Search

Taipei mass rapid transit (MRT), operational since 1996, serves up to two million passengers daily. Equipment malfunctions pose a safety risk, making the dual goals of cost reduction and safety a significant challenge. Recently, outsourcing non-core technical tasks has emerged as an effective cost-control strategy, allowing resource allocation to employee salaries and operational efficiency. This study uses the analytic hierarchy process (AHP) and fuzzy analytic hierarchy process (FAHP) to prioritize outsourcing for electromechanical equipment. It incorporates analysis from the outsourcing literature, historical data, and ISO documents from Taipei MRT. The research included interviews and surveys with seven senior managers, using software to analyze the outsourcing priorities of four key systems: electrical and fire safety, environmental air conditioning, escalators and elevators, and power supply. It suggests prioritizing environmental air conditioning, followed by power supply systems, escalators and elevators, and electrical and fire safety systems. Additionally, this study employed the FAHP and the technique for order of preference by similarity to ideal solution (TOPSIS) for the rigorous evaluation and monitoring of vendor selection to ensure quality service and effective contract execution. By comparing technical expertise, problem-solving capabilities, certifications, response times, and contractual performance, this study identified the most suitable vendors. It concludes with recommendations for Taipei MRT to enhance maintenance quality and reduce costs. [ABSTRACT FROM AUTHOR]

Machine vision systems use industrial cameras' digital sensors to collect images and use computers for image pre-processing, analysis, and the measurements of various features to make decisions. With increasing capacity and quality demands in the electronic industry, incoming quality control (IQC) standards are becoming more and more stringent. The industry's incoming quality control is mainly based on manual sampling. Although it saves time and costs, the miss rate is still high. This study aimed to establish an automatic defect detection system that could quickly identify defects in the gold finger on printed circuit boards (PCBs) according to the manufacturer's standard. In the general training iteration process of deep learning, parameters required for image processing and deductive reasoning operations are automatically updated. In this study, we discussed and compared the object detection networks of the YOLOv3 (You Only Look Once, Version 3) and Faster Region-Based Convolutional Neural Network (Faster R-CNN) algorithms. The results showed that the defect classification detection model, established based on the YOLOv3 network architecture, could identify defects with an accuracy of 95%. Therefore, the IQC sampling inspection was changed to a full inspection, and the surface mount technology (SMT) full inspection station was canceled to reduce the need for inspection personnel. [ABSTRACT FROM AUTHOR]

Sustainable ecotourism has become a strategy to balance tourism growth with environmental and sociocultural considerations. This study aims to propose an integrated approach of the Delphi technique and the decision-making trial and evaluation laboratory (DEMATEL) based on fuzzy set theory to investigate sustainable ecotourism indicators in Belize. The study covers six dimensions: environmental, social, cultural, economic, political, and intrinsic. Firstly, the Fuzzy Delphi technique constructs a comprehensive set of indicators with expert consensus, resulting in 51 relevant and representative indicators out of the initial 63. Secondly, the Fuzzy DEMATEL approach is then applied to analyze the interdependencies among indicators and identify their causal relationships, providing insights into the complex dynamics of sustainable ecotourism in Belize. The results provide a structured decision-making framework to prioritize actions, allocate resources effectively, and promote sustainable practices in the ecotourism sector. Therefore, these findings enhance the understanding of indicator interconnections across dimensions, enabling informed decision making for policymakers, industry practitioners, and researchers. Policymakers can develop policies and regulations that foster sustainable practices, while industry practitioners can enhance visitor experiences, engage with local communities, and ensure the industry's long-term viability. Researchers can further investigate specific dimensions and indicators to advance the knowledge and implementation of sustainable ecotourism. Finally, this investigation supports the goal of achieving a harmonious and sustainable balance between tourism development and environmental preservation in Belize. By safeguarding the natural and cultural heritage of the region, sustainable ecotourism can benefit present and future generations. [ABSTRACT FROM AUTHOR]

