Kelvin Connection Wire-Bond Defect Detection Circuit
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Solution Overview
Problem
Power semiconductor devices face defects in wire-bonds due to thermal stresses, leading to potential device failure, which can be hazardous and costly, as existing detection methods are not accurate or timely in identifying bond-wire issues before they cause damage.
Innovation Solution
A circuit and method that utilize a Kelvin connection to detect wire-bond failures by comparing gate and wire-bond signals with adjustable thresholds, allowing for accurate detection of defects during switching cycles, excluding transient effects and providing a versatile critical defect level for triggering responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal cycling is performed to switch the power device, then the power device can operate and perform its function, but thermal stresses cause bond-wire cracking or lifting-off leading to device failure
Solution Approach 1:
The patent applies preliminary action by detecting wire-bond defects before they cause complete device failure. The detection circuit continuously monitors wire-bond integrity during operation and triggers an alarm signal when defects are detected, allowing preventive maintenance before catastrophic failure occurs.
Solution Approach 2:
The patent implements feedback through a detection circuit that continuously monitors wire-bond status and provides real-time information about bond-wire integrity. The circuit compares detected signals against reference values and provides feedback signals that indicate when wire-bond defects have developed, enabling continuous monitoring and preventive action.
2Reliability
If wire-bond defects are detected early, then device failure can be prevented, but detection accuracy must distinguish between normal operation and actual defects
Solution Approach 1:
The patent applies parameter changes by using multiple detection thresholds and comparison circuits that evaluate wire-bond signals at different reference levels. The detection circuit changes detection parameters dynamically, comparing signals against multiple reference values to distinguish between normal operational variations and actual wire-bond defects, thereby improving measurement precision.
Solution Approach 2:
The patent applies local quality by implementing separate detection circuits for different aspects of wire-bond monitoring. The system uses specialized comparison circuits that evaluate specific signal characteristics locally, allowing precise discrimination between normal operation and defects by focusing on localized signal features rather than overall signal analysis.
3Difficulty of detecting and measuring
If detection circuits are added to monitor wire-bond status, then defect detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by integrating the detection circuit functionality into the existing power device structure. The detection circuit shares common components and signal paths with the power device operation, combining monitoring functions with the existing circuit architecture rather than adding completely separate monitoring systems, thereby reducing overall complexity.
Solution Approach 2:
The patent applies universality by designing detection circuit components that serve multiple functions. The comparison circuits and detection elements are configured to perform both normal power device operation and wire-bond defect detection using shared components, allowing a single circuit structure to fulfill multiple roles and reducing the need for separate dedicated monitoring hardware.
Data Source
AI summary
A circuit and method for detecting a failure of a switching power device is disclosed. The circuit and method utilize a Kelvin connection of a four-terminal configuration of the switching power device to sense a resistance of at least one wire-bond. The resistance corresponds to a defect or defects in the at least one wire-bond and so it can be used to detect a failure before damage occurs. A threshold used for detecting the failure can be adjusted to accommodate variations in the switching power device and/or the application in which it is being used. Additionally, the failure detection is carried out at a period after the switching power device is turned ON to prevent switching transients from affecting the detection.