PCB Control Module Layout to Prevent MOSFET Fire Paths
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Solution Overview
Problem
The existing electric heating devices for motor vehicles face a risk of fire or smoke generation due to the degradation of the printed circuit board material when a MOSFET undergoes a short-circuit, leading to excessive heat dissipation and potential damage.
Innovation Solution
A control module with a printed circuit board featuring a discontinuity, such as a slit, between the conductive tracks to prevent the degradation of the material from acting as a resistor and causing a short-circuit, thereby avoiding the risk of fire or smoke generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the printed circuit board material degrades due to excessive heat from MOSFET short-circuit, then the material becomes conductive forming a resistor, but this leads to fire or smoke generation
Solution Approach 1:
The printed circuit board is divided into two separate areas (first area and second area) by a discontinuity such as a slit. This segmentation prevents the degradation of insulating material from creating a conductive path between the drain and source, thereby eliminating the risk of fire or smoke generation while maintaining reliable operation.
2Power
If the MOSFET is in on state with high current, then heating function is achieved, but excessive heat degrades the printed circuit board material
Solution Approach 1:
The potentially harmful thermal effect is extracted and isolated by creating a discontinuity in the printed circuit board between the drain and source areas. This allows the MOSFET to operate at high power for heating while preventing the accumulated heat from degrading the insulating material and creating dangerous conductive paths.
3Reliability
If the printed circuit board material becomes conductive due to degradation, then a resistive path forms between drain and source, but this causes excessive heat dissipation of 10 to 15 W
Solution Approach 1:
The printed circuit board is segmented into distinct first and second areas separated by a discontinuity, preventing the formation of unwanted resistive paths. This ensures that electrical connections are maintained only where intended, eliminating energy loss through unintended conductive paths while preserving necessary electrical connectivity.
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
The discontinuity in the printed circuit board prevents the formation of a resistor between the drain and source terminals, reducing the risk of fire and smoke, ensuring safe operation of the heating device even in case of MOSFET degradation.
Implementation Method 1
a quantity of heat of, for example, between 2 W and 3 W is dissipated by the MOSFET in normal operation
Implementation Method 2
a current passes into the resistive elements so as to provoke the heating of the electrodes and of the heat sinks
Implementation Method 3
Two opposing heat sinks are fixed onto the electrodes, so as to increase the surface area of exchange with the flow of air to be heated
Data Source
AI summary
The invention relates to a control module (13) for an electric appliance (10), comprising a printed circuit board (19) whereon electrical and electronic components (26) are mounted along with at least one power transistor (18) fixed to a first region (20) of the printed circuit board (19) and comprising a drain (D) connected to a first electrically conductive track (22) of said first region (20) and a source (S) connected to a second electroconductive track (23) of a second region (21) of the printed circuit board (19). At least one opening (27) forms a material discontinuity between the first and second regions (20, 21) of the printed circuit board (19), said opening (27) being arranged between the first and second conductive tracks (22, 23).