warp and woof Threads in a woven screen that cross each other at right angles.

warpage The distortion of a substrate from a flat plane.

water based A description of a liquid system where the primary solvent is water.

water displacement Characteristic of certain materials, such as lacquers and protective coatings, that replace water.

water extract resistivity Value in ohm-centimeters, principally for liquid rosin fluxes, obtained by carrying out a standard test that measures the amount of ionizable material present. The higher the value, the higher the resistivity, hence the less ionizable material present.

water softener A system used to remove deposit-forming ions, by replacing them with non-scaling sodium ions. This low cost process is used in residential as well as commercial applications.

water soluble A description of a liquid system, where the prime solvent is not necessarily water. However, the system is soluble in water, i.e., can be dissolved in or by water.

water soluble organic flux A nonspecific term describing the composition of soldering of flux soluble in water and based on organic rather than inorganic chemicals: organic acids, amine hydrohalides, poly glycols, polyhydric alcohols, etc.

wattage A unit of electrical power determined mathematically by multiplying the electrical current by the voltage. Soldering irons are generally classified by wattage, which is indicative of the rate at which they will solder.

wave soldering The technique of soldering components to a substrate by passing the PCB assembly over a wave of molten solder in a soldering pot. The wave is maintained above the level of the pot by solder being pumped through a manifold in the bottom of the pot.

weave exposure Unbroken fibers of woven glass cloth that are not completely covered by resin on the base material surface.

webbing As applied to soldering, refers to a condition wherein the plastic basic material of the printed circuit board substrate is softened as it passes over the solder wave, with a resultant pick up of fine particles of solder onto the tacky surface of the plastic. This is generally the result of inadequate curing of the plastic material comprising the substrate. Particular difficulties result in printed circuit boards with closely spaced conductors and/or with high voltage present. Also known as spidering.

wetting A physical phenomenon of liquids, usually in contact with solids, wherein the surface tension of the liquid has been reduced so that the liquid flows and makes intimate contact in a very thin layer over the entire substrate surface. Regarding wetting of a metal surface by a solder, flux reduces the surface tension of the metal surface and the solder, resulting in the droplets of solder collapsing into a very thin film, spreading, and making intimate contact over the entire surface.

wetting agent A chemical material added to a liquid solution to reduce surface tension. The effect of this reduction of surface tension is to increase the power of the liquid mixture or solution to wet an object on which it is placed.

wetting balance Method of assessing solderability of metals.

whiskers A growth in the presence of condensed moisture and electrical bias resulting in metallic filaments between conductors. Also called dendritic growth.

wicking The flow of solder along conductors under insulation through via holes.

working fluid Usually a fully perfluorinated hydrocarbon that is extremely stable and is clear, odorless, and chemically inert.

worknest The stage that holds the substrate throughout the print cycle.