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Flip-chip technology is widely used in integrated circuit (IC) packaging. Molded underfill transfer molding is the most common process for these products, as the chip and solder bumps must be protected by the encapsulating material to ensure good reliability. Flow-front merging usually occurs during the molding process, and air is then trapped under the chip, which can form voids in the molded product. The void under the chip may cause stability and reliability problems. However, the flow process is unobservable during the transfer molding process. The engineer can only check for voids in the molded product after the process is complete. Previous studies have used fluid visualization experiments and developed computational fluid dynamics simulation tools to investigate this issue. However, a critical gap remains in establishing a comprehensive three-dimensional model that integrates two-phase flow, accurate venting settings, and fluid surface tension for molded underfill void evaluation—validated by experimental fluid visualization. This study aims to address this gap in the existing literature. In this study, a fluid visualization experiment was designed to simulate the transfer molding process, allowing for the observation of flow-front merging and void formation behaviors. For comparison, a three-dimensional mold flow analysis was also performed. It was found that the numerical simulation of the trapped air compression process under the chip was more accurate when considering the capillary force. The effect of design factors is evaluated in this paper. The results show that the most important factors for void size are fluid viscosity, the gap height under the chip, transfer time, contact angle between the fluid and the contact surfaces, and transfer pressure. Specifically, a smaller gap height beneath the chip aggravates void formation, while lower viscosity, extended transfer time, reduced contact angle, and increased transfer pressure are effective in minimizing void size. The overall results of this study will be useful for product and process design in selecting appropriate solutions for IC packaging, particularly in the development of void-free molded-underfill flip-chip packages. These findings support the optimization of industrial packaging processes in semiconductor manufacturing by guiding material selection and process parameters, ultimately enhancing package reliability and yield.

The signal-receiving contacts of ultra-miniature radio-frequency connectors are made of copper alloy sheets and stamped with progressive dies. However, the drawn cup corner often becomes extremely thin after progressive stamping, resulting in contact defects, insufficient mechanical strength, and reduced signal transmission quality. The present study investigates the effect of three forming methods, drawing with a blank holder, drawing without a blank holder, and drawing with a synchronous blank holder, on the corner-thinning phenomenon of the drawn cup by enlarging the scale of 10 for the workpiece. The feasibility of the first three forming stages was investigated. Finite element analysis was used, and the die-tryout further verified the findings. The results show that both drawing methods, with or without a blank holder, would cause necking or breakage at the corner at the third forming stage. The corner-thinning phenomenon becomes mild when drawing with a synchronous blank holder. The corner-thinning phenomenon is due to the low height of the drawn cup, resulting in too much plate material remaining on the flange, which makes the subsequent drawing ratio too large. Therefore, the conventional drawing methods are unsuitable, but drawing with a synchronous blank holder can be effective in this case study.

Metal flow tends to be complex and difficult to predict in the combined forward-backward extrusion (CFBE) process. Piercing and surface-crack defects are phenomenal in forming fasteners featuring a forward extruded pin and a backward extruded cup. In this work, a series of the CFBE tests with various combinations of the forward extrusion ratio (FER) and the backward extrusion ratio (BER) were conducted. A forming limit diagram, detailed with the piercing and surface-crack defects on the forward extruded pin or the backward extruded cup, was developed to provide a conception in choosing appropriate extrusion ratios in forming fasteners with such pin-and-cup features. With the aid of the forming load-stroke curves and the finite element analysis of fracture damage, the fracturing mechanism for the CFBE process was provided.

In the electrical discharge machining process, preliminary research has been able to effectively estimate machining accuracy in response to its long machining history and high discharge frequency characteristics. However, when processing abnormalities occur, it is difficult to identify them since the electrical discharge process contains multiple processing parameters, which increases the cost of repair or loss afterwards. Therefore, the question concerning how to monitor the abnormality of the discharge process in real time represents the main purpose of this research. This research develops an EDM process abnormal diagnosis system. First, the data are stored in a circular array to speed up the processing time, and the coefficient of variation feature is added, which has effectively extracted the abnormal characteristics. In terms of diagnostic methods, the composite voting model established by neural networks, random forests, and XGB-RF (extreme gradient boosting applying RF) can provide robust diagnostic results. Finally, through the Node-RED webpage and MQTT agreement, it can provide the ability to monitor machine abnormalities in real time. Through refinement and optimization of the previous research results, this study took the electrical discharge machining diamond grinding wheel as an example, and developed a warning that can be issued within 3 min when abnormalities (abnormal patterns such as polycrystalline diamond high protrusions) occur, with an accuracy of 93% and a false positive rate. The abnormal diagnosis ability is less than 0.2%. Therefore, the online abnormality monitoring system developed by this research institute will be able to provide online abnormality diagnosis for electrical discharge machining.

