Inertial Sensor Ceramic Body Dual Cavity Design
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Solution Overview
Problem
Inertial sensors face challenges due to the need for controlled environments and protection from moisture, leading to increased costs and complexity in packaging, as well as difficulties in testing individual components, which can result in scrapping functional parts when a single component is faulty.
Innovation Solution
The design features a ceramic body with two cavities, one for the sensing element and one for electronic circuitry, interconnected by conductive traces and leads, allowing for separate testing of components and eliminating the need for over-molding compounds, with hermetically sealed lids providing a controlled atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensing elements and electronics are mounted side-by-side on a substrate, then the sensor can be assembled in a compact arrangement, but the substrate surface area increases and trace routing becomes more complex
Solution Approach 1:
The patent transitions from a planar side-by-side mounting arrangement to a three-dimensional stacked configuration where the sensing element is positioned above the substrate and electronics are mounted on the underside of a lid. This vertical arrangement in the Z-dimension reduces the required substrate surface area while maintaining all necessary electrical connections through conductive traces that extend vertically through the structure.
2Ease of manufacture
If sensing elements and electronics are mounted side-by-side, then assembly is simplified, but separate testing of individual components becomes difficult or impossible
Solution Approach 1:
The patent physically separates the sensing element and electronics into distinct spatial locations - the sensing element is mounted on a pedestal above the substrate while the electronics are mounted on the underside of the lid. This segmentation allows independent access to each component for separate testing and characterization before final assembly, while still enabling simplified overall assembly through the modular structure.
3Reliability
If hermetic seals are used to enclose sensing elements, then moisture protection is achieved, but additional over-molding compounds are still required to protect electronics
Solution Approach 1:
The patent combines the protection functions for both the sensing element and electronics into a single hermetic seal structure. The lid with integrated hermetic seal encloses both the sensing element mounted on the pedestal and the electronics mounted on its underside, eliminating the need for separate over-molding compounds and multiple sealing layers. This unified approach maintains comprehensive moisture protection while reducing packaging complexity.
Data Source
AI summary
Inertial sensor having a body with first and second cavities on opposite sides thereof, a sensing element in the first cavity, electronic circuitry in the second cavity, electrical conductors interconnecting the sensing element and the circuitry, and leads connected electrically to the circuitry and extending from the body for mounting the sensor and making connections with the circuitry.