JPH104268A - Method of manufacturing multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the adhesive force between an inner layer circuit copper foil and an under coat by a method wherein, after coat drying the circuit surface of a circuit made copper clad laminated board with a specific under coat agent, prepregs made of epoxy resin impregnated and dried up are laminated and pressed on the board. SOLUTION: After the circuit surface of a circuit made copper clad lamination board is coat dried up with an undercoating agent comprising essential components exceeding one kinds out of epoxy resin, aromatic polyamine having ether coupling as a hardener, 2-undecylic imidazole, 1-cyanoethyl-2-undecylic imidazole, 2,4-diamino-6- 2'-undercylic imidazolle (1')}ethyl-s-triazine as a hardener, prepregs made of epoxy resin impregnated and dried up on a substrate are overlapped to be laminated and pressed. Through these procedures, satisfactory adhesion to the copper foils can be secured by the combination of end two functional normal chain type epoxy resin in a specific molecular weight, a specific aromatic polyamine and a specific imidazole compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board which has excellent adhesion between an inner layer circuit copper foil and an undercoat agent and can eliminate the need for black processing.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a multilayer printed wiring board, generally, a circuit surface of a copper-clad laminate having a circuit processed to be laminated on an inner layer is subjected to an oxidation treatment called a so-called black treatment. After roughening the circuit surface, one or more prepregs coated, impregnated and dried with a thermosetting resin applied to the substrate are overlaid, and a metal foil is overlaid on the top surface,
Pressing was performed using a heated hot platen. The purpose of the black treatment is to obtain good adhesion to the prepreg. Since the inner layer circuit not subjected to the black treatment and the prepreg have little adhesion, the black treatment is an essential technology. However, this technique is based on the oxidation phenomenon of the copper foil of the inner layer circuit board due to the chemical treatment. Basically, it is very difficult to control the process, and furthermore, a large amount of equipment investment and running cost are required. . Further, it has been pointed out that copper oxide has a weak acid resistance and a low physical strength, so that problems are likely to occur during multilayer molding, drilling or through-hole plating.

As a method of manufacturing a multilayer printed wiring board for forming a resin layer on a circuit surface of an inner layer copper-clad laminate processed by a circuit as shown in the present invention, Japanese Patent Application Laid-Open No. 53-132772
JP, JP-A-60-62194, JP-A-63-10
In each of the techniques, the goal is to improve the withstand voltage, the halo resistance, the heat dissipation, and the thickness of the insulating layer by reducing the voids during molding. This is for a completely different purpose from the present invention.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a multilayer printed wiring board capable of improving the adhesion between an inner layer circuit copper foil and an undercoat agent, thereby eliminating the need for black processing. Yes, in multi-layer printed wiring boards, undercoat agent to solve the problems of adhesion with inner layer copper foil, especially inner layer copper foil not subjected to black treatment, moisture absorption heat resistance, plating solution resistance and delamination As a result of diligent studies on the composition of the present invention, the present invention has been achieved.

[0005]

SUMMARY OF THE INVENTION The present invention provides a multilayer printed wiring in which a prepreg impregnated with a thermosetting resin on a substrate and dried is laminated on a circuit-processed single-sided or double-sided copper-clad laminate. In the method for manufacturing a board, (1) epoxy resin,
(2) an aromatic polyamine having an ether bond or an ether bond and a sulfone bond as a curing agent, and (3)
2-undecylimidazole, 1-
Cyanoethyl-2-undecylimidazole and 2,4
-Diamino-6- {2'-undecylimidazole-
(1 ') An undercoat agent containing at least one of ethyl-s-triazine as an essential component is applied, and a prepreg obtained by impregnating an epoxy resin with a base material and drying on one or both surfaces is laminated. The present invention relates to a method for manufacturing a multilayer printed wiring board to be pressed.

Hereinafter, the present invention will be described in detail. The object of the present invention is to eliminate the need for black processing of the inner layer circuit copper foil by improving the adhesion between the inner layer circuit copper foil surface and the undercoat agent, as described in the section of the problem to be solved by the invention. It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board which can be performed. The present inventor has conducted intensive studies on the composition of the undercoat agent. As a result of performing the black treatment, of course, even if the black treatment is not performed, the terminal bifunctional linear epoxy resin having a certain molecular weight, It has been found that a combination of an aromatic polyamine and a specific imidazole compound can ensure sufficient adhesion and heat resistance to the inner layer circuit copper foil.

As the epoxy resin, any epoxy resin can be used as long as it is used for ordinary laminated boards. However, in order to obtain sufficient adhesion to the inner layer circuit copper foil and eliminate the need for black processing, Preferably, the average epoxy equivalent is 450
A terminal bifunctional linear epoxy resin having a molecular weight of 6000 or less, typically a bifunctional linear epoxy resin obtained by reacting a bifunctional phenol and epihalohydrin,
There are terminally bifunctional linear epoxy resins obtained by alternate copolymerization reaction of a bifunctional epoxy resin and a bifunctional phenol, and these can be used in combination of several types. For example, bisphenol A epoxy resin, bisphenol F epoxy resin, tetrabromobisphenol A epoxy resin, propylene oxide bisphenol A epoxy resin, bisphenol S epoxy resin, biphenyl epoxy resin, 2,6 naphthol diglycidyl ether polymerization Products, bisphenol A type epoxy resin and tetrabromobisphenol A copolymer, bisphenol F type epoxy resin and tetrabromobisphenol A copolymer, bisphenol S type epoxy resin and tetrabromobisphenol A copolymer, and the like. For flame retardancy, a brominated epoxy resin can be used.