In this article, an alternate method for estimating the volatility parameter of Bitcoin is provided. Specifically, the procedure takes into account historical data. This quality is one of the most critical factors determining the Bitcoin price. The reader will notice an emphasis on historical knowledge throughout the text, with particular attention paid to detail. Following the production of a historical data set for volatility utilizing market data, we will analyze the fundamental and computed values of Bitcoin derivatives (futures), followed by implementing an inverse problem modeling method to obtain a second-order differential equation model for volatility. Because of this, we can accomplish what we set out to do. As a direct result, we will be able to achieve our objective. Following this, the differential equation of the second order will be solved by an artificial neural network that considers the dataset. In conclusion, the results achieved through the utilization of the Python software are given and contrasted with a variety of other research approaches. In addition, this method is determined with alternative ways, and the outcomes of those comparisons are shown. [ABSTRACT FROM AUTHOR]

Because of the intricate nature of real-world scenarios, experts could encounter many ambiguities throughout the decision-making (DM) process. Adopting a DM strategy in conditions of indeterminacy so that the decision makers are limited to a small number of experts is always helpful in real life. Neutrosophic conception is a convenient technique for handling inconsistent, ambiguous, and uncertain values. This research presents an autocratic DM strategy based on Neutrosophic Sets (NSs) to address these ambiguities. The essential component of the suggested technique is the conversion of diverse management decision and weight matrices into a unified evaluation matrix. Supplier Selection (SS) is a multi-criteria decision-making problem where a limited number of alternative suppliers are evaluated using a limited set of criteria. The suggested methodology based on different score functions is applied to SS issues involving construction materials. The numerical illustrations indicate the success of the introduced method in selecting the best supplier with the least computational complexity. The important point obtained in this research is that adopting a suitable score function appropriate to the characteristics of the data plays an important role in the decision-making process. [ABSTRACT FROM AUTHOR]

Creating a suitable travel package has become increasingly difficult for businesses within the tourism industry because of various factors affecting tourists' decision-making behavior and businesses' desire to make profits. This paper proposes a novel approach to service design within the tourism industry by integrating the analytic hierarchy process (AHP) and the theory of inventive problem solving (TRIZ) to design a suitable travel package while taking into account both consumer and business perspectives. Through a case study application, we identify the most important consumer and business factors with AHP and the Delphi method and then solve the existing contradiction with TRIZ. We collect both qualitative and quantitative data from experts and visitors through a survey approach consisting of 56 fully completed responses for a target of only 35 responses as required by AHP. We analyze these data using Super Decisions software to obtain the necessary results. AHP helps weigh and rank the 4 criteria and 16 sub-criteria, whereas TRIZ provides recommendations to resolve the contradiction, based on the 40 inventive principles, to create a cost-effective travel package to Belize in Central America. The main contradiction was feasibility versus cost, and the most applicable corresponding principles were dynamization, self-service, local quality, and prior action. Overall, this paper gives vital insights into the tourism sector to anyone interested in this topic and provides a precise AHP-TRIZ application framework with clear procedures. The results and methodologies could also help scholars and academics with future AHP-TRIZ applications in other research fields or possible expansions of this new approach. [ABSTRACT FROM AUTHOR]

To lower maintenance costs and improve a metro company's competitiveness, this research came up with an innovative technique using a considering sensitivity and analytic hierarchy process (CSAHP). Along with interviews with managers and workers at the Taipei Rapid Transit Corporation, this study was able to undertake quantitative analysis. To determine which subsystems and metro lines should be prioritized for outsourcing based on the CSAHP framework, we used the criterium decision plus (CDP) program. This research adds to the existing body of knowledge by advancing the existing analytic hierarchy process (AHP) technique and recommending the CSAHP strategy for assessment. According to the findings, the power supply system was the most in need of outsourcing, followed by air conditioning, firefighting, and elevator systems. When considering which of the four metro lines to outsource first, the blue line came out on top, followed by the red, green, and brown lines. By prioritizing the outsourcing of the power supply system as a result of this research, the Taipei Rapid Transit Corporation may cut the system's maintenance expenditures from USD 1.57 million to USD 1.33 million, saving 15% on maintenance costs. Applying these findings can improve the economic benefits of outsourced maintenance for the Taipei Rapid Transit Corporation. [ABSTRACT FROM AUTHOR]

