Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
1999-04-29
2002-10-29
Mullis, Jeffrey (Department: 1711)
Stock material or miscellaneous articles
Composite
Of metal
C428S461000, C428S462000, C524S504000, C525S242000, C525S263000, C525S284000, C525S285000, C525S286000
Reexamination Certificate
active
06472082
ABSTRACT:
TECHNICAL FIELD
The present invention relates to modified thermoplastic norbornene polymers obtained by graft-modifying a ring-opening polymer of a norbornene monomer or a hydrogenated product thereof with an unsaturated epoxy compound or unsaturated carboxylic compound, and a production process thereof, and more particularly to modified thermoplastic norbornene polymers which are excellent in electrical properties such as dielectric constant, adhesion property to other materials such as metals (metal foils, metallic wirings, etc.) and silicon wafers, heat resistance, moisture resistance, etc., can be prepared into high-concentration solutions, and are also excellent in the ability to uniformly disperse various kinds of compounding additives in such a solution, and a production process thereof.
The modified thermoplastic norbornene polymers according to the present invention are suitable for use in electrical and electronic fields as impregnating resins for prepregs, sheets, interlayer insulating films and the like making good use of these excellent various properties
BACKGROUND ART
With the rapid advancement of advanced information-oriented society in recent years, there is a strong demand for the speeding up of information processing and the miniaturization of apparatus or devices in a field of the electronic industry. In electronic parts used in electrical apparatus and electronic equipment, such as semiconductors, ICs, hybrid ICs, printed boards, display devices and display parts, insulating materials having a sufficiently low dielectric constant in a high-frequency region are required for purpose of realizing the speeding up and miniaturization in the high-frequency region. In order to ensure high reliability over a long period of time, insulating materials also excellent in heat resistance such as soldering heat resistance, and moisture resistance are also required. Further, the speeding up of information processing is pressed in a field of information processing apparatus such as computers and communication apparatus. In addition, their miniaturization and weight saving are required so as to be portable. In keeping with such requirements, it is strongly required of circuits installed in these apparatus to make circuit boards high performance such as multi-layer structure, high precision and minute processing.
In recent years, there has been developed a multi-chip module (MCM) for flip chip packaging, by which miniaturized and high-density packaging has been realized. In order to ensure high reliability over a long period of time, an insulating material used in an interlayer insulating film for this MCM is required to have, in addition to the above required properties, sufficient adhesion property to substrates such as silicon wafers, and conducting layers such as metal layers (metal foils, metallized films, etc.), since MCM is fabricated by laying many insulating layers and conductive layers on one another on a substrate such as a silicon wafer. In addition, since to be able to make a via diameter small by reduction in wiring pitch is require of MCM, it is required to impart photosensitivity to the insulating material in order to make minute processing possible.
As insulating materials for MCM, there have heretofore been investigated materials obtained by imparting photosensitivity to a polyimide resin or epoxy resin. However, the conventional photosensitive polyimide resins are insufficient in electrical properties such as dielectric constant in a high-frequency region and also in moisture resistance and hence have involved a drawback that it is difficult to cope with the achievement of high reliability over a long period of time. In the epoxy resins, it has been attempted to introduce a photosensitive group such as an allyl group therein to impart photosensitivity to the resins. However, such an attempt has involved a drawback that electrical properties. such as dielectric constant, of the resultant resins are deteriorated to a great extent, and their heat stability also become insufficient.
On the other hand, 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, an 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 of thermosetting resins such as the phenol resin, epoxy resin and polyimide resin is generally as high as at least 4.0, 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, circuit boards making use of thermoplastic resins such as the fluororesins and polybutadiene resins are poor in heat resistance and so may cause cracking and/or delamination in some cases upon soldering or the like. In addition, such resins have also been difficult to form a multi-layer structure due to their poor dimensional stability.
Accordingly, in recent years, it has been proposed to use thermoplastic norbornene resins as insulating materials.
For example, Japanese Patent Application Laid-Open No. 34924/1987 discloses a process comprising synthesizing a norbornene resin having an intrinsic viscosity [&eegr;] of 1.15 to 2.22 as measured at 135° C. in decalin by addition polymerization of a norbornene type cycloolefin and ethylene, kneading the norbornene resin 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 to crosslink the resin.
However, this process has involved problems that the process is complicated, and besides it is difficult to prepare a high-concentration solution of the norbornene resin, and the organic peroxide and other compounding additives are not uniformly dispersed. Accordingly, it is necessary to prepare a low-concentration solution in order to produce a prepreg using a solution of the resin obtained by this process. When the reinforcing base material is impregnated with the low-concentration solution, however, it takes a long time to dry the solution until it becomes tack-free at room temperature, and so the base material must be left at rest so as not to deform in the meantime. Therefore, this process involves a problem of poor productivity. In addition, various kinds of compounding additives must be added according to various uses. However, such compounding additives cannot be uniformly dispersed in the resin solution due to the high viscosity of the solution, and there is also an disadvantage that the resin solution and the compounding additives undergo phase separation from each other according to the kinds and compounding amounts of the compounding additives used. If the reinforcing base material is impregnated with the solution phase-separated into 2 phases, any prepreg in which the individual components are uniformly dispersed cannot be obtained. In addition, if a copper foil is laminated on the thus-obtained molding such as the prepreg, the resultant laminate has no sufficient peel strength and hence involves a problem of durability.
Japanese Patent Application Laid-Open No. 248164/1994 discloses a process in which a hydrogenated thermoplastic ring-opening norbornene resin, an organic peroxide, a crosslinking aid and a flame retardant such as brominated bisphenol are dispersed in a solvent, and casting is conducted using the resultant solution, or a reinforcing base material is impregnated with the solution, and the solvent is then removed to crosslinking the resin by heating, thereby producing a sheet, prepreg or the like. When the norbornene resin specifically disclosed in
Dinsmore & Shohl LLP
Mullis Jeffrey
Nippon Zeon Co. Ltd.
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