Conformal coating/film

Uses Conformal coating film providing physical and moisture banter for electronic devices, optical assemblies, temporary conformable gaskets and seals... 

Impreg na.tion Coa.ting. Impregnation coating is performed by saturation of the component with a low viscosity resia a thin film is coated on the component surface. This process is usually used with a cavity-filling or conformal coating process. 

Conformal coatings. Deposition of a thin film that nniformly coats all exposed parts of a three-dimensional strnctnre is known as conformal film growth. Conformality is a common requirement for dielectric films. Penetration and uniform coverage of all topography and interstices are vital and depend upon low viscosity, as well as low surface and interfacial energies. Fluoropolymer in supercritical solution might provide die required characteristics. 

The surface of the polyimide film of was observed by SEM to be as flat as that of The multilayer film of was prepared on a silicon wafer which contained evaporated aluminum lines in order to examine the coating ability of the present LB films. Figure 3(a) exhibits the mechanical stylus probe (Talystep) pattern of aluminum lines (30 nm high and 2000 nm wide) and (b) shows the lines after 120 layers of were deposited. Since the depth was observed as 30 nm in both cases, it is concluded that the multilayer film can conformally coat the uneven surface. This feature can be directly observed in the photographs of Figure 4 where a 60 layer film of is coated on an aluminum line (200 nm of high and 2000 nm wide). 

Perhaps the greatest disadvantage of CSD is the difficulty in depositing ultrathin films (thickness <30 nm). While the possibility has been demonstrated in selected systems, the method is not usually viewed as amenable to that thickness requirement. Another disadvantage of CSD is the fact that three-dimensioanl structures with high aspect ratios cannot be conformally coated. Lastly, while epitaxial films have been prepared by the method, ° generally the films produced are polycrystalline and often not oriented. 

An interesting alternative to pnrely chemical conversion methods is electrodeposition, which also allows conformal coatings to be obtained. So far, however, only somewhat shallower strnctnres have been coated truly conformally, while deep strnctnres, such as those of nanoporous films, are usually only coated close to the top surface. Figure 6.10 shows a thin CdTe layer deposited on a microporous Ti02 substrate (Ernst et al, 2003). As is apparent, some smoothing of surface features occurs in the deposition process. 

We present an XPS study of the interfaces P(VDF-TrFE)/Al and P(VDF-TrFE)/PEDOT PSS. As copolymer, we used P(VDF-TrFE) in a molar ratio of 70 30. The material was delivered as film from Piezotech SA, France. As solvent for spin coating, we used 2-butanone. We prepared different concentrations (as wt% P(VDF-TrFE) in 2-butanone) to investigate the dependence on layer thickness. After spin-coating at 6000 rpm, the film was annealed at 135 °C for 2 h to improve the crystallinity of the aXX-trans conformation, the so called P-phase [21]. The thickness of the spin-coated film was measured using a Taylor Hobson (Talystep) profilometer. 

Mechanical Tensile Properties, measured according to ASTM D638 on 3-mil thick cured films of the conformal coating, are modulus of 1750 psi, tensile of 2000 psi, and elongation-at-failure of 285%. 

Flexibility was determined on 2-mil thick films of the cured conformal coating on 0.23-mm thick aluminum sheets by bending over a 1/8 in mandrel according to Fed. Std. 141, Method 6221. The film showed no cracking or loss of adhesion at the bend. 

Volume Resistivity was determined on cured films of the conformal coating in accordance with ASTM D257 and found to be 3.5 x 10 ohm-cm at 23°C and 50% relative humidity. 

Conformal Coatings. To protect printed circuitry and electronic devices from contaminants such as moisture, particulates, and fumes, they are covered with thin films of polymers. These polymers may be applied as "all solids" formulations or as solvent-containing systems, or, as in a special case, by polymerization of a vapor deposited monomer. 

The plasma-assisted shrink techniques (e.g., MOTIF ) use plasma to deposit a thin film that conformally coats contact holes and spaces printed in resists, which on dry etching result in smaller contact holes and spaces. In the remainder of this section, we provide a more detailed treatment of the postexposure-hased singlelayer exposure techniques employed in advanced resist processing. 

The outer cover/insulator must be a tough, soil resistant, weather resistant and electrically insulating layer. It may be a flexible or conforming plastic film or a coating applied from solution. As a front layer, it is desirable that it act as a UV screen for the pottant while it must at the same time be >90% transparent to wavelengths from 0.4 to 1.1 microns. It must form stable bonds to the pottant and to other module materials to which it seals. 

While most of these films are clearly low-modulus materials, they possess properties useful for such radiation-cure coating applications as conformal coatings, electronic encapsulent gels, or fiber optic coatings, particularly where such applications demand silicones broad operational temperature range,... 

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