Etching treatments

The adherend metallurgy also indirectly determines the degree of smut buildup because the rate of smut formation is proportional to the etch rate [54J. For instance, the etch rate of A606 is four times greater than that of A514, due to differences in grain size, etc. As a result, a different etch treatment is required for each. In general, the roles of alloy and heat-treatment differences have not... 

While etch primers, also known as pretreatment primers and wash primers, can be regarded as priming paints which promote their own adhesion by etching the metal surface, they may also be regarded as phosphate/chromate etching treatments which leave an organic residue on the surface to form the basis of the subsequent paint scheme. A detailed account of the etch primers has been given by Coleman . 

To this point we have only discussed the annealing characteristics of the 1560 and 809 cm-1 absorption bands. The bands near 1660 cm-1 were also examined (Bergman et al., 1988a). The etching treatment used to remove a surface layer did not preferentially remove the 1660 cm 1 absorption. This band had a similar dissociation temperature as the features near 1560 and 809 cm-1. Further, in a cursory examination, there was no evidence found that one of the species was an annealing product of the others. 

Like other non-oxidic semiconductors in aqueous solutions, surface oxidized and photocorrosive InP is a poor photoelectrode for water decomposition [19,27,32,33], To enhance properties several efforts have focused on coupling of the semiconductor with discontinuous noble metal layers of island-like topology. For example, rhodium, ruthenium and platinum thin films, less than 10 nm in thickness, have been electrodeposited onto p-type InP followed by a brief etching treatment to achieve an island-like topology on the surface [27,28]. In combination with a Pt counter electrode, under AM 1.5 illumination of 87 mW/cm the metal (Pt, Rh, Ru) functionalized p-InP photocathodes [27] see a reduction in the threshold voltage for water electrolysis from 1.23 V to 0.64 V, and in aqueous HCl solution a photocurrent density of 24 mA/cm with a photoconversion efficiency of 12% [27]. 

While the cell efficiencies of these films were not specifically investigated, best parameters of 2 mAcm (ca. AMI illumination quantum efficiencies increased with decreasing illumination intensity due to diffusion limitations in the nanoporous film) 0.5 V and ca. 50% fill factor were obtained. However, great variation in these parameters were obtained one reason for this can be seen from a consideration of Figure 9.9. If a CdSe film is etched, but less than optimally (shorter time, more dilute HCl), it is clear that after a certain, unique etch treatment, zero net photocurrent will be obtained. The actual photocurrent (and other ontpnt parameters) of the film is a balance between photoanodic and photoca-thodic cnrrents. 

Figure 12.4. (a) X-ray topograph, (b) polarization photomicrograph (crossed Nicols), and (c) reflection photomicrograph after etching treatment of the same section prepared perpendicular to the c-axis of a beryl crystal, (d) Polarization photomicrograph of similar section of another sample [1]. 

An HgCdTe layer 2 is formed on a sapphire substrate 1. A resist layer 3 having windows is shaped on the HgCdTe layer and an etching treatment is carried out to form through holes 4 in the HgCdTe layer. At the same time two opposite side-walls are tapered. An indium layer is deposited and electrodes 5 are formed on the slanted side-walls and on the exposed regions of the sapphire substrate when the resist layer is removed. 

Because of the solvent and chemical resistance of acetal copolymer, special etching treatments have been developed for surface preparation prior to adhesive bonding. A chromic acid etch and a hydrochloric acid etch have been suggested. Acetal parts that have been formed by heat treatment or machining should be stress-relieved before etching. 

Room temperature etch. Treatment may be followed by passivation for 20 min in 5-10% w/v chromic acid solution... 

Figure 12 represents a cross section of a plated sample of ULTEM 1000 having a peel strength of 118 g/mm. Little physical surface change of the plastic has occurred as a result of the pretreatment steps. Figure 13 is a cross section of copper plated ULTEM 2312. While a mechanical component to adhesion is present, it is much less than that found in traditional swell and etch treatment (Figure 2). Physical alteration of the plastic is confined to the outermost 25ii. The bulk properties of the plastic (flexural strength, electrical resistivity) are unaffected by this new process (Table I).

In the first case, open symbols, a thin skin layer was created by an etch treatment. The second case shows a sample capped with a 200 nm thick cap. Either treatment seals the surface and prevents the escape of positronium. Below the surface layer, significant porosity can be observed. However, because the implantation profile is spread across larger depth regions in the second case, a careful data analysis must be undertaken to extract the actual porosity. 

Figure 4 W(4f) XPS spectra for tungsten polished without abrasive particles in the two oxidizer solutions compared with the spectrum on the sample given etch treatment to remove oxides.

One important area of resist research in recent years is the development of plasma-developable resist systems. The aim of plasma developable resists is to use nonsolvent, all dry development methods to avoid the problems of swelling and consequent resolution limitation associated with conventional resists. Much of the semiconductor fabrication process now utilizes plasma techniques as they are capable of providing high resolution images. An important consideration in this is that the plasma-developable resist images should stand up well to the plasma etching treatments. 

The electrochemically deposited single crystalline ZnO nanowires can be applied in LEDs [147, 148]. ZnO nanowire films can be embedded in an insulating spin-coated polystyrene layer. The spin-coating parameters are carefully fine-tuned to completely fill out the space between the ZnO nanowires and produce only a very thin coverage of the nanowire tips. The polystyrene layer thickness at the tips can be further reduced by the plasma etching treatment to make the n-type ZnO tip junctions outside. A top... 

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