Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-04-07
2002-12-10
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C525S107000, C525S123000, C525S132000, C525S165000, C525S180000, C525S332100
Reexamination Certificate
active
06492443
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a norbornene polymer composition comprising a norbornene polymer and a thermosetting resin as essential components, moldings formed from the composition, prepregs with a reinforcing base material such as a glass cloth impregnated with the composition, laminates with such prepregs laminated on each other, laminates with a film formed of the composition on a metal layer.
The norbornene polymer composition according to the present invention is excellent in electrical properties such as dielectric constant and dielectric loss tangent and also in peel strength (adhesion property) to metal foils as electrical conductors.
BACKGROUND ART
With the advancement of techniques, there are strong demands for achieving the speeding up and high reliability of arithmetic processing, and high-density packaging in circuits mounted in precision apparatus such as electronic computers and communication machines, and so it is advanced to provide circuit boards with high performance such as multi-layer structure, high precision and minute processing.
Such a circuit board is produced by impregnating a reinforcing base material, for example, a glass cloth with a resin varnish, drying the varnish to form a sheet (prepreg) in a semi-cured state, laying up a copper foil or outer copper-clad sheet, the prepreg, inner copper-clad sheet, and the like in that order between mirror plates and then hot-pressing the resultant laminate to completely cure the resin. As a resin material, there has heretofore been used a phenol resin, epoxy resin, polyimide resin, fluororesin, polybutadiene resin or the like.
However, the dielectric constant and dielectric loss tangent of thermosetting resins such as the phenol resin, epoxy resin and polyimide resin are generally as high as at least 4.0 and at least 0.01, respectively, and so their electrical properties are insufficient. Therefore, circuit boards making use of these thermosetting resins have been difficult to achieve the speeding up and high reliability of arithmetic processing.
On the other hand, norbornene polymers having repeating units derived from a norbornene monomer are known to be suitable for use as various kinds of moldings, sealing materials for electronic parts, insulating materials and the like, since they have various properties such as low moisture-absorption property and excellent dielectric properties and scarcely contain impurities. For example, it has been proposed to use a hydrogenated product of an addition copolymer of tetracyclododecene and ethylene, or a ring-opening polymer of methylmethoxy-carbonyltetracyclododecene as an insulating material for circuit boards or a sealing material for electronic parts. In particular, norbornene (co)polymers obtained by addition polymerizing a norbornene monomer have excellent heat resistance and hence are suitable for use as sealing materials, insulating materials and the like for electronic parts.
However, the norbornene polymers have a demerit that their adhesion properties to metals are insufficient. Therefore, they have involved a problem that a film formed of the norbornene polymer separates from a metal layer or cracks.
It has heretofore been proposed to produce a circuit board excellent in electrical properties such as dielectric constant and dielectric loss tangent by crosslinking a thermoplastic norbornene polymer with an organic peroxide. For example, Japanese Patent Application Laid-Open No. 34924/1987 discloses a process for obtaining a crosslinked sheet, comprising kneading an norbornene copolymer obtained by addition polymerization of a norbornene type cyclic olefin and ethylene, and a crosslinking aid, grinding the resultant mixture, impregnating the ground mixture with a solution of an organic peroxide, removing the solution and then press molding it.
Japanese Patent Application Laid-Open No. 248164/1994 discloses a process in which a norbornene resin, an organic peroxide, a crosslinking aid and a flame retardant are uniformly dispersed in a solvent, and the solvent is then removed to crosslinking the resin by heating. This publication discloses Examples wherein laminated sheets and prepregs were produced by this process.
However, these conventional processes have involved a problem that even when a metal foil such as a copper foil is laminated on the resultant sheet or prepreg, peel strength (adhesion property) between the sheet or prepreg and the metal foil is insufficient.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a norbornene polymer composition excellent in electrical properties such as dielectric constant and dielectric loss tangent and also in adhesion property to metals.
Another object of the present invention is to provide various kinds of moldings, sheets, films, prepregs, and laminates suitable for use as circuit boards and the like using the norbornene polymer composition having such excellent properties.
The present inventors have carried out an extensive investigation with a view toward overcoming the above-described problems involved in the prior art. As a result, it has been found that when a norbornene polymer composition obtained by blending a specific amount of a thermosetting resin with a thermoplastic norbornene polymer is used to crosslink the composition, moldings, prepregs, laminates and the like excellent in electrical properties such as dielectric constant and dielectric loss tangent and adhesion property to metals are obtained.
When a modified norbornene polymer obtained by introducing a polar group such as an epoxy, carboxyl or hydroxyl group into an unmodified norbornene polymer by, for example, a graft-modifying process is used as the norbornene polymer, its compatibility with the thermosetting resin and the adhesion property of the resulting composition to metals can be improved. When a polymer having a high glass transition temperature is used as the norbornene polymer, the heat resistance, such as soldering heat resistance, of the resulting composition can be improved. The present invention has been led to completion on the basis of these findings.
According to the present invention, there is thus provided a norbornene resin composition comprising 100 parts by weight of a thermoplastic norbornene polymer and 1 to 150 parts by weight of a thermosetting resin.
According to the present invention, there are also provided (1) a molding formed from such a composition, (2) a prepreg with a reinforcing base material impregnated with the composition, (3) a laminate obtained by laminating sheet-like moldings and/or prepregs obtained with the composition on one another and crosslinking them, (4) a laminate with a film formed of the composition laminated on a metal layer, and the like.
BEST MODE FOR CARRYING OUT THE INVENTION
Thermoplastic Norbornene Polymer:
The thermoplastic norbornene polymer useful in the practice of the present invention is a publicly known polymer disclosed in Japanese Patent Application Laid-Open No. 14882/1991, Japanese Patent Application Laid-Open No. 122137/1991, or the like. Specific examples thereof include hydrogenated products of ring-opening polymers of a norbornene monomer, addition polymers of a norbornene monomer, addition polymers of a norbornene monomer and another monomer (for example, olefin), and modified products of these polymers. As the modified products, are preferred those obtained by introducing a polar group such as an epoxy, carboxyl or hydroxyl group into these norbornene polymers, from the viewpoints of their compatibility with thermosetting resins and the adhesion property of the resulting compositions to metals.
(1) Monomer:
Norbornene monomer are publicly known compounds disclosed in the above-described publications and Japanese Patent Application Laid-Open Nos. 227424/1990 and 276842/1990, etc. Examples thereof include polycyclic hydrocarbons having a norbornene structure; alkyl-, alkenyl-, alkylidene- or aromatic-substituted derivatives thereof; derivatives substituted by a polar group such as a halogen, hydroxyl group, ester group
Kodemura Junji
Tsunogae Yasuo
Wakizaka Yasuhiro
Dinsmore & Shohl LLP
Mulcahy Peter D.
Nippon Zeon Co. Ltd.
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