Gyroscope Packaging Assembly Thermal Stress Reduction

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Solution Overview

Problem

Conventional planar resonator gyroscopes face issues with thermal expansion differentials, mechanical stress, warpage, and capacitive gap nonuniformity due to dissimilar materials in MEMS packaging, leading to sensing errors and drift, particularly in spacecraft applications where compact, lightweight, and cost-effective solutions are needed.

Innovation Solution

A packaging method for planar resonator gyroscopes that involves a carrier, substrate, and baseplate to create a cavity for the resonator, using materials like silicon and quartz, with electrical interconnects and a cap to secure the assembly, and incorporating active thermal management elements to minimize thermal and physical stress, while maintaining compatibility with existing manufacturing techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If dissimilar materials are used in MEMS packaging, then manufacturing flexibility and electrical connectivity are improved, but thermal expansion differentials cause mechanical stress, warpage, and capacitive gap nonuniformity

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidcapacitive gap uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies homogeneity by using the same material (silicon) for both the MEMS die and package substrate. This eliminates thermal expansion differentials between dissimilar materials, preventing mechanical stress, warpage, and capacitive gap nonuniformity that would otherwise occur during temperature cycling and operation.

Inventive Principle:
Principle #33Homogeneity

Solution Approach 2:

The patent employs composite material structures where silicon-based materials are used throughout the packaging assembly. The silicon MEMS die is mounted on a silicon package substrate, which is then attached to a silicon carrier, creating a homogeneous silicon-silicon interface that eliminates thermal mismatch problems.

Inventive Principle:
Principle #40Composite materials

2Reliability

If conventional MEMS packaging techniques are used, then electrical connectivity and structural support are achieved, but thermal gradients induce capacitive gap nonuniformity and sensing errors

Engineering Contradiction:
Improveelectrical connectivityVSAvoidsensing accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent eliminates thermal gradients by using homogeneous silicon materials throughout the packaging structure. The silicon package substrate and silicon carrier have matched thermal expansion coefficients, ensuring uniform temperature distribution and preventing capacitive gap nonuniformity that would degrade sensing accuracy.

Inventive Principle:
Principle #33Homogeneity

Solution Approach 2:

The silicon package substrate acts as an intermediary between the silicon MEMS die and the silicon carrier. This intermediate layer provides thermal management and mechanical support while maintaining material compatibility, preventing thermal stress transmission that would affect sensing elements.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Weight of moving object

If compact packaging is implemented, then device size and weight are reduced, but thermal management challenges increase

Engineering Contradiction:
Improvedevice weightVSAvoidthermal management
Core Design Contradiction:
Weight of moving objectVSTemperature

Solution Approach 1:

The homogeneous silicon construction enables efficient thermal conduction throughout the compact package. The silicon carrier and substrate provide thermal pathways that conduct heat away from the MEMS die, maintaining uniform temperature distribution despite the reduced device size and improved weight characteristics.

Inventive Principle:
Principle #33Homogeneity

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 enhances the physical and thermal stability of the gyroscope package, reducing sensing errors and drift, and allows for more efficient manufacturing of compact, lightweight, and cost-effective inertial sensors suitable for spacecraft applications.

Implementation Method 1

A packaging method for planar resonator gyroscopes that involves a carrier, substrate, and baseplate to create a cavity for the resonator... incorporating active thermal management elements to minimize thermal and physical stress

Methodology Applied
Scientific EffectThermal isolation: Thermal Insulation

Data Source

PatentEP2438399B1Gyroscope packaging assembly
Publication Date: 2015.07.08 THE BOEING CO
  • EP2438399B1 patent drawingFigure 1A~1B
  • EP2438399B1 patent drawingFigure 1C~1D
  • EP2438399B1 patent drawingFigure 2A

AI summary

Packaging techniques for planar resonator gyroscopes, such as disc resonator gyroscopes (DRGs) are disclosed. In one embodiment, a packaged resonator gyroscope comprises a carrier, a substrate layer mounted to the carrier, a baseplate coupled to the substrate to define a cavity between the substrate and the baseplate, and a resonator mounted to the baseplate and suspended in the cavity. Other embodiments may be described.