Post baking

Remove mask and wash away unpolymerized photoresist and post bake... 

Separate measurements have also shown that the resinous components are virtually non-volatile when baked at 350°F for five minutes without EB exposure. However, the liquid monomeric components are completely volatilized in the bake, demonstrating that no thermal conversion occurs. Thus, the weight measurements described above provide a measure of the amounts of liquid components which are lost in the EB unit and, from the post-bake weight, the total conversion to a non-volatile film. 

A limited number of sink effect studies have been conducted in full-sized environments. Tichenor et al. [20] showed the effect of sinks on indoor concentrations of total VOCs in a test house from the use of a wood stain. Sparks et al. [50] reported on test house studies of several indoor VOC sources (i.e., p-dichlorobenzene moth cakes, clothes dry-cleaned with perchloroethylene, and aerosol perchloroethylene spot remover) and they were compared with computer model simulations. These test house studies indicated that small-chamber-derived sink parameters and kj) may not be applicable to full-scale, complex environments. The re-emission rate (kj) appeared to be much slower in the test house. This result was also reported by other investigators in a later study [51]. New estimates of and were provided,including estimates of fca (or deposition velocity) based on the diffusivity of the VOC molecule [50]. In a test house study reported by Guo et al. [52], ethylbenzene vapor was injected at a constant rate for 72 h to load the sinks. Re-emissions from the sinks were determined over a 50-day period using a mass-balance approach. When compared with concentrations that would have occurred by simple dilution without sinks, the indoor concentrations of ethylbenzene were almost 300 times higher after 2 days and 7 times higher after 50 days. Studies of building bake-out have also included sink evaluations. Offermann et al. [53] reported that formaldehyde and VOC levels were reduced only temporarily by bake-out. They hypothesized that the sinks were depleted by the bake-out and then returned to equilibrium after the post-bake-out ventilation period. Finally, a test house study of latex paint emissions and sink effects again showed that... 

Figure 2. Distribution of sheet resistance of thin films before process control for a period of one month. (A) pre-bake and (B) post-bake.

Figure 4. Variation in pre-bake ( ) and post-bake ( ) sheet resistance with percent chromium for a fixed value of the resistance monitor. The films were baked at 300°C for 30 min. in air.

Device encapsulation conditions are summarized in Table IV. Upon completion of the encapsulation, the devices molded at 150°C were post baked for 16 hours at 150°C, and those molded at 175°C were post baked at that temperature. After trimming, clipping, and forming, the IC s had their final dual in-line package shape. The leads were dipped in 63/37 Sn/Pb solder using a halide-containing flux (Alpha 200). 

After exposure and post baking, the exposed areas of the /-BOC resist films are converted into PHOST. This is a polar, even acidic polymer that is soluble in a range of polar solvents such as alcohols or aqueous base, in which the precursor, PBOCST, is totally insoluble. Conversely, PBOCST is soluble in many nonpolar, lipophilic solvents in which the phenolic PHOST is insoluble. This large change in polarity that results... 

Alternatively, undesirable side reactions may lead to persistent cation radicals. Due to these side reactions doping (p-type) of the organic semiconductor may occur, leading to a higher conductivity, but lower luminescence efficiency (photo and electroluminescence). However, by chemical or thermal (post-bake step at 180 °C) treatment, complete dedoping is possible and the luminescence efficiency is fully recovered. Additionally, in some cases the cation radical is able to attack the oxetane through nucleophilic reaction and ultimately start the same chain reaction as above [33]. 

Murphy et al. (163) studied the DTA. of Vibrin 135 resins, the results of which are shown in Figure 7.50. Three samples of resin were studied two of them contained 2%. ferf-butylperbenzoate catalyst, the other 0.5%. Each catalyst-resin mixture was then heated (cured) for a definite period of time. The DTA. curves in (1) and (2) showed that two low-temperature exothermic peaks were observed, with ATmax values of 150 and l80°C, respectively. This first peak was missing from the post-baked (180°C for 24 hours) sample, although the 320°C peak was found in all three curves. The presence... 

Post-bake if necessary (for metal and parylene etching it is usually not necessary or advisable to post-bake). To post-bake place substrates into a HOC oven (30 minutes) or hotplate (2-5 minutes). 

The cleaned and silanized substrates were selectively patterned by photolithography using an electrically insulating photoresist [49]. A thin SU-8 2000.5 photoresist layer was spun at 6,000 rpm, soft-baked, exposed using a MJB4 mask aligner (60-80 mJcm ), post-baked, and developed in PGMEA for 30 s [49]. The applied soft and post-bake procedure was as follows 1 min at 65 °C, 1 min at 92 °C, and 1 min at 65 °C. 

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