MEMS Scanning Mirror Assembly With Decoupled Bond and Wire Bonding
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Solution Overview
Problem
Traditional piezoelectric MEMS scanning mirror systems face reliability issues due to the combination of electrical and mechanical functions in a single adhesive bond, leading to variations in mechanical strength and efficiency, causing the system to fail in maintaining the required voltage to move the mirror to the desired angle.
Innovation Solution
A structural bond with no conductive properties is used to attach the actuator frame to the substrate, allowing for separate electrical connections through wire bonding or a conductive trace, enabling maximum mechanical performance and increased efficiency by decoupling electrical and mechanical functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive adhesive is used to mechanically and electrically connect the frame to the substrate, then electrical connection is achieved, but mechanical performance of the bond deteriorates
Solution Approach 1:
The patent divides the connection function into two separate bonds: a structural adhesive bond for mechanical support and a conductive adhesive bond for electrical connection. This segmentation allows each bond to be optimized for its specific function, with the structural bond providing high mechanical strength and the conductive bond ensuring reliable electrical connectivity between the frame and substrate.
Solution Approach 2:
The patent introduces a conductive adhesive layer as an intermediary between the frame and substrate, applied after the structural adhesive bond is formed. This intermediary layer provides the electrical connection pathway without compromising the mechanical integrity established by the primary structural bond.
2Ease of manufacture
If consistency of conductive and structural adhesives varies at each attachment point, then manufacturing is simplified, but mechanical strength variations cause efficiency issues
Solution Approach 1:
The patent segments the adhesive application process into two distinct steps: first applying structural adhesive for mechanical bonding, then applying conductive adhesive for electrical connection. This segmentation ensures that each adhesive type is applied with appropriate consistency control for its specific function, eliminating the problems of mixed-adhesive variability.
Solution Approach 2:
The structural adhesive bond is formed first as a preliminary action, establishing a consistent mechanical foundation before the conductive adhesive is applied. This preliminary bonding ensures that mechanical strength requirements are met before electrical connection is established, allowing each adhesive to be optimized independently.
3Reliability
If conductive adhesive is used for electrical connection, then electrical connectivity is achieved, but mechanical strength is marginal causing system component failure
Solution Approach 1:
The patent clearly segments the bonding functions by using structural adhesive exclusively for mechanical support and conductive adhesive exclusively for electrical connection. This segmentation eliminates the compromise where conductive adhesive would need to provide both functions, allowing each material to perform its specialized function at optimal performance levels.
Solution Approach 2:
The patent creates a multi-functional connection system where the combined adhesive structure provides both mechanical support and electrical connectivity. The structural adhesive layer handles mechanical loading while the conductive adhesive layer provides electrical pathways, together forming a universal connection solution that delivers both functions simultaneously.
Data Source
AI summary
Electrical connections are created between the actuator frame of a piezoelectric MEMS scanning mirror system and the substrate separate from the structural adhesive creating the mechanical bond between the actuator frame and the substrate. A structural bond (with no conducive properties) is formed between the actuator frame and the substrate. After the bond is fully formed, separate electric connections can be created by one or both of: 1) coating the actuator frame with a coating that enables a surface of the actuator frame to be wire bondable and creating a wire bond between the actuator frame and the substrate; or 2) depositing a trace of conductive material on the outside edge of the mechanical bond between the actuator frame and the substrate and a final protection layer may be applied over the conductive trace to protect the trace from mechanical or environmental damage.