Film processing characteristics

The equipment for the slit-film fiber process is shown in Figure 15 (29). An olefin film is cast, and as in melt spinning, the morphology and composition of the film determine the processing characteristics. Fibers may be produced by cutting or slitting the film, or by chemomechanical fibrillation. 

PPQs possess a stepladder stmcture that combines good thermal stabiUty, electrical insulation, and chemical resistance with good processing characteristics (81). These properties allow unique appHcations in the aerospace and electronics industries (82,83). PPQ can be made conductive by the use of an electrochemical oxidation method (84). The conductivities of these films vary from 10 to 10 S/cm depending on the dopant anions, thus finding appHcations in electronics industry. Similarly, some thermally stable PQs with low dielectric constants have been produced for microelectronic appHcations (85). Thin films of PQs have been used in nonlinear optical appHcations (86,87). 

One of the requirements of this process is that the melt maintain good contact with the chill roU, ie, air must not pass between the film and the roU. Otherwise, air insulates the plastic and causes it to cool at a rate different from the rest of the plastic and this spoils the appearance of an otherwise satisfactory product. The melt should not emit volatiles, which condense on the chill roU, reduce heat transfer, and mar the film s appearance. The cast film process allows the use of a higher melt temperature than is characteristic of the blown film process. The higher temperature imparts better optical properties. 

Calculate the tube-side film coefficient for finned tube, hj. If water, use Figure 10-50A or 10-50B if other fluid, use Equation 10-44 or 10-47. Use an assumed or process determined tube-side velocity or other film fixing characteristic. 

The mechanisms described above tell us how heat travels in systems, but we are also interested in its rate of transfer. The most common way to describe the heat transfer rate is through the use of thermal conductivity coefficients, which define how quickly heat will travel per unit length (or area for convection processes). Every material has a characteristic thermal conductivity coefficient. Metals have high thermal conductivities, while polymers generally exhibit low thermal conductivities. One interesting application of thermal conductivity is the utilization of calcium carbonate in blown film processing. Calcium carbonate is added to a polyethylene resin to increase the heat transfer rate from the melt to the air surrounding the bubble. Without the calcium carbonate, the resin cools much more slowly and production rates are decreased. 

Reagent selection, solvent, and choice of solution reaction conditions serve to define the nature of the solution precursor species that are formed and that will be used for him deposition. The characteristics of these solution species serve to define him processing characteristics, including aspects such as cracking tendency,50 organic burn-out temperature,48 and for crystalline films, crystallization temperature.49,51... 

In order to develop polyimide films for semiconductor applications, many chemical, mechanical, thermal and film forming characteristics must be determined in order for the user to develop a viable process for reliable integrated circuits. 

High temperature film processing not only now permits film to be processed in the tropics and in high temperature locations but allows the specially hardened emulsions to develop very rapidly with no detrimental changes in their characteristics Color Photography... 

Consider an atmospheric-pressure process to deposit a silicon film from a silane (SifLj) precursor. The showerhead-to-wafer distance is 3 cm. In this process a helium carrier gas makes up the bulk of the flow, with the active silane accounting for only 0.17% of the inlet mixture. The precursor gases enter the reactor at 300 K, but the wafer temperature and inlet velocity are varied to observe different process characteristics. 

S. Metev, Process Characteristics and Film Properties in Pulsed Laser Deposition. In Pulsed Laser Deposition of Thin Films, ed. by D.B. Chrisey, G.H. Hubler (Wiley, New York Chichester Brisbane Toronto Singapore 1994) pp 229-254... 

The process itself is more art than science. There is hardly any information in the open scientific literature. Most publications have to do with spray drying of ceramic powders (ref. 15 and references therein, ref. 16). There are also some standard books about spray drying [17]. Important process parameters are the viscosity of the liquid, the solids content of the suspension, the film-forming characteristics, the type of atomizer, the temperature, the rotation speed of the wheel, gas velocity, etc. 

The present work is a continuation of our studies on Au-PPFC. We investigate the effects of film growth processes, influenced by different substrate biases, Us, and substrate temperatures, Ts, on the film surface characteristics. 

PMMA offers several advantages as a resist. These include extremely high resolution, ease of handling, excellent film-forming characteristics, wide processing latitude, and ready availability. Unfortunately, PMMA is a rel-... 

---