Ceramic Capacitor Defect Inspection via Transient Vibration Response
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Solution Overview
Problem
Conventional methods for detecting internal defects in ceramic capacitors are inefficient due to instability in measurement, insufficient sensitivity, and high complexity, making them unsuitable for high-speed production line applications.
Innovation Solution
A capacitor inspection method that applies a DC bias voltage and switches between different electric signal waveforms to generate transient vibrations, allowing for the measurement of transient response waveforms to determine capacitor quality without requiring external vibration sources or complex equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasonic microscopy is used for defect detection, then sensitivity to internal defects is improved, but measurement time increases and productivity decreases
Solution Approach 1:
The patent replaces the mechanical ultrasonic vibration system with an electrical excitation system. Instead of using external ultrasonic waves to vibrate the capacitor, the invention applies electrical signals directly to the capacitor terminals, utilizing the piezoelectric effect to generate mechanical vibrations internally. This substitution eliminates the need for complex mechanical coupling and medium transmission, enabling faster measurement while maintaining defect detection sensitivity.
Solution Approach 2:
The capacitor under inspection serves its own inspection function by converting electrical energy to mechanical vibration through its inherent piezoelectric properties. The capacitor's own structure and material properties are utilized to generate the vibration needed for defect detection, eliminating the need for external vibration sources and complex inspection equipment.
2Measurement precision
If electromechanical resonance method with frequency sweeping is used, then defect detection capability is improved, but inspection time increases substantially
Solution Approach 1:
The patent employs periodic excitation signals with specific frequencies that correspond to the natural resonance frequencies of the capacitor. By using periodic signals rather than continuous frequency sweeping, the method quickly excites the resonant modes of the capacitor structure, enabling rapid defect detection without the time-consuming process of sweeping through all possible frequencies.
Solution Approach 2:
The invention changes the excitation parameters (frequency, amplitude, waveform) to match the specific resonance characteristics of the capacitor being inspected. By adjusting these parameters to optimize resonance excitation, the method achieves high defect detection capability in minimal time, avoiding the need for exhaustive frequency sweeps.
3Measurement precision
If DC bias voltage and waveform switching are applied, then transient vibration response is generated for defect detection, but system complexity increases
Solution Approach 1:
The capacitor's own piezoelectric properties are utilized to convert the applied electrical signals into mechanical vibrations. The system leverages the inherent characteristics of the capacitor structure and material to generate the necessary vibration response, eliminating the need for external vibration sources, coupling media, or complex mechanical assemblies.
Solution Approach 2:
The patent replaces complex mechanical vibration generation and transmission systems with a simple electrical excitation system. Instead of using external ultrasonic transducers, mechanical couplants, and vibration tables, the invention uses electrical signals applied to the capacitor terminals, significantly simplifying the system configuration while maintaining or improving measurement precision.
4Productivity
If conventional electrical characteristic tests are performed, then production line compatibility is maintained, but sensitivity to mechanical defects is insufficient
Solution Approach 1:
The patent applies periodic excitation signals to the capacitor during inspection, causing the capacitor structure to vibrate at its natural resonance frequencies. This periodic vibration generates characteristic responses that are highly sensitive to mechanical defects such as cracks, delamination, and voids, while maintaining compatibility with production line testing protocols and timelines.
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 method enables fast, reliable, and accurate detection of internal defects in capacitors, reducing inspection time to milliseconds and allowing for high-speed production line implementation with simple and cost-effective equipment.
Implementation Method 1
When an oscillating electric field (voltage) is applied to a capacitor, mechanical vibration can be generated due to inverse piezoelectric effect
Implementation Method 2
The amplified mechanical vibration in turn generates electric field due to piezoelectric effect
Implementation Method 3
When the frequency of the applied electric field approaches to one of the resonance frequencies of the structure, amplitude of the mechanical vibration increases. The amplified mechanical vibration in turn generates electric field due to piezoelectric effect. The electric field generated by mechanical vibration is observed as additional potential difference across the capacitor. This generation of electric signal due to resonance with a mechanical oscillation is a phenomenon called electromechanical resonance.
Data Source
AI summary
A capacitor inspection method includes applying a direct current (DC) bias voltage to an inspection capacitor with a value which is equal to or lower than a rated value of the inspection capacitor; inputting a first electric signal to the inspection capacitor, switching the input electric signal from the first electric signal to a second electric signal having a different waveform than the first electric signal and thereby generating a vibration containing a transient vibration in the inspection capacitor and eliciting a reaction voltage as an output from the inspection capacitor which contains a vibration response voltage generated by the vibration and the DC bias voltage; and measuring a transient response waveform from the vibration response voltage contained in the reaction voltage. A capacitor inspection apparatus includes a holder for the inspection capacitor; a DC voltage supply device; a signal generator; and a voltage or current measurement device.