Vacuum baking

In carefully dried (vacuum-baked) and sealed glass containers gaseous S2O can be kept at 20 °C and partial pressures of below 1 mbar (100 Pa) for several days but at 180 °C the decomposition to SO2 and sulfur is complete within 1 min. At higher partial pressures gaseous S2O decomposes at 20 °C to SO2 and a yellow, relatively stable solid polymeric sulfuroxide of composition S>30 (see below). This decomposition is accelerated by traces of water and by irradiation with UV radiation [18]. 

The crystalline structure of adsorbents directly influences their gas sensitivity. Depending on the type of the problem to be addressed ad-sorption-sensitive semiconductors are monocrystals or monocrystal films with a predetermined crystallographic orientation of of>erational surface vacuum baked polycrystalline films, which, from their electrical standpoint, are similar to monocrystals but differ from the latter by ulti-... 

The fusion is best carried out in vacuum, suitably in the vacuum baking apparatus used in the sulfonation of amines by the baking process. When the water is evaporated from the melt, the mass foams and, in order to avoid clogging the suction tube, this tube should be sufficiently wide and the tray should not be more than half filled. In order to obtain good yields, it is necessary to use about twice the sodium hydroxide required theoretically, i.e., about 8 moles per mole of sodium benzenedisulfonate. 

A mixture of 50 grams of well dried O acid and 100 grams of technical sodium hydroxide is ground in a ball mill for 24 hours. The mixture is then placed in a vacuum baking apparatus (Fig. 30, page 181) which is evacuated and heated, as uniformly as possible by means of an oil... 

Cu/PI TFML substrates that have been vacuum baked for I6 hours at 150°C prior to hermetic sealing in an N2 atmosphere satisfy MIL-STD moisture levels of less than 5000 ppm H2O at lOO C. 

The results of the evaluations indicated that lowering the ramp rate from approximately 500 psi/min to 150 psi/min and performing a vacuum bake after every cycle drastically decreased or eliminated the evidence of cracks or discolored (stressed) areas in the epoxy. This indicates that the lower ramp rates decreased the stress on the epoxy and that the vacuum baking acted as a stress relief by removing the carbon dioxide gas which was absorbed in the epoxy. 

In this formulation, the ratio of NVC to PTCEM is 1 1 in the mixture. One micron thick film was spin coated on a silicon wafer using chlorobenzene as the coating solvent. The film was vacuum dried for an hour at room temperature and coated on the top with PVA film. The film was vacuum baked for an hour and exposed with an e-beam. After e-beam exposure, the PDE film was dipped in deionized water for 30 seconds to remove the PVA layer, and baked at 120° C for 30 minutes. The patterns were visible after the bake. The development of patterns was conducted in a barrel etcher using O2 plasma. The temperature inside the barrel etcher during the development was maintained at <90 C. SEM micrographs of some plasma developed patterns are shown in Figures 2 and 3. 

A series of device wafers were processed along with the KBr IR plates and magnetic and IR measurements were performed using varying cure ambients. It was found that a vacuum bake at 220° C was sufficient to cure the films completely and preserve the magnetic properties of the Ni/Fe films. Figure 12 shows typical IR comparisons of the air cured and vacuum cured films. For all device applications,a vacuum bake at 220° C was chosen as the standard processing condition. 

Grayson et al. (10) investigated untreated, vacuum-baked at 120°C, and fractionally reprecipitated PS. They analyzed the various samples for indigenous volatile content by vaporization-gas chromatography/mass spectrometry (33,36,37) and found that fractional reprecipitation was the only effective method to remove the volatile fraction from PS. Further, stress MS experiments with PS samples prepared from the fractionally reprecipitated polymer evolved only a trace of styrene monomer. 

Vacuum baking can reduce bleedout by removing adsorbed moisture and other polar contaminants, and it can also reduce bleedout due to pump oil backstreaming onto the surfaces. 

Insufficient pre-seal vacuum bake is indicated in Case 10 where large amounts of moisture were detected. Extended vacuum baking reduced the moisture content. 

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