Resistive Sensor Calibration via Joule Heating and Extraction
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Solution Overview
Problem
Current integrated circuit (IC) production faces challenges in accurately calibrating resistive sensors due to variations in resistive material properties and geometric variations, requiring extensive factory-level testing in a thermally-controlled environment, which is costly and time-consuming.
Innovation Solution
A system and method for on-line, package-level, die-level, or wafer-level thermal calibration of resistive sensors using a measurement resistor with an unknown temperature coefficient, integrated with a temperature reference sensor and an electrically-controllable heat source, allowing for single-test-insertion thermal calibration and generation of a mathematical relationship between resistance and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If extensive factory-level testing in a thermally-controlled environment is performed to calibrate resistive sensors, then measurement accuracy is improved, but production cost and time increase significantly
Solution Approach 1:
The patent extracts the essential calibration information by performing measurements at only two temperature extremes (minimum and maximum temperatures) rather than across the entire temperature range. This extraction of critical calibration points enables accurate temperature coefficient calculation without requiring continuous thermal chamber testing, thereby resolving the contradiction between measurement accuracy and production speed
Solution Approach 2:
The patent applies partial action by conducting calibration measurements at only two specific temperature points (minimum and maximum) rather than performing exhaustive testing across all possible temperatures. This partial measurement approach is sufficient to determine the temperature coefficient and enables accurate compensation across the full temperature range, thus improving productivity while maintaining measurement precision
2Measurement precision
If extensive factory-level testing in a thermally-controlled environment is performed to calibrate resistive sensors, then measurement accuracy is improved, but production cost increases
Solution Approach 1:
The patent extracts the essential calibration information by performing measurements at only two temperature extremes (minimum and maximum temperatures) rather than across the entire temperature range. This extraction of critical calibration points enables accurate temperature coefficient calculation without requiring continuous thermal chamber testing, thereby resolving the contradiction between measurement accuracy and production cost
Solution Approach 2:
The patent uses disposable or low-cost temporary calibration structures (such as test circuits and measurement apparatus) that are implemented only during the brief calibration phase and then discarded or reused, replacing the need for expensive, permanent thermal chamber testing infrastructure in production environments
3Measurement precision
If die-level, wafer-level, or package-level tests on individual ICs are performed in a thermally-controlled environment, then calibration accuracy is improved, but testing time and complexity increase
Solution Approach 1:
The patent merges the calibration function with the existing production test infrastructure by implementing calibration circuits and measurement capabilities that can operate within standard IC packaging and testing equipment. This merging eliminates the need for separate, complex thermal chamber testing setups, thereby maintaining calibration accuracy while reducing testing complexity
Solution Approach 2:
The patent introduces intermediary calibration circuits and temperature sensing elements that mediate between the resistive sensor and the measurement apparatus. These intermediaries enable accurate calibration measurements to be taken through simple electrical connections rather than requiring complex thermal environment control, thus improving calibration accuracy while reducing testing complexity
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
Enables accurate thermal compensation of resistive sensors with reduced testing requirements, improving measurement accuracy and efficiency by allowing calibration without extensive factory-level testing, resulting in a 10× improvement in resistance measurement accuracy over the temperature range.
Implementation Method 1
an electrically-controllable heat source integrated on the substrate and thermally coupled to the measurement resistor and the temperature reference sensor
Implementation Method 2
a temperature reference sensor thermally coupled to the measurement resistor, an analog-to-digital converter having an input coupled to the temperature reference sensor for providing an indication of a temperature of the measurement resistor
Implementation Method 3
a measurement circuit for measuring an indication of a resistance of the measurement resistor
Implementation Method 4
resistive materials typically exhibit a wide degree of variation of resistivity with temperature... the controller may generate or approximate a mathematical relationship between the resistance of the measurement resistor and the temperature of the measurement resistor
Data Source
AI summary
A system and method provide on-line, wafer-level, die-level, or package-level thermal calibration of an integrated measurement resistor with a single temperature insertion. The system includes a measurement resistor integrated on a substrate with an unknown temperature coefficient and a temperature reference sensor thermally coupled to the measurement resistor. A measurement circuit measures an indication of a resistance of the measurement resistor. An electrically-controllable integrated heat source is operated by a controller to change a temperature of the measurement resistor and the temperature reference sensor and stores values of the resistance indication and the sensed temperature corresponding to multiple temperatures of the temperature of the measurement resistor and the temperature reference sensor. The controller generates or approximates a mathematical relationship between the resistance of the measurement resistor and the temperature of the measurement resistor and the temperature reference sensor from the stored values.