Light Field Imaging Apparatus for Sub-Micron PCB Inspection
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Solution Overview
Problem
Current light field imaging technologies are inadequate for high-resolution measurements of solder paste deposit volume, height, and alignment on printed circuit boards, particularly in the sub-micron regime, and face challenges in monitoring deformation during the SMT reflow process due to limited space within the reflow oven.
Innovation Solution
A light field imaging apparatus comprising a lens array, a fiber optic image transferring device, and an image sensor, which captures and processes light fields to provide high-resolution measurements, and is designed to be compact enough to operate within the limited space of a reflow oven, using a processing device to control and stitch images for comprehensive surface inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If commercially available light field imaging is used for PCB inspection, then general imaging capability is provided, but sub-micron resolution requirement is not met
Solution Approach 1:
The imaging system is divided into multiple imaging modules, each capturing a specific portion of the light field. By segmenting the overall imaging task into multiple specialized modules, the system achieves both high resolution and measurement reliability for sub-micron PCB features
Solution Approach 2:
A light field intermediary device is introduced between the object and image sensor to capture and process light field information. This intermediary enables the system to achieve sub-micron resolution while maintaining measurement accuracy through specialized light field processing
2Adaptability or versatility
If imaging apparatus is provided in-situ inside reflow oven, then deformation monitoring capability is achieved, but space constraints of oven are exceeded
Solution Approach 1:
The imaging apparatus is designed with a nested structure where components are arranged concentrically or in compact configurations. The light field intermediary device and imaging modules are nested within each other, enabling the entire system to fit within the limited 50mm space of the reflow oven while maintaining full in-situ monitoring functionality
Solution Approach 2:
The imaging system utilizes the light field dimension to capture deformation information without requiring additional physical space. By processing light field data from multiple angles and depths, the system achieves comprehensive deformation monitoring within the constrained oven volume
3Volume of moving object
If compact imaging apparatus is designed for oven, then space constraints are satisfied, but imaging resolution may be compromised
Solution Approach 1:
Different parts of the compact imaging apparatus are assigned specialized functions optimized for their specific roles. The light field intermediary device is designed with local optical properties optimized for high-resolution light field capture, while imaging modules use specialized sensors optimized for sub-micron detection, ensuring high resolution is maintained despite the compact overall size
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 high-resolution surface inspection and deformation monitoring of printed circuit boards with sub-micron accuracy, meeting the requirements of modern PCB manufacturing and ensuring precise alignment and volume measurements within the constraints of the reflow oven environment.
Implementation Method 1
a fiber optic image transferring device having a first end and a second end, wherein the fiber optic image transferring device is coupled with the lens array at the first end, to transfer the light field to the second end
Data Source
AI summary
Embodiments of the present disclosure provide for a light field imaging apparatus and method. In one embodiment, an apparatus may comprise one or more imaging modules that may include a lens array, to receive a light field of a surface of an object or scene, and a fiber optic image transferring device having a first end and a second end. The fiber optic image transferring device may be coupled with the lens array at the first end, to transfer the light field to the second end. The apparatus may further include an image sensor coupled with the second end of the fiber optic image transferring device, to register the transferred light field and provide the registered light field for processing. Other embodiments may be described and/or claimed.