JPH02268486A - Printed wiring board material of low permittivity - Google Patents

Abstract

PURPOSE:To obtain an object which is excellent in dielectric property and copper foil exfoliation strength by using mixed unwoven fabric consisting of fluororesin and heat-resistant engineering plastic fibers, and getting an insulating layer wherein this is combined with low permittivity thermosetting resin which includes hardening matter of specific permittivity. CONSTITUTION:Fluororesin fibers consisting of polytetrafluoroethylene, tetrafluoroethylene, hexafluoropropylene copolymer, olefin-tetrafluoroethylene copolymer, etc., and heat-resistant engineering plastic fibers such as omniaromatic polyamide, polyphenylene sulfide, etc., are mixed at specified rate and are used as base material of mixed unwoven fabric. It is suitable that an insulating layer, wherein cyanate resin and thermosetting resin with low permittivity of 3.5 or less at 1MHz, wherein high boiling point compounds, wherein 2 to 7 pieces, on an average, of aromatics which are nonsubstituted or substituted for halogen atoms or low-grade alkyl groups are coupled in a straight chain shape, are arranged to the cyanate, are combined, should be used. Material for printed wiring, which is excellent in dielectric property and in which shrinkage in laminate formation is small and which does not bring about exfoliation, can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a printed wiring board material that has a substantially low dielectric constant and is ideal for high-speed calculations and high-frequency circuits, and is particularly suitable for thin multilayer printed wiring boards. It is suitable as a material for use.

[Conventional technology and its problems]

A fluororesin/glass cloth reinforcement board is known as a low dielectric constant multilayer printed wiring board. However, it has the disadvantage that it must be bonded at a high temperature of 350° C. or higher.

In addition, thermosetting resin laminates based on fluorocarbon fiber woven fabric and thermosetting resin laminates using porous fluororesin sheets as a base material are known, but they have the drawback of being expensive. A laminated plate using a thermosetting resin composition made of glass cloth as a base material and mixed with a resin powder is known, but it has a drawback of poor adhesion to metal foil.

Further, JP-A No. 63-69106 discloses a laminate using a fluororesin nonwoven fabric as a base material, but fluororesin alone has low tensile strength and high elongation.
It had the disadvantage of poor adhesion to thermosetting resins.

[Means to solve the problem]

The present invention was completed as a result of extensive research into a method that solves the above problems and allows printed wiring to be formed substantially on a low dielectric constant layer.

That is, the present invention uses a mixed nonwoven fabric made of fluororesin fibers and heat-resistant engineering plastic fibers as a base material, and combines it with a low dielectric constant thermosetting resin whose cured material has a dielectric constant of 3.5 or less at IMI. The heat-resistant engineering plastic fibers include wholly aromatic polyamide, polyphenylene sulfide, polyether ether ketone, polyether sulfone, polyether imide, and wholly aromatic polyamide. It is a fiber made of one or more kinds of plastics such as polyester, and is particularly a low dielectric constant printed wiring board material using wholly aromatic polyamide fiber.

The present invention will be explained in detail below.

The mixed nonwoven fabric of fluororesin fiber and heat-resistant engineering plastic fiber of the present invention has a monofilament diameter of 10 to 40. u, a porous or non-porous fluororesin fiber with a length of 0.1 to 10 cm and a heat-resistant engineering plastic fiber with a monofilament diameter of 5 to 40 cm and a length of 0.1 to 10 cm at a ratio of 80:2
A nonwoven fabric is produced by a dry method or a wet method at a weight ratio of 0 to 20:80. The thickness is 30~2007. s,
More preferably, it is 50 to 100p, and the weight is 501 and 2
0 to 60 g/m'' is preferred.

Examples of the fluororesin for fluororesin fibers include polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, and olefin-tetrafluoroethylene copolymer. In addition, heat-resistant engineering plastics include fully aromatic polyamide (aramid fiber),
Examples include polyphenylene sulfide, polyetheretherketone, polyethersulfone, polyetherimide, and wholly aromatic polyester, with aramid fibers being particularly suitable.

The dry method involves mixing side fibers in a predetermined ratio, placing them randomly on a net-like material, etc., and partially fusing the fluorine fibers and heat-resistant engineering plastic fibers by heating or other means. For the purpose of promoting fusion, for example, fine powder or fibers of fluororesin, low dielectric constant thermoplastic resin, thermosetting resin, etc. can also be used auxiliary.

In addition, the wet method is a method in which side fibers are dispersed in water etc. at a predetermined ratio and then paper-formed.Fluororesin fine particles are suspended and dispersed in this dispersion system, and the fine particles attached between the fibers are removed during drying or during drying. Examples include a method in which the material is fixed by melting it later, and a thermoplastic resin or rubber having a low dielectric constant that does not change in quality during the dispersion process may also be used as an auxiliary material.

Furthermore, during papermaking, fibers of low dielectric constant glasses such as low glass, S-glass, 5ll-glass, T-glass, and quartz glass, and other ceramics are used as supplementary materials.
It can also be used in amounts up to 0% by weight.

