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Wearable Electronics
Published in Muhammad Mustafa Hussain, Nazek El-Atab, Handbook of Flexible and Stretchable Electronics, 2019
Sherjeel M. Khan, Muhammad Mustafa Hussain
A circuit board, commonly referred to as printed circuit board (PCB), is the substrate that holds the electronic components on insulating material and connects the components to each other using electrically conductive metal tracks. A flexible circuit board is very similar to a rigid circuit board where the only difference is that the substrate is now flexible instead of being rigid. The metal interconnects are inherently flexible as their thickness is less than 500 µm. This allows the circuit board to possess any shape provided it stays within the bending limits of the substrate material. In previous subsections, we have discussed the flexibility of all the components in a wearable, and their integration on a flexible circuit board can help us envision a fully compliant wearable system. Commercial companies like Flexible Circuit© Technologies are dedicated to making flexible circuit boards for companies in need of making a flexible wearable device. The circuit boards need to be tested for performance under long term bending conditions.
Model-Based Flexible PCBA Rework Cell Design
Published in Cornelius Leondes, The Design of Manufacturing Systems, 2019
Printed circuit boards may be classified into two basic categories based on the way they are manufactured: graphical and discrete-wire interconnection boards. A graphical interconnection board is another term for the standard printed circuit board, in which the image of the master circuit patterns is formed photographically on a photosensitive material such as a glass plate or film. The image is then transferred to the PCB by screening or photoprinting the artwork generated from the master. Discrete-wire interconnection does not involve an imaging process for the formation of signal connections. Rather, conductors are formed directly on the wiring board with insulated copper wire. Wire-wrap, Unilayer-II, and Multiwire are some of the best-known discrete-wire interconnection technologies [14]. The majority of PCBs are graphically produced rigid boards and maybe classified into three classes as single-sided, double-sided, or multilayer boards. Single-sided boards have circuits on only one side of the board. Double-sided boards have circuits formed on both side of the boards. Multilayer boards (MLBs) have three or more circuit layers by definition. Some boards have as many as 60 layers.
Development of Test Access Port (TAP) design for IEEE 1149.1 standard improvements
Published in Kennis Chan, Testing and Measurement: Techniques and Applications, 2015
During handling or even manufacturing PCBs and ICs, defects may develop (Tseng et al., 2004). Those defects such as open circuits or short circuits may appear in or between circuit pathways and electronic components. E ective testing system is necessary for maintenance purposes and also for manufacturing quality insurance. The rapid development of electronic module assembly manufacturing requires a parallel development in test procedures (Moganti et al., 1996, Moganti and Ercal, 1998, Kusiak and Kurasek, 2001, Tong et al., 2004). PCB testing is becoming more expensive and difficult due to the complexity of PCBs design. The common methods for diagnosing PCBs are still suffering from many difficulties; it needs a long time, a lot of manual work, and direct contact with PCB, and it is so expensive (Sheen et al., 1997). Testing has to be good (having high defect coverage), cheap and fast. The IC defect level in 1970 was 1000 defective chips per million (DPM) delivered, but nowadays it bellows 10 DPM. Experts are still pushing this number to reach 0 DPM level (Vermeulen et al., 2004). Previously, the unique method to inspect PCBs was manual testing method; it involves using visual inspection, multi-meters, oscilloscopes and other testing equipments. This method is almost inapplicable for the recent PCBs due to the hugely mounted number of components installed on PCBs. Moreover, Generally, PCB includes many ICs on a single board, each of which is separately designed and verified before use. Multiple test patterns may be applied to a
Discovery of fault-introducing tool groups with a numerical association rule mining method in a printed circuit board production line
Published in International Journal of Production Research, 2023
Yeonju Lee, Youngju Kim, Bogyeong Lee, Chang Ouk Kim
Printed circuit boards (PCBs) are thin electronic circuit boards on which copper lines are printed; PCBs connect electronic components such as semiconductor chips and resistors. A PCB production line is a multistage line with various process steps and tools for each process step. The products are processed in units of lots; one lot comprises dozens of panels, which are large sheets containing several PCBs and hundreds of chips. Once all process work is completed, some panels in each lot are sampled, the number of faulty chips in each lot is counted, and the yield of the process, which is the ratio of nondefective products, is calculated. The PCBs are subsequently separated from the panels, yielding the finished PCB products. It is important for PCB manufacturers to reduce the number of faulty chips (i.e. increase the yield of the process) to ensure competitiveness.
Electrochemical double-pulse technique to modulate the roughened surface of copper foil for copper-clad laminates
Published in Transactions of the IMF, 2022
Ni Wang, Qi Chen, Xinyu Gong, Wencheng Hu
With the development of electronic products, higher requirements are being demanded for the intermediate materials, devices, and components of electronic terminal products. As an important component of electronic products, the printed circuit board (PCB) offers a mechanical support to mount electronic components, including resistors, capacitors, inductors, and chips.1 Meanwhile, the fine circuits formed by appropriate etching and metallised holes act as conductive networks to obtain electrical interconnections between the above-mentioned components.2 The core raw material of a PCB is the copper-clad laminate (CCL), which determines the characteristics of a PCB assembly and application fields. The current technology is primarily based on the etching method to prepare single- or double-sided PCBs and an additional laminating process to manufacture multilayer PCBs.
Solvent extraction of gold from a chloride-hypochlorite leached solution of waste printed circuit boards
Published in Geosystem Engineering, 2023
Rajiv Ranjan Srivastava, Nimra Ilyas
The multiple-fold increasing usage of modern devices is generating a huge amount of waste, namely e-waste (Dinkar et al., 2022; Rezaee et al., 2023). E-waste has become a global concern due to unmanageable proportions of this fastest-growing waste worldwide (Ilyas & Lee, 2013; Khanna et al., 2020). Over 50 million tons per annum of e-waste generation by 2020 at a 5% annual growth rate, which is estimated to be ~ 75 million tons by 2030 (Balde et al., 2017; Forti et al., 2020). Currently, Asia generates about 50% of the worldwide e-waste (Shittu et al., 2020) and after the waste dumping policy of China, countries like Vietnam, Pakistan, India, and Bangladesh became the popular destination for e-waste in the name of used items Ilyas, Srivastava, et al. (2021). Despite the preventive legislation, e-waste is continued to be poorly managed in these countries (Pathak et al., 2019). Notably, printed circuit boards (PCBs) are the essential components of e-waste which is accounted for ~40% of the waste generation (Ilyas, Srivastava, Kim, et al., 2022). PCBs are usually referring to the insulating board made of epoxy resin and plastics that contain about 6% metallic fractions comprising the surface layers of Cu-foils covered by a solder mask layer of tin and lead (Lee et al., 2021; Rocchetti et al., 2018). Although the heavy metals are harmful to the environment, they can be valuable as a secondary resource of precious metals like gold that range between 60 ppm and >400 ppm (Mir & Dhawan, 2022) significantly greater than the primary minerals containing about 4 ppm Au (Ilyas, Kim, et al., 2021). As an estimation, more than 260 million tons of gold are consumed to cater the demand of the technology-driven society (Rao et al., 2020).