Thickness Conductivity

The typical thickness of metallized Al layers ranging from few nm to several hundred nm corresponds to an area weight of approximately 100 mg m-2. Such film thicknesses cannot be reliably measured by mechanical meters or by weighing. Other laboratory measurement techniques are used, for example X-ray fluorescence (XRF) spectroscopy, ellipsometry, or ion scattering (RBS). All these techniques are unsuitable for in-line control during metallization, because they require 

Optical Density For aluminum, the most popular method of determination of the quantity metallized is measurement of optical density (O.D.). The vacuum-evaporated layer is exposed to light of intensity Jo and the part of the light transmitted I is measured. Optical density (O.D.) is a function of the light transmission, 

A typical A1 layer with an O.D. of 2.0 has a visible light transmission of 1%. Lambert s Law  

Surface Resistance For opaque substrates or very thick metal layers, measurement of the thickness optically is not feasible. For such materials eddy currents (induced current) are used to measure the electrical surface resistance of the metal layer and, consequently, the thickness of the metallized layer. The thinner the metal layer, the higher its resistance. Surface resistance is inversely proportional to the thickness of the layer (proportionality factor depending on the material). 

The surface resistance R n is defined for square test surfaces. If the resistance R is defined via the specific resistance pA (matter constant)  

---

Under steady-state conditions, the temperature distribution in the wall is only spatial and not time dependent. This is the case, e.g., if the boundary conditions on both sides of the wall are kept constant over a longer time period. The time to achieve such a steady-state condition is dependent on the thickness, conductivity, and specific heat of the material. If this time is much shorter than the change in time of the boundary conditions on the wall surface, then this is termed a quasi-steady-state condition. On the contrary, if this time is longer, the temperature distribution and the heat fluxes in the wall are not constant in time, and therefore the dynamic heat transfer must be analyzed (Fig. 11.32). 

Thermal characteristics of material layers for each type of wall must be specified, including thickness, conductivity, density, and specific heat. Moreover, the features of internal and external surfaces of each wall must be specified, including solar absorptance and roughness, which affect surface heat transfer coefficients. 

A.C. impedance (thickness conduction mechanisms and profiles compactness crystallinity)... 

Let us consider the semi-infinite (thermally thick) conduction problem for a constant temperature at the surface. The governing partial differential equation comes from the conservation of energy, and is described in standard heat transfer texts (e.g. Reference [13]) ... 

Lateral wicks have been introduced (Bl) in order to avoid a curved field without affecting the original arrangement of the electrodes, very thick conductive wicks being placed along both edges of the paper. To prevent these wicks from sucking the buffer out of the substrate curtain, they are specially fed with buffer solution in such a way that they neither... 

Gold Powder 507, 508, 509, 510 - chemically precipitated, spherical powder for thick conductive inks... 

Katoh et al used the linear thermal resistance model and the temperature dependent defect thermal resistance data for the composites constituents to predict the effect of neutron irradiation On temperature dependent thermal conductivity of the composites. The prediction suggested that the maximum and minimum post-irradiation through-thickness conductivity was 10-15 W/m-K at 800-1000"C for 3D architecture, and less than 5 W/m-K at <800"C for 2D architecture. 

Fig. 5.37. NIR-transmission of standard glass and ITO-coated glass top reference air bottom reference glass 1, 2 and 3 different coating conditions, resulting layer thickness, conductivity, etc.

Power of the vacuum pump Oxygen fraction in the furnace tube and exhaust stream Charge number of defect i Permeation improvement factor due to the surface modification Hollow fiber membrane thickness Conductivity of defect i Gas viscosity... 

Sedlakova, et al. 2003b. Noise of Carbon/Graphite Thick Conducting Films. Proc. of the 17th International Conference on Noise and Fluctuations, Prague, Czech Republic, p. 201-204. 

Dziedzic A, Golonka LJ, Licznerski BW, Hielscher G (1994) Heaters for gas sensors from thick conductive or resistive films. Sens Actuators B 19 535-539... 

---