5G networks require dynamic network monitoring and advanced security solutions. This work performs the essential steps to implement a basic 5G digital twin (DT) in a warehouse scenario. This study provides a paradigm of end-to-end connection and encryption to internet of things (IoT) devices. Network function virtualization (NFV) technologies are crucial to connecting and encrypting IoT devices. Innovative logistical scenarios are undergoing constant changes in logistics, and higher deployment of IoT devices in logistic scenarios, such as warehouses, demands better communication capabilities. The simulation tools enable digital twin network implementation in planning. Altair Feko (WinProp) simulates the radio behavior of a typical warehouse framework. The radio behavior can be exported as a radio simulation dataset file. This dataset file represents the virtual network's payload. GNS3, an open-source network simulator, performs data payload transmission among clients to servers using custom NFV components. By transmitting data from client to server, we achieved end-to-end communication. Additionally, custom NFV components enable advanced encryption standard (AES) adoption. In summary, this work analyzes the round-trip time (RTT) and throughput of the payload data packages, in which two data packages, encrypted and non-encrypted, are observed. [ABSTRACT FROM AUTHOR]

Astragaloside IV isolated from Astragalus membranaceus (Fisch.), which was reported to have anti-tumor, anti-asthma, and suppressed cigarette smoke-induced lung inflammation in mice. This study investigated whether astragaloside IV reduced the expression of inflammatory mediators and oxidative stress in BEAS-2B cells. BEAS-2B cells treated with astragaloside IV, and then stimulated with TNF-α or TNF-α/IL-4. The levels of cytokine and chemokine were analysed with ELISA and real-time PCR. Astragaloside IV significantly inhibited the levels of CCL5, MCP-1, IL-6 and IL-8. Astragaloside IV also reduced ICAM-1 expression for blocked THP-1 monocyte adhesion to BEAS-2B cells. Furthermore, astragaloside IV attenuated the phosphorylation of MAPK, and reduced the translocation of p65 into the nucleus. Astragaloside IV could increase the expression of HO-1 and Nrf2 for promoting the oxidant protective effect. Aastragaloside IV has an anti-inflammatory and oxidative effect via regulated NF-κB, MAPK and HO-1/Nrf2 signalling pathways in human bronchial epithelial cells. [ABSTRACT FROM AUTHOR]

The manufacturing industry faces the challenge of small and diversified customer orders. To meet this challenge, strong internal production capabilities are required. A lean manufacturing process that uses fewer resources and offers greater process improvement will help SMEs to continue to contribute to the global economy. Though SMEs provide most employment opportunities, previous studies have focused on large companies in auto-manufacturing-related industries. With the commitment and support of the management, and the application of a value stream map (VSM) and related improvement tools, we produced a practical process improvement model for a lean manufacturing system in an SME. With the commitment and support of the management and the joint efforts of the project improvement staff, the 10 improvement projects over a six-month period all achieved their goals: reduction in lead time from 26 days to 19.5 days, improvement of welding per people per hour (PPH) efficiency by 28.3%, improvement of packaging PPH efficiency by 64.1%, improvement of working in process (WIP) efficiency at the production site by 83.84%, and improvement of raw material storage by 83.84%. The efficiency of the raw material warehouse inventory was improved by 58.63%, and the efficiency of the shipment completion rate was improved by 14.5%. [ABSTRACT FROM AUTHOR]

Under the emerging topic of machine vision technology replacing manual examination, automatic optical inspection (AOI) technology has been adopted for the detection of defects in semi-finished/finished products and is widely used for the defect detection of printed circuit boards (PCB) in electronic industries where surface mount technology (SMT) is applied. In order to convert images from gray-scale to binary in the PCB process, a strict threshold value was set for AOI to prevent 'escapes', but this can lead to serious false alarm because of unwanted noises. Therefore, they tend to set up a Noise-Removal procedure after AOI, which increases the computational cost. By applying deep learning to circuit images of the ceramic substrates in AOI, this paper aimed to construct an automatic defect detection system that could also identify the categories as well as the locations of defects. This study proposed and evaluated three models with integrated structures: ResNeXt+YOLO v3, Inception v3+YOLO v3, and YOLO v3. The outcomes indicate that the defect detection system built on ResNeXt+YOLO v3 could most effectively detect standard images that had been misidentified as defects by AOI, categorize genuine defects, and find their location. The proposed method could not only increase the inspection accuracy to 99.2%, but also help decrease the cost of human resources generated by manual re-examination. [ABSTRACT FROM AUTHOR]

Under the prosperity of the global electronics industry, the current market requires consumer products, such as smartphones, notebook computers, tablet computers, and other portable electronic products, to become lighter, thinner, shorter, and smaller. The miniaturized design of the system-in-package (SiP) technology integrates multiple different chips, such as an array package [ball grid array/chip-scale package (BGA/CSP)] or a peripheral package [quad flat package/thin small outline package (QFP/TSOP)], as well as passive components, such as resistors and capacitors, into a single package module. The vacuum printing encapsulation system (VPES) features cost-efficiency and flexibility advantages, compared with traditional transfer molding and compression molding, and thus improves product reliability. However, as VPES is an emerging process, the impact of relevant VPES parameters has not yet been determined. Moreover, it has been discovered that there are still air bubbles in the cured epoxy molding compound (EMC). In this study, the Taguchi experimental design is applied to propose the optimal process parameter combination, including the squeegee moving speed: 20 mm/s, the printing delay time: 20 s, the number of squeegee printings: three, and the inner chamber vacuum: 3 kPa. The results of variance analysis show that the contributions of the number of squeegee printings and the inner chamber vacuum to the air bubble rate of the EMC adhesive material are 76.38% and 17.75%, respectively, which indicates that they have a significant impact. The results of confirmation testing show that the above optimal VPES process parameters can minimize the air bubble rate occurring in the EMC adhesive material and avoid the risks of short circuits in the tin bridge during the reflow process of the SiP module. [ABSTRACT FROM AUTHOR]

For system manufacturers, packaging of the ball grid array (BGA) of wireless communication modules can be performed via solder paste printing. As reballing can be conducted via the pretinning process, it can be compatible with its existing surface mount technology (SMT). This study referred to the Taguchi experimental design to plan its experiment. Three quality characteristics related to the consistency of the solder volume are applied for printing, that is, the standard deviation of the deposition volume of solder paste on all bonding pads of a single component, the coplanarity of the solder balls of the component, and the height range of the solder ball of a single component, which were regarded as the response values. Important design and process parameters related to the pretinning process and the relative location of the bonding pads of components on a connecting board are considered as the controlling factors. Then, this study applied and integrated the results of two multivariate analysis methods, i.e., gray correlation of the principal components and a technique for order preference by similarity to ideal solution (TOPSIS), in order to determine the ideal solution and propose the optimal parameter combination: general squeegee: pressure 40 N and speed 30 mm/s; steel: separation distance 3 mm, speed 2 mm/s, and aspect ratio 0.17; and cleaning frequency: cleaning of stencils after the printing of every two boards. This method effectively improves the control of the solder volume in the pretinning process and meets the acceptance criteria of manufacturers. [ABSTRACT FROM AUTHOR]

The distributed permutation flowshop scheduling problem (DPFSP) is a newly proposed topic in the shop scheduling field, which has important application in globalised and multi-plant environments. This study presents a modified iterated greedy (MIG) algorithm for this problem to minimise the maximum completion time among all the factories. Compared with previous approaches, the proposed algorithm is simpler yet more effective, more efficient, and more robust in solving the DPFSP. To validate the performance of the proposed MIG algorithm, computational experiments and comparisons are conducted on an extended benchmark problem set of Taillard. Despite its simplicity, the computational results show that the proposed MIG algorithm outperforms all existing algorithms, and the best-known solutions for almost half of instances are updated. This study can be offered as a contribution to the growing body of work on both theoretically and practically useful approaches to the DPFSP. [ABSTRACT FROM PUBLISHER]

