JPH01299837A - Production of laminate - Google Patents

Abstract

PURPOSE:To obtain a laminate retaining a low permittivity, a low dielectric loss tangent and high heat resistance and having increased flame retardancy, by laminate-molding prepregs formed from a varnish prepared by mixing a specified poly(aromatic cyanate) with a flame retardant and a catalyst and base material in a specified manner. CONSTITUTION:A varnish is prepared by mixing a poly(aromatic cyanate) of formula I with a flame retardant of formula II, a flame retardant of formula III and a reaction catalyst for the poly(aromatic cyanate). Base materials are impregnated with this varnish to form long belt-like prepregs, which are laid upon each other and laminate-molded in such a manner that they are continuously fed and taken up under applied heat and pressure to obtain the purpose laminate. In the formulas, Ar is an aromatic, B is a 7-20C polycyclic aliphatic group, D is an active hydrogen-free substituent, q, r and s are each 0, 1, 2 or 3, q+r+s>=2, t is 0-4 and x is 0-5.

Description

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

The present invention relates to a manufacturing method by continuous molding of 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 layer of printed wiring boards used in such high frequency ranges, it is important to have a smaller dielectric constant in order to shorten the signal propagation delay.
Furthermore, in order to reduce the electric power a, 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.
) and other resins, and by impregnating a base material such as plastic cloth with this resin and laminating and molding prepreg, attempts have been made to create a laminate that will serve as an insulating layer for a printed wiring board. In addition, it is effective to increase the resin content in the prepreg to reduce the dielectric constant of the laminate that becomes the insulating layer.In other words, it is effective to increase the resin content in the prepreg. If the volume fraction of the lath cloth base material is vc, the dielectric constant of the resin is εR1, and the dielectric constant of the lath cloth base material is εG, then the dielectric constant ε of the entire laminate is as follows: logε= VRlogεp + V C1ogε0
In general, the dielectric constant εR of resin is a positive dielectric constant CG
(Incidentally, the dielectric constant of the polymer of formula (■) of the present invention is about 2.8, whereas the dielectric constant of E plus dielectric constant is 7.23, and the dielectric constant of D glass is 4.74. ), the resin body, the integral ratio ■8 becomes larger, and the volume fraction vc of the lath cloth base material becomes smaller, the dielectric constant ε of the entire laminate becomes smaller (
On the other hand, the specific gravity of glass is about 2.2, the specific gravity of resin is about 1.4, and if the resin content is x% by weight, then V R = (x/ 1.4) / ((x / 1.4
)+(100-x)/2.21VC=1-VR, so the larger the The yI electric conductivity line of the entire plate becomes smaller.

Problems to be Solved by the Invention However, when forming an insulating layer using the above-mentioned resins, these have a low positive transition temperature (Tg) of about 180 to 200°C, and have insufficient heat resistance, and when processing through-holes. There are problems such as the occurrence of smear and the inability to obtain high reliability of through holes, making it impossible to form them into multilayer printed wiring boards. In addition, as mentioned above, it is advantageous to increase the resin content in order to lower the dielectric constant, and therefore it is desirable to manufacture a laminate using prepreg with a high resin impregnation rate. In the case of laminated molding using a multi-stage press, a large amount of resin flows during heating and pressure molding, which tends to cause slippage between the eyebrows of the prepreg, and when the resin content is 45 to 50% by weight or more, molding is almost impossible. becomes impossible. For this reason, there is a limit to increasing the resin content when molding is performed using a multistage press. 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 first objective is to increase the resin content and mold it, and the second objective is to lower the dielectric constant (as low as 5). [Means for Solving the Problems] The present invention provides a polyaromatic cyanate represented by the following formula (I), (wherein ^r is aromatic, B is C) ~2° polycyclic aliphatic group, D is each independently a substituent containing no active hydrogen, qtr
