Fabricating processing repeatability

Development required Fabrication process not repeatable Possible interference from CO and humidity (characteristics of all Pd-based hydrogen sensors)... 

When indium bumps are used to connect two chips having different thermal expansion coefficients and the chips are exposed to repeated temperature cycling, the mechanical stress in the bumps is reduced when the bumps are made taller. If the indium bumps are formed using vapor deposition through a photo-reduced mask pattern, the height of the bumps are limited to 6-9 microns A fabrication process for making taller indum bumps is disclosed in EP-A-0405865. 

The location of different unit operations in catalystmanufacturing production lines docs not lend itself to debate. Precipitation occurs at the beginning of a fabrication process calcination then activation, which will be treated later, are the final operations. Certain operations can be repeated in some processes but the final calcination will come after the last drying. On the other... 

Solid Freeform Fabrication (SFF) technologies have in common the capability to build objects with comphcated 3D geometries, directly from Computer-Aided Design (CAD) files, without the necessity of tooling. SFF technologies also have in common the employment of an additive building process, in which a 3D object is built up by the repeated addition of layers of material. This is in contrast to more standard technologies which are characterized by the implementation of a subtractive fabrication process, e.g., CNC (Computer Numerical Control), where the 3D object is manufactured by calculated removal of material from a block of raw material. 

As a matter of fact, it is well known that it is impossible to keep parameters constant while changing others. For example, if the enzyme loading is increased, the film thickness, the diffusional properties for the substrate and the products, the counter-ion movement, possible ET reactions, etc., may be altered simultaneously. Thus, a pseudo rational approach has to be complemented by combinatorial approaches in which the overall parameter space is addressed by means of a large number of measurements after permutation of ah possible influencing parameters. The knowledge gained should be comprehensively summarized in a related publicahon. The final consideration should be whether the sensor fabrication process described in a paper can be directly repeated successfully in another laboratory leading to similar sensor responses. 

The 4S and 2R conditions are considered to be requirements of gas sensor properties. 4S means sensitivity, selectivity, stability, and speed 2R means reversibiUty and repeatability. To realize the above conditions, we try to prepare devices according to optimal device design, fabrication process, and operational conditions. The sensing properties of metal oxide and SAW-type devices will now be described in brief. 

At this point in the fabrication process for the later RPVs, the welds were given a hot UT inspection to assure compliance with a pre-service examination. The shell course was then placed in a furnace and given a post-weld heat treatment (PWHT). The welds were then ground smooth on the external and internal surfaces. The ASME Code-required radiographic (RT) and MT inspections were then performed. Any required repairs of unacceptable indications were made at this point using manual metal arc (MMA) welding and a repeat of the preheat-post-weld heat treatment. 

The medium is prepared on a master form, consisting of a heavy fabric belt, surfaced on one side with a layer of rubber filled with small round pits imiformly spaced. These pits are 0.020 in. deep, and the number per unit area and their surface diameter determine the porosity of the sheet. A thin layer of latex is fed to the moving belt by a spreader bar so that the latex completely covers the pits, yet does not run into them. This process traps air in each pit. The application of heat to the under-surface of the blanket by a steam plate causes the air to expand, blowing little bubbles in the film of latex. When the bubbles burst, small holes are left, corresponding to the pits. The blown rubber film, after drying, is cooled and the process repeated until the desired thickness of sheet is obtained. The sheet is then stripped off of the master blanket and vulcanized. 

A different method of creating UHMWPE fibre-reinforced UHMWPE composites was presented by Mosleh et al. [179]. In this method, dry UHMWPE powder was mechanically oscillated through a funnel onto subsequent layers of short (25 mm) chopped UHMWPE fibres, or pieces of continuous UHMWPE fabric. By repeating this process with many layers of short chopped UHMWPE fibres or UHMWPE fabric, a layered stmcture was reported to have been created. These fibre assemblies were then heated under pressure to consolidate the structures. The short UHMWPE fibre-reinforced composites had a fibre volume fraction between 25 and 75%, while the continuous UHMWPE fabric-reinforced composites had a fibre volume fraction of 60%. Investigations into the potential application of these homocomposites in an articulation surface for a knee joint prosthesis were also described, as were the challenges associated with measuring the tribological performance of such fibre-reinforced materials [180]. 

The described impregnation-reduction steps are typically repeated 1-3 times in order to increase the thickness and electric conductivity of the electrodes. The third step is the secondary plating (or surface electroding) process to deposit additional Pt at the outer surface of the electrode to further increase the electrode surface conductivity. The composite is immersed in the Pt complex solution, and by using reducing agents such as hydroxylamine hydrochloride and hydrazine monohydrate, the platinum is deposited on the top of the initial Pt electrode layer. A detailed description of the fabrication process can be found in (Kim and Shahinpoor 2003). 

Fig. 2 Process flow (a) Starting Material, (b)Deposit SisN (c)Deposit poly-silicon, (d) Deposit Al, (e) Resist coating, (f) Soft bake, (g) Exposure mask, (h) Develop resist (i) Poly-silicon RIE, (j) Alum etch and stripe resist, ion(k) Dry oxidation, (1) Poly-silicon nanogap pattern with pad Pt/Au fabrication( Electrical checking of the device can be performed on the fabricated pad)(Repeat step (a) to (j) for mask 2). Fig. 3 shows the circuit after serial impedance is measured, a simple resistor model is developed representing the substrate and polysilicon layer. The capacitor also found in series to describe the device with no liquid test...

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