Polyimide , with thin-film adhesives

The aminosilane coupling agent 3-aminopropyltriethoxysilane or y-amino-propyltriethoxy silane—also abbreviated as 3-APS, y-APS, APS or A1100 (Union Carbide)—is widely used to promote adhesion between polyimide thin films and mineral surfaces such as native-oxide silica, alumina and various glass ceramics [1, 2]. The structure of APS and the hydrolysis reaction sire shown in Fig. 1. Typically, dilute aqueous solutions of 0.1 vol% or approximately 0.080 wt % are employed to prime the mineral surface. The mechanism for the interaction of the bifunctional aminosilane with the mineral surface is the subject of much speculation, although it is conjectured by Linde and Gleason [3] that the amine end initially forms an electrostatic bond with surface hydroxyls. Subsequently, possibly as the result of elevated temperatures, the silanol end of the molecule proceeds to form a siloxane-like bond with the surface and the amine... 

As an approach to a better understanding of adhesion mechanisms between polyimide and copper, we have studied the interaction between a set of model molecules for a polyimide and vapor deposited polycrystalline copper. Thin films and adsorbates of benzene, phthalimide, methyl-phthalimide, benzene-phthalimide, and malonamid, which are representative of separate parts of the polyimide repeat unit, were deposited in situ on clean copper and examined by means of X-ray and Ultraviolet photoelectron spectroscopy (XPS and UPS). In contrast to the previously observed bonding to the carbonyl oxygen in polyimide, as Cu is deposited on polyimide, our results show that most of these polyimide model molecules bond to Cu, through electron transfer, with the imide nitrogen atom as the primary reaction site. 

PI(3,3 /4, 4 -ODPA/4,4 -ODA) was the smallest, as shown in the polyimides from BPDA and E was maintained at 10 Pa at 400°C as a result of crystallization. The E values of PI(2,3,3, 4 -ODPA/ 4,4 -ODA) and PI(2,2,3, 3 -ODPA/4,4 -ODA) decreased drastically at the Tg, and showed high thermoplasticity. PI(2,3,3, 4 -ODPA/ 4,4 -ODA) could be prepared as thin film because of its high thermoplasticity [43, 45]. As the thin film maintained high strength even after molten adhesion, PI(2,3,3, 4 -ODPA/4,4 -ODA) was used with APICAL AH ( Kapton-type polyimide) as the thin film on the Small Solar Power Sail Demonstrator "IKAROS". Wholly aromatic polyimides without aliphatic moietes have electron-beam-resistant and proton-beam-resistant characteristics in space environments. 

Most of those systems were using (thin film) Ag/AgCl elements, which are not free from problems in manufacturing (e.g. related to poor adhesion of silver to glass/silicone) leading to poor potential stability [8]. Improvements proposed [8] included application of intermediate polyimide layer instead of previously applied metal ones and special formation of AgCl layer on top of silver film. Thus obtained sensors were characterized with increased stability of potentials in KCl (up to 8 h) as well as in interferent (KI or K2S) solutions [8]. 

Figure 27 Measurement of adhesion by the peel test method using thin film specimens coated on silicon wafers and cured at 350-400°C. (A) A 1 cm wide strip is cut in the polyimide film. (B) The wafer (a) is cut and broken perpendicularly to the film (b). (C) One end of the specimen is fixed with a clip (d) into the upper jig (c) of an Instron testing machine. The other part lies on a mobile carrier (e) designed to maintain a 90° peeling by means of pulleys (f) and counterweight (g).

Adhesion of copper films to PMDA/ODA polyimide was determined by peel tests conducted on samples that were prepared by vapor-depositing a thin layer of copper onto the polyimide and then building the thickness of the metal layer to about 18 p,m by electrodeposition of copper. Results of the adhesion measurements correlated well with substrate pretreatment. When the substrate... 

Fabrics coated with FEP and PFA can be laminated and heat-sealed into protective garments, canopies, etc. FEP-coated polyimide films are used in electronics and as a wire tape. FEP-based anticorrosion coatings are used in the chemical industry and as chemical barriers.18 A thin coating of FEP or PFA can be used as a hot melt adhesive for a variety of substrates, including PTFE-coated fabrics and laminates. 

Adhesive characteristics of thin SPI-100 films could not be measured directly because adhesive forces are generally larger than cohesive forces. To obtain some information on adhesion values, thin high molecular weight SPI-100 films on substrates were overcoated with about. 1 mm of a commercially available polyimide (Product A) to provide greater cohesive strength than can be obtained with SPI-100 alone. The combined layers were then pulled in an Instron tester giving the results shown in Table II which also includes the values for commercial products A and B. 

Kreuz and Zytkus l reported the corona treatment of FEP under an atmosphere of acetone (<5% to 40% by volume in nitrogen) which had the advantage over the previous atmospheric compounds of producing a film that did not block in roll form. Treated FEP could be printed and marked with inks, was heat-sealable, and adhered well to metals. Adhesion of FEP film (25 pm thick) to metal was accomplished by first laminating it to a thin polyimide... 

---