Packaged Environmental Sensor Sealing via Segmented Ring
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Solution Overview
Problem
Existing packaged environmental sensors face challenges in sealing the gap between the sensor and the casing, leading to exposure to aggressive agents and potential failure due to thermal expansion issues during soldering, which complicates manufacturing and increases costs.
Innovation Solution
A packaged environmental sensor design featuring a collar-shaped ring with multiple ring-attach regions and a protective layer that allows for flexible dimensions and shapes, enabling effective sealing and accommodating thermal expansion without detaching from the supporting structure, using a ceramic supporting structure and a silicone potting gel for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dome-shaped lid with a sealing surface is used to enclose the control chip, then sealing protection is provided, but the lid becomes complex and costly to produce, and thermal expansion forces during soldering may detach the lid from the supporting structure
Solution Approach 1:
The patent divides the lid into two separate functional components: a simple protective lid that covers the control chip area, and a separate sealing ring (gasket) that provides the sealing surface. This segmentation eliminates the complexity of integrating both protective and sealing functions into a single dome-shaped lid, while maintaining reliable sealing protection through the dedicated sealing ring.
2Reliability
If a large-area lid covering the control chip is used, then protection is provided, but the lid requires complex radiused neck structure for sealing, increasing manufacturing difficulty and cost
Solution Approach 1:
The protective lid and sealing functions are separated into distinct components. The lid can be a simple flat or slightly contoured piece that covers the control chip area without requiring complex radiused neck structures. The sealing function is provided by a separate sealing ring that interfaces with the supporting structure, greatly simplifying lid manufacturing.
Solution Approach 2:
A sealing ring (gasket) is introduced as an intermediary component between the lid and the supporting structure. This sealing ring assumes the complex sealing geometry requirements, allowing the lid itself to be manufactured with simple, flat surfaces that are easy to produce using standard PCB or ceramic manufacturing techniques.
3Strength
If the lid is soldered to the supporting structure, then secure attachment is achieved, but thermal expansion of the potting material during soldering may exert forces that detach the lid
Solution Approach 1:
The patent applies different attachment methods to different areas: the lid is attached using a method suitable for its large area (such as adhesive bonding or mechanical fastening), while the sealing ring provides the sealed connection. This local differentiation allows the lid to be securely attached without subjecting it to the thermal stress concentrations that would occur with soldering, thereby preventing detachment during the soldering process.
Solution Approach 2:
The sealing ring acts as a mediator that isolates the lid from direct thermal and mechanical stress during soldering. The sealing ring can be attached to the supporting structure in a way that accommodates thermal expansion, while the lid remains securely but flexibly attached, preventing the transmission of detaching forces.
4Reliability
If gaskets and shells are used to seal the gap between the sensor and casing, then sealing is achieved, but the structure becomes more complex and requires pre-loading mechanisms
Solution Approach 1:
The patent merges the sealing ring with the supporting structure itself, making the sealing surface an integral part of the supporting structure rather than a separate component. This integration eliminates the need for separate gaskets and shells, reducing structural complexity while maintaining reliable sealing of the gap between the sensor assembly and the device casing.
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 ensures the control chip is safely sealed from aggressive environments, allows for flexible manufacturing, reduces the risk of thermal expansion-induced failures, and lowers production costs by using a simple, scalable design that can accommodate various lid and gasket sizes.
Implementation Method 1
The potting material has a coefficient of thermal expansion that is much greater than that of the material forming the lid. During soldering, the potting material may exert on the dome-shaped portion forces that tend to detach the lid from the supporting structure.
Data Source
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AI summary
A packaged environmental sensor includes: a supporting structure (17); a sensor die (18), which incorporates an environmental sensor and is arranged on a first side (17a) of the supporting structure (17); a control chip (20), which is coupled to the sensor die (18) and is arranged on a second side (17b) of the supporting structure opposite to the first side (17a); and a ring (21), which is bonded to the first side (17a) of the supporting structure (17) and is open towards the outside in a direction opposite to the supporting structure (17), the sensor die (18) being housed within the ring (21).