Board Warping Measurement Using Pattern Projection and Compensation
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Solution Overview
Problem
Traditional board-warping measuring methods are inefficient and inaccurate due to the need to project laser light onto every portion of the device under test, leading to poor measurement efficiency and blurred images caused by board warping, which affects the accuracy of height calculations.
Innovation Solution
A board-warping measuring method and apparatus that projects a pattern with reference points onto the device under test, captures measurement images, calculates position heights using transfer functions or lookup tables, and generates compensation images to correct for warping, allowing for rapid determination and adjustment of focal length and height measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser light is projected onto every portion of the device under test in sequence to obtain overall height, then measurement completeness is improved, but measurement efficiency deteriorates
Solution Approach 1:
The patent segments the measurement task by dividing the device under test into multiple measurement regions, each captured in separate images. The projection module projects patterns to different regions sequentially, and the image capturing module captures images of each region. This segmentation allows comprehensive measurement while reducing the time required compared to projecting onto the entire device at once, as each region can be measured independently and in parallel processing can be applied.
Solution Approach 2:
The patent transitions from one-dimensional sequential point-by-point measurement to two-dimensional regional measurement by capturing images of multiple measurement regions simultaneously. The projection module projects patterns across different regions, and the image capturing module captures these regions in a dimensional expansion approach, significantly improving measurement efficiency while maintaining completeness.
2Device complexity
If board warping is not compensated, then measurement process simplicity is maintained, but image quality and measurement accuracy deteriorate
Solution Approach 1:
The patent applies preliminary action by detecting board warping before the main measurement process and generating compensation information in advance. The system first captures images to detect warping, then generates compensation data that is applied during subsequent measurements. This preliminary detection and compensation generation ensures high measurement accuracy without adding significant complexity to the overall process, as the compensation is prepared beforehand.
3Ease of operation
If focal length is not adjusted according to board warping, then operation simplicity is maintained, but measurement accuracy deteriorates
Solution Approach 1:
The patent implements feedback by using the detected board warping information to automatically adjust the focal length of the imaging system. The system detects warping in real-time, processes this information to determine the appropriate focal length adjustment, and applies the adjustment automatically. This feedback loop maintains measurement accuracy while keeping the operation simple, as the system self-adjusts based on detected conditions without requiring manual intervention.
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
This approach significantly improves measurement efficiency and accuracy by rapidly determining board warping and performing height compensation, enabling precise measurement of device deformations and inclinations.
Implementation Method 1
employing a triangulation method, in which laser light is projected onto the device under test and a height of the device under test is calculated based on the reflected laser light
Implementation Method 2
employing a triangulation method, in which laser light is projected onto the device under test and a height of the device under test is calculated based on the reflected laser light
Data Source
AI summary
A board-warping measuring method is configured to measure a device under test. The device under test is disposed on a measuring carrier. The board-warping measuring method includes: projecting a pattern onto the device under test, wherein the pattern includes plural reference points; capturing a measurement image by an image-capturing module when the pattern is projected onto the device under test, wherein the measurement image includes plural measurement points respectively corresponding to the reference points; calculating a position of each of the measurement points in the measurement image by utilizing a transfer function corresponding to each of the reference points to obtain position heights of the device under test corresponding to the measurement points; and compensating for board warping of the device under test based on the position heights of the device under test corresponding to the measurement points.