AuSn20

The gold-tin material AuSn20, also Au80Sn20 or 80Au20Sn, is a gold-based soft solder alloy. Soft solders are characterized by a liquidus temperature <450 ° C. High precious metal-containing special soft solders are always used when the properties of the classic SnPb soft solders do not meet the desired requirements. This is the case in different areas of electronics and microelectronics. The gold base special soft solders are characterized by considerable strength values. At the same time, these materials have almost negligible plastic elongation. AuSn20 will u. a. used as a mechanically highly durable, corrosion-resistant solder material for hermetically sealing ceramic IC housings and used for fixing laser crystals. Typical applications include solder frames for soldering gold-plated covers of FeNi or FeNiCo alloy onto metallized ceramic packages (flat pack) and the solder joint of molybdenum or tungsten base plates to the terminal electrode. For this purpose, in addition to the favorable mechanical and thermal properties, especially the low soldering temperature is important, which must be sufficiently far below the lowest-melting solder joint of the system located in the housing. AuSn solder joints also occur when contacting semiconductor crystals in the TAB technique when soldering the tinned Cu leads to the Au bumps. AuSn20 is also used as a starting material for special solder pastes. By adding tin, the welding tendency of the gold is somewhat suppressed, which is an advantage especially for contact materials.