Substrates thickness

Considering the absorption curve for silicon O igure 41) the penetration depth for a photon of wavelength 4 000 nm is 4 00 ym. Electron hole pairs produced within close proximity to the rear contact are also likely to suffer recombination due to the high recombination velocity present there. If good spectral response at long wavelengths is to be achieved the substrate thickness should therefore be 100 y. 

The effect of substrate thickness upon the short circuit current of p-n junction cells under AM4 is shown in figure 13. In practice the extent to which the thickness of single crystal solar cells may be reduced is normally limited by the fragility of the substrate - typically v 300 y thick. A similar limitation exists for Schottky Barrier cells, however, if thin film substrates are to be used it should be noted that the properties of the films will be widely different from the bulk material. This is particularly the case for a-silicon where absorption coefficients are more than 10 times greater and 5% efficient cells have been achieved using active regions 1, y thick.  

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Figure 6-15. The kinetic phase diagram of high-vacuum-sublimcd T6 films as a function of deposition T and nominal substrate thickness h.

The first LAPS utilized silicone nitride (S3N4) as a pH-sensitive layer [68], A light-addressable high resolution pH imaging sensor was applied to the detection of spatially resolved metabolic activity of Escherichia coli colonies on agar medium [69], For a silicone substrate thickness of 20 pm the reported spatial resolution was about 10 pm. The observed pH distribution was in good agreement with the results of simulation based on a two-dimensional diffusion model. 

The coatings were cured in two steps first, a room temperature exposure for at least five hours to allow any solvent present to evaporate and/or the resin to gel and, second, an elevated temperature cure. The vinyl ester, polyester and epoxies were baked at 60°C for 4-16 hours. The coating thickness after curing was measured with a micrometer, subtracting the substrate thickness. The thickness of the coatings ranged from 6 to 12 mils (150-300 urn) and is shown for each type in Table I. 

Poly(methyl methacrylate) with a variable degree of polymerization anchored to silica surfaces was synthesized following the room temperature ATRP polymerization scheme described earlier [45,46]. In the main part of Fig. 25 we plot the variation of the PMMA brush thickness after drying (measured by SE) as a function of the position on the substrate. Thickness increases continuously from one end of the substrate to the other. Since the density of polymerization initiators is (estimated to be 0.5 chains/nm ) uniform on the substrate, we ascribe the observed change in thickness to different lengths of polymer chains grown at various positions. 

Fig. 36 Dry thickness of polyfdimethyl aminoethyl methacrylate) (PDMAEMA) on an orthogonal PDMAEMA gradient grafted on a silica substrate. Thickness was measured in a grid of 5 mm x 5 mm on the substrate. (Reproduced with permission from [117])...

Substrate thickness 300 pm Insulating covering film material Teflon or polypropylene... 

Substrate Substrate thickness, mils Tensile shear strength, psi... 

During fuser-roll resist lamination processes, the copper-clad FR- substrate surface temperature was found to be inversely proportional to the substrate thickness. This temperature fluctuation has resulted in changes of adhesive forces in the copper/resist interface which in turn can affect the yield in the printed circuit manufacturing processes. By using infrared preheat... 

One obvious motivation behind industrial research is to improve the yield or connectivity of the printed circuitry. In this investigation, two main variables were studied concerning their influence on the yield of fine line circuitry substrate thickness and preheat conditions. Comparative data from the literature as well as from private communications will also be critically reviewed. 

Due to surface temperature fluctuations during lamination and the resulted changes in photoresist/copper interface adhesion, printed circuit yield is inversely proportional to FR-4 substrate thickness. Preheating the substrates, however, would improve the adhesion and result in a higher yield for the printed circuits. 

Substrate thickness Production 500-800 rm Finishing down to 50 j,m production 200-700pm Finishing down to 20 pm Specific ... 

Porous substrate Thickness (urn) Pore size (A) Water flux (gfd) Salt rejection (%)... 

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