Nondestructive IC Isolation Testing via Gas Breakdown
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Solution Overview
Problem
Current integrated circuit isolation devices (ICIDs) are not adequately tested for defects such as bubbles, voids, or cracks in the encapsulating mold compound, which can lead to high voltage transmission or arcing, and existing testing methods are destructive, failing to verify if devices meet clearance distance criteria without damaging the ICID.
Innovation Solution
A nondestructive testing method involving placing the ICID in a test gas atmosphere with a calculated breakdown voltage less than the ICID's isolation voltage limit, using a variable voltage source to ramp the voltage across the device's conductors while monitoring current, to determine if the ICID fails before reaching the breakdown voltage, thereby identifying defects without damaging the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive testing methods are used to verify clearance distance criteria, then defects such as bubbles, voids, or cracks can be detected, but the ICID is damaged and cannot be used
Solution Approach 1:
A gas atmosphere with a specific breakdown voltage serves as an intermediary medium between the test voltage source and the ICID. The gas breaks down at a controlled voltage level that is lower than the ICID's isolation voltage limit, allowing defect detection through arcing in the gas rather than direct damage to the device. This intermediary enables nondestructive testing by transferring the stress to the gas medium instead of the ICID.
Solution Approach 2:
The testing method changes the electrical parameter (voltage) dynamically during the test process. A variable voltage source ramps the voltage from zero upward, allowing the test to proceed incrementally. This parameter change enables the system to detect defects at the point of breakdown while stopping before reaching the ICID's maximum isolation voltage limit, thus preventing device damage.
2Reliability
If high voltage is applied to test clearance distance, then arcing and defects can be identified, but the ICID may exceed its isolation voltage limit and fail
Solution Approach 1:
The testing method applies a controlled excessive voltage that intentionally exceeds normal operating levels to detect defects, but stops before reaching the harmful threshold that would damage the ICID. The voltage is ramped up to a level sufficient to cause breakdown in defective areas (through the gas medium) but is limited to remain below the ICID's isolation voltage limit,从而实现 partial action that achieves defect detection without complete excessive action that would cause damage.
Solution Approach 2:
The testing system incorporates feedback through current monitoring during the voltage ramp process. When a defect is detected (indicated by abnormal current flow or arcing through the gas), the system receives feedback and stops the voltage increase, preventing further voltage application that would exceed the isolation voltage limit and cause device failure. This feedback mechanism enables real-time control to balance defect detection with device protection.
Data Source
AI summary
A method of testing an integrated circuit clearance distance device (“ICCDD”) having a predetermined clearance distance in air requirement and a predetermined isolation voltage limit including calculating a value of the breakdown voltage at the predetermined clearance distance for at least one gas; and selecting a gas in which the ICCDD has a breakdown voltage that is less than the predetermined isolation voltage.