individual strains, reducing acoustic noise transmission to the circuit substrate while maintaining a relatively simple vertical stacking configuration.
Solution Approach 2:
The invention introduces intermediate components in the mounting structure that act as strain-absorbing elements. The stacked configuration with components of different capacitance values creates an intermediary structure that absorbs and distributes mechanical strain, preventing direct transmission of acoustic noise to the circuit substrate.
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
Significantly reduces or prevents acoustic noise by attenuating strain transmission to the circuit substrate, as demonstrated by sound pressure level reductions of up to 20 dB compared to independent mounting, with the strain absorption mechanism ensuring minimal vibration at the joint point.
Implementation Method 1
when a voltage including a ripple component is applied, an electric-field-induced strain occurs in a capacitance portion, and a laminated body expands and contracts
Data Source
AI summary
A mounting structure includes a first ceramic electronic component including a ceramic body including internal electrodes and outer electrodes. When a voltage is applied to the outer electrodes, the ceramic body is strained with a first strain amount, and a second ceramic electronic component including a ceramic body including internal electrodes and outer electrodes. When a voltage is applied to the outer electrodes, the ceramic body is strained with a second strain amount greater than the first strain amount. The second ceramic electronic component is arranged above the first ceramic electronic component, and the first and second ceramic electronic components are connected to each other via each other's outer electrodes. The first ceramic electronic component to which the second ceramic electronic component is connected is connected to a land on a circuit substrate via the outer electrodes of at least the first ceramic electronic component.