Scalloped layer

Fig. 5.19 Schematic diagram of the evolution of straight nanotubes at constant anodization voltage (a) Oxide layer formation, (b) pit formation on the oxide layer, (c) growth of the pit into scallop shaped pores, (d) metallic part between the pores undergoes oxidation and field assisted dissolution, (e) fully developed nanotubes with a corresponding top view.

Scallop shells, of the family Pectinidae, thou once very popular, are now rather out of shion. They come in a variety of colours but the inner layer is usually a dull cream and is not nacreous. 

Hydrological parameters were monitored, and it was shown that Pr. reticulatum flourished under low salinity (30.59-32.60) and occurred at highest density in the surface layer (0-5 m depth) where effects from rainfall were greatest. In addition, dinoflagellate density increase and decrease were well correlated with inflows of oceanic water into the bay. YTX and 45-hydroxyYTX concentrations in scallops reached maximum levels 2 weeks after the maximum cell density of Pr. reticulatum, and high levels of the toxin continued for a month. Low levels of the toxin were detected even during periods when cells were not observed. ... 

Figure 5. Exposure artifacts illustrated by the constructive and destructive interference nodes in the resist layer over an underlying step (top figure). The resulting scalloped line edge profiles over such a step crossing showing global linewidth drifts as resist layer thickness changes (bottom figure). (Reproduced with permission from Ref. 29. Copyright 1981, SPIE.)...

Figure 1.2 High-performance thin-layer chromatogram of methyl esters of fatty acids, showing separation based on unsaturation. The plates were developed in the solvent system hexane/ diethyl ether, 92 8 vol./vol. a = a standard mixture of tetracosaenoic (24 1 vol./vol.) and docosahexaenoic (22 6 vol./vol.) fatty acid methyl esters b = sea scallop lipids c = dogfish liver d = menhaden e = redfish f=rapeseed g = cod liver. Reproduced with permission from Shantha, N. C. and Ackman, R. G., Silica gel thin-layer chromatographic method for concentration of longer-chain polyunsaturated fatty acids from food and marine lipids, Canadian Institute oj Food Science and Technology Journal, 24, 156-60, 1991.

Most studies show that Ag atoms do not participate in the interfacial IMC formation, except for Ref 42. They did energy dispersive x-ray (EDX) analyses of interfacial IMC between Sn-3.5Ag and Cu formed at 250 to 375 °C (482 to 707 °F) for 10 to 60 min. and found that the atomic composition of the scallop-shaped inter-metallic is Cu Sn Ag = 54.4 45.39 0.31, which corresponds to the p-Cu6(Sno.993Ago 007)5 phase. Following prolonged soldering reactions, a thin layer of IMC appears at the Cu6(Sno.993Ago.oo7)5/ Cu interface. The atomic composition of this thin layer of IMC is Cu Sn Ag = 75.21 24.70 0.09, which corresponds to the e-Cu3(Sno.996Ago.oo4) phase. 

A study of the Cu-Sn reaction couple at temperatures between 250 and 325 °C (482 and 617 °F), observed that the e-layer always grew as a somewhat undulated planar layer in phase with the q-phase scallops (Ref 40). This morphology indicated that the e grows by reaction of Cu with... 

Dense layer with scalloped interface. This appears similar to the cellular grains in plane view, but the layer is dense beneath the surface. The interface with the solder appears similar to scallops. 

Dense layer with planar interface. The morphology of the q-layer varies gradually from a cellular film with a rugged interface to a dense film with a scalloped interface as the Pb content, temperature, and reaction time increased. The 8-phase is always dense and nearly planar. 

Figure 8.3 shows transmission electron micrographs of selected regions of the anodic film located near the surface (Fig. 8.3a), within the film (Fig. 8.3b), and adjacent to the alloy/film interface (Fig. 8.3c). The anodic film reveals a porous morphology, with pores confined within alumina cells the barrier layer is evident beneath the pore base together with the scalloped alloy/film interface. The cell and pore diameters are about 30 and 10 nm, respectively, with a barrier layer thickness of 11 nm. Titania nanoparticles are distributed in a thin, outer layer of several tens of nanometres thickness the particles have diameters up to 10 nm. No particles are evident in the porous skeleton of the anodic film.

All three solder alloys dissolved the 1.0-pm Au layer to form the IMC AuSu4 throughout the solder ball bulk, and a second IMC, AgsSn. The AgsSn was distributed evenly in Sn-Pb-Ag alloy, but preferentially along the phase boundary of the Sn-rich grains in the Pb-free alloys. The microstructures are shown in Fig. 16. A very thin layer (approximately 0.5 pm) of Ni-Sn IMC was found to exist at the termination pad/solder interface of the Sn-Pb-Ag and Sn-Ag alloys. But the morphology of the Ni-Sn IMC was much different from CueSus at the interface which typically has a scalloped appearance [61,62]. A ternary compound existed at the termination pad/ Sn-Ag-Cu solder interface [60]. 

Several studies addressing the formation of solder alloys in Ni/Pb-Sn diffusion couples have been performed at temperatures above the liquidus [7,8,10,71-74]. Early during the reaction, scallops are found at the Ni interface, with grooves between the scallops that extend to the Ni interface. For instance, in diffusion couples with eutectic Pb-Sn and electroplated Ni/Pd metallization, Ni3Su4 scallops were observed [7,8] to form on the Ni surface and to coarsen over time. Kinetic data for the radial growth of the scallops and for the increase in the average thickness of the Ni3Su4 layer were computed. It was determined that the data fit well as an empirical relation between scallop radius, r, and time, r = with B a proportionality factor... 

The rate and extent of growth of (CuNi)gSn5 was determined to depend upon the thickness of the SAC solder. With a relatively large supply of SAC solder, the growth of this compound is prodigious, with a measured layer thickness of approximately 2 pm after a reflow of 60 sec at a temperature of approximately 230°C. The morphology of the layer was found to be somewhat similar to that observed in Pb-Sn/Cu joints, with evidence of scalloping [36]. The effect of a limited supply of SAC solder is discussed in Sec. IV. E. 

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