Folded MEMS Substrates for Compact Multi-Axis IMU
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Solution Overview
Problem
Current methods for creating compact inertial measurement units (IMUs) face challenges such as alignment errors, size limitations, and power consumption issues due to PCB-level assembly, and compromises in sensor performance when integrating in-plane and out-of-plane sensors on a single substrate.
Innovation Solution
A wafer-level folding structure is developed, where sensors are fabricated on a single substrate and assembled into three-dimensional polyhedral shapes like cubes or pyramids, using flexible hinges and interlocking latches for mechanical rigidity and electrical interconnects, allowing for high-performance single-axis sensors capable of measuring acceleration and rotation in three dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If off-the-shelf sensors are mounted onto PCBs and assembled into a three dimensional configuration, then the device achieves compact size and mature manufacturing process, but alignment errors vary for each device requiring extensive calibration and the device is inherently not very compact
Solution Approach 1:
The patent merges the sensor mounting structure with the PCB substrate by fabricating flexible hinges and interconnects directly on the PCB using standard PCB fabrication processes. This integration eliminates separate alignment steps and reduces calibration requirements while maintaining mature manufacturing processes.
Solution Approach 2:
The patent pre-fabricates the folded structure with integrated hinges and interconnects on the PCB before final assembly. This preliminary fabrication ensures precise geometric relationships are built-in during manufacturing, eliminating post-assembly alignment errors and reducing calibration needs.
2Area of stationary object
If in-plane and out-of-plane sensors are fabricated onto a single die, then the footprint of the system is small enough for chip-level packaging and lithographic alignment reduces calibration difficulty, but creating sensors for different axes requires very different design parameters and fabrication complexity
Solution Approach 1:
The patent uses a folded three-dimensional structure fabricated on a two-dimensional PCB substrate. This approach allows sensors oriented in multiple directions (in-plane and out-of-plane) to be created on a single flat substrate by folding different sections at different angles, achieving multi-axis sensing without requiring complex three-dimensional fabrication processes.
Solution Approach 2:
The patent divides the sensor array into multiple sections or facets on the PCB, each fabricated with sensors optimized for specific axes. These segmented sections are then folded together to create the three-dimensional sensing volume, allowing each section to use appropriate design parameters for its orientation while maintaining overall compactness.
3Volume of moving object
If a folded structure is assembled from multiple substrates, then compact three dimensional integration is achieved, but mechanical rigidity and structural stability must be maintained
Solution Approach 1:
The patent uses flexible hinges fabricated on the PCB substrate to connect the folded sections. These thin-film hinges provide the necessary flexibility for assembly while maintaining structural integrity when folded, enabling compact three-dimensional integration without sacrificing rigidity in the final assembled structure.
Solution Approach 2:
The patent creates a nested or interlocking structure where folded sections fit together with precise geometric relationships. This nesting approach, combined with integrated interconnects, provides structural stability while achieving compact volume integration.
Data Source
AI summary
An apparatus is fabricated with a plurality of semiconductor-device substrates and/or MEMS substrates with micromachined sensors, circuits, transducers, and/or MEMS devices fabricated on the plurality of substrates. A plurality of flexible hinges couple the plurality of substrates into a substantially flat two dimensional foldable assembly. Electrical interconnects coupled to the sensors, circuits, transducers, and/or MEMS devices extend other ones of the plurality of substrates. The foldable assembly of substrates is assembled or folded into a three dimensional polyhedral structure with the plurality of substrates configured in three dimensions to form defined relative orientations in space with respect to each other. The invention includes a wafer scale method of fabricating the apparatus.