JPH0424370B2 - - 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.

[Problem 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℃, and it is difficult to obtain high reliability of through holes due to the occurrence of smear during through hole processing. There were problems such as the inability to form 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, 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 that is significantly more stable against hydrolytic action 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' is a C _1-5 alkyl group. ) Among them, those having a, b, c, d, e, f, g or l are preferable, and more preferably a, b, c,
Among d and l, 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 removed. 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. In addition, t in formula () is an integer from 0 to 4, especially an integer of 0, 1 or 2, especially 0 or 1.
is preferable, and optimally 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 number from 0 to 5. The polyaromatic cyanates of formula () are found as mixtures of compounds in which x ranges from 0 to 5, and 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 of formula () is further blended to impart flame retardant properties required for printed wiring boards. The amount of flame retardant in formula () is set to the amount of Br contained in the flame retardant. That is, in the formula () where n=0, the Br content is 58% by weight and n=1
The one with Br content is 50%, and the one with n=2 is Br
The content is 48% by weight. If the Br content is less than 10% by weight based on the total amount of the polyaromatic cyanate of the formula () and the flame retardant of the formula (), the flame retardance is at the level of HB according to the UL standard, and the Br content but
If it is 10% by weight or more and less than 13% by weight, it is at a level of 94V-1, and in order to achieve a level of 94V-0, it is necessary to make the Br content higher than 13% by weight. Therefore, in order to achieve 94V-0, when n = 0, the flame retardant of formula () should be added in an amount of 22.4% by weight or more (77.6% by weight or less for formula ());
= 1, the flame retardant of formula () should be blended in an amount of 26.0% by weight or more (74.0% by weight or less for formula ()),
When n=2, it is desirable to set the blending amount of the flame retardant of formula () to 27.0% by weight or more (73.0% by weight or less for the flame retardant of formula ()). In the case of a flame retardant with n=0, if it is blended in an amount greater than the above-mentioned amount, a problem may arise in heat resistance, so it is desirable to set the flame retardant to the above-mentioned value. In addition, in the case of a flame retardant with n=1, there is no particular problem with heat resistance, and on the contrary, it has the effect of improving the dielectric loss tangent characteristics, so it can be blended up to 26% by weight or more and up to about 40% by weight. It is. For flame retardants with n=2, n=0
Due to the same reason as the above, the blending amount is 27% by weight.
The front and back are preferred. Considering the above, the blending ratio of polyaromatic cyanate of formula () and flame retardant of formula () is generally 60 to 90% by weight of the former and 60 to 90% by weight of the latter.
It is desirable to set it at 40 to 10% by weight. 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 a flame retardant of formula (), a reaction catalyst, etc. in an organic solvent. As an organic solvent, aromatic hydrocarbons, alcohols, alcohols, etc. can be used as long as they dissolve the polyaromatic cyanate of the formula () and the flame retardant of the formula () and do not adversely affect the reaction.
Ketones and the like are not particularly limited. 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 generally adjusted so that the solid content is 50 to 70% 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 ()) to the base material is 45% by weight or more. The level of dielectric constant is affected by the resin content, and when the base material is made of E glass cloth, the dielectric constant will change if it is impregnated with 45% by weight or more.
A dielectric constant of 4.0 or less can be achieved, and when the base material is made of D glass cloth, a dielectric constant of 3.5 or less can be achieved with impregnation of 45% by weight or more. 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. The polyaromatic cyanate in the prepreg is then polymerized and hardened by layering multiple sheets of the 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 adhering metal foil on both sides or one side of an insulating substrate made up of an insulating substrate. 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 layering metal foil on the substrate and molding it under heat and pressure. The molding conditions are heating temperature 170℃~230℃
℃, the pressure is ^about 30-40Kg/cm2 at the maximum pressure, and the time
It is common to set the time to 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 Parts by weight of polyaromatic cyanate (XU-71787, manufactured by Dow Chemical Company) represented by the following formula, Take 20 parts by weight of a flame retardant (tetrabromobisphenol A: TBBA) with n = 0 in formula () and add them to a 1:1 mixed solvent of methyl ethyl ketone and methyl cellosolve so that the solid content is 60% by weight. The mixture was stirred and dissolved, and cobalt naphthenate was added thereto as a reaction catalyst at a weight ratio of 50 ppm of cobalt ions to the polyaromatic cyanate to prepare a varnish. 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 and a molding pressure of 40 kg/cm ² for 90 minutes. After-curing was carried out 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 an inner layer printed wiring board. Example 2 An inner layer printed wiring board was prepared by etching the copper foil of the double-sided copper-clad laminate obtained in Example 1 to form a circuit. These three inner layer printed wiring boards were stacked with the three prepregs obtained in Example 1 interposed between them, and 18μ thick copper foil was further stacked above and below them via three prepregs, and this was carried out. By laminating and molding under the same conditions as Example 1 and further after-curing, the thickness
