Introduction

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.

Features

• 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. See chart for additional alloys.
• Indalloy #281 and #282 have joint properties similar to those of tin-lead solders, which 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.

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