MEMS Airflow Sensor Thermal Conduction via PCB Metal Layers
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Solution Overview
Problem
The MEMS airflow sensor in electronic cigarettes experiences poor heat dissipation due to its small size, leading to overheating of the ASIC chip and triggering of overheating protection, as the printed circuit board (PCB) is unable to efficiently transfer heat generated during operation.
Innovation Solution
The MEMS airflow sensor incorporates exposed upper and lower metal layers on the PCB, connected through a thermally conductive member, with the ASIC chip partially falling within the upper metal layer's range, enhancing thermal conduction and heat dissipation by allowing heat to be transferred outside the receiving space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the MEMS airflow sensor dimensions are reduced to less than or equal to 4 mm*3 mm*1.3 mm, then the device size is reduced, but the PCB heat dissipation performance deteriorates
Solution Approach 1:
The patent introduces metal layers on the upper and lower surfaces of the PCB, extending the heat dissipation path from a two-dimensional plane to a three-dimensional structure. The upper metal layer is positioned near the ASIC chip, and the lower metal layer is positioned on the opposite side, creating vertical heat conduction paths that significantly improve thermal performance without increasing the sensor's footprint area.
Solution Approach 2:
The patent introduces metal layers as intermediary thermal conduction paths between the ASIC chip and the external environment. These metal layers act as thermal mediators that facilitate heat transfer from the chip through the PCB to the surrounding air, effectively decoupling the heat dissipation performance from the PCB thickness and enabling better thermal management in compact designs.
2Device complexity
If the PCB is made thin to accommodate small MEMS airflow sensor, then the device integration is improved, but the heat transfer capability deteriorates
Solution Approach 1:
The patent compensates for the thin PCB design by introducing vertical heat conduction paths through metal layers on the upper and lower surfaces. This three-dimensional thermal path configuration allows efficient heat transfer despite the reduced PCB thickness, maintaining both compact integration and effective thermal management.
Solution Approach 2:
The patent creates a composite thermal management structure by combining the PCB with metal layers on its upper and lower surfaces. This composite structure leverages the high thermal conductivity of metal materials to enhance heat transfer efficiency, overcoming the limitations of thin PCB design and achieving both compactness and effective heat dissipation.
3Productivity
If the ASIC chip operates continuously, then the productivity is improved, but the overheating protection triggers
Solution Approach 1:
The patent establishes three-dimensional heat conduction paths through metal layers on the upper and lower surfaces of the PCB, creating vertical thermal pathways that efficiently carry heat away from the ASIC chip. This enhanced thermal management enables continuous chip operation without triggering overheating protection, maintaining both productivity and reliability.
Solution Approach 2:
The metal layers serve as thermal intermediaries that continuously conduct heat from the ASIC chip to the external environment. This steady thermal transfer mechanism prevents heat accumulation during continuous operation, allowing the chip to maintain stable temperature and operate without interruption while avoiding overheating protection triggers.
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
This design improves the overall thermal conduction effect of the PCB, effectively preventing overheating protection triggers by efficiently transferring heat generated during ASIC chip operation, ensuring continuous operation of the electronic cigarette.
Implementation Method 1
the via hole is filled with a thermally conductive member; and the upper metal layer and the lower metal layer are electrically connected through the thermally conductive member
Implementation Method 2
the side of the PCB close to the upper cover and a side of the PCB away from the upper cover are respectively provided with an upper metal layer and a lower metal layer that are exposed to a surface of the PCB and are electrically connected to each other
Data Source
AI summary
An electronic cigarette, including cigarette housing and micro-electromechanical system (MEMS) airflow sensor received in the cigarette housing. The MEMS airflow sensor includes a printed circuit board (PCB), an upper cover that covers PCB and encloses a receiving space together with PCB, and application specific integrated circuit (ASIC) chip and an MEMS chip with back cavity that are fixed to PCB and electrically connected to each other. The upper cover is provided with first sound hole passing therethrough. A side of PCB close to the upper cover and a side of PCB away from the upper cover are respectively provided with an upper metal layer and a lower metal layer that are exposed to a surface of PCB and are electrically connected to each other. A projection of ASIC chip on PCB at least partially falls within a range of the upper metal layer.