This high-strength, lead-free solder with a high-silver tin/silver/copper alloy is great for repairing joints on printed circuit boards and computers, audio/video equipment, radios, and more. Creates a strong, lead-free solder joint. The silver content minimizes the solubility of silver coatings. The high-activity, fully-activated flux creates more reliable soldering and leaves bright shiny solder joints after reflow. If the additional flux is needed, our 6400022 rosin soldering flux is recommended. Rosin activated flux will leave slight to moderate post-process residues. These residues may be left on noncritical applications but should be cleaned and removed from any critical or military-grade applications. It is recommended to perform any post-process cleaning within a two to three-hour period at a temperature of around 100Â°F. This flux-cored solder wire meets QQS-571E specification and applicable IPC-J-STD-004 and IPC-J-STD-006 requirements.