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Only one phase. Resoldering with lead-tin solder forms indium-tin and indium-lead phases and leads to formation of cracks between the phases, joint weakening and failure. [13] On gold surfaces gold-indium intermetallics tend to be formed, and the joint then fails in the gold-depleted zone and the gold-rich intermetallic. [37]
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. In addition to the type of solder used, the temperature and method of heating also play a crucial role in the soldering process.
The thin gold layer facilitates good solderability of nickel as it protects the nickel from oxidation; the layer has to be thin enough to rapidly and completely dissolve so bare nickel is exposed to the solder. [16] Lead-tin solder layers on copper leads can form copper-tin intermetallic layers; the solder alloy is then locally depleted of tin ...
Higher tin compositions give the solder higher corrosion resistances, but raise the melting point. Another common composition is 11% tin, 37% lead, 42% bismuth, and 10% cadmium. This combination has a low melting point and is useful for soldering components that are sensitive to heat. Environmental and performance requirements also factor into ...
The solder grade used for leadworking is plumber's solder (80% lead / 20% tin). [ i ] Although this is thought of as a high melting point solder amongst lead-tin solders, the solidus is relatively constant for all of these solders and it is the liquidus which climbs from the eutectic point at Sn 63% / Pb 37%.
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.
The most common dip soldering operations use zinc-aluminum and tin-lead solders. Solder pot metal: cast iron or steel, electrically heated. Bath temperature: 220 to 260 °C (for binary tin-lead alloys) or 350 to 400 °C (for lead-free alloys) Solder composition: 60% Sn, 40% Pb or eutectic alloy.
Tin whiskers were noticed and documented in the vacuum tube era of electronics early in the 20th century in equipment that used pure, or almost pure, tin solder in their production. It was noticed that small metal hairs or tendrils grew between metal solder pads, causing short circuits. Metal whiskers form in the presence of compressive stress.