, s are each independently an integer from 0.1.2 or 3, provided that the sum of QyrvS is greater than or equal to 2, and t is each independently an integer from 0 to 4. X is a number from θ to 5) A flame retardant represented by the following formula (n), (wherein 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 (I The present invention relates to a method for manufacturing a laminate, which comprises impregnating the prepreg to create a long strip-shaped prepreg, stacking a plurality of prepregs, continuously feeding them while taking them off, and heating and pressurizing them to form a laminate. The present invention will be explained in detail below. As the polyaromatic cyanate represented by formula (I), those disclosed in Patent Application Publication No. 1988-500434 can be used. That is, this polyaromatic cyanate provides an aromatic polytrianone (polyaromatic cyanate) 41 resin which is more stable against hydrolytic action and has excellent thermal stability than conventional polytrianone. In the polyaromatic cyanate of formula (1) used in the present invention, the aromatic group A" means any group containing an aromatic group, such as benzene, naphthalene, 7-enanthracene, anthracene, or Aromatic groups, two or more aromatic groups bridged by alkylene moieties, preferably benzene, naphthalene, biphenyl, vinyl, diphenylalkylene groups, and particularly preferably benzene groups. The C2-2o 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. Preferably, Dl is C1
... is an alkyl group of. ), especially (a) (b) (c
)(d)(e)(f)(g) or (1) is preferred, more preferably (a)(b)(c)(d)(1)
In particular, the latter (a) is preferable. D in formula (1) 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, flukoxy, nitro, carboxylate, sulfone, sulfide, carbonate, etc., preferably C8~. Alkyl %CI~1
The most preferred are alkenyl of °, nitro, halo, 7)'), alkyl of C1-3, alkynyl of C1-, bromo, and ricolo. Further, in formula (I), ``-'' is an integer from 0 to 4, and - is preferably an integer of 0.1 or 2, more preferably 0.
or 1, optimally 0. Each ( in formula (1) is defined independently. q%rs s is an integer of 0.1.2 or 3, and optimally is 1. q%rs S is independently defined. However, the sum of these is set to be 2 or more. Furthermore, X is a positive number from 0 to 5". The polyaromatic cyanate of formula (t) is a compound where X is 0 to 5*. and X is defined as the average number of this mixture.A preferred embodiment of the polyaromatic cyanate of formula (I) is represented by the formula Therefore, aromatic polytrianone (polyaromatic cyanate resin) obtained from polyaromatic cyanate of formula (1)
has a low dielectric constant CC2, around 78) and a low dielectric loss tangent (t
It has excellent properties as a resin constituting the insulating substrate of a printed wiring board, including an δ of about 0.003) and high heat resistance (lass transition temperature Tg of 250 or more, oven heat resistance of about 300° C.). Therefore, in the present invention, a flame retardant represented by formula (ff) and a flame retardant represented by formula (II[) are further blended to impart flame retardant properties required for printed wiring boards. It is. In the 7-eth/oxy-terminated tetrapromobisphenol A carbonated oligomer of formula (It), R and R' are aromatic or brominated aromatic substituents containing no active hydrogen, such as B' (R, is B', CH,, C2Hs, etc., or a combination of these, and the number is an integer of 1, 2, or 3).Also, in formula (n), n is a positive number that is not particularly limited, but Currently available items are n=10~
20 mixtures. Other values of n can also be used. The flame retardant effect of formula (If) or formula (1) flame retardant formulation depends on the amount of Br, and in order to obtain flame retardancy at the level of UL standard 94v-0, formula (1) The flame retardant of formula (II) is added so that the content of Br is 5 to 10% by weight based on the total amount of the polyaromatic cyanate and the flame retardant of formula (n) and formula (I[[), It is preferable to mix the flame retardants of formula (III) so that the Br content is 3 to 10% by weight.The flame retardant of formula 6 (■) should be blended so that the Br content is 5 to 10% by weight. In order to blend the flame retardant of formula (III) so that the Br content is 3 to 10% by weight, the compound should be blended in an amount of 10 to 20% by weight. The amount is generally set at 6-20% 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 a reaction catalyst for polymerizing the polyaromatic cyanate of formula (I), it is possible to use imidazoles, tertiary amines, and organic metal salts such as organic cobalt salts such as cobalt naphthenate and cobalt octylate. 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 (1) may be adjusted depending on the desired deltime of the varnish (described later). 10 to 700 pp- by weight ratio of
It is blended within a range of degrees. And the polyaromatic cyanate of the above formula (I), the formula (I[
) and the flame retardant of the formula (I[[), and a reaction catalyst, etc., are dissolved in an organic solvent to prepare a varnish. Examples of organic solvents include aromatic hydrocarbons, alcohols, as long as they dissolve the polyaromatic cyanate of formula (1) and the flame retardants of formulas (II) and (1) and do not adversely affect the reaction.