Ball grid array (BGA) package components are widely used in various electronic products, as they shorten the conductive path and greatly reduce the interference during current transmission. The BGA component solder ball has little flexibility for distortion, which may cause stress concentration and solder joint cracking. Red ink dye stain analysis testing can visually analyze the cracking area and the interface of the solder joint. At present, most companies use failure analysis (FA) specialists to observe the components and circuit board end images with a microscope. As component packaging technology becomes more complex and the number of input–output (I/O) signals of the chip increases sharply, FA operations require a long time and may be misjudged due to personnel fatigue and subjective determination. This paper aims to develop a machine vision image recognition system for intelligent decision analysis to judge the severity of solder ball cracking and the cracking interface type. This system uses charge-coupled devices (CCDs) to obtain the image. First, this paper uses affine transformation compensation to perform horizontal correction, which recognizes the actual position coordinates of each solder joint, estimates the solder ball according to the Hough Circle to obtain the center and the radius of the solder ball, and then a 2-D vector map (Gerber) file is used to establish the mask, and the region of interest (ROI) in the image feature is obtained through the iterator of the pixel access program. Second, the color space is converted from red, green, and blue (RGB) to hue, saturation, and value (HSV) to reduce the effects of light variations during image capture. This paper develops the range analysis model (uses the multiple-threshold method to judge whether a particular pixel in an image has the cracking (color) feature, as well as its cracking interface), and uses a morphology filter to filter image noise (filter pixels of overlapping features). The verification results show that the system developed in this paper and FA specialists have a consistency of more than 85% in the judgment of the severity of the cracking, and the false alarm ratio and the escape ratio of the system are about 9% and 16%, respectively. Regarding the judgment result of the solder ball cracking interface type, the consistency reaches 98%, which shows that the automatic failure identification system for solder joints, as developed in this paper, can effectively assist red ink solder joint FA. [ABSTRACT FROM AUTHOR]

The emergence of environmental awareness, particularly regarding green packaging, has caused SAC305, a tin-silver–copper alloy (Sn 96.5%, Ag 3%, and Cu 0.5%), to become a widely used lead-free solder material. The use of SAC305 increases in temperature requirements for reflow soldering roughly 15 °C–35 °C compared with that of the use of Sn63Pb37, a conventional tin-lead solder. However, component and printed circuit board (PCB) warpage may occur when subject to high temperature, leading to open solder joints and other defects. The ball grid array (BGA), quad flat pack, and dual-flat no-lead (DFN-8) packaging components of server PCBs were tested in this paper. First, the height of the component contacts, printing thickness of the solder paste, and PCB and component warpage were examined, and geometric principles were applied to establish an open solder joint model for nonflat solder joints. Subsequently, the Monte Carlo simulation method was used to sample the aforementioned parameters randomly and calculate the distance between the contacts at the bottom of the electronic component and the surface of the solder paste. A threshold value was used to determine whether the contacts at the bottom of the components were connected to the surface of the solder paste and independently evaluate the occurrence of open solder joints before and during reflow soldering. [ABSTRACT FROM AUTHOR]

This study investigates the application of a polyvinyl alcohol (PVA)/functionalized carbon nano-tubes (m-CNTs) composite in alkaline direct ethanol fuel cells (ADEFC). The m-CNTs are functionalized with PVA using the ozone mediation method, and the PVA composite containing the modified CNTs is prepared. Adding m-CNT into the PVA matrix enhances the alkaline uptake and the ionic conductivity of the KOH-doped electrolyte. Meanwhile, the m-CNT-containing membrane exhibited a lower swelling ratio and suppressed ethanol permeability compared to the pristine PVA film. The optimal condition for the ADEFC is determined to be under operation at an anode feed of 3 M ethanol in a 5 M KOH solution (at a flow rate of 5 cm 3 min −1 ) with a cathode feed of moisturized oxygen (with a flow rate of 100 cm 3 min −1 ) and the KOH-doped PVA/m-CNT electrolyte. We achieved a peak power density value of 65 mW cm −2 at 60 °C, which is the highest among the ADEFC literature data and several times higher than the proton-exchange direct ethanol fuel cells using sulfonated membrane electrolytes. Therefore, the KOH-doped PVA/m-CNT electrolyte is a suitable solid electrolyte for ADEFCs and has potential for commercialization in alkaline fuel cell applications. [ABSTRACT FROM AUTHOR]

This paper studies the design analysis and debugging mechanism against electrical product electromagnetic compatibility (EMC). The aim is to employ an effective electromagnetic interference suppression solution based on the integration of quality function deployment (QFD) and TRIZ during the early development phase of electronic products to reduce both unit cost and launch time. The QFD relationship matrix displays potential contradictions in technical requirements, and the TRIZ contradiction matrix methodology helps to suggest generic solutions which then serve as solution triggers. This paper takes the example of reducing a Notebook PC’s EMC to meet customer specification demands and with QFD applications. It then proposes an innovative approach in solving EMC contradictions including: (1) QFD-based case analysis for Notebook PC computer products, (2) key EMC issues derived out of QFD analysis, (3) innovative design solutions solving EMC issues by way of TRIZ, and (4) evaluation of multiple solution effectiveness. [ABSTRACT FROM AUTHOR]