A multilayer printed wiring board with a circuit configuration of 8 layers of 2.4 mm was obtained. Example 3 75 parts by weight of the polyaromatic cyanate (XU-71787 manufactured by Dow Chemical Company) used in Example 1, formula ()
n=1 flame retardant (tetrabromobisphenol A bis(2-hydroxyl ether);
Take 25 parts by weight of each product (manufactured by Great Lakes),
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 octylate as a reaction catalyst at a weight ratio of 75 ppm of cobalt ions to the polyaromatic cyanate resin. A varnish was prepared. After that, prepreg was prepared in the same manner as in Example 1, and laminated molding and after-curing were performed in the same manner as in Example 1 to determine the thickness.
A double-sided copper-clad laminate for a 0.4 mm inner layer printed wiring board was obtained. Example 4 Instead of using E glass cloth as the prepreg base material, D glass cloth (WDX-723 manufactured by Nittobo Co., Ltd.) was used.
A double-sided copper-clad laminate for an inner-layer printed wiring board having a thickness of 0.4 mm was obtained in the same manner as in Example 1, except that . Example 5 70 parts by weight of the polyaromatic cyanate (XU-71787 manufactured by Dow Chemical Company) used in Example 1, formula ()
n=2 flame retardant (GX manufactured by Daiichi Kogyo Seiyaku Co., Ltd.
-6107) were taken and dissolved in dimethylacetamide with stirring so that the solid content was 60% by weight, and 8% by weight was added to this as a reaction catalyst.
A varnish was prepared by adding a cobalt octylate solution containing Co ³⁺ at a weight ratio of 50 ppm of cobalt ions to the polyaromatic cyanate resin. After that, a prepreg was prepared in the same manner as in Example 1, and lamination 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. . 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 Example 1 so that the resin content was 45% by weight, and dried in the same manner as in Example 1 to prepare a prepreg. Next, four sheets of this prepreg were stacked, 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.
After cured for 2 hours, thickness 0.4
A double-sided copper-clad laminate for inner-layer printed wiring boards of mm 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 above and below it is layered with 18μ thick copper foil through three sheets of prepreg.
This was laminated and molded under the same conditions as Example 1, and then
By post-curing at 200° C. for 2 hours, a multilayer printed wiring board with a thickness of 2.4 mm and an 8-layer circuit structure was obtained. Comparative Example 2 Only the polyaromatic cyanate (XU-71787 manufactured by Dow Chemical Company) used in Example 1 was used (no flame retardant was used), and the solid content was added to a 1:1 mixed solvent of methyl ethyl ketone and dimethyl formamide. but
Stir and dissolve to a concentration of 60% by weight, and add cobalt naphthenate as a reaction catalyst to the polyaromatic cyanate resin in a weight ratio of cobalt ions to polyaromatic cyanate resin.
A varnish was prepared by adding 200 ppm. After that, a prepreg was prepared in the same manner as in Example 1, and lamination 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. . The electrical properties, thermal properties, etc. of the laminates of Examples 1 to 5 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 JISC6481.
Moreover, the glass transition temperature was measured from the chart of the viscoelastic spectrum. Furthermore, the coefficient of expansion in the thickness direction was measured using a thermomechanical analysis method in which the sample was heated and cooled to expand and contract to cause a mechanical dimensional change, and the amount of this change was measured. The expansion rate is 10 ⁶
It is shown as a multiplied value (ppm/°C).

[Table] As seen in the results of the table, each example in which the insulating substrate was formed with aromatic polytriazine obtained by polymerizing polyaromatic cyanate was different from that in which the insulating substrate was formed with polyamide resin. It is confirmed that the dielectric constant and dielectric loss tangent are lower than those of Comparative Example 1, and each Example in which a flame retardant was blended with polyaromatic cyanate was compared to Comparative Example 2 in which no flame retardant was blended. 94V from the HB level of
It is confirmed that the flame retardance is increased to a level of 0, and that the glass transition temperature and heat resistance temperature are maintained at high levels without significant deterioration.

【Effect of the invention】

As mentioned above, in the present invention, the laminate is manufactured by blending and using the polyaromatic cyanate of the formula () with the flame retardant of the formula (). Due to the low dielectric constant and dielectric loss tangent of the polymer, the high frequency properties of the laminate can be ensured, and by adding a flame retardant, the flame retardant grade of the laminate can be increased. 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, 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: