Hello,
this is a problem of heat transfer. We use 6" targets which were fixed by a teflon ring (covered with a metal ring) onto the magnetron base. A special graphite paper under the target improves the thermal contact. A silicon dioxide target is in use without copper back plate. If we slowly increase the power more than 250 W are possible without problems. We extended our work to ITO and Al2O3. All experts said: You need a backplate. But now I can report that these ceramic targets got cracks. RF plasma is not longer strable.The expansion coefficents of Cu and the target materials do not fit. This means the copper plates are well cooled. One supplier says that he often uses molybdenum instead of copper for such targets. This is not cheap. So I will order next targets without backplates. But you should evaluate the thermal conditions in your apparatus. Heating up of the targets can be tolerated up to a certain temperature.
Regards
Dietmar
Hello,
our cracked targets are bonded to copper with indium. But your paramaters could differ from ours.
Dietmar.
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