Substrate manufacturing

The design of sensitive elements (transducers) is based on the conductive principle of response registration the output signal appears to depend on the conductive properties of the TCNQ compound as a result of its interaction with gas components. The gas-sensitive substance of the transducer has been manufactured from complex TCNQ salts with N-alkylisoquinoUnium cations ([N-C H -iso-Qn] (TCNQ)Q [26]. The substance of the gas sensitive layer is put in contact with copper or silver current feeding electrodes, put on the dielectric substrate manufactured from glass-cloth laminate. 

These developments obviously create problems for the substrate manufacturer, but they can also offer significant opportunities for companies to exploit these demands and produce satisfactory new materials. 

As already stated, the assistance that substrate manufacturers can give for this problem is to improve the mechanical properties of flatness, warp, dimensional stability, and the supply of thinner copper layers with better adhesion to retain the bond of the narrower tracks. 

Experiments were started with the metal powder in order to reveal principal possibilities of laser sintering of powder layers deposited onto a substrate [2], In these experiments, the layer of Ni powder (with particle size about 0.5 pm) was deposited onto the surface of Ni substrate manufactured by traditional powder metallurgy (with particle size about 5 pm) and subjected to sintering by CW-Nd YAG laser (X = 1.06 pm). Layer thickness was about 2 pm. The joining of powder layer with the substrate was provided during sintering. The graded porous structure was formed on the surface as it is shown in Fig. 1 (the size of pores is about 2 pm for the sintered layer and 6 pm for the substrate). 

Eor the completion of MID assembhes after substrate manufacturing and plating, several further steps are normally necessary. 

HIDY The filter media used in this study was a teflon-coated glass fiber substrate, manufactured for us under very strict specifications. It was used uniformly for all aerosol sampling in the SURE. The filter medium is not subject to a sulfur dioxide adsorption artifact, but it is subject to adsorption of nitric acid. It does not adsorb NO or NO2, however. 

There are two main processes in the fabrication of semiconductor wafers (Wald and Jones 1987 Burgess 1995) - substrate manufacture and device fabrication (Irizarry and Blumstein 1997). These processes are carried out in clean rooms, which are designed to minimise contaminant particles in the environment from depositing and destroying the product. Airflow in clean rooms is continuous, filtered and recirculated. The relative humidity is often low. 

Current Status of Electrodes Fabrication Methods of Electrodes 277 Table IOlI Substrate manufacturing technologies [7]. 

Thus, it is important to understand the unique crystal structure of GaN and its asymmetry to design a fabrication process. In other words, attention should be paid to areas where the design of the entire substrate manufacturing process flow differs signili-cantiy from that of existing crystals such as Si and sapphire. 

It has not been unusual for LTCC substrate manufacturers to be presented with designs in which the overall part size cannot be changed. The cost of LTCC multilayer circuits is very dependent on overall part dimensions and the relationship to the foundry panel size, panel tooling, and the usable area within the panel. It is important to maximize the total number of parts within the usable area to achieve the lowest possible unit cost. A small dimensional increase could eliminate a row or column of parts or produce excess waste... 

Figure 1.3 Typical multilayer ceramic substrate manufacturing process.

Carborundum Corporation" published results of a program carried out there to improve the mean value and reduce the variability of the thermal conductivity of their substrates. As a result of their effort the mean thermal conductivity of AIN substrates manufactured by their process was improved fiom 172 W/(m K), with standard deviation of 19.6 W/(m K), to mean of 192 and standard deviation of 3.0 W/mK. 

The fifth generation PAFC electrode substrates are basically refinements of the Kureha s carbon substrate as mentioned before. These substrates manufactured by Toray have a mean pore size of about 20-30 p, about 0.3-0.4 mm thick and are very successfully used in UTCs 200 kw PC-25 power plants, being one of... 

The remarks below concern themselves only with the main points of materials selection and aspects of substrate manufacture. All other aspects are discussed in depth in Chapter 3. 

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