Bismuth in many languages1
German: Wismut - r
Bismuth (Bi) is being used more and more as a replacement for lead in solder alloys because it is non-toxic. Although the melting temperature of pure bismuth is 271°C, the addition of bismuth will lower the melting temperature of most metals it is alloyed with. Bismuth compounds are also widely used in medical and cosmetic applications.
- The most popular lead-free bismuth solder alloys are Indalloy® #281 (58Bi 42Sn) which melts at 138°C and Indalloy® #282 (57Bi42Sn1Ag) which melts at 140°C. The addition of the 1% Ag makes the alloy more malleable. Both alloys can be used for step soldering applications. After the initial joints are made with a standard SAC alloy (220°C) subsequent soldering operations can be done using the bismuth alloys.
- Indalloy #281 and #282 have joint properties similar to those of tin-lead solders, with superior fatigue and copper dissolution characteristics.
- Bismuth is the most diamagnetic and the least thermally conductive of all metals
- In addition to being non-toxic it does not oxidize as readily as lead does.
Bismuth Solders Technical Documents
Product Data Sheets
Safety Data Sheets
Bismuth Blog Posts
If you haven’t heard about Bi-containing (bismuth) solder alloys recently, that may change in the near future. Low-melting Bi-containing solders are now in increasing use and gaining popularity due to their lower melting temperatures—58Bi/42Sn is eutectic at 138°C and 57Bi/42Sn/1Ag melts…
I’ve always been a strong believer that a customer should not get a solder alloy that just “works” for their application, they should get the best alloy for their application. Of course, this is a compromise between all the factors that are important. Bond strength, unique properties,…
Folks, It surprises many people that the foundation metal of almost all solder alloys is tin. Alloy elements such as lead, silver, copper, indium, etc., are extremely important, as they lower the solder melting temperature below tin’s relatively high 232C and often improve wetting and other…
From One Engineer to Another®
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