This paper integrates the theory of inventive problem solving and cluster analysis to develop effective rework processes for underfilled electronic components. First, the function analysis is used to clarify the functional disadvantages such as underfill material attaching to the component, the printed circuit board (PCB), and the solder joints during the rework process. The cause–effect contradiction chain analysis then helps to identify engineering contradictions. Second, this research proposes clustered contradiction matrix. The optimal number of clusters for the inventive principles is determined by Ward’s method of hierarchical approach. The $K$ -means method is then used to allocate the engineering parameters to the appropriate cluster to achieve superior clustering performance. The priority of inventive principles considered as solution triggers is based on their corresponding frequency of appearances. Three solutions focused laser beam to remove electronics component, dispensable component bracket, and interchangeable PCB are proposed to rework the underfilled electronics components. Finally, the idealities of solutions are assessed and the most ideal solution interchangeable PCB is nominated for the U.S. patent. [ABSTRACT FROM AUTHOR]

Numerous technological problems that arise during the development of innovative products must be overcome in a short period of time. The lack of methods of systematically inventive problem-solving may lead to repeated failures during innovation processes. Therefore, this study combined the workout and the Theory of Inventive Problem-Solving (TRIZ) approaches to resolve technological inventive problems encountered during the development of a novel bamboo-skin film applicable to in-mold injection molding. The goal of this study was to resolve three technological innovation problems using the following methods: (a) the restrictive brainstorming approach and a 39 × 39 contradiction matrix to resolve problems concerning the poor adhesion between bamboo-skin films and plastics; (b) the restrictive brainstorming approach and the 40 principles of invention (also referred to as 40 principles of TRIZ or 40 innovative principles) to overcome the problem regarding bamboo-skin breakage; and (c) the non-restrictive brainstorming approach to reduce the time required for post-processing. The experimental results show that the proposed approach is able to solve the innovative problems. The exploited approach concerning bamboo is a valuable outcome and reference for further advanced implementations in electrical industry and others. [ABSTRACT FROM AUTHOR]

Tolerance design plays an important role in product development, which guarantees that the product appearance and function meet the product design specification. However, the existing tolerance analysis overlooks the process capacity of part suppliers, which results in variance of tolerance analysis between the designed product and the manufactured one. This study builds the supplier process capacity database with the production part approval process (PAPP), which is then introduced into the design phase for tolerance analysis. The results show the difference of tolerance analysis between conventional law of experience and supplier process capability database, and actual part dimensions are, respectively: (1) X axis: 601, 654, 640 DPPM; (2) Y axis: 964, 8290, 8535 DPPM; (3) Z axis: 29, 4798, 4557 DPPM. Further the study gives a detailed introduction to the construction method of the supplier process capacity database, which can provide reference for the product designers to improve the product design quality. [ABSTRACT FROM AUTHOR]

