Gatan 656, Руководство пользователя, Страница: 31 / 49

Operation
Dimple Grinder User’s Guide 21
• Use 0.05-µm gamma-alumina suspension polishing compound.
The time necessary to complete fine polishing will depend on the initial and
final thicknesses and the specific material. Silicon will normally take 15–20 min
to achieve a thickness of 2-3 µm. As with coarse polishing, this time should be
broken into short periods, interspersed by occasional cleaning and careful mon-
itoring of the progress of polishing.
4.9 Double-Sided Dimpling
Dimpling the specimen on both sides prior to further thinning allows the elec-
tron-transparent area to be positioned at a selected depth in the specimen for
viewing interfaces. Additionally, the residual stresses are better balanced.
It is necessary to accurately know the original specimen thickness and only
grind by setting a known dimple depth. Obviously, the depth of the two dimples
must be set so that together they come to less than the original specimen thick-
ness.
To do double-sided dimpling
1. After dimpling the first side, the specimen is removed from the mount.
Note: Thoroughly clean the specimen of all wax in order to ensure the accuracy
of the measuring system. Care must be taken in mounting the specimen for the
second time to ensure that no air bubble is trapped in the lower dimple. Other-
wise, the unsupported thin area will collapse.
2. Place a clean specimen mount on a hot plate set at 130 °C.
3. Place the specimen, dimpled side up, onto the hot plate to warm up the
specimen.
4. Melt a small amount of wax at the center of the specimen mount and
into the dimple of the specimen.
5. Carefully flip over the specimen with a fine pair of tweezers and gently
place it into the melted wax on the specimen mount.
6. Set the correct dimple depth on the Micrometer Drive.
7. Proceed as for normal dimpling.
4.10 Specimen Removal
Once dimpling has been completed on both sides, the specimen is removed
from the mount. Extreme care is required to prevent damage to the thinned area.