Fluorescence Measuring System for OSP Layer Thickness
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Solution Overview
Problem
Current methods for determining the thickness of organic solderability preservative (OSP) layers on printed circuit boards are destructive, time-consuming, and only provide average thickness measurements, making it difficult to ensure consistent solder connections and requiring expensive equipment.
Innovation Solution
A non-destructive fluorescence measuring system is used to determine the individual thickness of OSP layers by emitting a radiation beam and detecting fluorescent radiation, allowing for precise measurement without damaging the PCB and providing a thickness profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive methods (cutting or grinding) are used to measure OSP thickness, then measurement precision is improved, but the PCB is destroyed and the method becomes time-consuming and expensive
Solution Approach 1:
The patent replaces mechanical measurement methods (cutting or grinding with electron microscopy) with a fluorescence-based optical measurement system. The radiation source emits radiation that excites the OSP layer, causing it to fluoresce, and the detection unit measures the fluorescent radiation intensity to determine thickness non-destructively
Solution Approach 2:
The patent changes the measurement parameter from physical cross-section analysis to fluorescence intensity measurement. By correlating fluorescence intensity with OSP thickness through calibration, the system achieves precise thickness measurement without mechanical destruction of the PCB
2Productivity
If chemical dissolution method is used to determine OSP thickness, then measurement speed is improved, but only average thickness is obtained and the OSP is destroyed
Solution Approach 1:
The patent replaces chemical dissolution with optical fluorescence measurement. The fluorescence measuring system uses a radiation source to excite the OSP layer and a detection unit to measure emitted fluorescent radiation, enabling non-destructive measurement that preserves the OSP layer while providing individual thickness data
Solution Approach 2:
The patent utilizes the fluorescence property of the OSP layer - when excited by radiation, the OSP emits fluorescent radiation whose intensity correlates with thickness. This optical property allows non-destructive measurement without chemical dissolution, maintaining both speed and individual measurement capability
3Loss of time
If random sampling methods are used for OSP inspection, then measurement time is reduced, but comprehensive quality control is impossible and real-time inspection cannot be implemented
Solution Approach 1:
The patent creates a universal fluorescence measuring system that can measure OSP thickness at any location on the PCB. The system combines a radiation source, detection unit, and movement device to enable comprehensive measurement of all contact pads, not just random samples, making it suitable for complete quality control and real-time inspection
4Measurement precision
If sophisticated equipment and complex procedures are used for OSP measurement, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical preparation and sophisticated electron microscopy equipment with a relatively simple fluorescence measurement system. The system consists of a radiation source, detection unit, and movement device, eliminating the need for complex sample preparation while achieving accurate non-destructive measurement
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 method allows for quick, cost-effective, and reliable determination of OSP thickness, enhancing process reliability and enabling precise adjustment of OSP layers for consistent solder connections, suitable for large-scale production control.
Implementation Method 1
a radiation source suitable for emitting a radiation beam, a detection unit for detecting fluorescent radiation
Data Source
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AI summary
A method for obtaining information about a layer of an organic solderability preservative, OSP, on a printed circuit board, PCB, the method comprising • Providing a PCB (16) having a copper layer (18), wherein a solder resist (19) is placed on the copper layer (18), and the solder resist (19) has openings (21) wherein in the openings (21) a copper surface of the copper layer (18) is covered by a layer of an OSP, • Providing a fluorescence measuring system (10), comprising a radiation source (11), a detection unit (12), and a movement device (24), the method comprising: • a) Obtaining (S2) information about the location of the openings (21) on the PCB (16), • b) Selecting (S3) at least one of the openings (21), • c) Placing (S4) the radiation source (11) at such position that the radiation beam (22) irradiates into the at least one selected opening (21) on the layer of the OSP (20), • d) Detecting (S5) the fluorescent radiation (23) emitted from the OSP (20).