Microstructured selection steps

The stack assembly procedure also affects the seal selection process. For instance, a laminate structure of anode, electrolytes, and cathode is formed by the plasma spraying technique. The microstructuring processing steps must be controlled so that the interfacial reactions and interdiffusion between those layers can... 

The procedure consists of three steps. The first step is to identify all the desired product quality factors or attributes for the new product. Then what follows is the selection of the appropriate product form and microstructure, a stable surfactant system with the right performance based on phase behavior, and the appropriate active ingredients in order to realize those quality factors previously identified. Finally the process flowsheet will be created with the equipment units and process operating conditions determined. 

The choice of a suitable initiator represents an important step in creating a well-defined polymerization system in terms of initiation efficiency and confrol over propagation. The entire system can only be designed on a stoichiometric base when a quantitative and fast initiation occurs. This is of enormous importance, because the composition of the entire polymerization mixture needs to be varied within small increments in order to control the microstructure. The catalyst needs to be carefully selected from both chemical and practical points of view. Schrock [5,10,12,109,110] and Grubbs systems [6], both highly active in the ROMP of strained functionalized olefins, can offen be used. Since fhe preparafion and in particu-... 

Precise control of concentration and residence time can increase the selectivity of the sulfonation of toluene, as this allows to optimally set the interplay between the readions 4.4.1-4.4.4 [315,316], The highly exothermic nature of the reaction demands for good temperature control. A single microreador is not suited to condud the various readion steps with all their different needs on temperature and residence time. Thus, a continuously operated plant with many microflow tools was developed. The plant design was based on a fluidic backbone providing unitized ports and plant unit sites to facilitate the connection of microstructured components from different suppliers (see Figure 4.49). 

In addition to the anodic processing of A1 films, localized porous-type anodization, combined with selective etching of either A1 or porous AI2O3, can be used for the surface microstructuring of thick A1 substrates.7,30,58 As an example, Fig. 13 demonstrates a schematic presentation of processing steps. Photolithography (Step 1) was used to define 25-pm-diameter circular features separated by 37.5 pm pitch. Time and conditions of localized porous-type anodization (Step 2) were chosen such that U exceeded half of the pitch. Consequently, under chosen process conditions and feature dimensions, any three adjacent anodized areas overlapped. Finally,... 

Figure 15. Process flow for surface microstructuring with undercut being less than half of the pitch. (1) photolithography, (la) top view and (lb) cross-section view (2) porous-type anodization (3) application of an epoxy on the top and selective etching of A1 from the back and (4) selective etching of porous AI2O3. SEM images of microstructured A1 surface after Step 4, tilted samples with different shapes of anodized/etched features (left and middle) and separated features of porous AI2O3 on the epoxy film, after Step 3 (right). Images reproduced from Ref.30 with permission from ASME.

Lithography steps are followed by a number of subtractive and additive processes, transferring the lithography patterns into ICs or 3D micromachines. Table 3.2 is a partial list of subtractive steps used in building microstructures. In subtractive processes material is removed from the device under construction, usually very selectively, through the use of a resist or other mask pattern (e.g. an oxide or a nitride). 

---