The highly varied nature of the materials used to create sputtered layers requires a versatile method to clamp targets without the need for modifications. Gencoa have developed the low-profile clamping method that allows any bonded or non-bonded type of target of any thickness to be clamped without modifications to the clamps or anode position.

Gencoa cathodes as standard are supplied with a cooling diaphragm that provides the most convenient means of achieving good heat removal without the need to break a water seal during target change. For the situations where direct water cooling is required, the diaphragm and diaphragm clamp can be easily removed to allow mounting of a target or backing plate for direct cooling.

When using the diaphragm type of cooling, graphite conductor sheets are placed between the diaphragm and target or backing plate to improve conformity and heat removal. Some are supplied with a new cathode and replacements can easily be sourced. The target clamping system will compress the graphite to improve the thermal transfer between the surface - hence a new sheet should be used during each target change.

The next choice is whether to use just outer target clamps or add central clamps as well. As a general rule, magnetrons with target widths of 200mm (8") and greater should include a central clamp. This reduces the stress on the target or backing plate and prevents deformation or cracking of the target. The central clamping is usually a separate piece, but in some case a screw can pass through the target itself.

In some cases if very soft metals are clamped, then even on narrow targets (<100mm) it can be an advantage to use a centre clamp. An example would be 99.999+% pure Al material. Lower purity Al is more rigid and does not require the same precautions.

A wide variety of fragile materials as commonly used as sputter targets. These fragile materials cannot be directly clamped as it will crack the target. Hence, the target is bonded to the backing plate and then the backing plate is clamped. Each set of Gencoa target clamps can accomodate both bonded and directly clamped targets. The respective sputter target and backing plate drawings are contained in the magnetron manual or can be downloaded from the Gencoa Windchill on-line resource system available to all customers.

The choice of backing plate can also be important in order to maximise performance. Copper is the most common, but the use of molybdenum can increase the allowable target thickness and reduce the potential for cracking. As an example a silicon  target bonded to a molybdenum backing plate can withstand double the power density before cracking when compared to copper.

If you have specific demands or materials you wish us to consider during the cathode design phase, then we can recommend and supply the best options.