PCB Pin-Connection Inspection via Boundary Scan and Optical Imaging
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Solution Overview
Problem
The complexity of modern printed circuit board assemblies, particularly with high-density interconnects, poses challenges in delivering testing signals to internal connections, limiting the effectiveness of existing inspection methods and creating blind spots in testing.
Innovation Solution
A testing system combining boundary-scan testing technology with a signal sensing unit and processing unit to deliver and detect testing signals through the inner layers of the printed circuit board, allowing for the examination of connections between DUT pins and the board, even in high-density or inaccessible areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional testing methods (AOI, AXI, ICT) are used to examine pins on printed circuit board assembly, then inspection speed and cost are improved, but coverage of hidden pins (e.g., BGA) is lost
Solution Approach 1:
The patent introduces an intermediary substance (fluorescent dye or contrast agent) that penetrates into hidden areas such as BGA pin recesses and fills the gaps between pins and PCB. This intermediary enables the testing system to detect previously invisible connections by creating optical contrast that can be captured by the imaging device, thus resolving the contradiction between inspection speed and coverage.
2Measurement precision
If probes are connected to testing points for ICT, then accurate electrical testing is achieved, but the number of accessible testing points decreases with high-density interconnects
Solution Approach 1:
The patent replaces the mechanical probe-based testing system with an optical-based inspection system. Instead of physically contacting pins with probes, the system uses imaging devices to capture optical images of the pins and their connections. This substitution eliminates the need for physical access to testing points, thereby resolving the contradiction between testing accuracy and device complexity.
3Area of moving object
If distance between pins is decreased to increase integration density, then more functions are packed into smaller area, but signal delivery to internal connections becomes more difficult
Solution Approach 1:
The patent creates an optical copy or representation of the hidden pin connections through imaging. By capturing optical images that reveal the presence and condition of pins in high-density areas, the system can assess connections without physically accessing or electrically testing each pin individually, thus overcoming the difficulty of signal delivery in compact designs.
Data Source
AI summary
The invention provides a testing system and method suitable for determining whether a pin-out of an electrical component is properly connected to a PCB. The testing system includes a testing signal source, a signal detector, a signal processor, an analysis unit and an integrated circuit having boundary-scan test function to provide testing signals to the device under test (DUT) whose signal traces are passing through inner layer of PCB in order to detect whether the sensed signal is an error signal.