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| decap:purple_ceramic [2012/11/09 09:03] – [SEM imaging] azonenberg | decap:purple_ceramic [2012/12/21 03:22] – azonenberg | ||
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| The sample was a 40-pin CDIP with gold plating that had been used by someone at the RPI cleanroom to practice wire bonding on. The die attach area and leadframe were covered with poorly adhered bonds. | The sample was a 40-pin CDIP with gold plating that had been used by someone at the RPI cleanroom to practice wire bonding on. The die attach area and leadframe were covered with poorly adhered bonds. | ||
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| The sample was placed on top of a standard pin stub mount with double-sided carbon tape and then tape was run along both rows of pins, over the top of the chip, and to the sample holder. It was hoped that this would avoid charging without the need to coat the sample. | The sample was placed on top of a standard pin stub mount with double-sided carbon tape and then tape was run along both rows of pins, over the top of the chip, and to the sample holder. It was hoped that this would avoid charging without the need to coat the sample. | ||
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| The sample was inserted into the chamber of the SEM (JEOL JSM-840 using tungsten filament) and almost immediately began to charge severely. Since the evaporator was down for repairs at the time, carbon coating was impossible so the sample was removed from the chamber and sputtered with the standard thickness of Pt (several angstroms). It was considered unlikely that the coating would be of sufficient thickness to interfere with analysis. Once coated, no charging was observed. | The sample was inserted into the chamber of the SEM (JEOL JSM-840 using tungsten filament) and almost immediately began to charge severely. Since the evaporator was down for repairs at the time, carbon coating was impossible so the sample was removed from the chamber and sputtered with the standard thickness of Pt (several angstroms). It was considered unlikely that the coating would be of sufficient thickness to interfere with analysis. Once coated, no charging was observed. | ||
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| - | The conclusion is that the sample is composed primarily of alumina and silica, with titanium, chromium, and zirconium oxides present in small volume. While the oxidation states cannot be determined from EDS, preliminary reading of chemical properties suggests that Ti2O3, Cr2O3, and ZrO2 are the most probable compounds. | + | ====== Conclusions ====== |
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| + | The sample is composed primarily of alumina and silica, with titanium, chromium, and zirconium oxides present in small volume. | ||
| Reading of the MSDS for the commercial ceramic linked above, SiO2 and TiO2 are typical impurities in such ceramics. Na2O, CaO, and MgO are also mentioned as possible impurities. No Mg was observed and Na/Ca are present in sweat so the data is inconclusive as to whether they are present in the ceramic itself. | Reading of the MSDS for the commercial ceramic linked above, SiO2 and TiO2 are typical impurities in such ceramics. Na2O, CaO, and MgO are also mentioned as possible impurities. No Mg was observed and Na/Ca are present in sweat so the data is inconclusive as to whether they are present in the ceramic itself. | ||
| Based on the above MSDS it is considered unlikely that the Cr in purple-ceramic IC packages is present in the hexavalent form (CrO3) however this is a reddish-purple color so the possibility remains. The bulk ceramic should be relatively harmless in either case however dust-generating operations such as sanding should be avoided and hands washed after contact with it. | Based on the above MSDS it is considered unlikely that the Cr in purple-ceramic IC packages is present in the hexavalent form (CrO3) however this is a reddish-purple color so the possibility remains. The bulk ceramic should be relatively harmless in either case however dust-generating operations such as sanding should be avoided and hands washed after contact with it. | ||