Tin-indium solder

Lead-tin Lead-tin-indium Lead-tin-silver alloys Lead-tin solder Lead titanate... 

Reflow soldering involves the selective deposition of solder paste at termination pads or other features on printed wiring boards. Then, the electronic components and other devices are placed on the board, and the bond is completed by heating and melting the solder. The most common lead-free alternative alloys considered for solder paste are tin-silver (Sn-Ag), tin-silver-copper (Sn-Ag-Cu), and tin-silver-bismuth (Sn-Ag-Bi). Tin bismuth (SnBi), tin indium (Snin) and silver-fllled conductive epoxy are also considered for certain applications. 

The discussion in the previous section makes it clear that there are significant differences between lead-free, tin-based solder systems and other solders successfully used in the past. The anomalous crystal structure and allotropic transformations in tin-based alloys can affect the material properties that control the ultimate performance and reliability of these solders in microelectronic assemblies. Table 5 provides a comparison of several solder systems including high-lead and eutectic tin-lead alloys, white and gray tin, a lead-indium solder, gold-tin eutectic, and a fictitious ideal alloy. 

Solders. In spite of the wide use and development of solders for millennia, as of the mid-1990s most principal solders are lead- or tin-based alloys to which a small amount of silver, zinc, antimony, bismuth, and indium or a combination thereof are added. The principal criterion for choosing a certain solder is its melting characteristics, ie, soHdus and Hquidus temperatures and the temperature spread or pasty range between them. Other criteria are mechanical properties such as strength and creep resistance, physical properties such as electrical and thermal conductivity, and corrosion resistance. 

The low-melting-point (157 °C), silver metal is mainly used in alloys to decrease the melting point. Combined with tin, lead, and bismuth to produce soldering metal for wide temperature ranges. The element is highly valuable in the electronics age as its unique properties are ideal for solar cells, optoelectronics, and microwave equipment. The arsenide is used in lasers and is also suitable for transistors. ITO (indium tin oxide) is a transparent semiconductor with wide application in displays, touchscreens, etc. In the household, indium as an additive prevents the tarnishing of silverware. Some electronic wristwatches contain indium batteries. 

We cannot solder a wire to a lead redox electrode because the lead would melt. Furthermore, we cannot solder a wire to an indium-tin... 

It is possible to solder most metals directly to glass by use of indium metal (mp 155°C) or an indium alloy such as In 95 % Ag 5 % (mp about 145°C). The heated glass is rubbed with the molten solder to wet the surface and then heated in contact with the metal, which was previously tinned with the solder.10... 

The metals zinc and cadmium should be avoided because of their high vapor pressures. Metals that include zinc and cadmium alloys such as brass (copper and zinc) and some silver solders (cadmium) should also be avoided for the same reasons. It is possible to obtain cadmium-free silver solder and brazing materials that use tin, lead, and indium for vacuum use. Some steel screws are cadmium-coated and also must be avoided. 

An additional consideration for the selection of an adhesive system is that robust bonds must be formed to all surfaces involved in the interconnection. Materials commonly found include metallizations on the substrate and components (e.g., gold, solder, copper, aluminum, and indium tin oxide), polymer substrates and coatings (e.g., polyimide, polyester, epoxy, and acrylic adhesives), and chip passivation layers (e.g., Si02 and SI3N4). Adhesion promoters may be required. 

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