Solder paste is a vital material used in the manufacturing
of printed circuit boards. It connects surface mount components to pads on the
board through its sticky consistency once heated and forms a bond and an
electrical connection. Inside the paste, there are ingredients that serve as
activators that essentially remove oxides from the surface being soldered and
the powdered solder alloy itself once heated.
As the paste ages, however, its physical characteristics and overall effectiveness will change. Most solder pastes typically have a shelf life of around 3-6 months when refrigerated. This makes refrigeration the best and most effective way to get the longest use out of your solder paste. Once your paste reaches room temperature or higher, the six month shelf life can shorten to as little as 24 hours. Generally speaking, the ideal temperature for most pastes is between 0 and 10 degrees Celsius. Temperatures warmer than this could separate the flux medium from the body of the paste, possibly causing printing defects and errors.
While it is not recommended to leave solder paste in warm environments, freezing solder paste is also not recommended. Placing solder paste in too low of temperatures could result in the precipitation of the activators. There are many different solder paste options, but whichever paste you buy should be stored immediately as soon as it arrives.
Think of your solder paste as a carton of milk. You wouldn’t want to leave the milk sitting out in your car for hours before you finally arrive home from the grocery store. Solder paste generally comes in a package that has insulating materials or ice packs, but it is still recommended that you choose next day shipping and move it to a refrigerated environment as soon as possible.
Solder paste is designed to have quick reactions at higher temperatures but remain fairly dormant at lower temperatures. This is why it is extremely important to keep the paste at the aforementioned temperature range until removing for use. GoKimco offers a wide variety of different solder pastes, but each product includes details on the recommended handling and shelf life.