Publisher Summary This chapter explores the aspects of the design and building of the magnetron sputter sources to understand how the source operates and which features can affect the sputter source deposition systems. Three different configurations of magnetrons are discussed to present how changing the position and strength of the magnetic pole pieces can affect the field lines and hence the erosion profile. One of the trade-offs that is made in designing magnetrons is in the complexity of the shape and clamping of the target material. The first design is very simple and the targets require minimum machining. The second design requires more machining of the targets, and replacing the targets is more complex and takes longer. The third design also shows the use of an electromagnet that allows for modifications of the field strength. Other options are to move the target or the magnets to improve the erosion profile. The most widely used version of this technique is the rotatable magnetron design where the target is a cylinder and rotates around the rest of the magnetron design. Further, the common problems with sputtering sources can be grouped into failures in service and failure to restart following servicing. Occasionally, there may be a design-related failure. One design philosophy was to never have a water-to-vacuum seal but instead to have a water-to- air seal followed by an air-to-vacuum seal.