Reliability Risks with Lead-Free Soldering and Possible Solutions

The Japanese bans on solders containing Lead in mobile telecommunication products have caused the other telecommunication industries to go for Lead-Free solutions. The Lead-Free solder used by most telecommunication industries is SnAgCu-solder (95,8Sn3,5 Ag0,7Cu). This solder have a melting point of about 217 °C. This indicate the reflow temperature will increase by 30-40 °C, compared to the reflow temperature of the to day most used solder. (63Sn37PB with melting point 183 °C)

The increased solder reflow temperature will cause more intermetallics between Sn in the solder and Cu on the PCBs for example. This will have a negative effect on the long term reliability, especially for harsh applications as Power Train Electronics.

The increased reflow temperature will also increase the Pop Corn problem of IC-plastic packages, especially packages used in harsh environments. This can have a very negative effect on the long term reliability for system working in harsh environments.