JPH02302446A - Prepreg and wiring board using the same prepreg - Google Patents

Abstract

PURPOSE:To provide a prepreg giving a wiring board having an improved dielectric constant, a dielectric loss factor, a heat resistance, etc., by impregnating a substrate with a resin varnish comprising a polyaromatic cyanate, a polyhydric phenol, a polyaromatic cyanatephenol, a catalyst, etc., and subsequently drying the treated substrate. CONSTITUTION:A substrate such as glass fiber fabric is impregnated with a resin varnish comprising (A) a polyaromatic cyanate [preferably a compound of the formula (Ar is an aromatic group; B is a 7 to 20C polycyclic aliphatic group; D is an active hydrogen-free substituent; (q), (r) and (s) are 0 to 3; (t) is 0 to 4; (x) is 0 to 5)], (B) a polyhydric phenol, (C) a polyaromatic cyanate phenol, (D) a catalyst (preferably an organic cobalt salt such as cobalt naphthenate or cobalt octylate) and, if necessary, a flame retardant, followed by drying the treated substrate to provide the objective prepreg.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to high frequency wiring boards used in electronic equipment, electrical equipment, computers, communication equipment, etc., and prepregs used therein.

[Conventional technology]

In recent years, it has been used in fields such as the electronic industry, communications, and computers.
We will discuss this by shifting the frequencies used in the high-frequency range, such as MHz and GHz. In order to shorten the signal propagation delay, the dielectric constant of the insulating layer of printed wiring boards used in such high frequency ranges must be increased.
Further, in order to reduce power loss, it is desired that the dielectric loss tangent be smaller.

For this reason, polytetrafluoroethylene resin (Teflon) and polyphenylene oxide (PPO), which have a small dielectric constant and dielectric loss tangent, are used.
Attempts have been made to form the entire insulating layer using resins such as ).

[Problem that the invention seeks to solve]

However, when forming an insulating layer using these resins, the glass transition temperature (Tg) is low at about 180 to 200°C, and the heat resistance is insufficient, and the reliability of through holes is not high due to the occurrence of smear during through hole processing. Since this is not possible, there have been problems such as the inability to form multilayer printed wiring boards.

Furthermore, when a polyaromatic cyanate resin is cured alone, the cyanate forms a triazine ring and improves heat resistance, but the crosslinking density is extremely high, resulting in a decrease in impact resistance.
Cracks tend to occur on the inner wall during drilling during printed wiring board processing, which poses a problem in terms of through-hole plating reliability.

[Means for solving problems]

The present invention relates to a prepreg obtained by impregnating a base material with a resin varnish consisting of a polyaromatic cyanate, a polyhydric phenol, a polyaromatic cyanate phenol, a catalyst, and a flame retardant added as necessary and drying it, and a required number of sheets of the prepreg. Overlapping,
The above-mentioned purpose is achieved by a wiring board characterized in that it is formed by laminating and integrating a laminate in which an inner layer circuit material is interposed at a predetermined position between the prepregs as necessary, and then an outer layer circuit material is disposed on the outermost layer. The present invention will now be described in detail.

The polyaromatic cyanate used in the present invention is preferably one represented by the following general formula [1] in order to improve high frequency properties.

...Formula [1] However, Ar is aromatic and B is C? ~ The polycyclic aliphatic groups of 螞・ are each independently a Va substituent q*rsll that does not contain active hydrogen.
are independently 0.1, 2. or the integer t of 3 is each independently an integer of 0 to 4, and the integer It means all groups, such as benzene, naphthalene, phenanthracene, and anthracene.

or a biaromatic group, two or more aromatic groups bridged by alkylene moieties. Preferred examples include benzene, naphthalene, biphenyl, binaphthyl, and diphenylalkylene groups, particularly benzene groups. Cγ
The polycyclic aliphatic group B in 〜鵞・ means an aliphatic group containing two or more rings, and the polycyclic aliphatic group includes one
Preferred polycyclic aliphatic groups containing 3 or more double bonds or triple bonds include the following.

Dl is an alkyl group In the formula [1], D means all substituents that can be substituted on the organic hydrocarbon group, but substituents containing active hydrogen atoms are excluded. Active hydrogen atom means a hydrogen atom bonded to an oxygen, sulfur, or nitrogen atom. Each element in formula [1] is defined independently, for example,
Alkyl, alkenyl, alkynyl, aryl, alkaryl, aralkyl, halo, alkoxy, nitro, carboxylate, sulfone, sulfide, carbonate, etc., and preferably C1-1 alkyl mc1-1
Most preferred are alkenyl of o, nitro, halo, alkyl of 01-3, alkynyl of C1-3, furomo, and chloro.

The polyaromatic cyanate of formula [1] is found as a mixture of compounds in which X is from 0 to 5, and X is defined as the average number of this mixture.

A preferred embodiment of the polyaromatic cyanate of formula [1] is represented by the following formula.

Therefore, the aromatic polytriazine (polyaromatic cyanate resin) obtained from the polyaromatic cyanate of formula [1] has a low dielectric constant (g around 2.78
It has excellent properties as a resin constituting a printed wiring board, having a tan δ of about 0°003) and high heat resistance (glass transition temperature 'pg of 250 or more, open heat resistance of about 300°C). Therefore, in the present invention, it is further expressed by formula [2].

...Formula [2] However, the symbol Ar 6 B @ D 6 q * r @
8 * t -X is the formula % Formula % By adding polyhydric phenol, the crosslinking density during curing is lowered and the impact resistance is improved by plasticizing, and the isocyanate group of formula [1] is It increases the reactivity so that it does not remain as a chemical. Furthermore, the formula [
By adding the polyaromatic cyanate phenol shown in 3), the leakage and tightness of the base material such as glass cloth are improved.

...Formula [3] However, the symbols Arm B, Da qa re 8 * t,
X is the same as in formula [1].

As the melting medium, organic gold salts such as imidazole, tertiary cobalt 7-mys-7-tenoate and organic cobalt salts of cobalt octylate can be used.
Particularly preferred are organic cobalt salts, and the amount of the A0 catalyst blended is not particularly limited. For example, when organic cobalt salts are used as a reaction catalyst, the polyaromatic of formula C1] may be used depending on the desired gel time of the varnish. The weight ratio of cobalt ions to v and filtration of group cyanates is blended in a range of lO to 7 oppma degrees. As the flame retardant added as necessary, all commonly used flame retardants can be used. Furthermore, in order to adjust the overall viscosity, it may be diluted with alcohol, ketone, toluene, dimethylformamide F, methyl cellosolve, etc. alone or in mixtures, if necessary. The base material may be woven fabric, non-woven fabric, mat, or paper made of inorganic fibers such as glass and asbestos, organic synthetic fibers such as polyester, polyacrylic, polyvinyl alcohol, polyacrylic, and polyaramid, and natural fibers such as cotton. It is a combination base material. The inner layer circuit material to be used as required is one in which an electric circuit is formed on the metal surface of a double-sided or single-sided metal-clad laminate, and a required number of inner layer circuit materials are inserted between prepregs as necessary to form a multilayer wiring board. As the outer layer circuit material, single-sided metal-clad laminates or metal foils made of copper, aluminum, nickel, zinc, etc. alone, alloys, or composites are used. Preferably, double-sided roughened or planed foils with a thickness of 18 to 105 microns are used. More preferably, it is a copper foil with an aluminum carrier. In this way, the required number of prepregs obtained by impregnating and drying the above-mentioned resin varnish into the base material are piled up, inner layer circuit material is interposed between the prepregs at required positions as necessary, and then outer circuit material is placed on the outer layer. The arranged laminates are laminated and integrated at 170 to 230°C using a multi-stage press method, double belt method, multi-roll method, drum method, etc., and if necessary, after curing is performed for an additional 60 to 120 minutes. You can also do it.

The present invention will be explained below based on examples.

Example 60 parts by weight of polyaromatic cyanate (hereinafter referred to as - parts)
To this, 20 parts of polyhydric phenol before the cyanation reaction of polyaromatic cyanate, 20 parts of polyaromatic cyanate phenol, and 25 ppm of cobalt octylate were added and mixed, and then 8 parts of tetraprobisphenol A was added to this to make the solid content 70 parts. A resin varnish was obtained by diluting it with methyl ethyl ketone so that the ratio of %C or less was simply expressed as "excellent", and after drying a glass with a thickness of 0.15 fl to the resin varnish, the resin teeth became 501.
The prepreg was obtained by impregnating and drying the prepreg so that 8 sheets of the prepreg were stacked and a 35 micron thick copper foil was placed on each of the upper and lower surfaces, respectively, and a laminate was formed using a molding pressure of 50KQ/C1l.
After heating and pressure forming at 170°C for 90 minutes, the product was further cured at 220°C for 60 minutes under no pressure to obtain a double-sided steel clad laminate with a thickness of 1.6fl, and then electrical circuits were formed on both sides of the laminate. A laminate with two sheets of the above prepreg interposed on the upper and lower surfaces of the inner layer circuit material and a 35 micron thick copper foil placed on the outermost layer was formed under a molding pressure of 40 KQ/d.
, Lamination molding was carried out at 170° C. for 60 minutes to obtain a four-layer circuit wiring board.

Comparative Example A prepreg, a double-sided steel clad laminate, and a 4-layer circuit wiring were prepared in the same manner as in the example except that polyamino bismaleimide resin was dissolved in N-methyl 2-pyrrolidone so that the solid content was 60% and a resin varnish was used. I got the board.

Comparative Example 2 A prepreg, double-sided steel clad laminate,
A four-layer circuit wiring board was obtained.

The performance of the wiring boards of Examples and Comparative Examples 1 and 2 is shown in Table 1.

note *After immersion treatment in 150°C warm water for 48 hours.

*2 Possibility of plating liquid seeping through the through-hole wall.

〔Effect of the invention〕

The present invention is constructed as described above. The prepreg having the structure described in the claims and the wiring board using the same have the effect of improving dielectric blockage, dielectric loss tangent, heat resistance, and through-hole reliability.

Claims (3)

[Claims] (1) A prepreg characterized by impregnating a base material with a resin varnish consisting of polyaromatic cyanate, polyhydric phenol, polyaromatic cyanate phenol, a catalyst, and a flame retardant added as necessary, and drying. (2) Layer the required number of prepregs made by impregnating a base material with a resin varnish consisting of polyaromatic cyanate, polyhydric phenol, and polyaromatic cyanate phenol and drying, and place inner layer circuits at required positions between the prepregs as necessary. A wiring board characterized in that it is formed by laminating and integrating a laminate in which an outer layer circuit material is disposed on the outermost layer after interposing a material therebetween. (3) The wiring board according to claim 2, wherein the outer layer circuit material is a metal foil.