Stretch-flanging commonly appears at the concave edge of the panel part. Sheet thickness tends to decrease at the center of flange attributed to the outflow of metal flow, and hence causes a radial shrinking of the material. This shrinking pulls the ends of the flange and makes the adjacent surface overcrown. In this paper the effect of punch profiles on a laboratory scale profile, which assimilates the front fender part adjoining the head light, was investigated for the stretch-flanging process. Both the concave and convex punch profiles were considered. SUS 304 stainless steel sheet of 0.6 mm thick was used as the model metal sheet. DynaForm software was used in simulating the stretch flanging process and followed by experimental verification. The results show that a depression angle of 4.4° and an elevation angle 2.6° can produce lowest crown-contour for the concave and convex punches, respectively. The concave punch also causes less thinning at the flange center which makes it a favorable solution than that of the convex punch.

Bulge formation occurs in drawing with light reductions and large die angles. Reports concerning its effect on strain inhomogeneity in axi-symmetric drawing are limited. In this study, bulge formation is characterized by the occurrence of outward radial velocities in the finite element analysis. Strain distributions, including axial, radial, circumferential, shear, and effective strains, were analyzed to explain the effect of bulge formation on strain inhomogeneity. Hardness tests for the drawing experiment were conducted to verify the findings of the FE simulation. Optical microscopy of the microstructures produced by drawing under both a near homogeneous condition and a bulging condition was performed. The results indicate that bulging causes a peak in the axial strain distribution near the drawn workpiece’s surface, leading to a slight fall-off of effective strain on the surface. The peak is caused by the excessive redundant deformation of a local reversion from compressive to tensile axial strain. The strain peak is greater when drawing with light reductions and large die angles and becomes more noticeable with small strain-hardening exponents or large friction factors. Bulge formation also causes fibrous flow lines near the surface of the drawn workpiece.

High-pressure-gas cylinders are used in broad applications. Cracks on the open end would occur during the riveting stage. Such forming defects are caused by excessive hardening, although the open end has been annealed with induction heating prior to the sinking operation. Therefore, a proper design for the sinking dies is essential to the forming production of the HPG cylinders. In this paper, two die-design concepts were examined which included the conventional design for six-stage sinking with fixed die radius, and the economic design for five-stage sinking with incremental die radii. Finite element software DEFORM 2D was used to investigate the two sinking schemes. The effect of the sinking schemes on the sinking load, strain distribution, and lip thickness were analysed. The results show that the economic five-stage sinking with a large increment of die radii can provide less strain hardening as compared to other sinking schemes. Although the forming load level is acceptable and the change of lip thickness is insignificant, the production cost of the five-stage scheme is still high. A more economic measure by sinking with one-stage rotary swaging can provide an alternative scheme with advantages of simple die design and saving the lead for annealing.

Taiwanese students learn Chinese from 3 years old using Bopomofo (Zhuyin Fuhao), but they still struggle with spelling and reading, even in middle school. Thus, we guided students still struggling to read Chinese text to use their logical skills and creativity to incorporate the Bopomofo phonetic alphabet into the Rummikub strategy board game. Over six weeks of tutoring, the students shifted from a passive to an active learning attitude, enhancing their enthusiasm for learning. The Zhuyin Fuhao Rummikub board game developed by them received positive feedback in several areas: game experience (4.42/5), self-assessment of learning outcomes (4.31/5), clarity of rules (4.52/5), and learning motivation (3.85/5 and 3.79/5). These results indicate that the board game is highly effective and well-received, underscoring its value in Chinese language learning and teaching. In conclusion, this teaching module can benefit students, educators, and parents. Educators can use this game-based design to inspire the creation of more engaging instructional content.

Piercing or surface-crack defect occurs in combination-extruding the support pin. There has been so far insufficient knowledge in avoiding such forming defects in forming the similar products. In this paper, a combination-extrusion experiment, with various combinations of forward and backward extrusion ratios, was conducted to observe the occurrence of the defects. The result shows that the defects occur at low level of both forward extrusion ratio and backward extrusion ratio used in the combination-extrusion process. The low forming level causes the onset of insufficient plastic metal-flow, which is similar to that of inhomogeneous deformation in the unidirectional extrusion or drawing process. A forming limit diagram was constructed and can be used in the defect prediction for the future development of similar products.

Foxtail millet is one of the world’s oldest cultivated crops. It has been adopted as a model organism for providing a deeper understanding of plant biology. In this study, 45 simple sequence repeats (SSR) markers of Setaria italica were developed. These markers showing polymorphism were screened in 223 samples from 12 foxtail millet populations around Taiwan. The most common dinucleotide and trinucleotide repeat motifs are AC/TG (84.21%) and CAT (46.15%). The average number of alleles (Na), the average heterozygosities observed (Ho) and expected (He) are 3.73, 0.714, 0.587, respectively. In addition, 24 SSR markers had shown transferability to six related Poaceae species. These new markers provide tools for examining genetic relatedness among foxtail millet populations and other related species. It is suitable for germplasm management and protection in Poaceae.