Adhesive-Free Sensor Seal via Elastomeric O-Ring
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Solution Overview
Problem
Pressure sensors face inaccuracies due to thermal expansion mismatches between silicon or semiconductor materials and ceramic or PCB substrates, and adhesive failures in harsh or corrosive environments, leading to strain and seal breakdowns.
Innovation Solution
A pressure sensor assembly with a housing and a pressure sensor package that uses an elastomeric o-ring for an adhesive-free seal and anodically bonds a silicon sensing diaphragm to a glass substrate, eliminating the need for adhesives and reducing strain from thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If adhesive is used to attach MEMS device to substrate, then device assembly is simplified, but reliability deteriorates in harsh or corrosive environments due to adhesive breakdown
Solution Approach 1:
The patent removes the adhesive layer from the system by implementing a direct mechanical interface between the MEMS device and substrate through recessed mounting structures. The MEMS device is seated directly into a recess in the substrate with mechanical retention, eliminating the adhesive bonding step while maintaining assembly simplicity and dramatically improving reliability in corrosive environments.
Solution Approach 2:
The patent introduces a recessed mounting structure as an intermediary element between the MEMS device and substrate. This recess provides mechanical retention and alignment features that replace the adhesive's function while adding structural integrity and environmental protection without requiring chemical bonding agents.
2Ease of manufacture
If ceramic or PCB substrate is used, then manufacturing is easier, but measurement precision deteriorates due to CTE mismatch with silicon causing strain on sensing device
Solution Approach 1:
The patent segments the substrate structure into multiple functional zones: a CTE-matched interface region that directly contacts the silicon MEMS device, and a main substrate body that provides mechanical support. This segmentation allows the critical sensing interface to have minimal CTE mismatch while the bulk substrate maintains manufacturing advantages of ceramic or PCB materials.
Solution Approach 2:
The patent applies local quality by creating a specialized interface region with specific material properties optimized for CTE matching with silicon, while the rest of the substrate maintains its original material characteristics. The recessed mounting structure and surrounding support elements are designed with local geometric modifications that compensate for thermal expansion differences and minimize strain on the sensing diaphragm.
3Strength
If substrate is adhered to housing, then structural support is improved, but reliability deteriorates due to adhesive failure in harsh environments
Solution Approach 1:
The patent removes the adhesive layer from the substrate-to-housing interface by implementing a recessed mounting structure that provides mechanical retention. The substrate is secured to the housing through direct mechanical engagement in the recess, eliminating the adhesive bond while maintaining structural support and improving reliability in corrosive environments.
Solution Approach 2:
The recessed mounting structure serves as an intermediary mechanical interface between the substrate and housing. This recess provides geometric constraints and retention features that replace the adhesive's structural function, creating a reliable mechanical bond that is resistant to corrosive environmental degradation.
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 solution provides accurate and reliable pressure measurements by minimizing the impact of thermal expansion and preventing adhesive failures, ensuring a hermetic seal even in corrosive environments.
Implementation Method 1
a sealing element, such as an elastomeric o-ring, providing an adhesive-free seal between the housing and the substrate
Implementation Method 2
a semiconductor die including a sensing diaphragm attached to the substrate such that the diaphragm is exposed via the aperture
Data Source
AI summary
A sensor assembly comprising a housing defining a cavity, and a pressure sensor package arranged within the cavity. The pressure sensor package includes a substrate having an aperture defined therethrough, a semiconductor die including a sensing diaphragm attached to the substrate such that the diaphragm is exposed via the aperture, and at least one electrically conductive element in electrical communication with the semiconductor die arranged on the substrate. A sealing element, such as an elastomeric o-ring, provides a seal between the housing and the substrate. A connector is secured to the housing via a crimped connection for establishing electrical connections between the pressure sensor package and an external system.