Differential Temperature Sensing Circuit Using Seebeck Effect
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Solution Overview
Problem
Thermal management of aircraft-mounted electronic components is challenging due to the high density and power of smaller components, leading to temperature variations across a circuit board, especially when exposed to sudden intense heat sources like fires or burst ducts, making it difficult to detect temperature changes locally affecting one part of the circuit without impacting others.
Innovation Solution
A system using a printed circuit board with board stiffeners made of one material and traces made of another, connected to a differential amplifier, which generates a voltage differential to determine which side of the circuit is closer to a high temperature by utilizing the Seebeck effect, allowing for precise temperature detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal management systems use traditional temperature sensors, then they can detect temperature changes, but they cannot determine which specific side or location of the circuit board is exposed to high temperature
Solution Approach 1:
The circuit board is divided into multiple sides or regions, each monitored by dedicated trace-stiffener assemblies. By segmenting the monitoring function across different board edges, the system can identify which specific side is exposed to high temperature while maintaining accurate temperature detection capability.
Solution Approach 2:
Board stiffeners serve as intermediary elements between the trace network and the high-temperature environment. These stiffeners are strategically positioned at different board edges and act as thermal mediators, allowing the electrical circuit to indirectly sense temperature conditions at specific locations without placing sensors directly in the harsh thermal environment.
2Ease of manufacture
If the circuit board uses uniform material composition, then manufacturing is simplified, but temperature gradient detection capability is reduced
Solution Approach 1:
The circuit board employs local material differentiation by using board stiffeners with specific Seebeck coefficient properties at strategic locations. While the base board material remains uniform for ease of manufacture, the localized insertion of stiffeners with tailored thermal-electrical properties enables temperature gradient detection without complicating the overall manufacturing process.
Solution Approach 2:
The temperature detection system utilizes composite construction by combining board stiffeners made of materials with specific Seebeck coefficients with copper traces. This composite approach allows the system to detect temperature gradients while maintaining compatibility with standard circuit board manufacturing processes, as the stiffeners are integrated into existing board structures.
3Power
If high density electronic components are used, then power and functionality are increased, but thermal management complexity increases
Solution Approach 1:
The board stiffeners serve multiple functions simultaneously: they provide mechanical support to the high-density circuit board, act as thermal pathways for heat dissipation, and function as sensing elements for temperature detection. This multi-functionality reduces thermal management complexity by combining structural, thermal, and sensing roles into single components rather than requiring separate systems for each function.
Solution Approach 2:
The existing board stiffeners, which are already present for mechanical support in high-density assemblies, are repurposed to provide temperature detection functionality. This self-service approach allows the structural components to simultaneously perform thermal sensing without adding separate detection hardware, thereby increasing power capability while minimizing thermal management 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 detection of temperature gradients across the circuit board, producing a positive or negative pulse to identify which side is exposed to higher heat, effectively addressing the challenge of thermal management in high-temperature environments.
Implementation Method 1
The traces connect the first end of the first and second board stiffeners to the control unit and connect the second end of the first and second board stiffeners to one another. The control unit is configured to determine whether the first edge or second edge is closer to the high temperature based on a voltage differential between a trace connecting it to the first end of the first board stiffener and a trace connecting to the first end of the second board stiffener.
Data Source
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AI summary
A system for determining a side of an electrical circuit exposed to a high temperature includes a printed circuit board (300) having at least two outer edges (320,322,324,326) and first and second board stiffeners (302,304) of a first material disposed along the outer edges. The system also includes a control unit (312) and a plurality of traces (340) formed of a material that is different than the first material and has a second Seebeck coefficient. The control unit determines whether the first edge or second edge is closer to the high temperature based on a voltage differential between a trace connecting it to the first end of the first board stiffener and a trace connecting to the first end of the second board stiffener.