The nonwoven fabric can be used as is, but it is preferable to use one that has been surface-treated to improve its adhesion to the thermosetting resin. Examples include treatment with a coupling agent such as a titanate coupling agent, treatment with a nonionic heat-resistant surfactant such as a fluorine-based surfactant, and these can be used in combination as appropriate.

Next, the thermosetting resin composition of the present invention having a dielectric constant of 3.5 or less refers to cyanato resin (Japanese Patent Publication No. 41-1928, No. 4
5-11712, 44-1222, German Patent No. 1190184, USP-4,578,439, etc.),
Cyanate ester-maleimide resin, cyanate ester-maleimide epoxy resin (Special Publication No. 54-30440
No., etc., Special Publication No. 52-31279, Ro 5P-41103
64 etc.), cyanate ester-epoxy resin (Special Publication No. 4)
6-41112), cyanic acid, such as a composition prepared by blending a cyanato resin with a high boiling point compound in which an average of 2 to 7 aromatic nuclei, unsubstituted or substituted with a halogen atom or a lower alkyl group, are bonded in a linear chain. Ester resin; Modified maleimide resin whose main components are polyfunctional maleimide, diamine, epoxy compound, isocyanate compound, etc.
No. 79, etc.); incyanate-oxazolidone resins containing isocyanate compounds and epoxy compounds as main components (JP-A-55-75418, etc.); thermosetting resins such as compositions of polyphenylene ether and crosslinkable monomers or prepolymers , as well as known amines, acid anhydrides, phenols, organic metal salts, metal chelate compounds, organic peroxides, etc. as curing agents and curing catalysts for these resins, and are suitable. Examples include a cyanato resin and a composition formed by blending the cyanato resin with a high boiling point compound in which an average of 2 to 7 aromatic nuclei, unsubstituted or substituted with a halogen atom or a lower alkyl group, are bonded in a straight line. .

In addition to these, the above thermosetting resin composition also includes:
Silicone-based compounds, fluorine-based compounds,
Nonionic heat-resistant surfactants, silane coupling agents, titanate coupling agents, waxes, diene rubbers, non-grade or low crystallinity saturated polyester resins,
Compounds and resins such as urethane resins, vinyl acetate resins, and polyethylene resins; low molecular weight compounds that are reactive as viscosity modifiers (reactive diluents), such as aromatic vinyl compounds such as styrene, trimethylolpropane tri(meth) Acrylates such as acrylates, monoglycidyl ethers, etc. can be added in an amount of less than 30% by weight of the resin component, and it is preferable to use coupling agents to improve adhesiveness with the base material. .

The heat-resistant engineering plastic fibers mentioned above/
A known method may be used to produce a prepreg by impregnating, applying, and adhering a thermosetting resin composition to a nonwoven fabric of fluorine fibers. The amount of resin adhered to the nonwoven fabric is preferably in the range of 45 to 85% by volume based on the entire prepreg volume. A specific method is to impregnate a nonwoven fabric with a thermosetting resin composition as a varnish dissolved in a solvent and dry it; obtain a liquid thermosetting resin composition without a solvent at room temperature or under heating; A method of impregnating a thermosetting resin powder; a method of preparing a thermosetting resin powder, distributing it uniformly on a nonwoven fabric, and fixing it on the nonwoven fabric by heating and melting it. These methods may include vacuum, solvent solution, solvent vapor, or other impregnation methods after substantially removing air.

The metal foil of the present invention is a well-known copper foil, iron foil, aluminum foil 1, aluminum/copper foil, or the like used for ordinary metal foil-clad laminates. One or both sides of the metal foil may be surface-treated, or it may be used as a metal foil with adhesive.

The laminated material for a printed wiring board of the present invention is a laminate manufactured by laminating the above-described prepreg or the prepreg and metal foil by a known method and integrating them, a metal foil-clad laminate, etc. Refers to the laminate, the inner layer board with printed wiring for the intermediate layer, and the prepreg itself.

In addition, it is naturally possible to partially use prepregs other than the above-mentioned prepregs in the lamination molding.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. In addition, parts and percentages in the examples are based on weight unless otherwise specified.

Example 1 A polytetrafluoroethylene fiber with a diameter of 22p1 and an average length of 30mm and an aramid fiber with a diameter of 12-1 and a length of 5Illff+ were used in a weight ratio of 50:50 to have a thickness of 10mm.
01, Argon plasma treatment (0.2 Torr, 110kHz, 25kV,
1 minute), and then treated with an epoxy silane coupling agent.

2.2-bis(4-cyanatophenyl)propane prepolymer (number average molecule 1i 1,000) 95 parts,
Bisphenol A type epoxy resin (epoxy equivalent: 450
~500) and 0.01 part of iron acetylacetonate were dissolved in methyl ethyl ketone (hereinafter referred to as MBK) to prepare a varnish (hereinafter referred to as varnish 1). The dielectric constant after curing this resin is 3.3 (at 1MHz)
Met.

