Electronic Assembly Testing with Ultrasonic Signals for Defect Detection
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Solution Overview
Problem
Existing methods for quality control and condition monitoring of electronic assemblies, particularly power-electronic assemblies, are inadequate in detecting manufacturing defects and aging-induced damage, such as delamination, cracks, and material aging, especially in optically inaccessible areas or during operation, leading to inaccurate service life predictions and unplanned outages.
Innovation Solution
An electrical characterization method using ultrasonic waves to excite component parts of electronic assemblies, combined with impedance spectroscopy and signal analysis, to detect material changes and defects by comparing impedance spectra with and without ultrasonic excitation, allowing for non-destructive and reliable detection of defects and aging-induced damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical imaging and electrical testing are used to examine electronic assemblies, then quality control can be performed, but detection reliability for certain defects (printed circuit board warping, large-scale blowholes, delamination, inadequate laser weld joints) is insufficient
Solution Approach 1:
The patent applies mechanical vibration in the form of ultrasonic waves to excite the electronic assembly. This vibration causes material changes that alter the electrical characterization signals, enabling detection of defects such as delamination, cracks, and warping that are invisible to optical imaging and electrical testing alone
Solution Approach 2:
The patent introduces ultrasonic waves as an intermediary that mediates between the examination system and the electronic assembly. The ultrasonic excitation acts as a mediator that translates mechanical defects into detectable electrical signal changes through the piezoelectric effect in the semiconductor chip
2Reliability
If model-based estimation methods and impedance spectroscopy are used for condition monitoring, then service life prediction can be attempted, but accuracy is very poor due to high complexity of dependencies and small signal sizes
Solution Approach 1:
Ultrasonic vibration is applied to the electronic assembly to amplify mechanical signals related to aging and defects. This vibration enhances the detectability of material changes in solder joints, bonding wires, and chip metallizations, providing clearer indicators for service life prediction without requiring complex models
Solution Approach 2:
The patent changes the physical state of the electronic assembly by applying ultrasonic excitation, which induces material changes that alter electrical parameters. These parameter changes provide more accurate and interpretable signals for condition monitoring and service life prediction compared to passive impedance spectroscopy
3Reliability
If preventive replacement of power modules is performed to avoid unexpected shutdowns, then operational reliability can be maintained, but productivity is reduced due to unnecessary replacements and downtime
Solution Approach 1:
The patent enables preliminary detection of aging and defects through ultrasonic excitation and electrical characterization before critical failures occur. This allows for condition-based maintenance planning that replaces modules only when actually needed, avoiding both unexpected shutdowns and unnecessary preventive replacements
Solution Approach 2:
The system provides continuous feedback on the condition of power modules through ultrasonic-based electrical characterization. This feedback enables real-time monitoring of aging processes and defect development, allowing operators to make informed decisions about maintenance timing to optimize both reliability and productivity
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
Enables reliable, non-destructive detection of defects and aging-induced damage during operation, facilitating predictive maintenance and improving service life predictions, particularly in power-electronic assemblies, by amplifying mechanical signals indicative of defects and allowing continuous monitoring.
Implementation Method 1
the examined component part is excited by means of ultrasonic waves (130) in such a way that alterations in the signal of the electrical characterization method are caused thereby
Implementation Method 2
at least one impedance spectrum (Zus, Zo) is determined by means of a measurement device (200)
Data Source
AI summary
Various embodiments of the teachings herein include a method for quality testing an electronic assembly. An example includes: examining a component part of the electronic assembly including generating a electrical signal and exciting the examined component part using ultrasonic waves; evaluating resulting alterations in the electrical signal of using signal analysis; and determining material changes in the component part based on the evaluation.