It is not particularly limited to 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 the varnish is 50 to 70% by weight of solids.However, when preparing prepreg, there are no particular restrictions on the base material, but it is common to use plush fiber fabric or nonwoven fabric. This base material is impregnated with 7 varnish and dried by heating. It is common for E to use lath as the plus that makes up the glass fiber, but E
The dielectric constant of ff lath is 7.23, while the dielectric constant of D plus is as low as 4.47, so it is desirable to use the plus fiber of D plus from the viewpoint of dielectric constant. However, lath fibers with E being lath are superior in terms of processability and cost. Although Qlf lath has an extremely low dielectric constant of 3.89, it is not practical in terms of processability and cost. The amount of varnish impregnated into the base material is such that the ratio of solid content (compound of formula (I) and compound of formula (II) and formula (I[[)) to the base material is 50% by weight.
It is preferable to set the dielectric constant to ~70% by weight. By increasing the resin content, the dielectric constant can be lowered as described above. For example, if E is a lath cloth as the base material,
The dielectric constant of the laminate is about 3.3 to 3.6, and the dielectric loss tangent is 0.
When Dff lath plus cloth is used as the base material, the dielectric strength of the laminate is 3.
．． 1 to 3.4, dielectric loss tangent 0°001 to 0.005
It can be done to a certain extent. Resin impregnation rate is too high. Since the resin tends to foam and become uneven during molding, it is preferable to set the upper limit of the impregnation rate to 70% by weight as described above. The heating and drying conditions when preparing prepreg are influenced by the amount of reaction catalyst mixed, etc.
In the present invention, since molding is carried out by a continuous molding press, it is preferable to advance the reactivity of the prepreg slightly more than in the case of a multistage press, for example, at 170°C.
It is preferable to set the reactivity of the prepreg so that the gel time at 170°C is about 45 to 70 seconds.To set the reactivity of the prepreg to this level, the gel time of the varnish at 170°C is about 3 to 4 minutes. It is recommended to set it to . In the present invention, a prepreg is prepared in the form of a long strip using a long strip as a base material, and it is preferable to store it by winding it into a roll. Then, a laminate can be manufactured using a continuous molding press, for example, as shown in FIG. Fig. 1 shows a continuous forming press device of the group belt type, which is equipped with a pair of upper and lower steel belts 1.1, in which a plurality of sheets of prepreg 2, 2, etc. are continuously fed out from a roll, and as they are stacked on top of each other, Furthermore, long strip-shaped metal foils 3 are superimposed on both or one side of the upper and lower sides, and these are continuously introduced between the steel belts 1 and 1. steel belt 1,1
A heating device is installed on the steel belt 1゜1.
