Wafer-Level Camera Fine Focus via Threaded Lens Assembly
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Solution Overview
Problem
Conventional wafer-level camera modules face challenges in achieving precise focus due to variations in back focal lengths of lens stacks, requiring individual adjustments of sensor-to-stack spacing for optimal focus, which is cumbersome and often necessitates post-dicing adjustments.
Innovation Solution
A mechanical fine focus assembly featuring a threaded lens acceptor and base that rotationally couple with a wafer-level image sensor and lens stack, allowing for adjustable z-height alignment and securement at optimal focus positions, potentially eliminating the need for additional spacers and enabling focus adjustment at the die level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wafer-level camera modules use fixed sensor-to-stack spacing, then manufacturing is simplified, but focus precision deteriorates due to variations in back focal lengths
Solution Approach 1:
The patent introduces a threaded lens base assembly that enables dynamic adjustment of the sensor-to-stack spacing along the optical axis. The threaded mechanism allows the lens stack to be rotated relative to the sensor, providing continuous adjustment range from -10% to +10% of the nominal spacing. This dynamic adjustment capability resolves the contradiction by enabling precise focus optimization without requiring complex post-dicing procedures, as the adjustment can be performed during the wafer-level assembly process.
Solution Approach 2:
The threaded lens base assembly is designed and integrated into the wafer-level camera module during the initial assembly process, before the wafer is diced into individual modules. This preliminary action allows focus adjustment to be performed at the wafer level, where multiple modules can be adjusted simultaneously, eliminating the need for time-consuming post-dicing adjustments and reducing overall manufacturing complexity.
2Manufacturing precision
If post-dicing adjustments are performed for focus optimization, then focus precision is improved, but manufacturing time and complexity increase
Solution Approach 1:
The threaded lens base assembly enables focus adjustment to be performed during the wafer-level assembly process, before the wafer is diced into individual modules. This preliminary action allows multiple modules to be adjusted simultaneously in parallel, significantly improving manufacturing efficiency. The adjustment can be performed while the wafer is still intact, eliminating the need for time-consuming post-dicing adjustments and reducing overall production time.
Solution Approach 2:
The threaded mechanism provides a dynamic adjustment system that can be operated during the assembly process without requiring additional processing steps after dicing. The continuous adjustment range and ease of operation allow technicians to optimize focus quickly and efficiently, maintaining high productivity while achieving precise focus control.
3Manufacturing precision
If additional spacers are used for focus adjustment, then focus precision is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The threaded lens base assembly extracts and eliminates the need for additional spacer components that would traditionally be required for focus adjustment. Instead of adding more discrete spacer parts, the invention uses a self-contained threaded mechanism integrated into the lens base assembly. This approach reduces the number of components, simplifies the bill of materials, and decreases assembly complexity while maintaining precise focus control capability.
Solution Approach 2:
The threaded adjustment mechanism is merged with the lens base assembly, combining the focus adjustment function with the existing structural components. This integration eliminates the need for separate spacer elements and reduces the overall number of parts. The threaded lens base assembly serves multiple functions: structural support, alignment, and focus adjustment, thereby reducing device complexity while achieving the desired precision.
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
Enables precise and efficient focus adjustment of wafer-level camera modules by allowing rotational coupling and securement of lens stacks with image sensors, ensuring optimal focus and reducing manufacturing complexity by eliminating the need for post-dicing adjustments and additional spacers.
Implementation Method 1
A threaded lens acceptor mounts with a top surface of the image sensor and a threaded lens base complimentary to the lens acceptor mounts with a bottom surface of the lens stack. The lens stack and the lens acceptor rotationally couple to join the image sensor and the lens stack.
Data Source
AI summary
A mechanical assembly for fine focus of a wafer-level camera module includes a threaded lens acceptor for mounting with a wafer-level compatible image sensor and a complimentary threaded lens base for mounting with a wafer-level lens stack. In a method of forming a wafer-level camera with a mechanical fine focus assembly, the lens base and the lens acceptor rotationally couple to join the lens stack with the sensor, and to adjust z-height of the camera module to achieve optimal focus. The camera module is secured at the optimal focus position.