Reactive pad

Explain why softer pads remove more material than harder pads at low pressures, but why harder pads remove more material than softer ones at high pressures. 

As the abrasive size increases, the values of ATpad and of fe in Equation 5.5 both decrease. Use this information to sketch R versus %A or R versus [A] curves for the polishing rate of an abrasive larger than the 20 nm as shown in Eig. 5.17. Qualitatively explain the difference in pohshing rate changes as abrasive concentrations increase at both low and high concentrations. 

Explain qualitatively why dishing can reach a maximum value for long overpohshing times, while erosion keeps increasing with time. 

What are the general requirements of polishing pads for 1C CMP process Explain why polyurethane pads are the most commonly used pads in CMP practice. Suggest some alternative materials. 

What are the differences in microstructures of the four main types of polishing pads Suggest an additional type. 

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Zhang J, Keleher J, Hellring S, Shipp D, Li Y. Reactive pads for metal CMP. Proceedings of 22nd International VLSI Multilevel Interconnection Conference (VMIC), Ferment CA, October 4-6 2005. pp 251-259. 

Li Y. Reactive pads for metal CMP. 10th International S5miposium on CMP. NY Lake Placid 2005. 

Fuc (1990)/ = Fuchlgami Y. "Hydrolysis of Methyl Acetate in Distillation Column Packed with Reactive PadExchange Resin", J. Chem. Eng. Japan 23 (3), (1990) 35-359... 

The principal additive shrink-resist treatment uses the polymer Synthappret BAP (Bayer AG) which is a polypropylene oxide polyurethane containing reactive carbamoyl sulfonates (or isocyanate bisulfite adduct groups, —NHCOSO —Na" ). An aqueous solution of this polymer is padded onto woven fabrics, which are immediately dried. Other polymers may be appHed at the same time to modify the handle. 

These methods 2, J, and 4) are only used when applyiag fiber-reactive dyes. In all methods thermofixation conditions are 60—90 s at 190—220°C depending on the choice of disperse dye. In method (/) the chemical pad is caustic and hydrosulfite for vat dyes, and alkaU and salt for fiber reactives. This is the most popular method ia the United States. 

FiaaHy, ia method (4) the fabric is padded with a mixture of medium energy disperse dyes, carehiUy selected higher reactivity, and rapid diffusiag fiber-reactive dyes, up to 10 g/L sodium bicarbonate depending on depth of shade, and proprietary auxiHary agents. 

The alternative approach is to pad the fabric with the alkaline naphthol and dry, foUowed by printing directly onto this prepared fabric diazonium salts or stabilized diazonium salts. Coupling is instant and the only further treatment needed is to remove aU the uncoupled naphthol and surface azo pigment in a subsequent washing treatment. Because the choice of colors is limited from one naphthol component, other shades are obtained by using other classes of dye alongside the azoic colors, eg, reactives. This approach is widely used in the production of African prints. 

Pulsed amperometric detection (PAD), introduced by Johnson and LaCourse (64, 65) has greatly enhanced the scope of liquid chromatography/electrochemistry (66). This detection mode overcomes the problem of loss of activity of noble metal electrodes associated with the fixed-potential detection of compounds such as carbohydrates, alcohols, amino acids, or aldehydes. Pulsed amperometric detection couples tlie process of anodic detection with anodic cleaning and cathodic reactivation of a noble metal electrode, thus assuring a continuously cleaned and active... 

Combined dyeing and easy-care finishing of cotton using bis-nicotinotriazine reactive dyes and DMDHEU in a pad-dry-HT steam process [325]... 

Introduction of quaternary N groups 1,1 -Dimethyl-3-hydroxyazetidinium chloride in presence of strong alkali by pad-bake (Scheme 10.59) Dyeable with reactive dyes at pH 7 without salt, giving extremely high fixation... 

Pad-dry-cure for 3 min at 100 °C. Scheme 10.62 represents the reactive and nucleophilic sites that may exist on the surface of the treated fibre... 

Polyepichlorohydrin and dimethylamine Polymerisation of epichlorohydrin in carbon tetrachloride with boron trifluoride/ether catalyst, then reaction with dimethylamine. Applied to cotton by exhaust method or pad-dry. Scheme 10.65 Good yields with direct dyes using only 2 g/l salt. Excellent build-up with most reactive dyes only 10% of normal salt usage needed for low-reactivity dyes and none for highly reactive types. Washing fastness very good but light fastness impaired. 

Table 12.19 Pad liquor formulations and fixation conditions for application of monofunctional and heterobifunctional reactive dyes by three continuous dyeing methods [162]...

Table 12.20 Print paste and fixation pad liquor formulations for two-phase flash age printing with reactive dyes [29]... 

Exploitation of the dichlorotriazine dyes soon led to parallel development of the much less reactive aminochloro-s-triazine derivatives, which ultimately became the most successful of all reactive dye systems. Aminochlorotriazine dyes (such as 7.2) are readily prepared by a substitution reaction (Scheme 7.2) at 30-40 °C between an arylamine and the dichlorotriazine precursor (7.1 in this instance). Dyes of the aminochlorotriazine type [6] were launched simultaneously as Cibacron (Ciba) and Procion H (ICI) brands shortly after the dichlorotriazine dyes had been introduced. More stable pad liquors could be formulated... 

Further work with the same dye (7.43) and carbodiimides (7.44 and 7.45) concentrated on this problem of limited efficiency. Cotton fabric padded with the dye phosphonate solution was aftertreated with the carbodiimide dissolved in various alcoholic solutions to avoid hydrolytic decomposition. Under these conditions cyanamide was much more effective than dicyandiamide. With conventional reactive dyes the efficiency of the dye-fibre reaction is limited by competing hydrolysis of the active dye. Although phosphonated or carboxylated reactive dyes do not hydrolyse, their level of fixation is limited by competing hydrolysis of the carbodiimide activator [46]. 

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