Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-07-16
2001-04-10
Woodward, Ana (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S506000, C524S507000, C525S180000, C525S183000, C428S473500
Reexamination Certificate
active
06214923
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a polyimide-based composite formed using a precursor comprising a polyimide component and another polymer component, to electronic parts employing the polyimide-based composite and to a polyimide-based aqueous dispersion prepared by dispersing a precursor comprising a polyimide component and another polymer component in an aqueous medium.
1. Prior Art
Metal-clad laminates, which are prepared by impregnating a substrate such as glass fibers with a thermosetting resin solution and then laminating a prescribed number thereof which have been dried (prepregs), attaching copper foil or the like to one or both sides thereof and using heat contact bonding to harden the thermosetting resin, are used in printed wiring boards for industrial electronic instruments, OA devices, electrical appliances for public use, etc., and demand therefor has been increasing. In recent years, the trend toward smaller, lighter and more highly integrated electrical and electronic parts has accelerated efforts for greater stratification and higher density, and a strong demand has emerged for improvements in the adhesion, heat resistance and electrical properties of resin materials and the like used for such parts.
2. Problems to be Solved by the Invention
The most widely used thermosetting resins for electronic parts in the past have been epoxy resins which are mainly of the bisphenol A type. However, while such epoxy resins are superior in terms of the solubility of their uncured compositions in various solvents, their post-molding adhesion with metals such as copper foil and their chemical resistanc, heat resistance and electrical properties have been inadequate. In particular, the notable reduction in electrical properties after moist heat resistance testing has been an obstacle to their application for more highly integrated parts.
The use of polyimide resins has therefore been attempted in an effort to improve heat resistance.
Polyimide resins obtained by reaction between tetracarboxylic acid anhydrides and diamines have excellent electrical insulating properties, solvent resistance and mechanical properties and are used in many different fields including electric and electronic materials, aerospace technology, etc. However, in addition to problems such as poor solubility of their uncured forms in organic solvents making their impregnation into substrates difficult and the requirement for heat treatment at high temperature for curing reaction, they have generally been associated with other problems including low adhesion with various substrates, low water resistance and the tendency to cause deformation when coated onto metal thin films, because of the differences in thermal expansion coefficients.
On the other hand, with the recent downsizing and thickness and weight reduction of electrical products in recent years, there has been an increase in the use of flexible printed boards having metal foils attached to one or both sides of film-like resins, and metal-clad laminates (film laminates) for multilayer printed boards. There has also been an increased demand for electronic parts with resin layers formed using film-like resins. Currently, polyimide resins and polyester resins are primarily used as film-like resins. However, when a polyimide resin is used it is necessary to employ an adhesive at the interface with the copper foil, while polyester resins do not provide adequate heat resistance.
Moreover, increasing social awareness recently with regard to environmental safety in particular is creating a need to switch the media used from organic solvent systems to aqueous systems in the field of electronic materials as well. Yet, when it is attempted to supply a polyimide-based material with an aqueous medium the poor solubility of the polyimide in the aqueous medium makes it necessary to provide an aqueous dispersion form where the polyimide is dispersed in the aqueous medium. However, it has been very difficult to ensure sufficient storage stability for conventional polyimide-based aqueous dispersions.
SUMMARY OF THE INVENTION
Object of the Invention
It is an object of the present invention to provide a polyimide-based composite that can be suitably used for electronic parts and the like, possessing the original heat-resistant, electrical insulating and mechanical properties of a polyimide as well as excellent adhesion and water resistance, and electronic parts which employ the composite.
It is another object of the invention to provide a polyimide-based aqueous dispersion with excellent storage stability and electrodeposition properties, in which there is dispersed a precursor that forms a polyimide-based composite possessing the original heat-resistant, electrical insulating and mechanical properties of the polyimide.
Features of the Invention
According to the invention, the aforementioned objects of the invention are achieved by providing the following polyimide-based composites, electronic parts and polyimide-based aqueous dispersions.
[1] A polyimide-based composite formed using a precursor comprising (A) a polyimide component and (B) another polymer component,
the polyimide-based composite being characterized in that in the composite the polyimide forms a continuous phase and the other polymer forms a discontinuous phase, and the elastic modulus of the composite is less than 10 GPa.
[2] A polyimide-based composite according to [1] above, wherein the number-mean particle size of the discontinuous phase is in the range of 0.01-0.9 &mgr;m.
[3] A polyimide-based composite according to [1] above, wherein the glass transition temperature of the other polymer is in the range of −200° C. to 120° C.
[4] A polyimide-based composite according to [1] above, wherein the amount of the (A) polyimide component used is at least 5 wt % and less than 50 wt % with respect to the total amount of the polyimide-based composite.
[5] A polyimide-based composite according to [1] above, wherein the (A) polyimide component is at least one type selected from among polyimide-based polymers and polyamic acid,
the (B) other polymer component comprises an elastic polymer with a reactive group and an elastic modulus of 0.0001-0.5 GPa, and
the precursor is obtained by reacting the (A) polyimide component and the (B) other polymer component.
[6] A polyimide-based composite according to [1] above, which is formed using a polyimide-based aqueous dispersion obtained by dispersing the precursor in particle form in an aqueous medium.
[7] A polyimide-based composite according to [1] above, which is formed using an organic solvent solution of the precursor.
[8] A polyimide-based composite according to [1] above, wherein the (B) other polymer component is (B-1) a cationic polymer component, and which is formed using a polyimide-based aqueous dispersion obtained by dispersing the precursor in particle form in an aqueous medium in the presence of a polyacid.
[9] A polyimide-based composite according to [1] above, wherein the (B) other polymer component is (B-2) an anionic polymer component, and which is formed using a polyimide-based aqueous dispersion obtained by dispersing the precursor in particle form in an aqueous medium in the presence of a polyamine.
[10] A polyimide-based composite according to [1] above which forms a film.
[11] A polyimide-based composite according to [10] above, which is formed by electrodeposition of the precursor.
[12] An electronic part having a layer comprising a polyimide-based composite according to [1] above.
[13] A polyimide-based aqueous dispersion prepared by dispersing in particle form in an aqueous medium a precursor which forms a polyimide-based composite,
the polyimide-based aqueous dispersion being characterized in that the particles of the precursor include in the same particles (A) a polyimide c
Goto Hirofumi
Ito Nobuyuki
Yamada Takako
JSR Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Woodward Ana
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