PCB Differential Temperature Sensing for Hot-Side Detection
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Solution Overview
Problem
In high-temperature environments, such as aircraft-mounted electronic components, it is challenging to detect temperature changes locally on a circuit board that may affect the functionality of electronic circuits, especially when sudden heat sources like fires or burst ducts occur, as conventional thermal management methods struggle to isolate and manage heat effectively across the board.
Innovation Solution
A system using a printed circuit board with board stiffeners and traces made of materials with different Seebeck coefficients, connected to a differential amplifier, which determines the side of the circuit exposed to high temperature by measuring the voltage differential across these materials, producing pulses to indicate the temperature gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional thermal management methods are used to manage heat across the board, then heat can be moved from hot components to cooler locations, but the ability to detect local temperature changes and identify which side is exposed to high temperature is insufficient
Solution Approach 1:
The patent utilizes the Seebeck coefficient parameter difference between dissimilar materials (traces and board stiffeners) to generate measurable voltage signals in response to temperature gradients. By changing the material parameters to have different Seebeck coefficients, the system can detect temperature differences and identify which side of the board is exposed to high temperature through voltage differential measurements.
Solution Approach 2:
The patent introduces board stiffeners made of dissimilar materials as intermediary elements between the PCB traces and the high-temperature environment. These stiffeners act as mediators that convert thermal exposure into electrical signals through the Seebeck effect, enabling indirect detection of temperature gradients without direct thermal contact sensors on the PCB.
2Reliability
If dissimilar materials with different Seebeck coefficients are used to create temperature sensing traces and board stiffeners, then voltage differential can be generated to detect which side is exposed to high temperature, but the device structure becomes more complex
Solution Approach 1:
The board stiffeners serve multiple functions: they provide structural support to the PCB and simultaneously act as temperature sensing elements through their dissimilar material composition. The traces also serve dual purposes as electrical conductors and temperature gradient indicators. This multi-functionality reduces the need for separate sensing components, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent employs composite construction by combining dissimilar materials (different metals with distinct Seebeck coefficients) in the traces and board stiffeners. This composite approach enables the generation of voltage differentials in response to temperature gradients, providing reliable temperature side identification while integrating the sensing capability into existing structural components.
3Speed
If sudden intense heat is applied to electronic components, then thermal management systems can move heat to cooler locations, but circuits closest to the heat source are exposed to temperatures outside their operating range before thermal management can respond
Solution Approach 1:
The patent implements preliminary detection capability by positioning the dissimilar material stiffeners and traces to detect temperature gradients before they reach critical levels. The system proactively identifies which side of the board is exposed to high temperature, enabling early warning and preventive action before circuits are damaged by excessive heat.
Solution Approach 2:
The patent replaces traditional thermal management approaches with an electrical detection system based on the Seebeck effect. Instead of relying solely on thermal conduction and heat sinking, the system uses electrical voltage measurements to rapidly detect temperature gradients, providing faster response to sudden heat exposure than purely thermal methods.
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
Effectively identifies which side of the circuit board is exposed to high temperatures, enabling timely thermal management and preventing operational failures in critical systems like FADEC systems by accurately detecting temperature variations and gradients.
Implementation Method 1
the first and second board stiffeners are formed of a first material having a first Seebeck coefficient... a plurality of traces formed of a second material that is different than the first material and has a second Seebeck coefficient... determines whether the first edge or second edge is closer to the high temperature based on a voltage differential
Data Source
AI summary
A system for determining a side of an electrical circuit exposed to a high temperature includes a printed circuit board having at least two outer edges and first and second board stiffeners of a first material disposed along the outer edges. The system also includes a control unit and a plurality of traces 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.