Parylene plastic

Parylene The melting point of these film and coating plastics ranges from 290 to 400° C (554 to 752°F), and Tg from 60 to 100°C (14 to 212°F). Their cryogenic performances are excellent. Physical properties are unaffected by thermal cycles from 2°K to room temperature. Good thermal endurance in air, absence... 

Parylene C plastic microstructures were formed by an additive process. A sacrificial layer of photoresist was used to define the channel regions. The structures were supported on a PC substrate [139,231] or Si substrate [231,691]. 

This polymer is of interest in that extremely thin films can be deposited when the vapour is condensed onto a cooled surface. Parylene film has been shown to offer a reasonable barrier to water vapour and a good barrier to essential oils. For example, LDPE coated with a thin film of parylene has substantially increased the retention of lemon oil which would otherwise have been lost rapidly. It also withstands high temperatures of around 220°C. It is, however, an expensive plastic and has been used as a coating onto rubber. 

FIGURE 6.3.15 (a) The cross-sectional illustration of organic transistors on plastic films with polyimide gate dielectric layers and parylene passivation layers. Transfer characteristics with bending radii of = 20, 10, 5, 2, 1, and 0.5 mm these correspond to inward (b) and outward (c) bending strains. A Vq is swept from 20 to -40 V with application of = 0 V. 

Perhaps the simplest strategy is to laminate a plastic sheet on top of the transistors with a suitable adhesive [99]. It is also possible to coat OFETs with a layer of parylene, teflon, or other compatible polymer and optionally seal the devices using a metal vapor barrier layer (e.g. [100]). Heating many OFET materials for dehydration in an inert ambient is also possible, and may be important depending on the material s reactivity with water [101]. 

Xie et al. [5] used vapor-deposited parylene-C to fabricate ESI tips on silicon microfluidic devices, enabling integrated liquid chromatography with mass spectrometry detection with comparable performance to conventional techniques. The drawback for these devices is the complexity involved in their fabrication, requiring many sequential photolithography steps in a clean room. However, parylene is a material with high chemical resistance and may be a useful choice for the construction of nanospray tips in future work. For example, Kameoka et al. [6] constmcted a nanospray tip comprising a parylene film sandwiched between two plastic plates (Fig. 2b). This device is relatively easy to... 

Unlike most plastics, parylene is not produced and sold as a polymer. It is not practical to melt, extrude, mold, or calender as with other thermoplastics. Nor can it be applied from solvent systems, because it is insoluble in conventional solvents. The parylene process starts with a dimer rather than a polymer and polymerizes on the surface of an object. To achieve this, the dimer must first go through a two-step heating process. The solid dimer is converted to a reactive vapor of the monomer. When passed over room temperature objects, the vapor will rapidly coat them with polymer. The coating thickness is very uniform and controlled simply by regulating the amount of dimer that is vaporized. 

Mechanical Properties. Many of the mechanical properties of the parylenes are similar to those of other conventional plastics. The values in Table 4 are typical of those quoted for the parylenes, but in any particular case can vary with aging or annealing. In an outstanding instance of this effect, the 200% elongation quoted for Parylene C is the value commonly observed on the freshly... 

Figure 6-61. Heat-resistance properties of resins retaining 50 percent of properties obtainable at room temperature with resin exposure and testing at elevated temperature. Zone 1 Acrylics, cellulose esters, LDPE, PS, PVC, SAN, SBR, UF, etc. Zone 2 Acetals, ABS, chlorinated polyether, ethyl cellulose, EVA, ionomer, PA, PC, HDPE, PET, PP, PVC, PUR, etc. Zone 3 PCTFE, PVDF, etc. Zone 4 Alkyds, fluorinated ethylene-propylene, MF, polysulfone, etc. Zone 5 TS acrylic, DAP, epoxy, PF, TS polyester, PTFE, etc. Zone 6 Parylene, polybenzimidazole, silicone, etc. Zone 7 PAI, PI, etc. Zone 8 Plastics in R D etc. Since plastics compounding is rather extensive, certain basic resins can be modified to meet different heat-resistance properties.

Gorham, W. F. Parylene Polymers. In Modem Plastics Encyclopedia, pp. 230-34. New York McGraw-Hill, 1969. 

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