Abstract: In high rate sputter coating sources, it is generally necessary to liquid cool the sputter targets. In one type of source, a cooled wall of a cathode assembly is closely adjacent a sidewall of the sputter target. During normal operation the sidewall of the target expands thermally into tight contact with the cooled wall, whereby cooling of the target is effected without the need for bonding the target to the cooled wall using a solder or other adhesive. Thus, replacement of worn conventional targets is a relatively simple procedure. When the targets are made of certain special materials, such as fragile materials or materials with low coefficients of thermal expansion, target warping, cracking or melting can occur. Such problems are overcome or alleviated by the novel design approach of the present invention, which employs a sputter target assembly in place of a conventional target.