Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-09-28
2002-12-10
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S448000, C428S450000, C428S473500, C528S026000, C528S322000, C528S310000, C526S262000, C526S347100, C525S464000
Reexamination Certificate
active
06492030
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thermosetting low dielectric resin composition that adheres extremely well to metals with a low dielectric constant and low dielectric dissipation factor, and for which there is very little scattering of the resin during punching, cutting or other such operational processes. The present invention further relates to a laminate used in printed wiring, a laminate for a circuit, and the like.
This application is based on patent applications filed in Japan (Japanese Patent Application Nos. Hei 11-26710 and Hei 11-26711), the contents of which are incorporated herein by reference.
BACKGROUND ART
Signal speeds and operating frequencies for electronic systems have increased rapidly in recent years. As a result, printed wiring used in electronic systems employed in the high frequency regions have required prepregs and laminates that have excellent thermal resistance and superior adherence properties with a low dielectric constant and low dielectric dissipation factor. In particular, the propagation speed of the electric signal can be increased by employing a laminate consisting of a low dielectric material in the printed wiring. As a result, it has become possible to process signals at a faster speed.
Fluororesins and polyphenylene ether resins that have a small dielectric constant have been proposed as materials for this type of laminate.
However, the reliability of these types of resins is problematic as they have poor workability and adherence properties.
Epoxy denatured polyphenylene ether and polyphenylene ether denatured epoxy have been proposed with the goal of improving workability and adherence properties. However, due to their high dielectric constant, satisfactory properties have not been obtained from epoxy resins.
In addition, thermosetting resin compositions are known (see Japanese Patent Application, First Publication No. (A) Sho 57-185350) that are formed in a pre-reaction by compounding polyphenylene ether resin, multifunctional cyanate ester resin, and another resin, and then adding a radical polymerization initiator. Even in this case, however, the reduction in the dielectric constant is not sufficient.
Furthermore, while a thermosetting polybutadiene resin having as its main component 1,2-polybutadiene has a low dielectric constant, its adherence and thermal resistance properties are not sufficient.
As an example of a low dielectric resin, a composition is known (Japanese Patent Application, First Publication No. (A) Sho 61-83224) in which 5~20 parts by weight of 1,2-polybutadiene resin, 5~10 parts by weight of a bridging monomer, and a radical bridging agent are compounded to 100 parts by weight of a polyphenylene ether resin. However, when employing 1,2-polybutadiene resin having a molecular weight of several thousand, a stickiness remains once the solvent has been removed from the composition. The prepreg obtained by coating and impregnating the composition into fiberglass cannot maintain a tack-free state as a result, making practical application problematic. Moreover, while a method is available that employs high molecular weight 1,2-polybutadiene in order to eliminate the stickiness, solubility in the solvent is reduced. As a result, the solution becomes highly viscous and has poor flow characteristics, so that this too is problematic with respect to practical application.
A low dielectric laminate and copper-clad laminate have been proposed (see Japanese Patent Application (B2) No. 2578097) in which a thermosetting resin is impregnated in a cloth consisting of fluorocarbon fibers. In order to increase the adherence between the fluorocarbon fibers and the thermosetting resin, however, it is necessary to treat the surface of the fluorocarbon fibers. Moreover, fluorocarbon fibers are expensive, so that the final laminate and copper-clad laminate become extremely costly, making this approach impractical.
Multi-layer printed circuit boards that also have electric circuits on their inner layers are used in electronic devices and other equipment. These multi-layer printed circuit boards are obtained by placing an electrically insulating prepreg between an inner layer circuit board, on which circuitry has been formed in advance, and a copper foil, which is employed for the outer layer circuit. Thermocompression molding is then carried out to fabricate a copper-clad laminate that has circuits on its inner layers. Finally, specific circuits are formed to the outer layer of this copper-clad laminate to complete the multi-layer printed circuit board.
A prepreg consisting of epoxy resin and thin glass cloth having a thickness of 30~100 &mgr;m has been conventionally employed for the prepreg used here.
However, in the case of this type of prepreg, the cloth weave is readily embossed, while the concavities and convexities of the inner layer circuit board cannot be easily absorbed within the prepreg. As a result, these irregularities readily appear on the surface of the outer layer, impairing the smoothness of the surface and hindering formation of micro wiring.
Accordingly, methods are available in which a resin film that does not contain glass cloth is used as a prepreg in place of the glass cloth epoxy resin prepreg, or in which copper foil attached to a resin base, which already contains a laminated resin base layer that adheres to one side of the copper foil that is used for the outer layer circuit, is employed for both the prepreg and the outer layer circuit.
However, in these types of substitute prepregs, various problems occur when conveying, cutting or laminating the resin film or copper foil attached to a resin base. Namely, resin cracking and deletion may occur; the insulating layer that is between layers may become extremely thin at areas where inner layer circuitry is present during thermocompression molding in the case where employing the prepreg as an insulating material for connecting between the layers in a multi-layer board; the insulation resistance between layers may fall; and shorts may occur. In order to avoid these problems, a resin capable of forming a film is employed for the resin used in this resin film and in the copper foil attached to a resin base.
Various resins with this type of film forming capability have been proposed, including thermoplastic polyimide adhesive film (U.S. Pat. No. 4,543,295), high molecular weight epoxy resin (Japanese Patent Application, First Publication (A) No. Hei 4-120135), acrylonitrile butadiene copolymer/phenol resin (Japanese Patent Application, First Publication (A) No. Hei 4-29393), phenol resin/butyral resin (Japanese Patent Application, First Publication (A) No. Hei 4-36366), and acrylonitrile butadiene copolymer/epoxy resin (Japanese Patent Application, First Publication (A) No. Hei 4-41581), among others.
However, these film-forming resins have poor dielectric constants and cannot process signals at faster speeds.
Furthermore, the low dielectric resin disclosed in the aforementioned Japanese Patent Application, First Publication (A) No. Sho 61-83224 is not reliable with respect to thermal resistance, workability, and adherence, and, moreover, has poor film forming capability. Accordingly, practical application of this resin has not been satisfactory.
DISCLOSURE OF INVENTION
The present invention was conceived to resolve the above-described problems, and has as its objective the provision of a thermosetting low dielectric resin composition for use in printed wiring that adheres extremely well to metals with a low dielectric constant and low dielectric dissipation factor, and for which there is very little scattering of the resin during operational processes. The present invention further relates to a prepreg, laminate, and a laminate for a circuit, that forms a resin film or metal foil attached to a resin base, that employs the aforementioned thermosetting low dielectric resin composition.
The present invention's thermosetting low dielectric resin composition is characterized in the inclusion of a component (a), which is a siloxane denatured polyimide in
Hashimoto Takeshi
Kobayashi Masaharu
Orino Daisuke
Sato Takeshi
Dawson Robert
Feely Michael J
Tomoegawa Paper Co. Ltd.
LandOfFree
Thermoplastic resin composition having low permittivity,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thermoplastic resin composition having low permittivity,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thermoplastic resin composition having low permittivity,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2969246