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26 SMT007 MAGAZINE I SEPTEMBER 2024 optimization for new solder alloys. Recent flux advancements include: • Improvements of head-on-pillow and non-wet-opens for BGA soldering • Optimization for small solder powder sizes (Types 6 and 7) for miniaturized electronics • Improvement in no-clean flux reliability for more rigorous surface insulation resis- tance (SIR) and electrochemical migration (ECM) conditions. ere is also a shi to completely halide- and halogen-free solder pastes, which may improve reliability. • Optimization of no-clean solder pastes for high-power applications like electric vehicles Solder alloy advancements include high-reli- ability alloys for harsh environments, and low melting alloys. e elements used to reduce the melting point of Sn (tin) based solders are Bi (bismuth) and In (indium), and both ele- ments can improve the "reliability" of Sn-based solders when used as alloy additives. In some cases, the "high reliability" alloys also have a lower melting point than SAC305 and may fit into both categories. High-reliability alloy development is mainly targeted at the automotive industry as the cur- rent automotive alloys have some weaknesses, and the volume of consumption is very high. Low melting alloys are being developed to reduce defects like head-on-pillow and non- wet-opens for BGA soldering and other tem- perature-related defects. Using lower solder temperatures facilitates the use of less costly laminates like CEM (paper based) and reduces energy consumption and costs. SMT007 Mike Konrad is founder and CEO of Aqueous Technologies, and vice president of communications for SMTA. To read past columns, click here. Researchers at Linköping University, Sweden, have developed a digital display screen where the LEDs themselves react to touch, light, fingerprints and the user's pulse, among other things. "We've now shown that our design principle works. Our results show that there is great poten- tial for a new generation of digital displays where new advanced features can be created," says Feng Gao, professor in optoelectronics at Linköping Uni- versity (LiU). The most modern LCD and OLED screens on the market can only display information. To become a multi-function display that detects touch, finger- prints or changing lighting conditions, a variety of sensors are required that are layered on top of or around the display. The LEDs are made of a crystalline material called perovskite. Its excellent ability of light absorption and emission is the key that enables the newly developed screen. The device can also be charged through the screen thanks to the perovskites' ability to also act as solar cells. But many challenges remain before the screen is in everyone's pocket. Zhongcheng Yuan, a researcher at the University of Oxford, previously a postdoc at LiU, and the other lead author of the paper, believes that many of the problems will be solved within ten years. (Source: Linköping University) Breakthrough for Next-generation Digital Displays