Varnish 1 was impregnated with the above nonwoven fabric and dried at 140°C for 6 minutes to obtain a prepreg with a resin content of 71% (hereinafter referred to as CPAI), and 8 sheets of the CllAl were stacked, and 18-0 copper with a thickness of 18-0 was coated on both sides. Layer foil, 180℃, 2 hours, 20kg/-
A double-sided copper-clad laminate with a thickness of 0.8 was produced by lamination molding.

The dielectric constant of this laminate at 1MHz is 3.2, and the dielectric loss tangent is 0.
．． 0060. The solder heat resistance at 280° C. showed no blistering after 30 seconds or more, and the copper foil peel strength was 1.0 kg/Cm (1.8 cm copper foil).

Example 2 55% polytetrafluoroethylene fibers with diameter 221 and average length 30 mm, 5% fine powder of tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer and diameter 3
Polyether sulfone fibers with an average length of 5 mm are used at a weight ratio of 60:40, with a thickness of 100 mm and a weight of 80 g.
/m' was treated with argon plasma in the same manner as in Example 1, and then treated with an aminosilane coupling agent.

2.2-Bis(4-cyanatophenyl)propane prepolymer (number average molecular weight 1.000) 90 parts, polyethersulfone 10 parts, and zinc octylate 0.0
Three parts were dissolved in methylene chloride (hereinafter referred to as MC) to obtain a varnish (hereinafter referred to as varnish 2). Note that the dielectric constant of this resin after curing was 3.4 (at 1 MHz).

Varnish 2 was impregnated with the above nonwoven fabric and dried at 150°C for 6 minutes to prepare a prepreg with a resin content of 70% (hereinafter referred to as CI' 2
) was obtained.

On the other hand, a raw glass plain woven fabric with a thickness of 100 mm was soaked in Varnish 2 and dried at 140°C for 6 minutes to obtain a prepreg with a resin content of 50% (hereinafter referred to as FGPI).
Stack two sheets, and layer 351 thick double-sided roughened copper foil on both sides,
Add a protective film and heat at 180℃ for 2 hours for 40k.
A double-sided copper-clad laminate with a thickness of 0.2 mIT+ was produced by lamination molding at g/cIIll. The dielectric constant of this laminate at IMIIz was 3.9, and the dielectric voltage contact was 0.0035.1) This double-sided copper-clad laminate was etched to form a predetermined intermediate wiring network, and was used as an inner layer board.

After layering these three types of inner layer plates and copper foil with a thickness of 181 mm on both sides with two sheets of CP 2 manufactured above interposed therebetween,
℃, 2 hours, laminated molding at 20 kg/ci, thickness 1.4
A multilayer board with six inner layers was obtained.

The effective dielectric constant at I M It z of the inner layer wiring of this multilayer board was 3.6, and the dielectric loss tangent was 0.0040.

Furthermore, the multilayer board was subjected to a soldering heat resistance test at 1280° C. for 30 seconds without any defects such as delamination.

[Operation and effects of the invention]

As is clear from the above detailed description and examples, the printed wiring board material based on a nonwoven fabric made from heat-resistant engineering plastic fibers and fluorine fibers of the present invention has excellent dielectric properties, etc. It also has excellent properties when used in printed wiring boards, such as solder heat resistance and copper foil peel strength.

Non-woven fabrics using only fluorine fibers generally have an elongation of 10%.
However, the disadvantage is that the base material elongates during the resin impregnation process, and shrinkage increases when the obtained prepreg is heated and laminated.On the other hand, the nonwoven fabric of the present invention has a small elongation of less than 5%. The drawback of shrinkage during laminated molding is largely eliminated.Furthermore, fluorocarbon fibers alone cannot be used with thermosetting resin compositions even after corona discharge treatment or surface treatment with a metallic sodium surface treatment agent. Due to insufficient adhesion, the resin and the fluorocarbon base material tend to peel off due to bending stress, etc. In contrast, the mixed paper-made nonwoven fabric of the present invention has a bond between the base material and the thermosetting resin by surface treatment. In particular, the remarkable improvement in adhesion strength with heat-resistant engineering plastic fibers greatly prevents peeling between the resin and the base material due to bending stress, etc., and prevents deterioration of insulation properties as a printed wiring board.

Therefore, it is clear that the printed wiring board material of the present invention is optimal for printed wiring boards for high frequency circuits, multilayer printed wiring boards, adhesive prepregs, and the like.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] 1. A mixed nonwoven fabric made of fluororesin fibers and heat-resistant engineering plastic fibers is used as a base material, and is combined with a low dielectric constant thermosetting resin whose cured material has a dielectric constant of 3.5 or less at 1 MHz. Low dielectric constant printed wiring board material consisting of an insulating layer. 2. The heat-resistant engineering plastic fiber is
The low dielectric constant printed wiring board material according to claim 1, which is made of wholly aromatic polyamide.