Needle Probe Card Safety System for High-Voltage Power Semiconductor Testing
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Solution Overview
Problem
Current safety systems for needle probe cards fail to effectively interrupt the power supply to all needles in case of overcurrent in one needle, leading to potential damage to the device under test, the support structure, and the probe card, especially during high-voltage and high-current testing of power semiconductor devices, where parasitic inductances cause overvoltages and overheating.
Innovation Solution
A safety system comprising a control unit and switching devices associated with each needle, capable of selectively interrupting current flow in individual needles, ensuring that if an overcurrent is detected in one needle, the current can be quickly and fully interrupted across all needles, preventing damage and maintaining low parasitic inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety system monitors total input current to the probe card and interrupts current only when total current exceeds a predetermined value, then the system provides basic overcurrent protection, but it fails to interrupt current in individual needles when local overcurrent occurs, leading to potential damage to the device under test, support structure, and probe card
Solution Approach 1:
The safety system is segmented into multiple independent protection units, with each needle having its own monitoring and switching device. This allows localized overcurrent detection and interruption for each needle independently, preventing damage while maintaining overall system safety without requiring complete system shutdown for single-needle issues.
Solution Approach 2:
Switching devices are introduced as intermediary elements between the power supply and each needle. These switching devices act as mediators that can rapidly interrupt current flow to individual needles when overcurrent is detected, providing precise control and protection without affecting other needles or requiring complex total-current monitoring schemes.
2Power
If high current is applied to multiple needles simultaneously to achieve high-voltage and high-current testing, then the testing capability is improved, but parasitic inductances cause overvoltages during switching that can damage the device under test and test machine
Solution Approach 1:
The high-power testing capability is achieved through segmentation of current paths into multiple independent needle channels. Each channel can be controlled independently with its own switching device, allowing high total current to be distributed across multiple low-inductance paths, reducing parasitic effects while maintaining high power capability.
Solution Approach 2:
The switching devices are designed to operate extremely rapidly, skipping through the transient period where parasitic inductances would generate damaging overvoltages. The fast switching action completes the current interruption before significant voltage spikes can develop across the parasitic inductances, enabling high-power testing without overvoltage damage.
3Reliability
If the safety system interrupts current in one needle, then local overcurrent is stopped, but current may redistribute to other needles causing them to exceed their current ratings and fail
Solution Approach 1:
The electrical system is segmented into independent needle channels, each with its own switching device and current monitoring. When one needle experiences overcurrent, only that specific channel is interrupted while other channels continue operating independently. This prevents current redistribution to healthy needles and maintains overall system productivity by isolating failures to individual channels.
Data Source
AI summary
A safety system for a needle probe card for test machines for high-voltage and high-current testing of power semiconductor electronic devices is provided. The needle probe card has a plurality of needles adapted to be placed in contact with a device under test (DUT), each needle being configured to allow a flow of electric current. The safety system has a control unit capable of determining the electric current flowing in every single needle, and a plurality of switching devices configured to selectively interrupt the electric current flowing in the needles. At least one switching device is associated with each needle of the needle probe card. The control unit is configured to drive every single switching device to selectively interrupt the flow of electric current in a corresponding needle.