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Limitations materials properties/processes

The data used to generate the maps is taken from a simple statistical analysis of the manufacturing process and is based on an assumption that the result will follow a Normal distribution. A number of component characteristics (for example, a length or diameter) are measured and the achievable tolerance at different conformance levels is calculated. This is repeated at different characteristic sizes to build up a relationship between the characteristic dimension and achievable tolerance for the manufacture process. Both the material and geometry of the component to be manufactured are considered to be ideal, that is, the material properties are in specification, and there are no geometric features that create excessive variability or which are on the limit of processing feasibility. Standard practices should be used when manufacturing the test components and it is recommended that a number of different operators contribute to the results. [Pg.54]

Materials information includes toxicity, permissible exposure limits, physical properties, reactivity, corrosivity, thermal and chemical and hazardous effects of inadvertent mixing of different materials.Process information consists of 1) process flow diagrams, 2) process chemistry descriptions, 3) maximum amounts of chemicals, 4) safe ranges for temperatures, pressures, flows oi 5) evaluation of the con.sequences of deviations. [Pg.27]

The second slop is to obtain all the information about the process that will be needed for a Ihorongh evaluation including but not limited to the process materials used and their physical properties, the chemistry and tlicnnodynamics of the process, a plant layout, and a description of all the equipment used including controls and instrumentation. The last part of the information gathering step nitty be viewed as the preliminary formation of the What If questions. [Pg.443]

Many engineering thermoplastics (e.g., polysulfone, polycarbonate, etc.) have limited utility in applications that require exposure to chemical environments. Environmental stress cracking [13] occurs when a stressed polymer is exposed to solvents. Poly(aryl ether phenylquin-oxalines) [27] and poly(aryl ether benzoxazoles) [60] show poor resistance to environmental stress cracking in the presence of acetone, chloroform, etc. This is expected because these structures are amorphous, and there is no crystallinity or liquid crystalline type structure to give solvent resistance. Thus, these materials may have limited utility in processes or applications that require multiple solvent coatings or exposures, whereas acetylene terminated polyaryl ethers [13] exhibit excellent processability, high adhesive properties, and good resistance to hydraulic fluid. [Pg.56]

At sufficiently low strain, most polymer materials exhibit a linear viscoelastic response and, once the appropriate strain amplitude has been determined through a preliminary strain sweep test, valid frequency sweep tests can be performed. Filled mbber compounds however hardly exhibit a linear viscoelastic response when submitted to harmonic strains and the current practice consists in testing such materials at the lowest permitted strain for satisfactory reproducibility an approach that obviously provides apparent material properties, at best. From a fundamental point of view, for instance in terms of material sciences, such measurements have a limited meaning because theoretical relationships that relate material structure to properties have so far been established only in the linear viscoelastic domain. Nevertheless, experience proves that apparent test results can be well reproducible and related to a number of other viscoelastic effects, including certain processing phenomena. [Pg.820]

Another limitation is related to the fact that synthetic poly(amino acids) have rather unfavorable material properties. For instance, most synthetic poly (amino acids) derived from a single amino acid are insoluble, high-melting materials that cannot be processed into shaped objects by conventional fabrication techniques. The often undesirable tendency to absorb a significant amount of water when exposed to an aqueous environment is another common property of many poly (amino acids) (7). Finally, high molecular weight poly-(amino acids) are best prepared via N-carboxyanhydrides which are expensive to make. Hence poly(amino acids) are comparatively costly polymers, even if they are derived from inexpensive amino acids (8). [Pg.196]

As the maturity of the process increases, only these key parameters would require continued monitoring. Ultimately, the data collected on these properties would permit the generation of appropriate material specifications. If the work had been performed properly, then it would be possible to specify limits for raw-material properties that would ensure the final product will be satisfactory. These guidelines would naturally apply only to the specific formulation, but through continued use of the systematic Materials Science approach the more general trends would become apparent. [Pg.33]

An acceptable middle way is to cut test pieces from the product. This has the advantage that the properties measured relate to the material as processed in the factory rather than to test pieces prepared under laboratory conditions. The only disadvantage is the limitation in obtaining suitable test pieces from many products. [Pg.50]

The other main areas of development required to overcome present limitations are in the improvement of efficiency and reliability. At the basic research level, this implies a better understanding of the relation between the deposition processes, the electronic material properties and the resulting device properties and the improvement in the quality of all individual layers building up the module. [Pg.355]

The expected impact of the material properties reviewed in Table II on the polishing mechanisms reviewed in the previous section is summarized in Table IV. As might be expected from previous discussion on structure vs properties, a high degree of interaction between properties and process effects is evident. Publicly available evidence to support materials properties effects on the CMP process is relatively limited. This is reviewed in Section IV. [Pg.169]


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Limitations properties

Limiting processes

Materials processing

Materials processing properties

Process limitations

Process material

Processing limitations

Processing process limitations

Processing properties

Properties processes

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