Probe Needle Current Limiting for High-Current Power Device Testing
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Solution Overview
Problem
Existing methods for testing power semiconductor chips in wafer or chip form face challenges in making reliable contact, leading to potential damage from high current testing and difficulty in identifying contact problems, which can result in yield loss and costly maintenance.
Innovation Solution
A test apparatus with current limiters and sensors is used to limit current flow through each probe and detect excessive current, preventing damage and allowing for real-time monitoring of contact resistance to predict and prevent maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high current testing is performed on power semiconductor chips in wafer or chip form, then the chips can be tested at their rated conditions to ensure proper functionality, but the probes and chips may be damaged due to excessive current flow through individual probes
Solution Approach 1:
The patent divides the current flow into multiple parallel probe paths, with each probe assigned a specific current limit. This segmentation allows high total current to be distributed across multiple probes while preventing any single probe from receiving excessive current that would cause damage. The current limiter circuit implements this by independently controlling each probe's current contribution.
Solution Approach 2:
The patent employs current sensing and feedback control mechanisms that continuously monitor the current flow through each probe and adjust the current delivery accordingly. When a probe approaches its current limit or shows signs of overheating, the feedback system automatically reduces or shuts off current to that probe, preventing damage while maintaining testing capability.
2Power
If multiple probes are used to handle high current, then the total current capacity increases, but it becomes difficult to identify which probe has poor contact or is damaged
Solution Approach 1:
The patent implements individual current monitoring for each probe, providing feedback signals that indicate the current status of each probe connection. This allows the system to detect which probes are carrying expected current and which are experiencing poor contact or damage, enabling identification of problematic probes among the multiple parallel probes.
Solution Approach 2:
The patent employs visual indicators such as LED lights or color-coded markers on or near each probe that change color or illuminate based on the probe's operational status. This provides immediate visual feedback about which probes have good contact and which may be damaged or have poor connection, making it easy to identify problematic probes without complex measurement systems.
3Reliability
If probe tips are pressed firmly against bonding pads to ensure good contact, then contact resistance decreases, but the bonding pads and probe tips may experience mechanical damage or wear
Solution Approach 1:
The patent optimizes the mechanical contact parameters including the applied force, contact area, and material properties to achieve the best balance between electrical contact quality and mechanical durability. By carefully controlling the probe tip geometry, material hardness, and contact pressure, the system achieves low contact resistance without causing excessive wear or damage to either the bonding pads or probe tips.
Data Source
AI summary
A test system, apparatus and method for applying high current test stimuli to a semiconductor device in wafer or chip form includes a plurality of probes for electrically coupling to respective contact points on the semiconductor device, a plurality of current limiters electrically coupled to respective ones of the plurality of probes, and a current sensor electrically coupled to the plurality of probes. The current limiters are operative to limit current flow passing through a respective probe, and the current sensor is operative to provide a signal when detected current in any contact of the plurality of probes exceeds a threshold level.