Thermal impedance reducing

K same as previous run, with a greater thermal impedance to reduce helium... 

A novel method for achieving low thermal impedance between the chip and substrate has been developed at Stanford University (163-165). Reentrant microcapillaries (3-5 (xm wide) are etched into the substrate (either a silicon wafer or a ceramic coated with a polyimide) and partially filled with a fluid such as silicone oil. This structure increases the heat-transfer area, reduces the interfacial thermal resistance, and provides a stress-free, re-... 

The selection of highly conductive adhesives is a necessary factor, but not the only one in minimizing thermal impedance. Applying as thin a bond line as possible and avoiding the introduction or creation of voids are also essential in reducing thermal impedance. 

The three-dimensional models predict that the stress level can be reduced if the bond line thickness is increased from 25 to 75 or even 175 xm. However, the curves of Figure 50 show, e.g. that the maximum shearing stress decreases by a factor of two, from 33 to 17 MPa, when the thickness of the adhesive layer increases from 25 to 100 xm. A bond line thickness of 50-75 xm is generally recommended for the die attachment because of the negligible thermal impedance penalty. The experimental results indicate that, between 20 and 80 xm, the thickness of the adhesive joint does not greatly affect the thermal transfer capability. This behaviour has been explained by the fact that the interfacial thermal resistances between the adhesive and both the die and the substrate are much higher than that contributed by the bulk thermal conductivity of the adhesive materials. 

Alberti et al. investigated the influence of relative humidity on proton conductivity and the thermal stability of Nafion 117 and compared their results with data they obtained for sulfonated poly(ether ether ketone) membranes over the broad, high temperature range 80—160 °C and RHs from 35 to 100%. The authors constructed a special cell used in conjunction with an impedance analyzer for this purpose. Data were collected at high temperatures within the context of reducing Pt catalyst CO poison-... 

Effect of Thermal Processing. The effect of boiling shrimp after removal from storage at 27°C on impedance measurements is shown in Figure 6. Results clearly indicate that boiling reduces I-value compared with raw samples, although both... 

TMS production involves one specific functional group (-OH, -COOH, =NH, -NH2, or -SH), which loses an activated hydrogen and is replaced by a trimethylsilyl group (Proestos et ah, 2006). To achieve silylation, some authors have used BSTFA (N,0-hA(trimethyl-silyl)trifluoroacetamide) and TMCS (trimethylchlorosilane) successfully in several matrices (e.g. aromatic plants, cranberry fixiit) (Zuo et ah, 2002 Proestos et ah, 2006). Using silylated derivatives is advantageous for several reasons phenols and carboxylic acids are prone to silylation, these compounds can be derivatized in the same part of the process, and the minor products do not impede analysis and are well documented (Little, 1999 Stalikas, 2008). A two-step methylation procedure was used to analyze catechins and tannins in plant extracts. The first step used trimethylsilyl diazomethane (TMS-diazomethane) to pre-methylate the sample, and the second step used thermally assisted hydrolysis and methylation (THM). The pre-methylation step with TMS-diazomethane stabilized the dimer molecule m/z 540) by minimizing isomerization and reducing reactivity. (Shadkami et ah, 2009). 

Nielsen and Hackleman ° found that the dissolution of thermal S1O2 in BHF solutions is impeded by the application of a cathodic potential of 2-AV across the oxide film and postulated that a layer of partially reduced oxide is formed on the surface and... 

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