Solder paste is used in the electronics industry to solder (create a strong electrically conductive bond) electronic components to a printed circuit board. It is a mixture of solder powder and flux which consists of rosin/resin, activators, rheological additives and solvents. The solder powders in solder pastes are usually made of tin, lead, silver, copper and other elements. The integral flux helps clean the surfaces for solder and prevent reoxidation during the reflow process.
Paste is applied to a printed circuit board (PCB) using a stencil, and then reflowed in a reflow oven to form strong, reliable solder joints. Solder paste is available in a variety of compositions and alloys to suit different surface mount technology requirements.