In the meantime, the prepreg 2 is heated while being pressurized, and the polyaromatic cyanate impregnated into the prepreg 2 polymerizes and hardens, and a plurality of prepregs 2 are laminated and a double-sided metal foil cladding with metal M3 bonded to the outer layer is formed. Alternatively, a laminated plate 4 coated with metal foil on one side is formed. The laminate 4 is cooled while being pulled out from between the steel belts 1 by a cooling roll 5, and further cut into a predetermined length by cutting W16. In this way, in the continuous forming press method, the prepreg 2 is heated and press-formed between the steel belts 1 and 1 while the tension force is applied by taking it off. Free movement such as slipping will not occur (molding is done. Therefore, even if a material with a high resin content is used as the prepreg 2, slipping will occur in the opening of the prepreg 2 due to the flow of resin as in the case of a multi-stage press. There is no risk that this will occur,
The prepreg 2 with a high resin impregnation rate can be used to form a laminate 4 with a high resin content. Here, the metal foil is an aluminum carrier with shoulders! 19μ
Thick copper foil, 18μ thickness, 35μ thickness, 70μ thickness, 105μ thickness
Thick and roughened on both sides! 1! Foil etc. can be used. In addition, the molding conditions in this continuous molding press are as follows: molding temperature 170
It is common to set the temperature to ~230°C, a molding pressure of 10 to 50 kg/am'', and a molding time (passage time between the steel belts 1 and 1) of about 2 to 3 minutes. Double-sided metal molded as described above The inner layer printed wiring board 7 can be created by forming the circuit 8 by etching the metal foil 3 of the laminated board 4 which is foil-covered or one-sided metal foil-covered. A multilayer printed wiring board can be created by stacking a plurality of inner layer printed wiring boards 7 via the prepreg 2 and stacking the metal foil 3 on the outermost layer, and molding them under heat and pressure.The molding conditions are as follows: , heating temperature from 170℃
Generally, the temperature is set at 230°C, the pressure is set at a maximum pressure of about 30-40 kg/cm2, and the time is set at about 90-120 minutes. When 77 turquoise is carried out at a temperature of about 220 to 230°C after molding, a molding temperature of about 170 to 180°C is sufficient. [Examples] The present invention will be explained in detail below using examples. A mixture of 78 parts by weight of a polyaromatic cyanate (XU-71787, manufactured by Gutsu Chemical Co., Ltd.) represented by the following formula, in which R and R′ are formula (b) in formula (II), and n is 10 to 20. 15 parts by weight of a flame retardant (brominated carbonate oligomer; Be-58 manufactured by Great Lakes), a flame retardant with n=0 in the formula (I[[) (tetrabromobisphenol A: T
7 parts by weight of BBA) were taken (total Br content was 13
% by weight), these were combined with methyl ethyl ketone and N,N
The mixture was stirred and dissolved in a 1 layer 1 mixed solvent of '-trimethylformamide so that the solid content was 60 parts by weight, and cobalt octylate was added thereto as a reaction catalyst at a weight ratio of 300 ppm of cobalt ions to polyaromatic cyanate. hand,
A varnish was prepared. Apply this varnish to a long 2116 type Eff lath cloth base (
116E (manufactured by Nittobo Co., Ltd.) so that the solid content (polyaromatic cyanate and flame retardant) was 63% by weight.
A prepreg was prepared by heating and drying at 60° C. for 4 minutes. The gel time of this prepreg at 170°C was 60 seconds. The long belt-shaped prepreg thus produced was then wound into a roll. Next, these four sheets of prepreg are pulled out from the roll and stacked, and a long double-sided roughened copper foil of 70μ thickness is layered on both sides of the top and bottom, and this is continuous between the steel belts of the gruple belt as shown in Figure 1. The molded material was heated and pressure molded while being removed with a cooling roll. The molding conditions were a heating temperature of 200°C, a molding pressure of 25 kg/am'', and a molding time of 2 minutes (feeding speed 2 m/min). It is cooled under pressure at 140℃ with a pressure of 40kg/Cm'', then cut with a cutting device, and then electrically opened!
A double-sided steel-clad laminate for an inner layer printed wiring board having a thickness of 0.5 mm was obtained by subjecting the product to 77 cycles at 230° C. for 2 hours. K (2116 type Dff lath cloth base material (manufactured by Nittobo Co., Ltd., WDX) instead of 2116 type ETF lath cloth base material as the base material)
-723) was used to create the prepreg, but the same process as in Example 1 was carried out to form and press the prepreg to a thickness of 0.5 m.
