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SYSTEMATIC MECHANICAL PERFORMANCE STUDY FOR SILICON CHIP IN ELECTRONIC PACKAGING USING UNIFIED APPROACH
No full textUltra-thin chip technology has the potential as the possible solution on overcoming the bottlenecks in silicon technology for new miniaturized applications. However, it increases the potential mechanical risk with such ultra-thin silicon chip solution and requires a comprehensive understanding to appropriately characterize its mechanical integrity and fracture. Hence, the lack of a full structural study from initial silicon chip break strength (SBS) study, to the interaction impact from assembly processes on a final assembled thin packages' silicon chip stress has been identified as the opportunity on this research work. A four stages unified approach for potential silicon chip cracking risk quantification is proposed. First, a simple and practical experimental three pint bend (3PB) SBS investigation with beam theory was initially carried out to study the key silicon process parameters without a need to undergo a complex and heavy computational analysis. Simultaneously, a useful stress-based modeling approach on those critical factors as identified in design, test process and reliability were carried out to analyze and predict the silicon surface stress parametrically. Then, a practical application integrating both experiment and modeling through a universal defect metric with bending stress, namely is established. The realistic risk analysis on those identified electronic packaging (EP) design options and test interaction could be easily predicted, although the preliminary assessment showed an approximately 40% of survival margin for an ideal conditions initially. However, with further inclusion of the critical safety factors, combining the laser marked SBS and higher chip surface stress build up in reliability test, the margin was reduced to <5%, which revealed the significance of this newly developed unified approach in predicting the realistic mechanical assessment for the EP's silicon chip. Besides, a further study was extended to explore a potential and cost effective SBS enhancement option with surface protection opportunity, which improved the SBS by approximately 33%, and validated to be transparent to existing process flow. Through the few test cases with unified approach, it was also suggested that a better EP stiffness control along with a surface protection like the overmold (OM) EP solution was needed for better ultra-thin chip performance enhancement. The completion of this research produced a good benchmark on the effectiveness of systematic unified approach to quantify the ultra-thin silicon chip cracking risk. This unified assessment with a well-structured four phases of research study drives for a potential optimization in design, material and process selection, as well as enhancement opportunity to improve the EP's silicon chip mechanical performance. This approach enables a quick and direct risk level assessment on various critical factors for potential silicon chip cracking failure avoidance
Synergistic Effects of CNF-TiO2 Composites and Process Parameters on DMFC Performance Enhancement
No full textThis article is index by ScopusDirect methanol fuel cells (DMFCs) face challenges from methanol crossover and performance degradation caused by inefficient microporous layer (MPL) designs, where conventional carbon-based MPLs show limitations in surface coverage uniformity, catalyst utilization efficiency, and pore structure balance. To address these issues, this study developed an optimized MPL using carbon nanofiber-titanium dioxide (CNF-TiO2) composites through parametric optimization of the fabrication process. Key variables included MPL loading density, CNF:TiO2 mass ratio, Nafion binder concentration, and methanol feed concentration, which were analyzed via screening experiments and Response Surface Methodology (RSM) using a Central Composite Design (CCD). The optimization targeted three response metrics: power density (R1), open-circuit voltage (R2), and peak current density (R3).
The results demonstrated that the modified CNF-TiO2 microporous layer (MPL) exhibited a synergistic effect when optimized with the selected parameters. Initial screening experiments examined MPL loading, CNF-to-TiO2 ratio, Nafion® content, and methanol concentration, revealing that the composition ratio, Nafion® content, and methanol concentration had significant impacts on the cell's performance responses. These key parameters were further explored using Response Surface Methodology (RSM). The optimized MPL exhibited improved..see more
