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Top1. Introduction
The report Research and Markets (2019) estimates that the total value of the electronics assembly worldwide was US$1.3 trillion in 2018. This is expected to grow to approximately US$1.5 trillion in 2023 and shows that the market potential of electronics assembly is relatively high, in which the electronics manufacturing services (EMS) are regarded as the determinant force in electronics production, accounting for 42% of all the assembly tasks. EMS are also deemed to be the most desired manufacturing model in the world for original equipment manufacturers (OEMs) therefore, the market is expected to grow from US$542 billion in 2018 to US$777 billion in 2023. Due to the substantial growth in production of the aforementioned electronic products, the requirements for product quality and productivity of EMS have become stricter and more complicated in recent years (Barrad and Valverde, 2020). On one hand, the EMS companies have to design, manufacture, test, distribute and provide field return services, in which small and precise electronic components are used in the PCBs’ design. On the other hand, customers have become more demanding in relation to product quality and reliability throughout the entire product life cycle. In view of the above considerations, EMS companies are looking for improvements in manufacturing capabilities, productivity performance and product quality assurance. In addition to the current electronics manufacturing industry, as manufacturing technology continues to flourish, production manoeuvring in the factory is being shaped into smart manufacturing architecture. Production mixes in different dimensions of “High volume - low variety” and “Low volume - high variety” become essential in maintaining business competitiveness. Smart manufacturing facilitates the advantage of economic production runs and strategic supply chain management for mass customization and personalization of manufacturing paradigms (Mourtzis, 2016).
For the mass production of electronic products, PCBA is deemed to be a critical process in manufacturing the designated PCBs by means of the appropriate assembly method, such as through-hole technology (THT) and SMT (Lau et al., 2016). Currently, most of the THT operations have been replaced by SMT, which is suitable for producing high volumes of products of a certain level of quality. With the adoption of SMT, the yield performance and product quality of the finished PCBs are the concerns of the EMS companies. As shown in Figure 1, the generic PCBA process using SMT is illustrated, and there are 10 major multi-stages in the work flow, namely (i) PCB cleaning, (ii) solder paste printing, (iii) solder paste inspection (SPI), (iv) modular SMT, (v) reflow oven, (vi) buffering, (vii) automatic optical inspection (AOI), (viii) in-circuit tester (ICT), (ix) PCB depanelizer and (x) storage and distribution of finished PCBs. With regard to the SPI, AOI and ICT, these are added in the PCBA process to inspect the quality of PCBs during the surface mount process (Dong et al., 2012). Therefore, the quality of the finished PCBs can be guaranteed, while the entire production flow can operate in an automatic manner from the bare PCBs to the mounted PCBs.
Figure 1. Generic SMT-based PCBA process
Apart from enhancing operations management, the PCB design does not consider the process performance of PCBA and capabilities of manufacturing sites, since the knowledge of critical factors in PCBA and machine parameter settings cannot be shared effectively. Subsequently, the PCB designs from the Gerber drawing may not be suitable for the specific manufacturing sites, in which process performance is relatively uncertain in relation to the EMS companies and clients. Therefore, an effective measure to estimate process performance and manufacturing capabilities should be developed at the planning stage of designing PCBs. In addition, effective measures of knowledge transfer in the manufacturing industry are lacking (Chuang, 2014). Valuable work experience can only be passed on gradually from one person to another. Manufacturing knowhow is strictly self-reliant, unstructured and limited to certain close team members. Thus, manufacturing knowledge is difficult to transfer which should be the norm in the manufacturing electronic industry.