JPH0424372B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for manufacturing a laminate used as a printed wiring board.

[Conventional technology]

In recent years, frequencies used in fields such as the electronic industry, communications, and computers have shifted to high frequency regions such as MHz and GHz. In the insulating layers of printed wiring boards used in such high frequency ranges, it is necessary to have a smaller dielectric constant in order to shorten signal propagation delay, and a smaller dielectric loss tangent in order to reduce power loss. Each is desired. For this reason, attempts have been made to form an insulating layer using resins such as tetrafluoroethylene resin (Teflon) and polyphenylene oxide (PPO), which have small dielectric constants and dielectric loss tangents.

[Problems to be Solved by the Invention] 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, making it difficult to process through-holes. There were problems such as the occurrence of smear and the inability to obtain high reliability through the through holes, making it impossible to form them in multilayer printed wiring boards. The present invention has been made in view of the above points, and provides a method for manufacturing a laminate that can maintain low dielectric constant, dielectric loss tangent, and high heat resistance, and can also improve flame retardancy. The purpose is to

[Means to solve the problem]

The present invention provides a polyaromatic cyanate represented by the following formula (), (In the formula, Ar is aromatic. B is a _C7-20 polycyclic aliphatic group. D is each independently a substituent containing no active hydrogen.
q, r, and s are each independently an integer of 0, 1, 2, or 3, provided that the sum of q, r, and s is greater than or equal to 2. t is an integer from 0 to 4, each independently. x is a number from 0 to 5) A flame retardant represented by the following formula (), (In the formula, R and R' are aromatic or brominated aromatic substituents that do not contain active hydrogen. n is a positive number) A flame retardant represented by the following formula (), (In the formula, n is an integer of 0, 1 or 2) A varnish is prepared by blending with a polyaromatic cyanate reaction catalyst, and a base material is impregnated with this varnish to create a prepreg, and this prepreg is laminated and molded. The present invention relates to a method for manufacturing a laminate, which is characterized by the following. The present invention will be explained in detail below. As the polyaromatic cyanate represented by the formula (), those disclosed in Patent Application Publication No. 1988-500434 can be used. That is, this polyaromatic cyanate provides an aromatic polytriazine (polyaromatic cyanate resin) that is significantly more stable against hydrolysis and has superior thermal stability than conventional polytriazine. In the polyaromatic cyanate of formula () used in the present invention, the aromatic group Ar means any group containing an aromatic group, such as benzene, naphthalene, phenanthracene, anthracene, or biaromatic group. group, two or more aromatic groups bridged by alkylene moieties. Suitable examples include benzene, naphthalene, biphenyl, binaphthyl, and diphenylalkylene groups, with benzene groups being particularly preferred. The C _7-20 polycyclic aliphatic group B means an aliphatic group containing two or more rings, and the polycyclic aliphatic group has one or more double bonds or triple bonds. may be included.
Suitable polycyclic aliphatic groups include the following. (In the formula, Y is -CH ₂ -, -S-,

【formula】

[Formula], and D ¹ is a C _1-5 alkyl group. ) Among these, (a)(b)(c)(d)(e)(f)(g) or (l) are preferable, and (a)(b)(c)(d )(l), and (a) is particularly preferred. D in formula () 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 D in formula () is defined independently, and includes, for example, alkyl, alkenyl, alkynyl, aryl, alkaryl, aralkyl, halo, alkoxy, nitro,
carboxylate, sulfone, sulfide, carbonate, etc., preferably _C1-10 alkyl,
C _1-10 alkenyl, nitro, halo, C _1-3
most preferred are alkyl, _C1-3 alkynyl, bromo, chloro. Further, t in formula () is an integer from 0 to 4, preferably an integer of 0, 1 or 2, more preferably 0 or 1, and most preferably 0. Each t in formula () is defined independently.
q, r, s are integers of 0, 1, 2, or 3, and optimally 1. Although q, r, and s are each defined independently, their total is set to be 2 or more. Furthermore, x is a positive number from 0 to 5. The polyaromatic cyanate of formula () has x of 0
It is found as a mixture of up to 5 compounds, where x is defined as the average number of this mixture. A preferred embodiment of the polyaromatic cyanate of formula () is represented by the following formula. Therefore, the aromatic polytriazine (polyaromatic cyanate resin) obtained from the polyaromatic cyanate of formula () has a low dielectric constant (ε2.78 or so), a low dielectric loss tangent (tan δ0.003 or so), and high heat resistance. (Glass transition temperature Tg250 or higher, oven heat resistance 300
It has excellent properties as a resin constituting the insulating substrate of a printed wiring board.
Therefore, in the present invention, a flame retardant represented by the formula () and a flame retardant represented by the formula () are further blended to impart flame retardant properties required for printed wiring boards. In the phenoxy-terminated tetrabromobisphenol A carbonated oligomer of formula (), R and R' are aromatic or brominated aromatic substituents containing no active hydrogen, e.g.

