Soldering (see RoHS), has led to a change in formulation of both solders and fluxes. Water-soluble non-rosin-based fluxes have been increasingly used since the 1980s so that soldered boards can be cleaned with water or water-based cleaners. This eliminates hazardous solvents from the production environment, and from factory effluents. Those regulations have also reduced the use of lead based solders, and caused the melting temperatures of solders in use to increase by up to . "Hot-bar reflow" is a selective soldering process where two pre-fluxed, solder coated parts are heated with heating element (called a thermode) to a sufficient temperature to
Hash join As with the anti-join, semi-join can also be left and right: The records are returned right after they produced a hit. The actual records from the hash table are ignored. This is more efficient when the IN table is smaller than the FROM table With this algorithm, each record from the hash table (that is, FROM table) can only be returned once, since it is removed after being returned. This is more efficient when the IN table is larger than the FROM table Hash join The hash join is an example of a join algorithm and is used in the