Solder energy consumption

The primary resins used in this market are the radiation-curable epoxy acrylates, accounting for 60% of the resins used. A small amoimt of cycloaliphatic epoxies are also used in UV-curable inks and resists. Phenol and cresol epoxy no-volacs, and bisphenol A based epoxies are used in thermally cured formulations. The epoxy novolacs are used where higher heat resistance is needed such as in solder masks. Both free-radical and cationic-curable UV inks and colored base coats have grown rapidly because of the needs for higher line speeds, faster cleanup or line turnaround, less energy consumption, less capital for a new hne, and fewer emissions. 

Science (NCMS) estimated that replacing Pb in electronic assemblies will result in a material cost of US 140-900 million dollars in the United States alone, with supply chain costs likely to run in the tens of billions of dollars [66]. Cost issues are related to materials (solders, components, boards, protective atmospheres during processing, additional energy consumption due to the higher process temperatures required for most lead-free solders, and operational costs). 

As indicated in the Product Assessment Matrix (Table 5), an environmental assessment of mining metal must consider the energy consumption and the solid, liquid and gaseous residues that result from the various mining processes. Availability of the metals is an additional consideration. Table 6 lists the world reserves of the major metals typically utilized in electronic assemblies. Sn-Ag-Cu alloy is one of the major compositions proposed as a replacement for Sn-Pb solder. Silver is 300 times less available than lead. Half of the silver available comes as a by-product from mining lead, copper and zinc. Antimony and bismuth are also obtained as by-products of lead, copper and silver mining. 

During machine startup (warm-up time) more energy is consumed per hour than during wave operation. Typical heat-up time for eutectic tin-lead solder (250°C) is 3 consuming approximately 34 kWh for a standard commercial unit. In contrast, the maximum wave temperature required for Sn-Cu solder is much higher, approximately 280 °C. The heat-up time for Sn-Cu solder is about 5 hours with an energy consumption of 36 kWh. The power consumption required to maintain the solderpot at temperature was determined to be similar for both alloys despite the temperature dilference. 

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