No Clean Solder Paste
Today’s no clean lead-free solder pastes are the newest, high technology solder pastes on the market. Research and development efforts have been focused on no clean lead-free solder pastes due to the increasing use of these products. Water-soluble, lead-free solder pastes are still used, but the volume of consumption is declining.
No clean solder paste is widely used because the flux residues do not need to be washed off of the circuit board after reflow. This simplifies the overall surface mount assembly process. The elimination of the wash process also allows for the use of components that cannot be exposed to water.
No clean solder pastes leave a residue that is safe for the circuit board. Any remaining active materials are encapsulated in the rosin from the flux. If the rosin “shell” is broken then it is possible for active ingredients to contribute to issues like corrosion or dendritic growth.
No clean flux residues can be removed with an appropriate chemical cleaner. If partially cleaned flux residues are left behind then corrosion or dendritic growth may occur. When using no clean solder pastes, it is important to leave the flux residues undisturbed to ensure that they are safe for the circuit board.