Stacked MEMS Pressure Sensor with Through-Hole Cap
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Solution Overview
Problem
The existing absolute MEMS pressure sensors require excessive amounts of expensive viscous gel for protection, which increases costs and complexity.
Innovation Solution
The solution involves stacking the MEMS pressure sensing element on top of the ASIC, with a cap that partially fills with gel to minimize the volume required for protection, reducing thermal stress and media contamination while maintaining pressure sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If components are protected with a large volume of viscous gel, then protection from media contamination is improved, but cost increases and thermal stress increases
Solution Approach 1:
The patent implements a nested structure where the cap encloses the MEMS pressure sensing element and ASIC, creating a protected internal volume. This nested enclosure allows gel to be contained precisely where needed, reducing the overall amount of gel required while maintaining protection from media contamination.
Solution Approach 2:
The cap serves as an intermediary structure between the external environment and the sensitive components. It provides a physical barrier that reduces the need for large volumes of gel, while still allowing the gel to perform its protective function within the enclosed space.
2Object-affected harmful factors
If components are protected with a large volume of viscous gel, then protection from media contamination is improved, but manufacturing cost increases
Solution Approach 1:
The nested cap structure enables precise gel containment, reducing material consumption and associated costs. The cap creates a defined workspace that minimizes gel volume requirements while maintaining protective functionality.
Solution Approach 2:
The invention changes the spatial parameters of gel containment by introducing a cap structure. This parameter change from open-space gel filling to enclosed-volume gel containment reduces the total quantity of gel needed, thereby lowering manufacturing costs.
3Productivity
If components are stacked vertically, then packaging efficiency is improved, but thermal stress management becomes more challenging
Solution Approach 1:
The stacked configuration with the cap creates a nested vertical arrangement that improves packaging efficiency. The compact vertical structure allows better thermal management by reducing horizontal thermal gradients and enabling more effective heat dissipation paths through the stacked layers.
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 approach reduces the amount of gel needed, lowers manufacturing costs, and minimizes thermal mismatch, resulting in a more efficient and cost-effective MEMS pressure sensor design with improved packaging efficiency.
Implementation Method 1
The gel 336 is flowed into the cap 324 through the opening in the top surface of the cap
Implementation Method 2
confine the gel and reduce the amount of gel to encapsulate those electrical components
Implementation Method 3
the deflection creates (changes) stress on a resistive Wheatstone bridge circuit (not shown) formed in the diaphragm 205
Data Source
AI summary
A MEMS pressure sensing element and integrated circuit (IC) are mounted on a circuit board. The sensing element and IC can be either stacked or unstacked. Bond wires connect the IC to the circuit board. Other bond wires connect the sensing element to the IC. A cap covers the sensing element and IC. The cap is attached to the circuit board and has a small hole in it, through which viscous gel is inserted. The gel encapsulates the MEMS sensing element, IC and bond wires in the cap. The hole also allows pressurized fluid to enter the cap and exert force on the MEMS pressure sensing element after encapsulation in the gel. Chip capacitors can also be mounted on the circuit board, outside the cap. Electrical signals are generated, which represent pressure applied to the MEMS pressure sensing element through the hole and gel.