Adhesion polyimides

High adhesive polyimide films were prepared by Kaneshiro et al. (2) consisting of 2,2-bisaminophenoxylphenylpropane and paraphenylene diamine, pyro-mellitic dianhydride, and 3,3, 4,4 -benzophenone tetracarboxylic dianhydride. 

Keywords Aminosilane adhesion polyimide ceramic PMDA-ODA silica interface coupling. 

Adhesive Polyimide Resin, Film and Paste, High Temperature Resistant, 315°C or 600°F... 

Many choices of conductor materials are available for lamination-type adhesiveless laminates. Due to the special combination of conductor materials with stainless steel and copper alloy foils, this noaterial has a variety of uses in multilayer rigid/flexible aerospace applications and in wireless suspension of disk drives. Generally, the adhesive polyimide is difficult to etch using standard alkaline etching solutions, so strong chemistry or a physical process such as plasma etching is required for the process. 

Polyimides became popular for die-bonding adhesives because they are cleaner (in terms of ionic contaminants) than equivalent epoxy products. The market at present, however, is dominated by high-purity epoxy adhesives. Polyimides are always applied from solvent solution and require higher curing temperatures than epoxies. They are stable to higher temperatures. Solvent-borne thermoplastics pastes (or cast-film preforms) have been used for some lower reliability die-attachment applications. 

Compared with epoxy adhesives, polyimides share a very small part of the global market, limited to military, aerospace, and geothermal applications requiring long-term stability at elevated temperatures. Owing to their aromatic heterocyclic structure, virtually all polyimides are stable at 300 °C. When loaded with inorganic particles such as alumina, silica, silicon nitride, or aluminum, the thermal stability is still better. By contrast, some metals used in the composition of conductive adhesives, in particular silver and nickel, dramatically decrease the thermal resistance. This means that the adhesive strength of most polyimides is excellent at 200 °C,... 

Grunze M, Unertl W N, Ganara]an S and French J 1988 Chemistry of adhesion at the polyimide-metal interface Mater. Res. Soc. Symp. Proc. 108 189... 

Miscellaneous Applications. Ben2otrifluoride derivatives have been incorporated into polymers for different appHcations. 2,4-Dichloroben2otrifluoride or 2,3,5,6-tetrafluoroben2otrifluoride [651-80-9] have been condensed with bisphenol A [80-05-7] to give ben2otrifluoride aryl ether semipermeable gas membranes (336,337). 3,5-Diaminoben2otrifluoride [368-53-6] and aromatic dianhydrides form polyimide resins for high temperature composites (qv) and adhesives (qv), as well as in the electronics industry (338,339). 

Polyimides (PI) were among the eadiest candidates in the field of thermally stable polymers. In addition to high temperature property retention, these materials also exhibit chemical resistance and relative ease of synthesis and use. This has led to numerous innovations in the chemistry of synthesis and cure mechanisms, stmcture variations, and ultimately products and appHcations. Polyimides (qv) are available as films, fibers, enamels or varnishes, adhesives, matrix resins for composites, and mol ding powders. They are used in numerous commercial and military aircraft as stmctural composites, eg, over a ton of polyimide film is presently used on the NASA shuttle orbiter. Work continues on these materials, including the more recent electronic apphcations. 

Polyimides of 6FDA and aUphatic diamines with good low temperature processkig and low moisture swelling are known to be useful as hot-melt adhesives (109). Aluminum strips bonded by this polymer (177°C/172 kPa (25 psi) for 15 min) exhibited a lap-shear strength of 53 MPa (7690 psi) at room temperature and 35 MPa (5090 psi) at 100°C. The heat- and moisture-resistant 6F-containing Pis useful ki electronic devices are prepared from... 

Printed circuit boards manufacture is aided by the use of KMnO. Alkaline permanganate solution is used to remove resin smeared on the interior hole wall of multilayered printed circuit boards. Additionally the hole wall is etched, resulting in a surface with excellent adhesion characteristics, for electrodeless copper (250). The alkaline permanganate etchback system containing >60 g/L KMnO and 40-80 g/L NaOH at 70—80°C, is effective for difunctional, tetrafiinctional, and polyimide resin substrates, where the level of etchback is direcdy proportional to the immersion time (10—20 min) (251). 

Epoxies are the most commonly used adhesives (qv). Silver and gold are sometimes added to an epoxy to improve its thermal conductivity. Polyimide, also used as an adhesive, has low shrinkage as well as low viscosity and can be cured at 180°C its primary drawback is a tendency to absorb water, as much as 6% by weight. 

Intractable, rigid, rod-like polyimides have been synthesized by way of polyisoimides (50). A large number of high molecular weight polyisoimides were also synthesized and characterized for the purpose of preparing semiinterpenetrating (SIPN) polyimide matrices and adhesives (51—53). 

A number of polymeric coatings, primarily polyimides, epoxies, and sHicones, are used as adhesives and ia other aspects of packagiag, as well as for final eacapsulatioa and protection of the iategrated circuit. 

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... 

The most common aerospace adhesives include nitrile epoxy systems, epoxy polyamides, epoxy phenolics, and various unmodified epoxies [18]. Polyimides... 

Bis-maleimide resins composed of BMI and diamines have been reported in the early 1960s in the patent literature. Since that time, a number of patents have appeared describing improvements in their properties and uses [3]. Although many bis-maleimide resins are commercially developed, relatively few reports of their use as adhesives are to be found in scientific journals [4-10]. Improvements of maleimide resins are mirrored in the improvements of thermosetting polyimides. For example, the method of in situ polymerization of monomer reactants (PMR method) was developed [6]. 

St. Clair et. al. investigated a series of maleimide and nadimide terminated polyimides and developed LARC-13 [8,9]. Changing the terminal group from maleimide to nadimide, the value of the lap shear strength of a titanium lap shear joint increased from 7 to 19 MPa [9]. They also added an elastomeric component to the adhesive formulation. The introduction of 15 wt% of a rubbery component, ATBN (amine terminated butadiene nitrile polymer) and ADMS (aniline terminated polydimethyl siloxane) enhanced the adhesive properties as follows 19 MPa to 25 MPa (ATBN) titanium T-peel strength 0.2 kN/m to 1.4... 

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