The term defect rate designates the portion of defective elements in relation to all items produced. The rate is deduced by dividing the number of defective elements by the number of non-defective elements. This number is a measure of quality of the production. The defect rate in the electronic industry is expressed in ppm (marts per million) or dpmo (defects per million opportunities). In the entertainment electronics production, values of 1000 ppm are frequently acceptable, whereas in the automotive industry 20 ppm is the rule. To achieve such low defect rates, the soldering process plays a vital role. Only excellent equipment, providing a high level of repeatability, can assure these low rates.