Passive Packages

Another disadvantage of the can is the customer s perception of it - they compare cans with flexible, polyethylene terephthalate (PET) containers, and the can does not seem to be very modern. In other words, new packages spark new interest. 

Consumers reap benefits from all these package developments in terms of user-friendly containers, such as longer product shelf life, and convenient ready-to-eat foods. Everybody keeps looking for the elusive perfect material. 

Until recently, the emphasis has been on passive barriers, which just sit there and act as a barrier between the environment and the product. Such materials are often mixed so 

Oxygen and moisture are not the only substances that must be kept on the appropriate side of a package, since flavour and aroma barriers become more necessary. So packages are being developed to make sure that the good flavours are kept in and the bad flavours out. These materials can be polyester or oriented polypropylene metallised with a thin coat of aluminium. 

There are numerous other possible packaging combinations. Materials such as PET, polyamides and polypropylene are coated with silicon or aluminium oxide to create barriers for oxygen and organics. Clay-polyimide nanocomposites have been evaluated as barrier materials for oxygen, carbon dioxide and water vapour. 

---

These processes are considerably more complex in actual CMOS fabrication. First, the lower layers of a CMOS stmcture typically have a twin-tub design which includes both PMOS and NMOS devices adjacent to each other (see Fig. 3b). After step 1, a mask is opened such that a wide area is implanted to form the -weU, followed by a similar procedure to create the -weU. Isolation between active areas is commonly provided by local oxidation of sihcon (LOCOS), which creates a thick field oxide. A narrow strip of lightly doped drain (LDD) is formed under the edges of the gate to prevent hot-carrier induced instabiUties. Passivation sidewalls are used as etch resists. A complete sequence of fabrication from wafer to packaged unit is shown in Figure 10. 

Metal is then deposited into the opened vias (openings) in the oxide layer and over its surface. During the subsequent photolithography process, it is patterned to form the desired electrical interconnections. These two steps are repeated for each succeeding level to produce additional levels of interconnections. Finally, a protective overcoat of oxide/nitride is applied (passivation), and vias are opened so that the wires eonnectlng the IC chip to its carrier package can be bonded to output pads. 

Lakeman, C. D. E. Fleig, P. F. 2002. High resolution integrated passives using microcontact printing. Proc. SPIE Inti. Microelec. Packaging Soc. (IMAPS). pp. 755-759. 

Do not lose sight of the domain terms even in your code. Use refinement to maintain trace-ability even as your code becomes more decoupled and reusable. Wherever possible, recast the problem domain descriptions themselves using these orthogonal and more abstract views remember, you are actively constructing a model of reality and not passively discovering it. Use frameworks (see Chapter 9, Model Frameworks and Template Packages) to explicitly document the mapping from domain terms to terms and roles in the abstract problem descriptions. 

Even if LiPFe is replaced by more thermally stable salts, the thermal stability of passivation films on both the anode and the cathode would still keep the high-temperature limits lower than 90 °C, as do the thermal stability of the separator (<90 °C for polypropylene), the chemical stability of the insulating coatings/sealants used in the cell packaging, and the polymeric binder agents used in both cathode and anode composites. 

Let us take the exposure packages as an example technically, most of these assays are highly automated, require small amount of compounds and have a brief cycle time. Scientifically, they fulfill requirements to predict exposure by addressing the three major contributing factors solubility, passive permeability and metabolic (hepatic) clearance. These type of packages are ideal to explore or diagnose scaffold characteristics and define project flowcharts. They can be used repeatedly to test newly synthesized compounds and guide SAR. A number of compounds within a... 

---