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Soldering copper pipes using a propane torch and a lead-free solder. Solder is a metallic material that is used to connect metal workpieces. The choice of specific solder alloys depends on their melting point, chemical reactivity, mechanical properties, toxicity, and other properties.
Solderability when using lead-free alloys can differ significantly from solderability when using lead based alloys. Noble metals may be easy to solder but they have brittle joints. The metals in the good category require a large amount of heat therefore oxidation is an issue. To overcome this a flux is required.
Tin-silver-copper (Sn-Ag-Cu, also known as SAC), is a lead-free alloy commonly used for electronic solder.It is the main choice for lead-free surface-mount technology (SMT) assembly in the industry, [1] as it is near eutectic, with adequate thermal fatigue properties, strength, and wettability. [2]
The solder used in the process can vary in composition, with different alloys used for different applications. Common solder alloys include tin-lead, tin-silver, and tin-copper, among others. Lead-free solder has also become more widely used in recent years due to health and environmental concerns associated with the use of lead.
The more common lead-free solder systems have a higher melting point, e.g. a 30 °C typical difference for tin-silver-copper alloys, but wave soldering temperatures are approximately the same at ~255 °C; [47] however at this temperature most typical lead-free solders have longer wetting times than eutectic Pb/Sn 37:63 solder. [49]
Microscopic view of tin used to solder electronic components, showing a whisker. Metal whiskering is a crystalline metallurgical phenomenon involving the spontaneous growth of tiny, filiform hairs from a metallic surface. The effect is primarily seen on elemental metals but also occurs with alloys.
Soldering performed using alloys with a melting point above 450 °C (840 °F; 720 K) is called "hard soldering", "silver soldering", or brazing. In specific proportions, some alloys are eutectic — that is, the alloy's melting point is the lowest possible for a mixture of those components, and coincides with the freezing point.
Solder is a metal alloy used to form electrical, thermal, and mechanical interconnections between the component and printed circuit board (PCB) substrate in an electronic assembly. Although other forms of cyclic loading are known to cause solder fatigue, it has been estimated that the largest portion of electronic failures are ...