Integrated LED Probe Card Illumination for Photosensitive Chip Testing
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Solution Overview
Problem
Existing test devices for photosensitive chips face challenges in flexibility, light uniformity, and efficiency due to complex opto-mechanical systems, limited light source stability, and the need for high power, which hinders parallel testing and adaptability in production lines.
Innovation Solution
A probe card with integrated lighting means, such as LEDs, positioned close to the wafer, receiving energy and control signals directly from the test head, allowing for flexible and uniform illumination of chips during testing, and featuring a removable and controllable lighting system to ensure safety and efficient testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a complex opto-mechanical system with external light sources is used to illuminate the wafer, then the illumination can cover a large area, but the device complexity increases and the light uniformity becomes difficult to achieve
Solution Approach 1:
The patent merges the light source with the probe card by integrating LED elements directly into the card structure. This combination eliminates the need for separate external illumination systems and complex opto-mechanical components, while still providing sufficient illumination area for parallel chip testing
Solution Approach 2:
The patent replaces complex mechanical opto-mechanical illumination systems with solid-state LED light sources integrated into the probe card. This substitution eliminates moving parts and complex mechanical adjustments, simplifying the overall system while maintaining illumination effectiveness
2Power
If high power light sources are used to provide sufficient illumination energy, then the light intensity is adequate, but the light source stability decreases and the system requires more power
Solution Approach 1:
The patent employs LED light sources that are integrated into the probe card, replacing traditional high-power halogen lamps. LEDs consume less power, have longer operational lifetimes, and provide stable light output without the degradation issues associated with high-power thermal light sources
Solution Approach 2:
The patent changes the fundamental parameters of the light source by transitioning from thermal radiation sources (halogen) to electroluminescent sources (LEDs). This parameter change results in lower power consumption, improved stability, and extended operational life while maintaining adequate illumination intensity
3Device complexity
If the light source is placed outside the test head, then the test head structure is simpler, but the overall device size increases and light delivery becomes more complex
Solution Approach 1:
The patent nests the light sources within the probe card structure, which itself is integrated into the test head assembly. This nested arrangement allows the illumination system to be compact and self-contained, eliminating the need for external light sources and reducing the overall device footprint
4Power
If conventional halogen lamps are used as light sources, then sufficient light energy is produced, but the optical properties are neither uniform nor stable in time
Solution Approach 1:
The patent replaces unstable halogen lamp sources with LED elements that provide consistent optical properties over time. LEDs have no filament degradation, no bulb blackening, and maintain stable spectral characteristics and intensity output throughout their operational lifetime
Solution Approach 2:
The integrated LED sources in the probe card provide self-contained illumination without requiring external stabilization systems. The LEDs inherently maintain uniform optical properties through their solid-state construction, eliminating the need for additional optical uniformity correction mechanisms
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
This configuration enables efficient, flexible, and uniform illumination of multiple chips in parallel, reducing production line downtime and improving testing accuracy by integrating the light source close to the wafer, thus overcoming the limitations of conventional test devices.
Implementation Method 1
A probe card with integrated lighting means, such as LEDs, positioned close to the wafer
Data Source
AI summary
A probe card and its corresponding illumination device are provided for performing electrical operating tests, preferably done in parallel, with respect to a plurality of chips provided with connection pads, under illumination conditions given by a lighting source, the probe card being a printed circuit board (PCB) including electrical connections to the chip on its lower face, the probe card also including electrical connections to the lighting.