$6.88 $4.49
Cardas Quad Eutectic Solder 5 foot (1.5m) roll
5 foot (1.5m) roll
Cardas QE is 20g (0.032"/0.8mm) rosin core with a 350ºF (177ºC) melting point.

Some of the best connections are soldered. The problem is only one type of soldered connection is truly a joint. Many solders, such as the popular 60/40, are a slurry mixture of Tin and Lead. The Tin/Lead mixture melts, but as it solidifies it does so one metal at a time. It goes into a slurry state where one metal is liquid and the other is very small solid particles. Next, the other metal solidifies, and creates a multitude of small connections. This type of connection is not favorable or permanent. A phone company used this type of solder on their main frames. Every joint had to be reheated once a year to insure reliability. Even then, the "cold joint" was a common occurrence. Noisy or open joints were the main cause of failure in early printed circuit boards and electronic equipment. Then it was learned that eutectic joints were more reliable. By the mid-seventies or early eighties most electronic equipment utilized Eutectic solder (63/37). The reliability of printed circuit boards went up nearly 1000%. The melting point of a Eutectic solder is lower than any of its component parts, so there is no slurry state in these solders. They solidify as one creating an actual solder joint. Most Audio wire is Copper or Silver, so George Cardas developed an ultra pure Tin/Lead/Silver/Copper eutectic, or Quad-Eutectic solder. This solder is widely used in the Audio industry where Lead is an option.

(The above was taken in part and paraphrased entirely from George Cardas's paper Soldered vs. Crimped Connections).

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