Hi;
You should use tungsten or molybdenium boat for nickel or gold. Most
suitable materials are these because of their thermal properties. Alimuna is
very strong material. But if suddenly temperature to be different (hot or
cold), alimuna will be damaged.

Solutions;
* You can use different type boat that i said that
* You can evaporate very very slowly (But it can be caused of different
problems.)


Tolga YELBOGA
Project Engineer
Nanotechnology Researh Center
Bilkent University
Bilkent, Ankara 06800 TURKEY
Voice: 90-312-290-1020
http://www.nanointurkey.com
http://www.nanotam.bilkent.edu.tr

-----Original Message-----
From: Kagan Topalli [mailto:kagan@metu.edu.tr]
Sent: Sunday, May 25, 2008 12:12 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Damaging of boats during nickel evaporation

Dear all,

I am trying to coat nickel in a thermal evaporator. I have a problem
related with the (Alumina coated) Tungsten boats where the nickel
pellets are placed in. I have observed that nickel pellets melted as I
increased the current to ~250 Amperes. After 60-70 seconds (while the
deposition was continuing without any problem), suddenly the boat has
been damaged (There occurred a hole at the mid of the boat). I have
tried the experiment with reduced number of pellets. But the result is
same. Please note that the boats can withstand even a current of 350
Amperes during gold deposition. Is there anyone that can identify the
problem? Is there any solution for that?