Image Sensor Alignment Using Fiducial Markers on Ceramic Frames
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Solution Overview
Problem
In systems utilizing multiple image sensors, precise alignment between sensors is challenging, often requiring extensive calibration with test patterns, especially when sensors are placed on different packages, leading to difficulties in achieving accurate relative positioning.
Innovation Solution
The use of a ceramic package with raised walls and a silicon frame featuring distinct fiducial markers for alignment, along with optical filters supported by the walls, allows for accurate alignment and bonding of multiple image sensors, enabling efficient assembly and alignment of image sensors in a package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple image sensors are placed on different packages, then the system can achieve greater versatility and adaptability, but the alignment precision and relative positioning accuracy deteriorate
Solution Approach 1:
The patent implements a universal alignment framework where the same fiducial marker design and calibration procedure can be applied across multiple packages and sensor types. The frame structure with standardized fiducial markers serves as a multi-functional component that enables consistent alignment procedures regardless of which specific image sensors are used, thus maintaining manufacturing precision while supporting system versatility
Solution Approach 2:
The patent introduces fiducial markers as intermediary reference elements that mediate between different image sensors and their packages. These markers serve as a common language for alignment, allowing sensors from different packages to be precisely positioned relative to each other through the intermediary reference framework, thereby resolving the alignment precision issue while maintaining adaptability
2Measurement precision
If extensive calibration using test patterns is performed, then the measurement precision of relative positioning is improved, but the productivity and assembly time deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-positioning fiducial markers on frames before the image sensors are assembled. This preliminary placement of reference markers establishes an alignment framework in advance, eliminating the need for extensive post-assembly calibration with test patterns. The fiducial markers are prepared and positioned beforehand, allowing for rapid sensor placement and alignment without time-consuming calibration procedures
Solution Approach 2:
The patent extracts the calibration function from the final assembly process and incorporates it into the manufacturing of the frame and fiducial markers. By embedding reference markers directly into the frame structure during frame fabrication, the calibration references are extracted and prepared separately in advance, allowing the main assembly process to proceed without extensive calibration steps, thus improving productivity while maintaining measurement precision
3Ease of operation
If fiducial markers are made visible on the frame, then the ease of operation for alignment is improved, but the device complexity increases
Solution Approach 1:
The patent merges the fiducial markers with the frame structure itself, combining the reference marking function with the mechanical support function. The fiducial markers are integrated into the frame rather than being separate components, which simplifies the overall device structure. This merging approach maintains ease of alignment operation while avoiding the complexity that would arise from separate, additional alignment components
Solution Approach 2:
The frame structure serves multiple functions: it provides mechanical support for the image sensors and simultaneously incorporates visible fiducial markers for alignment. This multi-functionality eliminates the need for separate alignment devices or complex marking systems, achieving ease of operation without proportionally increasing device complexity. The frame's dual role as both structural element and alignment reference creates an efficient, uncomplicated design
Data Source
AI summary
An image sensor assembly and a method for assembling. The assembly includes: a ceramic package; at least one wall raised from the ceramic package, one of the walls for dividing a first surface region and a second surface region of the ceramic package; a frame supported by the ceramic package; a first set of fiducial markers and a second set of fiducial markers visible on the frame; a first die for placement onto the first surface region, the first die including an image sensor and respective fiducial markers for alignment with the first set of fiducial markers; a second die for placement onto the second surface region, the second die including an image sensor and respective fiducial markers for alignment with the second set of fiducial markers; and at least one optical filter each associated with one of the dice and supported by at least one of the walls.