We suggest using a tall, Intermetallic crucible with a shielded, tantalum crucible heater. Intermetallic crucibles are composed of 50% Titanium Boride (TiB2) and 50% Boron Nitride (BN). Its density is 2.77 g/cc, with a thermal expansion coefficient (CTE) of 7 (in/in/°Cx10-6) and thermal conductivity of 70 (W/m°K)/25°C. This material combination works well with aluminum because the material is both lubricious and electrically conductive. The crucible is both strong and conductive, yet its lubricious properties prevent material spill-over and crucible cracking. Taller crucibles help inhibit the spillover of the material by maintaining a cool lip around the top. Tall Intermetallic crucibles offer a longer lifetime of both the crucible itself as well as the crucible heater.
Some of our production customers have indicated they can get 10-15 runs out of the Intermetallic crucibles. These users are very experienced in thermally evaporating aluminum in high volumes. Therefore, they have refined their processes so it is possible that these results may not be typical in all applications. An example of a heater-crucible set-up would be our EVCH1 or EVCH10 paired with EVC9INTSPL01 if using one of our vacuum systems.
Category: Evaporation Sources
Sub-Category: Crucibles and Crucible Heaters