| 摘要 |
<p>#CMT# #/CMT# Heat-activable adhesive tape for producing and reprocessing flexible circuit boards has an adhesive composition containing, at least, (a) an acid- or acid anhydride-modified acrylonitrile-butadiene copolymer and (b) an epoxide resin such that the a/b weight ratio is over 1.5 and no additional polymer hardener is used. #CMT#USE : #/CMT# The heat-activable adhesive tape is used for bonding flexible printed circuit boards and for bonding to polyimide (all claimed). #CMT#ADVANTAGE : #/CMT# Epoxide resins can be flexibilized with elastomer chains, but the chains are very short and their effect is limited. If elastomers are added, i.e. not chemically crosslinked, they must have long enough chains to ensure high viscosity at high temperature, which often limits their solubility, but are difficult to apply by the hot melt process without premature crosslinking. The present composition can be activated and cured by heat, flows well on the substrate when heated, has good adhesion to polyimide and is soluble in organic solvents in the uncured state. #CMT#POLYMERS : #/CMT# Preferred Composition: The nitrile rubber is at least partly hydrogenated and its acrylonitrile content is 15-50 wt.%. The tape may contain more than one epoxide resin and also contain tackifying resin, accelerator, dye, carbon black and/or metal powder and/or other elastomers. It is cured at temperatures above 150[deg]C. #CMT#EXAMPLE : #/CMT# For sample (A) 80 parts weight (pw) Nipol NX 775 (RTM; nitrile rubber with 26 wt.% acrylonitrile and 7 wt.% acid modification) and 20 pw Bakelite EPR 166 (RTM; epoxide resin; epoxide equivalent 184) were dissolved in butanone. The solution was applied to paper with a release coat to give a 25 mu m thick (dry) coating. Control (B) used a solution of 75 pw Breon N41H80 (RTM; nitrile rubber; with an acryloniltrile content of 41 wt.% and Mooney viscosity ML 1 + 4 at 100[deg]C of 72-88) and 25 pw same epoxide resin in butanone. To bond flexible printed circuit boards (FPCB), a strip of the adhesive tape was laminated to the polyimide film of the FPCB laminate of polyimide/copper foil at 100[deg]C (using a strip somewhat shorter than the FPCB for later gripping), then a second polyimide film of another FPCB was bonded to the tape and the entire laminate was pressed at 200[deg]C and 1.3 MPa. The T-peel strength of the laminate (180[deg] peel at 50 mm/minute, 20[deg]C and 50% relative humidity) was (A) 12.6, (B) 2.7 N/cm. The temperature resistance was determined by the static T-peel test at 70[deg]C, using a 500 g load attached to one side. The rate of peel was (A) 5, (B) over 50 mm/hour.</p> |
