Strain Relief Bridge for MEMS Packages
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Solution Overview
Problem
Existing MEMS packages face challenges in protecting sensitive components from mechanical stress and strain, as previous solutions like compliant adhesives fail to effectively absorb and dissipate forces, leading to component damage and device malfunction.
Innovation Solution
A strain absorption bridge is introduced, comprising a first substrate and an elastically deformable element that absorbs and dissipates mechanical strain between a circuit board and a MEMS device, utilizing materials like polyimide or PTFE, and can be configured in various shapes to minimize stress transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the spacing between the keyboard PCB and the outer case is reduced to minimize device size, then device thickness is reduced, but the likelihood of damage to MEMS components from mechanical stress increases
Solution Approach 1:
A bridge structure is introduced as an intermediary component between the PCB and the MEMS device. This bridge includes a first substrate connected to the PCB and a second substrate connected to the MEMS device, with an elastically deformable element coupling them. The bridge acts as a mediator that absorbs mechanical stress and strain, preventing direct transmission of forces to the sensitive MEMS components while maintaining the reduced device thickness configuration.
Solution Approach 2:
The elastically deformable element in the bridge is constructed from flexible materials such as polyimide or PTFE. These thin film materials provide the necessary elasticity to deform under mechanical stress, absorbing forces before they reach the MEMS device. The flexible nature of these materials allows the bridge to protect the MEMS components while maintaining a thin overall structure.
2Ease of manufacture
If compliant adhesive is used to mount MEMS components, then ease of assembly is improved, but the adhesive loosens over time and fails to protect MEMS components from mechanical stress
Solution Approach 1:
The mounting structure is segmented into distinct functional components: a rigid bridge structure for mechanical support, an elastically deformable element for stress absorption, and controlled adhesive joints at specific locations. This segmentation allows each component to perform its specialized function - the bridge provides structural integrity, the elastic element absorbs stress, and adhesives are used only where necessary for electrical and mechanical connection, preventing the entire mounting structure from loosening over time.
Solution Approach 2:
The bridge structure combines multiple materials with different properties: rigid substrate materials (such as ceramic or metal) for structural support, elastic materials (polyimide or PTFE) for stress absorption, and controlled adhesive joints. This composite construction creates a hierarchical structure where each material layer performs its specific function, providing both ease of assembly through standardized interfaces and long-term reliability through differentiated material properties.
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 bridge significantly reduces or eliminates stress and strain on MEMS devices, enhancing device reliability and user satisfaction by preventing damage and malfunction due to mechanical forces.
Implementation Method 1
an elastically deformable element that absorbs and dissipates mechanical strain communicated from a circuit board before the mechanical strain can reach the MEMS device
Data Source
AI summary
A strain absorption bridge for use in a MEMS package includes a first substrate that is configured to be attachable to a circuit board. A first elastically deformable element is coupled to the first substrate and the first elastically deformable element is configured to be attachable to a MEMS device. Alternatively, the MEMS device may be attached to the first substrate. The elastically deformable element at least partially absorbs and dissipates mechanical strain communicated from the circuit board before the mechanical strain can reach the MEMS device.