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An Overview of Hybrid Assemblies
Published in Fred W. Kear, Hybrid Assemblies and Multichip Modules, 2020
When the term hybrid is used, it implies the combining of two or more packaging methods into a single packaging scheme. For instance, the print-and-fire process allows certain components to be manufactured by deposition in conjunction with the creation of printed circuits that are screened onto the ceramic substrate. This is followed by screening of solder paste, placement of surface-mount components, and reflow soldering. Wire bonding, tape automated bonding, flip-clip technology, and other techniques enhance the options offered by the modern user of hybrid assemblies. The use of through-hole components, although not completely excluded from this technology, is diminishing rapidly. When a hybrid circuit assembly is complete, it is not unlike an integrated circuit (and, indeed, these are often called “integrated hybrid circuits”). From this perspective it is easier to differentiate between a hybrid circuit assembly and an ordinary printed circuit assembly.
Shadow moiré interferometry with a phase-stepping technique applied to thermal warpage measurement of modern electronic packages
Published in C A Walker, Handbook of Moiré Measurement, 2003
The system for temperature-dependent shadow moiré analysis of electronic packaging materials was described by Stiteker and Ume [9] and it was improved by applying the phase-stepping technique so that the system is able to analyse the fringe patterns automatically. The heating system is capable of simulating a variety of soldering processes, such as wave soldering and infrared reflow soldering. Figure 11.3.3 is a diagram of the system. The optical grating is set on a stage that is driven by a computer-controlled stepper-motor. The test sample is set inside of an insulated chamber and its temperature is measured by multiple thermocouples interfaced through signal conditioning circuitry to a desktop computer. The signal of a master thermocouple is compared with a user-entered temperature profile and the heater is controlled accordingly. The fringe pattern images are recorded in real time by a CCD camera and the recorded images are later analysed.
Electronic Connections
Published in Milenko Braunovic, Valery V. Konchits, Nikolai K. Myshkin, Electrical Contacts, 2017
Milenko Braunovic, Valery V. Konchits, Nikolai K. Myshkin
The eutectic alloy Sn–0.7Cu with a melting temperature of 227°C is similar to Sn–37Pb for surface-mount use. However, owing to melting temperature that is 10°C higher than tin/silver/copper, this alloy is undesirable for reflow applications. In wave-soldering applications, the temperatures that the boards and components reach are much lower than in reflow soldering. Because this alloy does not contain silver or bismuth, it is one of the cheapest lead-free solder alloys available and thus its use in wave soldering is advantageous as a low-cost alternative to tin-lead solder in wave-soldering applications. The alloy apparently works well in high-temperature applications, such as those required by the automotive industry.
Effect of isothermal ageing on the microstructure, shear behaviour and hardness of the Sn58Bi/SnAgCuBiNi/Cu solder joints
Published in Welding International, 2021
Jian Chang, Yang Liu, Hao Zhang, Min Zhou, Xue Yuxiong, Xianghua Zeng, Rongxing Cao, Penghui Chen
Our previous results showed that the SnBi/SACBN/Cu composite solder joints with superposition structure can be successfully fabricated and the interface brittleness of SnBi/Cu solder joints is effectively suppressed after reflow soldering. However, the performance changes of the composite solder joints during ageing are still unknown. Therefore, the evolution of the microstructure, shear behaviour and hardness of the SnBi/SACBN/Cu composite solder joint during isothermal ageing were investigated in this study in comparison with the SnBi/Cu and SACBN/Cu solder joints.
Many-objective flow shop scheduling optimisation with genetic algorithm based on fuzzy sets
Published in International Journal of Production Research, 2021
Wen-Jie Xu, Li-Jun He, Guang-Yu Zhu
In this section, the scheduling problem of PCB assembly is studied. In PCB assembly shop, all PCB boards (jobs) will be mounted through six main processes: solder paste printing, component placement, pre-reflow automated optical inspection (AOI), reflow soldering, post-reflow AOI, final inspection and functional test. Each PCB is handled by one machine in each process and shall go through all processes. The processing time of each job at each process is different. This is a flow-shop scheduling problem and can be optimised with many objectives.