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Self Calibrating Light Source

Self Calibrating Light Source. Self Calibration of Probe Card Light Source Sponsored By :. What is a Probe Card?. A Probe card is the interface between the Die to be tested and the Test equipment.

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Self Calibrating Light Source

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  1. Self Calibrating Light Source Self Calibration of Probe Card Light Source Sponsored By :

  2. What is a Probe Card? • A Probe card is the interface between the Die to be tested and the Test equipment. • The probe card is positioned over each die and with small probes touches the bond pads to turn the part on and test device

  3. Overview • On Semiconductor has several devices that are light sensing devices. • These Devise measure Ambient and IR light • The primary market for these devices are cellphones but there are other applications. • The tester for these products does not have a light source to stimulate the parts during testing. • A PC board with some LEDs is added to the Probe card to give us a light source.

  4. Current Probe Card Light Source LED PCB Top Headers for interface to Generic J750 Probe Card LED PCB Bottom 2 Ambient LEDs (Osram Obsolete) 1 IR LED (Osram Obsolete)

  5. Light Measurement • We have to know how much light is being exposed to the devices in order to test them to the limits • We have to measure inferred light and ambient light • In order to give us this capability we add a second board to the probe card with calibrated sensors.

  6. Light Measurement Headers for interface to Generic J750 Probe Card Ambient Light Sensor Inferred Light Sensor • Ambient Light (400nm – 700nm) • Inferred Light (850nm) • Both of the Sensors are ON semi proto type parts that are now obsolete and need to be replaced

  7. CalibrationSystem Using 2 Sensors board, (one on top and one on bottom of the probe card),the Light source is manually tested and calibrated on a Test bench before it is used on the test floor. This process is done manually is time consuming and tedious Results are good but inconsistent from Board to board

  8. Problems: • Inconsistent Light from the LED light source • Inconsistent light from probe card to probe cade • Inconsistent light from site to site, 12 sits tested at a time • No on site calibration for the light source • Only Manual calibration of the light source is currently available • Must be calibrated on a test bench away from the tester. • This waists tester time and engineering resources.

  9. Illustration of the Problem: Approximate Ambient Light Pattern Ambient LEDs LED PC board Approximate Inferred Light Pattern Wafer Die 12 sites Inferred LEDs

  10. Solution: • The solution to the problem is to build a new probe card with a better measurement system and better light source management • We have to solve three problems • We have to build a better Light source • We have to provide a better measurement system • Both the Light Source and the measurement system have to be compatible with a calibration algorithm

  11. Project Proposal • The proposal is a three part process. • build a light source that will provide a better average of light over a wider area • Build a better system for measuring the light. • We will need more measurement location • Verify all individual LEDs are working. • Use off the shelf parts for easier long term maintenance. • High consistency from part to part • Create an algorithm that will adjust the light level automatically and compensate for LED difference from part to part and degradation overtime

  12. Participants • There is a need for two to three participants on this project • Hardware Designer • Probe Card and LED PC board layout • Tester interface and resource management • Lighting and Measurement Designer • Light distribution for IR and Ambient Sources • Light distribution model using Matlab • Measurement scheme and hardware • Algorithm Development • Develop a process of measuring the light and adjusting the light source but can not change the response of the LEDs • Test each individual LED to verify functionality

  13. Project Opportunity With a Potential Employer Thanks for your time Samuel Anderson

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