Ceramic Substrate for MEMS Scanning Mirror Parasite Mode Control
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Solution Overview
Problem
MEMS scanning mirror systems experience exaggerated and unintentional movement due to substrate flexing, leading to reduced power efficiency, audible noise, and decreased reliability, primarily caused by parasite modes in glass-reinforced plastic substrates.
Innovation Solution
A ceramic substrate with specific material properties, such as an elastic modulus greater than 58 GPa and a low coefficient of thermal expansion, is used to support the actuator frame and scanning mirror assembly, reducing or eliminating undesired resonant modes and providing a stiffer mechanical support to minimize unintended movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass-reinforced plastic substrate is used to support the actuator frame and scanning mirror assembly, then the substrate provides mechanical support and electrical interface, but the substrate flexes during operation causing parasite modes that lead to exaggerated and unintentional movement of the scanning mirror
Solution Approach 1:
The patent changes the material parameters of the substrate by specifying a minimum elastic modulus of 58 GPa and a maximum coefficient of thermal expansion of 10 ppm/K. These parameter changes ensure the substrate maintains sufficient rigidity to prevent flexing and parasite modes while still providing the required mechanical support and electrical interface functionality.
Solution Approach 2:
The patent allows for composite material constructions that meet the specified elastic modulus and thermal expansion criteria. By using composite materials designed to satisfy these parameters, the substrate achieves both the structural strength needed for mechanical support and the dimensional stability required to eliminate flexing during operation.
2Ease of manufacture
If glass-reinforced plastic substrate is used, then the substrate can be manufactured with standard processes, but the substrate flexing generates audible noise and reduces power efficiency
Solution Approach 1:
The patent establishes specific material parameter thresholds (elastic modulus ≥58 GPa, thermal expansion ≤10 ppm/K) that directly address the harmful effects of substrate flexing. By enforcing these parameters, the substrate prevents parasite mode excitation, thereby eliminating audible noise and maintaining power efficiency while still being manufacturable through appropriate processes.
3Adaptability or versatility
If glass-reinforced plastic substrate is used, then the substrate provides electrical interface to components, but the substrate flexing causes stress runaway that reduces reliability
Solution Approach 1:
The patent specifies stringent material parameters (elastic modulus ≥58 GPa, thermal expansion ≤10 ppm/K) that ensure the substrate maintains dimensional stability under operational conditions. This prevents flexing that would otherwise cause stress runaway in mounted components, thereby protecting reliability while preserving the electrical interface functionality.
Data Source
AI summary
A system that includes a substrate for microelectromechanical system (MEMS) scanning mirror systems is provided. The MEMS scanning mirror system includes a substrate that includes a ceramic body. An actuator frame is mounted on the ceramic body of the substrate. The actuator frame includes at least one moveable member. At least one actuator is operatively connected to the at least one moveable member such that the actuator is configured to move the at least one moveable member. A scanning mirror assembly is mounted to the at least one moveable member such that movement of the at least one moveable member moves the scanning mirror assembly.