Refers to the joining of semiconductors to substrates using temperature and ultrasonic energy. Gold solders or gold surfaces are often used. The process is also known as eutectic scrubbing if a eutectic solder such as Au80Sn20 is used. Ultrasonic energy can be used to bring the preheating temperature below the melting point. In some cases, however, scrubbing is simply a vibrating movement to remove voids from the molten solder. The solder is brought above the melting point and the scrubbing process is then started.