【formula】

【formula】

[Formula] (R ₁ is Br, CH ₃ , C ₂ H ₅ , etc., or a combination thereof, m is an integer of 1, 2, or 3)
etc. Further, in the formula (), n is a positive number without limitation, but those currently available are mixtures where n=10 to 20. Other values of n can also be used. The flame retardant effect of formula () or formula () combination of flame retardants is determined according to the amount of Br, and in order to obtain flame retardancy at the level of UL standard 94V-0,
The flame retardant of the formula () is added so that the Br content is 5 to 10% by weight based on the total amount of the polyaromatic cyanate of the formula (), the flame retardant of the formula (), and the flame retardant of the formula (). It is preferable to mix the flame retardants of formula () so that the ratio is 5 to 10% by weight. The flame retardant of formula () has a Br content of 5 to 10
In order to blend the flame retardant of formula () so that the Br content is 5 to 10% by weight, the compound should be blended in an amount of 10 to 20% by weight. The blending amount of each is generally set at 10 to 20% by weight. If the amount of flame retardant is too large, problems may arise in heat resistance, so the upper limit is preferably set to the above value. As the reaction catalyst for polymerizing the polyaromatic cyanate of formula (), organic metal salts such as imidazoles, tertiary amines, organic cobalt salts such as cobalt naphthenate and cobalt octylate can be used, and in particular Organic cobalt salts are preferred. Although the amount of the reaction catalyst is not particularly limited, for example, when organic cobalt salts are used as the reaction catalyst, the amount of cobalt ions relative to the weight of the polyaromatic cyanate of formula () may be adjusted depending on the desired gel time of the varnish (described later). Weight ratio: 10~
It is blended in a range of about 700ppm. and polyaromatic cyanate of the above formula (),
A varnish is prepared by dissolving formula (), a flame retardant of formula (), a reaction catalyst, etc. in an organic solvent. The organic solvent is not particularly limited as long as it dissolves the polyaromatic cyanate of formula () and the flame retardant of formula () and formula () and does not adversely affect the reaction, such as aromatic hydrocarbons, alcohols, and ketones. For example, toluene, acetone, methyl ethyl ketone, dimethyl formamide, methyl cellosolve, etc. can be used alone or in combination of two or more. The concentration of varnish is 50 to 70 solids.
It is common to adjust it so that it is % by weight. However, when preparing prepreg,
The base material is not particularly limited, but woven or nonwoven glass fiber fabric is generally used, and this base material is impregnated with varnish and dried by heating. The amount of varnish impregnated into the base material is preferably set so that the ratio of solid content (compound of formula () to compound of formula (), formula ()) to the base material is 45% by weight or more. The dielectric constant level is affected by the resin content, and when the base material is made of E glass cloth, a dielectric constant of 4.0 or less can be achieved with impregnation of 45% by weight or more. In addition, when the base material is made of D glass cloth, it is 45% by weight.
With the above impregnation, a dielectric constant of 3.5 or less can be achieved. The heating drying conditions when preparing prepreg are influenced by the amount of reaction catalyst blended, etc., but for example, if the heating temperature is 160 ° C., by setting the heating time to about 3 to 10 minutes, It is possible to obtain a desired prepreg stroke gel time. The stroke gel time of prepreg varies depending on molding conditions, etc., but is generally about 2 to 10 minutes at 170°C. Then, the polyaromatic cyanate in the prepreg is polymerized and hardened by layering multiple sheets of prepreg prepared in this way, then layering metal foil such as copper foil on both or one side of the top and bottom, and molding this under heat and pressure. A double-sided metal foil-clad laminate or a single-sided metal foil-clad laminate can be produced by laminating and bonding metal foil on both sides or one side of an insulating substrate configured by the above method.
An inner layer printed wiring board can be created by etching the metal foil of this laminate to form a circuit, and by stacking a plurality of inner layer printed wiring boards via a plurality of the above prepregs, the outermost layer A multilayer printed wiring board can be created by overlaying metal foil on the substrate and molding it under heat and pressure. Molding conditions include heating temperature of 170℃~
Generally, the temperature is set at 230°C, the maximum pressure is about 30 to 40 kg/cm ² , and the time is about 90 to 120 minutes.
When after-curing at a temperature of about 220 to 230°C after molding, a molding temperature of about 170 to 180°C is sufficient.

