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[IEEE 2018 International Conference on Cyberworlds (CW) - Singapore, Singapore (2018.10.3-2018.10.5)] 2018 International Conference on Cyberworlds (CW) - Towards Automatic Optical Inspection of Soldering Defects
摘要： This paper proposes a method for automatic image-based classification of solder joint defects in the context of Automatic Optical Inspection (AOI) of Printed Circuit Boards (PCBs). Machine learning-based approaches are frequently used for image-based inspection. However, a main challenge is to manually create sufficiently large labeled training databases to allow for high accuracy of defect detection. Creating such large training databases is time-consuming, expensive, and often unfeasible in industrial production settings. In order to address this problem, an active learning framework is proposed which starts with only a small labeled subset of training data. The labeled dataset is then enlarged step-by-step by combining K-means clustering with active user input to provide representative samples for the training of an SVM classifier. Evaluations on two databases with insufficient and shifting solder joints samples have shown that the proposed method achieved high accuracy while requiring only minimal user input. The results also demonstrated that the proposed method outperforms random and representative sampling by ~ 3.2% and ~ 2.7%, respectively, and it outperforms the uncertainty sampling method by ~ 0.5%.
关键词： Classification of solder joint defects,active learning,Automatic Optical Inspection (AOI),SVM classifier,K-means
更新于2025-09-23 15:23:52
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Effect of Laser Loop on Surface Morphology of Copper Substrate and Wettability of Solder Joint
摘要： The effect of different laser loop parameter on the geometry of micro-groove pattern on copper substrate and its effect on the wettability was investigated. The micro-grooves pattern was fabricated on the copper surface through laser surface texturing process. 3D measuring laser microscope and contact angle measurement test was conducted to measure the geometry of the micro-grooves pattern and wettability of the solder joint respectively. The results showed that the improvement in laser loop parameter increased the depth of the micro-grooves due to the more exposed time which allows more material ablation. It also showed that the contact angle of textured substrate is smaller than the untextured substrate which results in better wettability.
关键词： wettability,laser loop,copper substrate,solder joint,surface morphology
更新于2025-09-19 17:13:59
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Random Voids Generation and Effect of Thermal Shock Load on Mechanical Reliability of Light-Emitting Diode Flip Chip Solder Joints
摘要： To make the light-emitting diode (LED) more compact and effective, the flip chip solder joint is recommended in LED chip-scale packaging (CSP) with critical functions in mechanical support, heat dissipation, and electrical conductivity. However, the generation of voids always challenges the mechanical strength, thermal stability, and reliability of solder joints. This paper models the 3D random voids generation in the LED flip chip Sn96.5–Ag3.0–Cu0.5 (SAC305) solder joint, and investigates the effect of thermal shock load on its mechanical reliability with both simulations and experiments referring to the JEDEC thermal shock test standard (JESD22-A106B). The results reveal the following: (1) the void rate of the solder joint increases after thermal shock ageing, and its shear strength exponentially degrades; (2) the first principal stress of the solder joint is not obviously increased, however, if the through-hole voids emerged in the corner of solder joints, it will dramatically increase; (3) modelling of the fatigue failure of solder joint with randomly distributed voids utilizes the approximate model to estimate the lifetime, and the experimental results confirm that the absolute prediction error can be controlled around 2.84%.
关键词： randomly distributed voids,solder joint,flip chip,light-emitting diode,reliability
更新于2025-09-16 10:30:52
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Controlling the Solder Joint Reliability of eWLB Packages in Automotive Radar Applications Using a Design for Reliability Approach
摘要： A DfR (Design for Reliability) approach which is systematically based on simulation, sensitivity analysis and experimental validation is applied for identifying, understanding and controlling the key factors which determine the solder joint reliability of eWLB (Embedded Wafer Level Ball Grid Array) packages that carry embedded 77 GHz dies and sit on hybrid PCB (Printed Circuit Board) stacks. The hybrid stack investigated in this work is characteristic to automotive RADAR (Radio Detection And Ranging) applications and consists of one low-loss RF (Radio Frequency) layer and several FR4 layers. In line with previous work [1], the mechanical material properties of the low-loss RF laminate material are found to be the key factor. Simulation is used to systematically screen for mechanical properties which are favorable for achieving a high solder joint reliability on the unconstrained PCBs used for standardized solder joint reliability testing. A simplified virtual assessment of PCBs constrained by the mounting in system module housings is done. Both simulation and experimental results show that RF laminate materials with low Young’s modulus are the class of materials which allows for the highest solder joint reliability for all the conditions investigated in this study.
关键词： RF laminate,Design for Reliability,eWLB,solder joint reliability,automotive RADAR
更新于2025-09-10 09:29:36