Polyimide substrate

In a subsequent publication [68] the influence of the substrate on the self-assembly process was elucidated. The comparison of a polyimide substrate with a native oxide (Si( )A) covered wafer revealed that differences in interac-... 

Figure 12.12 Image of an organo-metallic palladium precursor solution that was deposited by the author on a flexible polyimide substrate via spin coating and thermally processed at 200 °C for 30 seconds.

Thin-fihn transistors have been fabricated by depositing 50 nm of CdS onto SiOz-covered n Si and evaporating two A1 elechodes (source and drain) onto the CdS [45]. Similar devices were also made using CdS deposited on polyimide substrates with three (source, drain, and gate) evaporated metal electrodes and various sputtered insulator layers for the gate electrode. 

Figure 15.24 shows the fabrication process of the optical filter on a fluorinated polyimide substrate. First, the low-thermal-expansion-coefficient PMDA/TFDB poly(amic acid) solution was spin-coated onto a Si substrate and baked. Then alternate TiO2 and SiO2 layers were formed on the polyimide film by ion-assisted deposition. The multilayered polyimide film was diced and peeled off from the Si substrate. In this way, thin optical filters on a fluorinated polyimide substrate are easily fabricated. 

The most common substrates used to deposit gold are glass [6,10,12] or various forms of quartz or fused silica [7,8,11,13,14], although an other polyimide substrate named Kapton HN [9] has been used. In many cases, adhesion of the deposited film to the substrate may be inherently poor. It is extremely desirable in such cases to deposit a thin layer of an intermediate material as titanium [6,8,12] or chromium [10,13] that has better adhesion to the substrate. 

A 0.125-mm-thick polyimide substrate named Kapton HN (Good-fellow), an epoxy resin (CW2400) obtained from RS Components and self-adhesive washers of 5 mm internal diameter (19.6 mm2 of internal area) are used to construct the working electrodes. 

The three-electrode potentiostatic system is schematised in Fig. 36.1. Working electrodes are made on 5 x 5 cm2 supports of 0.125-mm-thick polyimide substrate named Kapton HN (Goodfellow). The kapton slide is cleaned with ethanol and after drying, it is covered with gold by... 

To confront these difficult tasks, we have incorporated old and new solutions. For example, strong yet flexible Kapton polyimide substrates are promising, and the neutral-carrier type ion-selective membranes offer the advantage of using similar fabrication methods for sensors of different ions of interest. We are also working on the biocompatibility problems, and all new designs are subject to in vivo tests. 

Kapton polyimide has been widely used in the electronic industry because of its low dielectric constant, good mechanical properties and high thermal stability. Many applications require good adhesion between Kapton polyimide film and metal. Various processes to improve adhesion of metal to Kapton polyimide have been reported in the literature. DeAngelo et al., (D describe a process to form metal oxides on the surface of polyimide to improve adhesion. Other efforts to improve adhesion of a metal layer involve roughening of the surface of polyimide substrate by methods such as cathodic sputtering (2), chemical attack (2., 1), and reactive ion etching (1,4). 

For a number of years, polymers such as polyimide, have been subjected to widespread research, because of their increasing importance as dielectric materials for the fabrication of microelectronic devices (1). In particular, the adhesion of metal or polyimide films deposited on polyimide substrates and vice versa, is of considerable importance in most applications, and many studies ranging from adhesion testing to detailed spectroscopic analysis of interfaces have been reported previously (2,3.. 5.6). 

Fig. 22 Example NEXAFS data from an aligned PF2/6 film spin cast on rubbed PI. Parallel Geometry refers to E-field parallel to the rubbing direction. 0 is the angle between surface normal and electric field vector of the incident light in conjunction with the rubbing direction of the polyimide substrate. See [114] for details...

Ion-selective membrane -Inner solution Ag/AgCI film Polyimide substrate... 

Yamamoto et a. [60-62] and Kurata et al [63] prepared polythiophene layers by vacuum evaporation. To ensure the deposition of poly- and not oligothiophenes, they removed low molecular weight material ( < 15-17) by Soxhlet extraction with CHCI3, The evaporated material is assumed to consist of poly-thiophene with a molecular weight of about 1500-2000 and 20-25 thiophene units. The X-ray and electron diffraction data of Yamamoto et al. point to a (partially) crystalline film with the polymer axes oriented perpendicular to a carbon or gold substrate plane if sub = 423 K. At lower substrate temperatures, the orientation and crystallinity are worse. This behaviour is not only true for the first deposited layer, but at least up to 10 layers, i.e, 100 nm. On polyimide substrates, however, the molecules lie on the substrate plane and orient along the rubbing direction of the polyimide [61]. 

Anno, H., Nishinaka, T., Hokazono, M., Oshima, N., Toshima, N., 2015. Thermoelectric power-generation characteristics of PEDOT PSS thin-hhn devices with different thicknesses on polyimide substrates. 

Fig. 5.3. Azimuthal ( ) dependencies of the SHG intensity for an 8CB monolayer adsorbed on a rubbed polyimide substrate. The first index in the label designates the polarization of the fundamental and the second the polarization of the SHG beam. Solid lines are fits according to reference [15] where s- and -p indicate polarisation directions perpendicular and parallel to the optical plane respectively.

FIGURE 17.26 2D grazing-incidence XRD patterns recorded by Knaapila et al. 1322] of an intermediate molecular weight PF2/6 polymer thin film thermally annealed on top of an oriented polyimide substrate. Patterns are (a) the equatorial (hkO) and (b) the (hOC) planes. The dotted lines highlight a few reflection planes of the type I crystal orientations. The black and white indices corresponds to the types I and II, respectively. These two orientations are shown schematically on top. (Reprinted from Knaapila, M., et al.. Macromolecules, 38, 2744,2005. With permission.)... 

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