- A double-sided copper-clad laminate for an inner layer printed wiring board was obtained. An inner layer printed wiring board was created by etching the II4 foil of the double-sided copper-clad laminate obtained in Example 1 to form a circuit. The two sheets of prepreg obtained in Example 1 are overlapped, and two more sheets of prepreg are placed above and below them.
Copper foils with a thickness of 8 μm were stacked, and this was layered using a bottle lamination method to position the area between the eyebrows, and multi-stage press molding was performed under the conditions of a molding temperature of 170°C, a molding pressure of 40 kg/am2, and a molding time of 90 minutes. Furthermore, after molding, it was heated in an electric oven at 230°C for 2 hours with 77 Turkey Air, resulting in a thickness of 2.0II! A multilayer printed wiring board having a circuit configuration of 8 layers was obtained. The same process as in Example 3 was carried out, except that an inner layer printed wiring board made from the double-sided copper-clad laminate obtained in Example 2 was used, and the prepreg prepared in Example 2 was then used. No. 8
A multilayer printed wiring board with a circuit configuration of layers was obtained. Δ1 Juice L A polyimide resin varnish was prepared by dissolving polyamide 7 bismaleimide resin (Kelimide 601 manufactured by Nippon Polyimide Co., Ltd.) in N-methyl-2-pyrrolidone so that the solid content was 601i% by weight. This varnish was applied to the same D as in Example 2.
A terrace base material was impregnated with a resin content of 45% by weight and dried in the same manner as in Example 2 to create a prepreg. Next, five sheets of this prepreg were stacked and 7 layers were applied on both the upper and lower sides.
Double-sided roughened copper foils with a thickness of 0 μ were stacked and laminated by multi-stage press molding at a molding temperature of 170°C, a molding pressure of 40 kg/cm”, and a molding time of 90 minutes, followed by an electrical open circuit at 200°C for 2 hours. A double-sided copper-clad laminate for an inner-layer printed wiring board with a thickness of 0.5 mm was obtained by subjecting the laminate to a double-sided copper-clad laminate with a thickness of 0.5 mm.The foil of the double-sided copper-clad laminate thus obtained was etched to form a circuit. An inner layer printed wiring board is created by doing this, and the two inner layer printed wiring boards are stacked with the same three prepregs as above interposed between them, and 18μ thick copper is placed above and below them via three additional prepregs. The foils were layered and laminated under the same conditions as above, and further heated at 77°C for 2 hours at 200°C.
A multilayer printed wiring board having a circuit configuration of 8 layers and having a thickness of 2.01 mm was obtained by turquoising. A varnish was prepared in the same manner as in Example 1 using only the polyaromatic cyanate (XU-71787 manufactured by Dow Chemical Company) used in Example 1. After that, a 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 form a double-sided inner layer printed wiring board with a thickness of 0°51 m. A copper-clad laminate was obtained. Thoughts 1” A polyaromatic cyanate of the formula (1) same as in Example 1, a polyaromatic cyanate of the formula (
n) and a flame retardant of formula (I [[), 75 parts by weight of polyaromatic cyanate of formula (1) and 1 part of flame retardant of formula (n)
2.5 parts by weight and 12.5 parts by weight of a flame retardant of the formula CI A varnish was prepared by dissolving in a mixed solvent with stirring so that the solid content was 60% by weight, and adding cobalt heptanoate as a reaction catalyst to the mixture at a weight ratio of 150 ppm of cobalt ions to the polyaromatic cyanate resin. A prepreg was prepared by impregnating a 2116 type E lath cloth base material with this varnish to a solid content of 45% by weight and heating and drying it at 150°C for 4 minutes. Five sheets were stacked together, and double-sided roughened copper foil with a thickness of 70μ was stacked on both the top and bottom sides, and the molding temperature was 170℃.
