Alloys covered by this standard are intended for use in various consumer, industrial, and commercial electronic soldering applications of industry and, when adopted by a governing entity, military electronic hardware. The following are general comments regarding the selection of various alloys and fluxes for use in electronic soldering. Users should consult with applications experts at various solder manufacturing companies for detailed alloy and flux selection and usage information.

Alloys Tin-lead solder alloys, particularly eutectic and near-eutectic alloys, are used to make solder connections in hardware assemblies and for many general purpose soldering applications. A broad range of alloys are available to accommodate variations in electronic soldering, such as lead trimming and multiple-pass hardware assembly.

Antimony Alloys A slight amount of antimony (approximately 0.2 to 0.5%) was previously added to tin-based electronic solder alloys to prevent a condition called tin pest, where ultra-pure tin transforms at very low temperatures from a metallic form to white powder. The minimum requirement for antimony in tin-based alloys has been deleted, because current test results indicate tin pest is not a problem when the tin is diluted with 0.2% of almost any other metallic element and therefore the addition of antimony in tin-lead solder alloys is an unnecessary added cost. Although antimony is not a problem in most solder alloys, the rapid formation of antimony-silver intermetallics requires a reduced level of antimony in alloys containing silver to prevent reduction in the beneficial effects of silver.

Bismuth Alloys Bismuth is used in soldering alloys to achieve ultra-low soldering temperatures.

Cadmium Alloys Cadmium alloys are useful for electromagnetic shielding. Because of possible carcinogenic effects of cadmium, appropriate measures for personal safety should be used when soldering with alloys containing cadmium.

Copper Alloys Copper is added to tin-lead alloys to reduce tip degradation on soldering irons used in hand soldering operations.

Gold Alloys Ultra-high purity gold alloys are used in barrier-free, die-attachment applications. Standard gold alloys are advantageous in high-reliability hybrid assembly and are used in assemblies which operate at microwave frequencies.

Indium Alloys Indium based soldering alloys provide some advantages when soldering to gold coatings as long as the soldering temperature of 120 degrees C [248 degrees F] is not to be exceeded for long periods of time. When a high temperature, humidity, and/or salt spray operating environment is expected to be encountered by the assemblies being soldered, indium based soldering alloys should not be used without being hermetically sealed or conformally coated. They are better than standard tin-lead solders in soldering assemblies which will operate at microwave frequencies.

Users are cautioned concerning the use of high percentage indium solders with copper because of the formation of excessive intermetallic.

Silver alloys Silver-tin alloys, silver-lead alloys, and tin-lead-silver alloys are frequently used to solder parts which have a silver plating to prevent the leaching of the silver before the soldering is completed. Silver is also alloyed with tin and lead to change the temperature characteristics and to make harder solder.

Tin-Silver-Copper Alloys with or without Antimony Although they have melting ranges higher than more common eutectic Tin-Lead alloys, these alloys are considered as "lead free" replacement alloys. They also have other properties similar to Tin-Silver alloys.