Infrared Crack Detection in Ceramic Substrates Without Contact Media
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Solution Overview
Problem
Existing methods for detecting cracks in ceramic substrates, such as Scanning Acoustic Microscopy and high voltage testing, suffer from contamination risks, sample destruction, and low sensitivity, necessitating a more effective and non-destructive detection method.
Innovation Solution
An apparatus and method utilizing infrared cameras and temperature sources to detect cracks by measuring black body radiation differences across sample sections, leveraging thermal resistance and conductivity variations to identify crack planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Scanning Acoustic Microscopy is used to detect cracks, then detection capability is improved, but contamination risk and metal oxidation increase due to contact with coupling medium
Solution Approach 1:
The patent replaces the mechanical contact-based Scanning Acoustic Microscopy with an optical/infrared detection system. The infrared camera detects thermal radiation from the sample surface without requiring physical contact, thereby eliminating the need for coupling media and avoiding contamination and oxidation risks while maintaining crack detection capability
Solution Approach 2:
The patent changes the detection parameter from acoustic wave transmission (requiring coupling medium) to infrared thermal radiation detection. By measuring temperature differences caused by thermal resistance variations at crack locations, the system achieves crack detection without mechanical contact or coupling materials
2Measurement precision
If high voltage test is used to screen ceramic, then defect detection is achieved, but the ceramic is destroyed resulting in yield loss
Solution Approach 1:
The patent converts the destructive high voltage test into a non-destructive thermal detection method. Instead of applying high voltage that causes breakthrough and destruction, the system applies thermal energy and detects temperature variations at defect locations, preserving the ceramic samples while maintaining defect detection capability
Solution Approach 2:
The patent replaces the electrical high voltage testing method with a thermal-infrared detection system. By using infrared cameras to measure temperature distributions on the ceramic surface during heating or cooling, the system identifies defects without causing breakdown or damage to the samples
3Measurement precision
If high voltage test is used for defect screening, then sensitivity to defects is achieved, but the method destroys the sample
Solution Approach 1:
The patent transforms the destructive electrical testing approach into a non-destructive thermal method. Defects are detected through their thermal signature (temperature differences) rather than electrical breakdown, preserving sample integrity while maintaining detection sensitivity
Solution Approach 2:
The patent changes the testing parameter from electrical voltage to thermal temperature. By monitoring temperature variations at defect locations during heating or cooling cycles, the system achieves sensitive defect detection without compromising sample reliability or integrity
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
Provides a non-destructive, high-sensitivity method for detecting cracks in ceramic substrates, suitable for various materials and configurations, enhancing yield and reducing contamination risks.
Implementation Method 1
The one or more infrared camera measures the black body radiation emitted by the sample which depends on the temperature of the sample
Implementation Method 2
The measurement principle is based on the higher thermal resistance of a crack which is typically filled with air. Accordingly heat transfer is reduced across the crack plane so a low temperature region will be formed behind the crack
Implementation Method 3
If the back side of the ceramic is anchored to a fixed temperature, reduced heat flow (due to conductivity difference) will result in higher temperatures in the crack cut plane
Implementation Method 4
If the sample is taken out from an oven, the larger surface area from the crack means higher dissipation to environment and lower temperature on the crack cut plane
Data Source
AI summary
An apparatus for detecting cracks in a plurality of samples includes: a temperature source configured to heat or cool a section of the samples; one or more infrared cameras positioned near one or both sides of the samples and configured to receive infrared image data from the samples; a data acquisition and processing unit configured to generate a two-dimensional image out of the infrared image data to detect cracks in the samples; and a conveyor unit configured to transport the samples past the temperature source and the one or more infrared cameras.