A coating source as a material supply for a PVD coating, including a) a holder and a plate supported in a holder, having a plate front, a plate back, and a centering means; the holder has a frame-shaped plate mount for accommodating the plate, the plate is a target, and the plate front is provided for converting coating material from the surface into the gas phase during the PVD process and the centering means is embodied so that the centering is assured at different plate temperatures b) a cooling device, which is provided on the plate back, is equipped with a cooling conduit and a closed cooling plate that is embodied in the form of a movable diaphragm; in order to ensure a good thermal contact between the plate back and the diaphragm, a self-adhesive graphite film is glued to the plate back; the elements of a bayonet fitting are provided on the holder and the cooling device so that the holder with the centered plate can be affixed to the cooling device by means of the bayonet fitting, wherein: • in order to hold the target, at least three guide protrusions (1f, 2f) and/or grooves (1n, 2n) spaced apart from one another are respectively provided in the target and in the target mount; the guide protrusions (1f, 2f) of the target and/or the target mount form "guide protrusion/groove" pairs with the grooves (1n, 2n) of the target mount and/or the target so that the guide protrusions (1f, 2f) of the target and/or target mount are held in the corresponding grooves (1n, 2n) of the target mount and/or target when the target is attached to the target mount, • the "guide protrusion/groove" pairs (1f, 1n; 2f, 2n) are distributed so that in each "guide protrusion/groove" pair (1f, 1n; 2f, 2n), the position of the middle of the width of the groove (1n, 2n) coincides with the position of the middle of the width of the corresponding guide protrusion (1f, 2f) and this position is selected so that at room temperature, it is situated in an axial direction of the target center, and, after a thermal expansion of the target and/or of the target mount at higher temperatures, this position remains unchanged in the same axial direction of the target center, • the material of the plate has a first thermal expansion coefficient α1 and the material of the holder has a second thermal expansion coefficient α2, where: α1 > α2. a) a holder and a plate supported in a holder, having a plate front, a plate back, and a centering means; the holder has a frame-shaped plate mount for accommodating the plate, the plate is a target, and the plate front is provided for converting coating material from the surface into the gas phase during the PVD process and the centering means is embodied so that the centering is assured at different plate temperatures b) a cooling device, which is provided on the plate back, is equipped with a cooling conduit and a closed cooling plate that is embodied in the form of a movable diaphragm; in order to ensure a good thermal contact between the plate back and the diaphragm, a self-adhesive graphite film is glued to the plate back; • in order to hold the target, at least three guide protrusions (1f, 2f) and/or grooves (1n, 2n) spaced apart from one another are respectively provided in the target and in the target mount; the guide protrusions (1f, 2f) of the target and/or the target mount form "guide protrusion/groove" pairs with the grooves (1n, 2n) of the target mount and/or the target so that the guide protrusions (1f, 2f) of the target and/or target mount are held in the corresponding grooves (1n, 2n) of the target mount and/or target when the target is attached to the target mount, • the "guide protrusion/groove" pairs (1f, 1n; 2f, 2n) are distributed so that in each "guide protrusion/groove" pair (1f, 1n; 2f, 2n), the position of the middle of the width of the groove (1n, 2n) coincides with the position of the middle of the width of the corresponding guide protrusion (1f, 2f) and this position is selected so that at room temperature, it is situated in an axial direction of the target center, and, after a thermal expansion of the target and/or of the target mount at higher temperatures, this position remains unchanged in the same axial direction of the target center, • the material of the plate has a first thermal expansion coefficient α1 and the material of the holder has a second thermal expansion coefficient α2, where: α1 > α2.