Rugged MEMS Package with Dual-Modulus Coatings for Shock Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

MEMS movement sensors are prone to damage and failure due to repeated mechanical shocks, which affect their robustness and accuracy, especially during handling and assembly processes, as they experience high accelerations that lead to malfunctioning or failure.

Innovation Solution

A MEMS device with a rugged package is fabricated using an injection molding system, featuring a substrate with two coating regions: a first coating region with a high Young's modulus for mechanical protection and a second coating region with a lower Young's modulus for impact absorption, decoupling mechanical stresses and maintaining performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical stoppers are added to increase robustness, then the device can withstand abrupt movements better, but the stoppers undergo gradual damage and failure under repeated mechanical shocks

Engineering Contradiction:

ImproverobustnessVSAvoidservice life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the material parameter (Young's modulus) of the coating layer to create a compliant interface that reduces impact acceleration. By selecting a coating material with appropriate elastic properties, the device can withstand repeated shocks without the gradual damage that plagues rigid mechanical stoppers.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite structure combining the substrate material with a coating layer of different mechanical properties. This composite approach allows the coating to absorb and dissipate impact energy through deformation, preventing the catastrophic failure modes seen in homogeneous rigid structures with mechanical stoppers.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the dimensions of MEMS devices are increased to improve robustness, then the device can better withstand mechanical shocks, but the resonance frequency changes and performance is affected

Engineering Contradiction:

ImproverobustnessVSAvoidperformance

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies a thin film coating layer that provides mechanical protection and impact absorption without significantly altering the overall dimensions of the MEMS device. This thin film approach maintains the original resonance frequency and performance characteristics while improving robustness.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

Instead of changing geometric parameters (dimensions), the patent changes material parameters (Young's modulus of coating layer) to achieve improved robustness. This allows the device to withstand mechanical shocks while maintaining its original dimensional characteristics and resonance frequency.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If resin packaging is used to absorb acceleration, then robustness is increased, but the device still experiences high impact accelerations during handling and assembly

Engineering Contradiction:

ImproverobustnessVSAvoidimpact acceleration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a localized coating layer directly on the substrate surface where impact forces are transmitted. This localized protection at the critical interface provides targeted impact absorption exactly where needed, reducing impact acceleration more effectively than bulk resin packaging.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The coating layer is applied beforehand to the substrate, creating a pre-positioned cushioning layer that is already in place to absorb impact forces during handling and assembly operations, rather than relying on external packaging that may not be optimally positioned.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 dual-coating approach enhances the robustness of MEMS devices by reducing the impact acceleration and increasing the height of fall without compromising electrical or detection characteristics, ensuring stable performance and prolonged usability.

Implementation Method 1

a first coating region (25), having a first Young's modulus, surrounding the MEMS structure (10) and in contact with part of the surface (5A) of the substrate (5)

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a second coating region (37) having a second Young's modulus, surrounding the first coating region (25) and in contact with part of the surface (5A) of the substrate (5), wherein the first Young's modulus is higher than the second Young's modulus

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Data Source

PatentUS11873215B2Mems device having a rugged package and fabrication process thereof

Publication Date: 2024.01.16 STMICROELECTRONICS SRL

AI summary

A MEMS device formed by a substrate, having a surface; a MEMS structure arranged on the surface; a first coating region having a first Young's modulus, surrounding the MEMS structure at the top and at the sides and in contact with the surface of the substrate; and a second coating region having a second Young's modulus, surrounding the first coating region at the top and at the sides and in contact with the surface of the substrate. The first Young's modulus is higher than the second Young's modulus.