Tomosynthesis X-ray Inspection for High-Density PCB Solder Defects
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Solution Overview
Problem
Current image inspection systems face challenges in accurately identifying defective pins on high-density parallel board connectors like NeXLev®, particularly due to the reflow process impacts, obscuration by connector blades, and subtle differences between defective and non-defective solder balls, leading to high false call rates and increased manufacturing costs.
Innovation Solution
An X-ray inspection system using tomosynthesis imaging techniques processes X-ray images by determining displacement values of assembly portions relative to a plane, applying rules to these values to determine defect status, and employing image processing algorithms to correct artifacts and reconstruct three-dimensional slices for accurate defect identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional X-ray imaging is used to inspect high-density parallel board connectors, then the inspection process is simple, but the measurement precision is insufficient due to obscuration by connector blades and subtle differences between defective and non-defective solder balls
Solution Approach 1:
The patent transitions from conventional 2D X-ray imaging to 3D tomosynthesis imaging by acquiring multiple X-ray images at different angles and reconstructing them into three-dimensional slices. This dimensional change enables accurate defect detection by eliminating obscuration artifacts and providing depth information, allowing precise identification of solder ball defects that are invisible in 2D projections.
2Reliability
If manual inspection methods are used to identify defective pins, then false call rates are high, but the productivity is reduced and manufacturing costs increase
Solution Approach 1:
The patent implements an automated inspection system that performs defect detection and classification independently without manual intervention. The system automatically processes 3D tomosynthesis images, identifies defective solder balls based on morphological features, and generates inspection results. This self-service capability eliminates false calls while maintaining high productivity through automated high-throughput imaging and analysis.
3Ease of manufacture
If the reflow process is performed on high-density connectors, then the manufacturing process is complete, but the solder balls become obscured and artifacts are produced making defect detection difficult
Solution Approach 1:
The patent uses 3D tomosynthesis reconstruction to create cross-sectional slices through the connector assembly at different depths. This dimensional approach separates overlapping structures that cause obscuration in 2D images, allowing clear visualization of solder balls even when obscured by connector blades in conventional imaging. The 3D slices enable defect detection despite artifacts produced during the reflow process.
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 reduces false call rates, enabling more accurate detection of defective pins with minimal manual intervention, thus enhancing manufacturing efficiency and reducing costs by providing reliable fault coverage.
Implementation Method 1
An X-ray inspection system using tomosynthesis imaging techniques processes X-ray images by determining displacement values of assembly portions
Implementation Method 2
An X-ray inspection system using tomosynthesis imaging techniques processes X-ray images by determining displacement values of assembly portions relative to a plane
Data Source
AI summary
According to one embodiment, a method for processing one or more X-ray images includes: receiving at least one image of the one or more X-ray images, the one or more X-ray images being of an assembly extending along a plane; based on the at least one image, autonomously determining a respective displacement value for each of portions of the assembly with respect to one or more directions of the plane, each of the displacement values being determined relative to a respective actual value; storing the displacement values; and applying a rule to the stored displacement values, the rule being for determining a defect status of the assembly.