Aluminum Nitride Electronic Package
Specimen Preparation (Class 4 Procedures)
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Ceramics such as alumina, beryllia (BeO) and aluminum nitride (AlN) are commonly used ceramics sustrate materials for metallizing because they provide thermal conductivity and electrical resistivity. The most common material used is alumina, however beryillia and aluminum nitride are used to improve performance at high frequencies.
The cross section preparation of electronic coatings and features on ceramic substrates can be very difficult because of edge rounding and phase relief. In order to maintain the integrity of the metallic layers the specimen must first be sectioned properly to avoid chipping and cracking of the ceramic substrate/ metal interface. Proper sectioning involves orientating the sample so that the coating is in compression (blade direction is into the coating and then into the ceramic substrate). It is also important that a fine grit diamond abrasive blade be used to minimize cracking and fracturing of the ceramic interface. Proper grinding is accomplished with as small a diamond abrasive as possible. Note there is a trade-off between planar grinding time (abrasive size) and induced damage. In some cases for ceramics, it is better to take more time and minimize damage at planar grinding in order to reduce overall polishing times. The use of SIAMAT colloidal silica also provides a chemical mechanical polishing (CMP) action which is the most effective means for eliminating both surface and subsurface damage. The combination of SIAMAT colloidal silica with DIAMAT polycrystalline diamond also produces the required surfaces finishes.
SECTIONING
Diamond Wafering blade - medium grit / low concentration
MOUNTING
Castable Mounting with Epoxy or Acrylic resins.
POLISHING
| Abrasive/surface | Lubricant | Force/ sample | Speed (Head/base) |
Time | Individual Force mode |
Central Force mode |
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| 45 um Diamond Lapping Film* |
POLYLUBE Diamond Extender |
5-10 lbs | 100/100 rpm | Planar |
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| 30 um Diamond Lapping Film* |
POLYLUBE Diamond Extender |
5-10 lbs | 100/100 rpm | 3 min |  |
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| 9 um Diamond Lapping Film |
POLYLUBE Diamond Extender |
5-10 lbs | 100/100 rpm | 2 min | |
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| 6 um Diamond Lapping Film |
SIAMAT colloidal silica | 5-10 lbs | 100/100 rpm | 5 min | |
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| 1 um DIAMAT diamond on ATLANTIS polishing pad |
1 um DIAMAT diamond on ATLANTIS polishing pad |
5-10 lbs | 100/100 rpm | 5 min | |
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| TEXPAN polishing pad | SIAMAT Colloidal silca | 5 lbs | 100/100 rpm | 2 min | |
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*Required for central polishing force. Click here for more information on central vs. individual polishing force polishing.
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| AlN substate with a molybdenum/ nickel, gold coating
400X (B.F.) |
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| AlN substate with a molybdenum/ nickel, gold coating
400X (D.F.) |
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| AlN substate with a molybdenum/ nickel, gold coating 400X (DIC) |
ETCHING
Common Etchants
CAUTION:Safety is very important when etching. Be sure to wear the appropriate protective clothing and observe all WARNINGS on chemical manufacuters SDS (Safety Data Sheets). Also review the COMMENTS and CONDITIONS Section for each etchant.
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