Reflow effect

For certain clearcoat systems a partial healing of scratches can be observed on the time scale. In literature this is known as the reflow effect [21], Thermal relaxation phenomena may be used for a physical explanation of this effect. In connection with scratch resistance the cross-linking density of clearcoats is also a decisive factor. Meanwhile, dynamic mechanical analysis (DMA) has been established as a method to determine cross-linking density [21-23],... 

Figure 11. The effect of reflow nearby the glass transition temperature for a PMMA-DR1 waveguide (a) device structure, (b) SEM picture of waveguide before reflow, (c) idem after reflow.

If desired, plasma oxide films can be doped much as the plasma nitride film we discussed earlier. In fact, doping with boron and phosphorus has been carried out as an alternative to the standard atmospheric-pressure thermal CVD process for BPSG.11 12 The latter process has the drawbacks of high defect density and poor thickness uniformity, so it was hoped that plasma BPSG would be an improvement. However, there are differences in the films in terms of H2 and N2 content, and their effect on reflow temperature, intrinsic stress and passivation effectiveness had to be examined. 

P. Golino, P.R. Maroko and T.E. Carew, The effect of acute hypercholesterolaemia on myocardial infarct size and the no-reflow phenomenon, during coronary occlusion-reperfusion, Circulation 75, 292-298 (1987). 

For a sufficiently thin film, such as the BSG overcoat on a silicon water, a single NDP spectrum is capable of depicting the thickness, the distribution profile, and the total amount of boron present. After treatment to drive out trapped reaction products and voids in the glass, any boron or other mass losses can be quantified. Also, the effect of reflowing the glass film on the original boron profile can be identified (7). 

The kinetic parameters of Tc-HMPAO retention in the human brain have been studied (Lassen et al. 1988), and measurements of CBF have been compared to Xe (Andersen et al. 1988). CBF was quantified using dynamic single-photon emission computer tomography (SPECT) (Murase et al. 1992). The role of SPECT with Tc-HMPAO in ischemic stroke has been evaluated (Heiss 1983 Podreka et al. 1987). Reflow hyperemia in subacute stroke has been described as luxury perfusion (Lassen 1966) and was later explained by hyperfixation of " Tc-HMPAO (Lassen and Sperling 1993). Increased regional blood flow in subacute stroke has been measured with " Tc-HMPAO (Moretti et al. 1990). The effect of acetazolamide on CBF was reported in patients with severe internal carotid artery stenosis/occlusion (Asenbaum et al. 1995), and has been studied in primates (Dormehl et al. 1997). " Tc-HMPAO SPECT was evaluated in patients with cerebrovascular disease by comparison with F-fluoromethane positron emission tomography (PET) (Heiss et al. 1990). A pattern of focal abnormalities in CBF was derived in patients with degenerative dementia (Holman et al. 1992). 

Brain retention of Tc-l,l-ECD is caused by intracellular stereospecific hydrolysis of the ester, producing the monoethyl ester (Walovitch et al. 1988). The D,D-isomer showed back-diffusion (Ti,2 30 min). Once the metabolite is formed in the brain, it cannot cross the BBB in either direction (Walovitch et al. 1989). Effect of hypoxia on esterase function might interfere with reflow hyperemia in subacute stroke (Dormehl et al. 1997). Elimination from brain is expressed by two exponential functions, corresponding to half-times of 1.3 h (40%) and 42.3 h (60%, 3.8% ID), respectively (Vallab-hajosula et al. 1989). 

The postexposure-based techniques are grouped into three broad categories, namely, reflow-based. shrink techniques, chemical-based shrink techniques, and plasma-assisted shrink techniques. The reflow-based shrink techniques comprise thermally induced reflow and electron-beam heating-induced reflow of patterned resist features. The chemical-based shrink techniques comprise those techniques that either increase or decrease the sidewall thickness of already patterned resist features, thus effectively altering their critical dimension. Examples of chemical-based shrink techniques that result in an increase in the sidewall of the patterned features include techniques based on RELACS (resolution enhancement of lithography assisted by chemical shrink) and CARL (chemical amplification of resist lines).Examples of chemical-base shrink techniques that result in decrease... 

A fourth generation of electrically conductive adhesives based on cyanate esters and modified cyclo-olefin thermoset (MCOT) resins was introduced in the 1990s. These resins were specially formulated for low moisture absorption, high thermal stability, and low stress to be compatible with solder-reflow conditions. They were developed to prevent or reduce the so-called popcorn effect, a failure mode attributed... 

The composition advantageously displays a thermal resistance effective to withstand the high temperatures encountered in a reflowing oven. Further, the high-temperature compositions more closely match the thermal shrinkage of PBT, which is presently used in solder connector applications. 

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