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
Asymmetric C-element into account the common and the asymmetric minus inputs. All these inputs must be low for the down transition to happen. The figure shows the gate-level and transistor-level implementations and symbol of the asymmetric C-element. In the figure the plus inputs are marked with a 'P', the minus inputs are marked with an 'm' and the common inputs are marked with a 'C'. In addition, it is possible to extend the asymmetric input convention to inverted C-elements, where a plus (minus) on an input port means that an input is required for the inverted output to fall (rise). Asymmetric C-element