Package-on-package (PoP) is one of the major manufacturing strategies for achieving an electronic component miniaturization. Achieving a desired process yield is critical to maintaining competitiveness. This paper develops a scientific approach to assess the PoP assembly yield in both the x–y in-plane and the z-direction using a Monte Carlo simulation. Influences of variations of materials such as components and printed circuit boards (PCBs) are investigated. Equipment accuracy and different process strategies are also under consideration. The scenarios under which defects occur are defined through the geometric phenomena, process incidence, and theoretical inferences. Defects such as shorts and soldering open may occur after reflow soldering if there is an excessive amount of offset between the centers of the solder ball and the bonding pad during the component placement stage. The amount of component/PCB warpage during the reflow heating and coplanarity of the solder balls beneath the substrate will also impact the package stacking yield. The simulation-based design for experiment is employed to investigate the effects of soldering materials, stencil thickness, reflow temperature profile, and component ball height variation on the assembly yield. The optimal materials and process combinations are then identified. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to employ data mining as a new diagnosing scheme for investigating void formation to the thermal pad in quad flat non-lead (QFN) assembly. Occurrences of voiding in various scenarios of component design, materials selection and manufacturing process are analyzed. Design/methodology/approach – This research investigates the process yield of a PCB assembly for a handheld device in the electronics manufacturing industry using the chi-square automatic interaction detection (CHAID) algorithm and chi-square test. Practical data generated by an X-ray apparatus from the shop floor are collected. The critical attributes to the void formation (in the solder joint) of the QFN component are identified. Findings – Stocking the PCB material beyond ten days may increase the level of voiding by 1%. Using PCB provided by vendor U helps decrease the level of voiding by 1.6%. Stocking the component material above 43 days may increase the level of voiding by 1.9%. In addition, reflow soldering profile with time above liquid (TAL) less than or equal to 62 sec and with peak temperature higher than or equal to 241°C generate less voids. Finally, the via-in-pad design causes a concave geometry on the surface of thermal pad which contributes to the voiding formation. The amount of voiding can be further diminished by plugging the via with plated copper. Originality/value – This research implements CHAID that extracts useful knowledge from a huge amount of manufacturing data in order to realize the complex interaction effects through automated analysis. The extent of voiding in the samples using the optimal process suggested through CHAID algorithm can be reduced from 16% to 10.2%. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) have been adopted in a wide variety of lighting situations. As lighting technology evolves, illumination devices are moving toward miniaturization and high-power applications. Packaging of illumination devices is essential to providing a path for heat dispersion. A full understanding of the viscosity change of the encapsulation material is critical to ensure manufacturability and improved process yield. The typical viscosity model is the initial viscosity plus the change in viscosity over time at a given temperature. The change in viscosity is a function of the reaction rate and the pro-exponential factor. This paper includes the pro-exponential factor in the regression model to improve the prediction accuracy. Through experimental data, the material's viscosity is determined as a function of process temperature, the ratio of the curing agent, and the curing time. A computer-aided parametric design is used to assess the effect of the variation of individual factors on the quality function and proposes a robust LED encapsulation process. An artificial neural network that considers interactions between parameters and establishes fitness functions is used to further enhance the accuracy of predictions and determine the optimal process solution through an iterative training algorithm. The optimal process scenario suggested by this research is a 10% curing agent preheated at 333^\circK for 40 min. This robust process can improve the signal-to-noise ratios by approximately 43%. [ABSTRACT FROM PUBLISHER]

One lead free solder candidate, Sn-Ag-Cu305 (Sn96.5/Ag3.0/Cu0.5), has come into widespread use as a replacement for traditional tin-lead solder (Sn63/Pb37). However, the price of silver has increased dramatically in recent years. This has increased manufacturing costs, impacting firm competitiveness. This paper evaluates the performance of the low cost Sn–Cu–Ni solder alloy used for wave soldering. Sample products for several applications are used to assess critical factors in the wave soldering process. A principal component analysis was performed in this paper to integrate multiple quality characteristics, namely assembly yield and solder joint strength, for process development. As a result, a parameter combination of 270^\circC soldering temperature and 8 s dwell time is recommended. A test vehicle with daisy-chain circuitry design is used to investigate the performance of samples prepared by the optimal process. Samples are subject to the thermal cycling test. The performance of the recommended process is therefore verified. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to comprehensively explore the effects of critical parameters on solder deposition and to establish a systematic approach for determining guidelines for solder paste inspection (SPI) workstations. Design/methodology/approach – This study explored the effects of process parameters, stencil and printed circuit board designs on solder deposition and identified the major post-reflow defect scenarios. Through the investigation of correlation between the results of SPI analysis and post-reflow defective scenarios, SPI specifications are suggested for minimizing the total cost of poor quality. Findings – The higher the printing pressure the lower the solder deposition. There was a significant difference in solder deposition between the front squeegee and the rear squeegee. Insufficient distance between the stencil aperture and the initial printing location resulted in irregular solder paste and variations in solder deposition. A stencil with a higher area ratio resulted in greater solder deposition and less variation. Stencil apertures parallel to the direction of printing were superior to a 45° vector print. Further, the nominal solder thickness should take into account the thicknesses of the solder mask and the legend ink. There was an offset in the results of SPI measurements between the solder mask defined (SMD) pads and non-SMD pads. The specifications for solder deposition with irregular stencil apertures need to be adjusted. Originality/value – To address the arbitrariness of existing industry practice, this study was a joint effort with a Taiwan-based electronics manufacturing service company. Real data were taken from a mass production environment and inferences were then made based on a statistical analysis. [ABSTRACT FROM AUTHOR]