【Example】

The present invention will be explained in detail below using examples. Example 1 75 parts by weight of polyaromatic cyanate (XU-71787 manufactured by Dow Chemical Company) represented by the following formula, In formula (), R and R' are formula (b), and n is 10
12.5 parts by weight of a flame retardant mixture of ~20 (brominated carbonate oligomer; BC-58 manufactured by Great Lakes), and 12.5 parts by weight of a flame retardant (tetrabromobisphenol A: TBBA) with n = 0 in formula () (total Br content is 13% by weight),
These were stirred and dissolved in a 1:1 mixed solvent of methyl ethyl ketone and dimethyl formamide so that the solid content was 60% by weight, and to this was added cobalt naphthenate as a reaction catalyst at a weight ratio of 150 ppm of cobalt ions to polyaromatic cyanate. A varnish was prepared. This varnish was impregnated into a 2116 type E glass cloth substrate (116E manufactured by Nittobo Co., Ltd.) to a solid content (polyaromatic cyanate and flame retardant) of 45% by weight, and heated at 150°C for 4 minutes. A prepreg was prepared by drying. Next, four sheets of this prepreg were stacked together, and 70 μ thick double-sided roughened copper foil was stacked on both sides of the top and bottom, and laminated molding was performed at a molding temperature of 170°C, a molding pressure of 40 Kg/cm ² , and a molding time of 90 minutes. After molding, the product was after-cured in an electric oven at 230° C. for 2 hours to obtain a double-sided copper-clad laminate with a thickness of 0.4 mm for inner layer printed wiring boards. Example 2 Varnish was prepared in the same manner as in Example 1, except that n=1 (tetrabromobisphenol A bis(2-hydroxyl ether); manufactured by Great Lake) was used as the flame retardant of formula (). A prepreg was prepared, and laminated molding and after-curing were performed in the same manner as in Example 1 to obtain a double-sided copper-clad laminate with a thickness of 0.4 mm for an inner layer printed wiring board. Example 3 A varnish was prepared and a prepreg was prepared in the same manner as in Example 1, except that n = 2 (GX-6107 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as the flame retardant of formula (). Further, lamination molding and after-curing were performed in the same manner as in Example 1 to obtain a double-sided copper-clad laminate for an inner layer printed wiring board having a thickness of 0.4 mm. Comparative Example 1 A polyimide resin varnish was prepared by dissolving polyamino bismaleimide resin (Kelimide 601 manufactured by Nippon Polyimide Co., Ltd.) in N-methyl-2-pyrrolidone so that the solid content was 60% by weight. This varnish was impregnated into the same E glass cloth base material as in the example so that the resin content was 45% by weight, and dried in the same manner as in the example to prepare a prepreg. Next, four sheets of this prepreg were stacked together, and double-sided roughened copper foil with a thickness of 70μ was stacked on both the top and bottom sides, and laminated molding was performed under the same conditions as in Example 1, and then in an electric oven at 200℃,
After curing under certain conditions, the thickness is 0.4mm.
A double-sided copper-clad laminate for inner-layer printed wiring boards was obtained. An inner layer printed wiring board was created by etching the copper foil of the double-sided copper-clad laminate thus obtained to form a circuit. It is layered with two sheets of prepreg, and three more layers are placed above and below it.
A layer of 18μ thick copper foil was layered through two sheets of prepreg, and this was laminated and molded under the same conditions as above, and further heated at 200℃.
By performing after-curing for 2 hours, a multilayer printed wiring board having an 8-layer circuit structure with a thickness of 2.4 mm was obtained. Comparative Example 2 Only the polyaromatic cyanate (XU-71787 manufactured by Dow Chemical Company) used in the example was used (no flame retardant was used), and the solid content was dissolved in a 1:1 mixed solvent of methyl ethyl ketone and dimethyl formamide. 60
% by weight, and add cobalt naphthenate as a reaction catalyst to this by weight ratio of cobalt ion to polyaromatic cyanate resin.
A varnish was prepared by adding 200 ppm. Thereafter, a prepreg was prepared in the same manner as in the example, and lamination molding and after-curing were performed in the same manner as in the example to obtain a double-sided copper-clad laminate for an inner layer printed wiring board having a thickness of 0.4 mm. The electrical properties, thermal properties, etc. of the laminates of Examples 1 to 3 and Comparative Examples 1 and 2 obtained as described above were measured, and the results are shown in the following table. In the following table, dielectric constant, dielectric loss tangent, heat resistance, and oven heat resistance were measured based on JIS C 6481. Moreover, the glass transition temperature was measured from the chart of the viscoelastic spectrum.

