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
Electrical length of "(2N+1)λ"/2. The electrical length of an antenna element is, in general, different from its physical length For example, increasing the diameter of the conductor, or the presence of nearby metal objects, will decrease the velocity of the waves in the element, increasing the electrical length. An antenna which is shorter than its resonant length is described as ""electrically short"" , and exhibits capacitive reactance. Similarly, an antenna which is longer than its resonant length is described as ""electrically long"" and exhibits inductive reactance. An antenna's effective electrical length can be changed without changing its physical length by adding reactance,