Wei Fang, Mingyu Fu and Lianyu Zheng
This paper aims to perform the real-time and accurate ergonomics analysis for the operator in the manual assembly, with the purpose of identifying potential ergonomic injuries…
Abstract
Purpose
This paper aims to perform the real-time and accurate ergonomics analysis for the operator in the manual assembly, with the purpose of identifying potential ergonomic injuries when encountering labor-excessive and unreasonable assembly operations.
Design/methodology/approach
Instead of acquiring body data for ergonomic evaluation by arranging many observers around, this paper proposes a multi-sensor based wearable system to track worker’s posture for a continuous ergonomic assessment. Moreover, given the accurate neck postural data from the shop floor by the proposed wearable system, a continuous rapid upper limb assessment method with robustness to occasional posture changes, is proposed to evaluate the neck and upper back risk during the manual assembly operations.
Findings
The proposed method can retrieve human activity data during manual assembly operations, and experimental results illustrate that the proposed work is flexible and accurate for continuous ergonomic assessments in manual assembly operations.
Originality/value
Based on the proposed multi-sensor based wearable system for posture acquisition, a real-time and high-precision ergonomics analysis is achieved with the postural data arrived continuously, it can provide a more objective indicator to assess the ergonomics during manual assembly.
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Keywords
Shan Li, Li Juan Zheng, Cheng Yong Wang, Bing Miao Liao and Lianyu Fu
In an integrated circuit (IC) substrate, more fillers, including talcum powder and aluminium hydroxide, are added, which leads to much higher rigidity and hardness compared with a…
Abstract
Purpose
In an integrated circuit (IC) substrate, more fillers, including talcum powder and aluminium hydroxide, are added, which leads to much higher rigidity and hardness compared with a traditional printed circuit board. However, the micro drilling of IC substrates is harder. This paper aims to test the drilling process of IC substrates to improve the drilling process and the micro hole quality.
Design/methodology/approach
Substrate drilling by a micro drill with 0.11-mm diameter was used under several drilling conditions. The influence of drilling conditions on the drilling process was observed. Drilling forces, drill wear and micro hole quality were also studied.
Findings
The deformation circle around holes, hole location accuracy, bugle hole and burrs were the major defects of micro holes that were observed during the drilling of the substrate. Reducing the drilling force and drill wear was the effective way to improve hole quality.
Originality/value
The technology and manufacturing of IC substrates has been little investigated. Research data on drilling IC substrates is lacking. The micro hole quality directly affects the reliability of IC substrates. Thus, improving the drilling technology of IC substrates is very important.
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Dantian Lin, Chengyong Wang, Lianyu Fu, Yong Ke, Yuxing He, Gexian Fang, Junxiong Yao, Xin Huang and Lijuan Zheng
Large capacity current carrier printed circuit board (PCB) imposes strict control requirements on the hole wall roughness. The key factors are chip removal, drilling temperature…
Abstract
Purpose
Large capacity current carrier printed circuit board (PCB) imposes strict control requirements on the hole wall roughness. The key factors are chip removal, drilling temperature and tool wear. This paper aims to find out a cryogenic drilling process to control the chip removal, chip morphology, tool wear and finally reduce the hole wall roughness.
Design/methodology/approach
The chip removal process, chip morphology, tool wear and hole wall roughness of glass fiber epoxy resin copper clad laminate (FR-4) drilling were observed and analyzed. The influence of cold air on the chip removal process, chip morphology, tool wear and hole wall roughness was also investigated. An optimization process of cold air auxiliary drilling was proposed to control the hole wall roughness of FR-4.
Findings
The results showed that the discharge time of copper foil chips with obvious characteristics can be used as the evaluation criterion for the smoothness of chip removal. The cold air can promote chip removal and reduce tool wear. In addition, the chip removal and cooling performance will be the best when using −4.7 °C cold air with the injection angle consisted with the angle of helical flute of the drill. The hole wall roughness of FR-4 could be controlled by drilling with −4.7°C cold air.
Originality/value
This paper was the first study of the effect of three kinds of cold air on PCB drilling. This provided a reference for the possibility that the cryogenic drilling methods apply to PCB drilling. A new cold air auxiliary drilling process was developed for large capacity current carrier FR-4 manufacturing.
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Xiong Liang, Bing Li, Lianyu Fu, Xiaoyu Wu, Hongyan Shi, Taijiang Peng and Bin Xu
This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder…
Abstract
Purpose
This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder molding (micro-UPM for short) by utilizing PCB micro-hole array.
Design/methodology/approach
To optimize the drilling process, the paper proposes the on-line monitoring methods for the drilling process including drilling force, drilling temperature, high-speed photography and vibration signals. Taking 0.10 and 0.15 mm micro-drilling as examples, the paper analyzes the drilling process of ultra-small micro-holes. Finally, by taking the PCBs with 0.10 and 0.15 mm micro-hole arrays as the micro-cavity inserts, utilizing ultra-high-molecule weight polyethylene powder with the average particle size of about 150 μm as raw material, two sizes of micro-cylinder array polymer parts are fabricated through micro-UPM process.
Findings
PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling has the advantages of low costs, high efficiency and good consistency. Taking 0.10 and 0.15 mm micro-drilling as examples, it is found that the both measured apertures are about 10.0 μm more than the diameter of the micro-drill bits on average. The average diameter of the micro-cylinders by micro-UPM process is smaller than that of the micro-hole with the same specification, while the value of the roughness of the cylinder surface is more than that of the hole-wall surface with the same specification.
Originality/value
This paper describes the challenges and the developments of mechanical drilling and by using PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling, two different micro-cylinder array polymer parts are successfully made and thus the application area of PCB micro-drilling is broadened.
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Wen Cheng and Pham Ngoc Thien Nguyen
This study aims to investigate the relationship between academic motivations and the risk of Not in Employment, Education or Training (NEET) among university undergraduates and…
Abstract
Purpose
This study aims to investigate the relationship between academic motivations and the risk of Not in Employment, Education or Training (NEET) among university undergraduates and Vocational Education and Training (VET) undergraduates.
Design/methodology/approach
The sample included 402 Vietnamese university undergraduates and 250 VET undergraduates in the southern region of Vietnam. Students took part in a survey, with all participants being informed about the study’s purpose and assured that their involvement was entirely voluntary. In addition to descriptive statistics, the study employed linear regression in SPSS to examine hypotheses.
Findings
The findings indicate that, for university students, intrinsic motivation and mastery approach motivation are associated with reduced NEET risk, while performance avoidance motivation is positively linked to this tendency. In contrast, for VET students, extrinsic motivation and performance approach motivation are negatively associated with NEET risk, but mastery approach motivation may exacerbate the risk.
Originality/value
Grounded in the principles of Self-Determination Theory (SDT) and Achievement Goal Theory (AGT), the study proposes that university students may prioritize competence improvement, knowledge acquisition and the satisfaction of their learning interests, which they believe will help them acquire valuable knowledge beneficial for their future careers. Conversely, VET students emphasize performance and external achievement, which may enhance their outcome and reduce NEET risk. These findings offer significant theoretical and practical insights into the adoption of SDT and AGT and also provide educators or policymakers with more detailed information regarding university and VET students’ learning and development.