[Table] As seen in the results in the table, each example in which the insulating substrate was formed using aromatic polytriazine (polyaromatic cyanate resin) obtained by polymerizing polyaromatic cyanate was formed using polyimide resin. It is confirmed that the dielectric constant and dielectric loss tangent are lower than those of Comparative Example 1 in which an insulating substrate was formed, and each of the examples in which a flame retardant was blended with polyaromatic cyanate had a lower dielectric constant and dielectric loss tangent. It was confirmed that the flame retardancy increased from the HB level of Comparative Example 2, which did not contain a flame agent, to the level of 94V-0, and it was also confirmed that the glass transition temperature and heat resistance temperature levels remained high without deterioration. be done.

【Effect of the invention】

As mentioned above, in the present invention, the laminate is manufactured by blending the polyaromatic cyanate of the formula () with the flame retardants of the formula () and the formula (). Due to the low dielectric constant and dielectric loss tangent of the polyaromatic cyanate polymer, the high frequency characteristics of the laminate can be ensured, and the flame retardant grade of the laminate can be improved by adding a flame retardant. It is possible to maintain a high level of heat resistance.

Claims (1)

[Claims] A polyaromatic cyanate represented by the primary formula (), (In the formula, Ar is aromatic. B is a _C7-20 polycyclic aliphatic group. D is each independently a substituent containing no active hydrogen.
q, r, and s are each independently an integer of 0, 1, 2, or 3, provided that the sum of q, r, and s is greater than or equal to 2. t is an integer from 0 to 4, each independently. x is a number from 0 to 5) A flame retardant represented by the following formula (), (In the formula, R and R' are aromatic or brominated aromatic substituents that do not contain active hydrogen. n is a positive number) A flame retardant represented by the following formula (), (In the formula, n is an integer of 0, 1 or 2) A varnish is prepared by blending with a polyaromatic cyanate reaction catalyst, and a base material is impregnated with this varnish to create a prepreg, and this prepreg is laminated and molded. A method for manufacturing a laminate, characterized by: