A cartridge system for a cartridge type soldering iron has a sleeve stopper with hooks and a sleeve which goes over the stopper. The hooks of the sleeve stopper lock with a socket assembly of the soldering iron which connects to an electrical source. A tip cartridge of the soldering iron has a tip retaining mechanism to fix the sleeve stopper with respect to the tip cartridge. The sleeve is made from a non-heat conducting material to protect a user's fingers from heat.