Thixotropic Adhesive Interface for MEMS Bonding
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Solution Overview
Problem
Adhesives used in micro electro mechanical systems (MEMS) often exhibit unsuitable rheological properties, leading to co-mingling of conductive and non-conductive adhesives, resulting in wide variance in conductance properties and less than optimum performance of Fast Scan MEMS devices.
Innovation Solution
A structural adhesive interface is implemented, comprising a conductive structural adhesive portion and a non-conductive structural adhesive portion that surrounds it, with both having a thixotropy index greater than one, along with specific properties such as high viscosity and shear strength, to control flow and prevent co-mingling during deposition and curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional adhesives with low thixotropy index are used, then the adhesive flows easily during deposition, but the conductive and non-conductive adhesives co-mingle, resulting in wide variance in conductance properties
Solution Approach 1:
The patent changes the rheological parameters of the adhesive by specifying a thixotropy index greater than one, which transforms the adhesive's flow behavior to prevent co-mingling while maintaining depositability. This parameter change resolves the contradiction between ease of deposition and pattern definition precision.
Solution Approach 2:
The patent uses a composite adhesive system comprising both conductive and non-conductive adhesive portions with specific rheological properties. The composite structure allows the adhesive to maintain its shape and prevent co-mingling while still providing the necessary conductivity where required, resolving the contradiction between manufacturability and precision.
2Ease of manufacture
If adhesive with high flowability is used, then deposition is easy, but the adhesive spreads excessively and loses structural integrity
Solution Approach 1:
The patent specifies a thixotropy index greater than one, which creates a time-dependent viscosity change. The adhesive remains fluid during application for ease of manufacture, then develops higher viscosity over time to maintain structural integrity, resolving the contradiction between ease of application and structural strength.
3Device complexity
If conductive and non-conductive adhesives are mixed, then a single adhesive formulation is simpler, but the conductance properties vary widely and performance is suboptimal
Solution Approach 1:
The patent segments the adhesive into distinct conductive and non-conductive portions with different formulations. This segmentation allows each portion to perform its specific function optimally while maintaining consistent conductance properties in the conductive areas, resolving the contradiction between formulation simplicity and conductance reliability.
Solution Approach 2:
The patent applies different adhesive formulations to different locations within the bonding interface. Conductive adhesive is applied where electrical connection is needed, while non-conductive adhesive is applied where insulation is required. This local differentiation resolves the contradiction between overall formulation simplicity and localized conductance consistency.
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 configuration enhances the rheological properties of the adhesives, ensuring consistent conductance and improved performance of MEMS devices by preventing excessive flow and co-mingling, thereby achieving better flex capability and stability.
Implementation Method 1
The conductive structural adhesive portion and the non-conductive structural adhesive portion have a thixotropy index greater than one
Data Source
AI summary
A micro electro mechanical system is provided. The micro electro mechanical system includes a first part bonded to a second part by a structural adhesive interface. The structural adhesive interface includes a conductive structural adhesive portion, and a non-conductive structural adhesive portion at least partially surrounding the conductive structural adhesive portion. The conductive structural adhesive portion and the non-conductive structural adhesive portion have a thixotropy index greater than one.