Polyimide capacitor

Figure 5. Relative capacitance of a polyimide capacitor versus moisture. (Reproduced with permission from Ref. 12. Copyright 1985 The Metallurgical Society.)...

Hence, Tct is seen to increase with pore density and pore radius. However, a problem appears at a porous substrate when thin films are to be deposited during metallization to form interconnections, thin-film capacitors, etc.335 Sputtered material falls deep into the pores, which affects the planarity of the deposited layer and the electrical resistivity of the oxide layer underneath.335 To cope with this effect, the porous oxide should be padded by inorganic (A1203 and Si02) or organic (polyimide, negative photoresist) layers. 

Dielectric enrichment, 23 109 Dielectric materials, polyimide, 20 278 in multilayer capacitors, 11 102 Dielectric measurements, 10 17, 425-426 Dielectric overlayers, in compound... 

Figure 11 Description of dual microcoil probe. (A) Two coils wrapped around a polyimide sleeve (B) Dual-coil probe mounted on top of the probe head. (C) Schematic of balanced tank circuit used for each microcoil. Coil (L), series capacitors (Cs) 3.3 pF, tuning capacitors (CT) 0.6-4.5 pF, matching capacitor (CM) 0.6-4.5 pF, bridge capacitors (CB) 24 pF. (Reproduced with permission from Ref. 41. Copyright 2002 American Chemical Society.)...

Metal thin films deposited on polymers are widely used in various industrial domains such as microelectronics (capacitors), magnetic recording, packaging, etc. Despite much attention that has been paid in the recent literature on the adhesive properties of metals films on polyimide (PI)( 1 - 5 ) and polyethyleneterephtalate (PET)((L) it appears that a better knowledge of the metal/polymer interface is needed. In this paper we focus ourself on the relationship between the adhesion and the structural properties of the aluminum films evaporated (or sputtered) on commercial bi-axially stretched PET (Du Pont de Nemours (Luxembourg) S.A.). A variety of treatment (corona, fluorine,etc.) have been applied in order to improve the adhesion of the metallic layer to the polymer. The crystallographic... 

Polyimides are high-performance polymers, mainly used as films and as substrates for flexible printed circuits, bar code labels, and transformer and capacitor insulation. The rigid structure is responsible for a Tg greater than 300 °C. Since Kapton is flexible, lightweight and withstands very low and very high temperatures, it is an important aerospace material. Potential uses include as a thin film absorber for solar cells114. 

The fabrication of humidity sensors on silicon chips has recently become possible using 1C. production technology [37, 49], This realizes a small, low cost humidity sensor, and makes it possible to integrate the humidity sensor with other sensors or signal-handling circuitry on the same chip. A new integrated temperature and humidity sensor developed by Yamamoto et al., consists of a polymer capacitor on the p-n diode of a temperature sensor [50] as illustrated in Figure 20-33. A thin film of polyimide is used as the moisture-sensitive material... 

The principle of the Thomson polymer IR sensor is represented by Fig. 14 and Fig. 15. The P(VF2 TrFE) copolymer constitues the pyroelectric layer (5-10 pm), the insulation layer is a polyimide (10 pm). The upper electrode is also the infrared absorber and is made in aluminium or gold black. The lower level is the CCD level which constitues the second electrode. The polarisation of the polymer is realized by application of 100 V/pm between the two electrodes of the pyroelectric capacitor. 

DuPont polyimide separators are thin, offer lower ionic resistance when filled with electrolyte, are made with higher-temperature stable materials that offer very low shrinkage at high temperatures, and offer very good wettability with typical organic electrolytes used in batteries and capacitor applications. 

Many polymer films have been examined as capacitor dielectrics but those principally used are polyethylene terephthalate, polystyrene, polycarbonate, polytetrafluoroethylene, polyimides and polypara-xylylene. A number of these materials are more familiar by their trade names ... 

For the production of capacitors that must function at elevated temperatures, a dielectric of polytetrafluoroethylene (PTFE) or a polyimide (PI) may be selected. 

Aromatic polyimides have been the subject of much attention as a material for use in the electronics and other leading-edge industries. Films are used in flexible printed circuit boards, as wire and cable wrap, motor-slot liners, transformers and capacitors. Molded parts are used in applications requiring resistance to thermally harsh environments such as automotive transmission parts, thermal and electrical insulators, valve seats, rotary seal rings, thrust washers and discs, bushings. 

---