Laminate molding was performed in a multi-stage press under the conditions of a molding pressure of 40 kg/c theory 2 and a molding time of 90 minutes, and after molding, the inner layer was printed with a thickness of 0.511 Ial by 77 turrets at 230°C for 2 hours in an electrical open circuit. A double-sided copper-clad laminate for wiring boards was obtained. The electrical properties, thermal properties, etc. of the laminates of Examples 1 to 4 and Comparative Examples 1 to 3 obtained as described above were measured, and the results are shown in barley. For barley, dielectric constant, dielectric loss tangent, flame resistance, and open heat resistance were measured based on JIS C6481. In addition, as seen in the results of the viscoelasticity table, the glass transition temperature was determined for each example in which the insulating substrate was formed from aromatic polytriazine (polyaromatic cyanate resin) obtained by polymerizing polyaromatic cyanate. It has been confirmed that the dielectric constant and dielectric loss tangent are lower than those of Comparative Example 1 in which the insulating substrate is formed of polyimide resin, and the positive transition temperature and heat resistance temperature are also maintained at high levels. In addition, in each example in which a flame retardant was blended with polyaromatic cyanate, in Comparative Example 2 in which a flame retardant was not blended.
It is confirmed that the flame retardancy increases from the HB level of 94V-0. As is clear from the comparison between Example 1 and Comparative Example 3,
It is confirmed that the dielectric constant of Example 1, which was manufactured by continuous molding press so as to have a high resin content, can be lowered than that of Comparative Example 3, which was manufactured by multistage pressing and had a low resin content.

【Effect of the invention】

As mentioned above, in the present invention, by laminating and molding a prepreg made from a varnish prepared by blending the polyaromatic cyanate of the formula (1) with the flame retardants of the formulas (II) and (III), Since we started manufacturing laminates,
Due to the low dielectric constant and dielectric loss tangent of the polyaromatic cyanate polymer, high frequency characteristics of the laminate can be ensured, and the flame retardant grade of the laminate can be increased by adding a flame retardant. , it is possible to maintain a high level of heat resistance.Also, since the molding is performed using a continuous molding press that heats and presses multiple sheets of the prepreg as described above and continuously feeds them while taking them off, the prepreg is Heat and pressure molding is performed without slipping between the prepregs due to tension, and even if prepregs with a high resin content are used, slipping will occur between the prepregs. It is possible to mold without such fear, and it is possible to mold a laminate with a high resin content (and a lower dielectric constant) using prepreg with a high resin impregnation rate. It is.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a continuous molding method using a gruple belt method, and FIG. 2 is a schematic diagram showing a laminated structure for manufacturing a multilayer printed wiring board. 1 is a steel belt, 2 is a prepreg, 3 is a metal foil, 4
is a laminate.

Claims (1)

[Claims] (1) The polyaromatic cyanate shown in the following formula (I) has ▲mathematical formulas, chemical formulas, tables, etc.▼...Formula (I) (In the formula, A_r is aromatic. B is a polycyclic ring of C_7_ to_2_0 Formula 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 less than 2. is greater than or equal to 2. t is each independently an integer from 0 to 4. x is 0 to 4.
5) Flame retardants shown in the following formula (II), ▲There are mathematical formulas, chemical formulas, tables, etc.▼...Formula (II) (In the formula, R and R' are aromatic or Brominated aromatic substituent. n is a positive number) The flame retardant shown in the following formula (III), ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼...Formula (III) (in the formula, n is 0, 1 or an integer of 2) A varnish is prepared by blending with a reaction catalyst of polyaromatic cyanate, and a base material is impregnated with this varnish to create a long belt-shaped prepreg, and a plurality of prepregs are stacked and taken off to create a continuous strip. A method for manufacturing a laminate, characterized by carrying out lamination molding by heating and pressurizing while feeding the laminate.