When the aromatic polyamine is used as a hardener, an ether bond or an aromatic polyamine having an ether bond and a sulfone bond is used in consideration of the adhesion to raw copper not subjected to black treatment. The adhesion is improved by about 10 to 20% as compared with the case of the aromatic polyamine. It is considered that this is because any of the bonds does not directly make a chemical bond with the copper element having the oxidation number of 0, but has high chemical affinity. 4,4′-diaminodiphenyl ether, bis [4- (4-aminophenoxy) phenyl] ether as the aromatic polyamine,
4,4′-bis (4-aminophenoxy) biphenyl,
Examples thereof include 1,4-bis (4-aminophenoxy) benzene and bis [4- (4-aminophenoxy) phenyl)] sulfone.

The amount of the aromatic amine to be blended can be used in an equivalent ratio to the epoxy resin in the range of 0.1 to 2.0, but the heat resistance (particularly the solder heat resistance after moisture absorption) and the interlayer adhesion 0.5 to 1.5 is a preferable range in order to achieve both. Usually, the equivalent ratio of the aromatic amine to the epoxy resin is approximately 1, but in the present invention, larger or smaller values can be used. However, if the equivalent ratio is larger or smaller than the range of 0.5 to 1.5, the heat resistance and the adhesiveness tend to be reduced.

Reference will be made to the molecular weight of the epoxy resin.
In consideration of the adhesion to copper that has not been subjected to black treatment, it has been found that the higher the molecular weight, the higher the adhesion, but the solder heat resistance after moisture absorption tends to deteriorate. Although there are some differences in the absolute value depending on the base skeleton of the epoxy resin and the base skeleton of the aromatic polyamine,
This trend remained almost the same. The peel strength of the inner layer circuit required for practical use of epoxy resin multilayer printed wiring boards is generally said to be 0.5 kN / m.
By using the epoxy equivalent of 450, the peel strength of the inner copper foil not subjected to the black treatment was at a practically minimum level. If the average epoxy equivalent exceeds 6000, the necessary moisture absorption heat resistance may not be sufficiently exhibited even though the inner layer peel strength not subjected to the black treatment is at a sufficient level of 1.1 kN / m. . It is considered that this is because the epoxy groups, which are crosslinking sites, are too far apart.

As a curing accelerator for improving the curability of the undercoat agent, an imidazole compound, which is a general curing accelerator for epoxy resins, is used. In the present invention, moisture absorption heat resistance and interlayer adhesion are used. 2-undecylimidazole, 1-cyanoethyl-2-undecylimidazole or 2,4-diamino-6- {2′-
Undecyl imidazole- (1 ′)｝ ethyl-s-triazine is used alone or in combination. Epoxy resin 10
The amount of these curing accelerators is from 0.2 to 0 parts by weight.
0.9 parts by weight is preferred. If the addition amount exceeds 0.9 parts by weight, curing is too fast and moldability deteriorates,
Solder heat resistance and interlayer adhesion after moisture absorption are not compatible, or both characteristics are deteriorated. On the other hand, 0.2
If the addition amount is less than parts by weight, the heat resistance becomes particularly insufficient due to insufficient curing, and the adhesiveness also decreases.

When applying the above composition to the inner circuit board, it is possible to adjust the viscosity with a solvent. Solvent species include acetone, methyl ethyl ketin, toluene, xylene, ethylene glycol monoethyl ether and its acetate compound, propylene glycol monoethyl ether and its acetate, dimethylformamide, methyldiglycol, ethyldiglycol, methanol, ethanol, etc. Is mentioned.

In addition, depending on the application method, an inorganic filler can be blended to impart thixotropy and heat resistance. For example, aluminum hydroxide, hydrated silica, alumina, antimony oxide, barium titanate,
Colloidal silica, calcium carbonate, calcium sulfate,
Examples include mica, silica, silicon carbide, talc, titanium oxide, quartz, zirconium oxide, zirconium silicate, boron nitride, carbon, graphite, and the like.

[0014] A coupling agent can be added for improving the adhesion to copper or the adhesion to the inorganic filler. As the coupling agent, a silane coupling agent,
Titanate-based coupling agents, aluminum chelate-based coupling agents, and the like can be used. For example, chloropropyltrimethoxysilane, vinyltrichlorosilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, N -Β- (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, isopropyltriisostearoyl titanate, isopropyltrimethacrylate titanate, isopropyltri (dioctylphyrophosphate) titanate, isopropylisostearoyldi ( 4-aminobenzoyl) titanate and the like.

It is also possible to add a silicone type antifoaming agent, an acrylic type antifoaming agent, a fluorine type surfactant or the like for defoaming or breaking. Furthermore, it is generally known that toughness is very effective for improving the peel strength with a copper foil. For example, terminal carboxyl-modified butadiene acrylonitrile rubber (CTB manufactured by Ube Industries, Ltd.)
N), an epoxy-modified polybutadiene rubber or the like can be added.

The method of applying the undercoat agent includes a roll coater, a curtain coater, a casting method,
There are methods such as spinner coater and screen printing,
Coating is possible by either method. Further, the method is not limited to the above-described coating method as long as the method can apply the inner circuit surface without leakage. In any method, since the undercoat agent has an optimum viscosity required, it is necessary to adjust the reactive diluent, the type of the solvent, the type of the inorganic filler, the particle size, and the amount of the compound depending on the application method. .

The cured state of the undercoat agent will be described. The cured state is generally A, which is a completely uncured state.
It can be divided into a stage state, a B-stage state which is a semi-cured state, a gel state which has been further cured, and a C-stage state which is a completely cured state. Although any state can be used for this purpose, handling is facilitated by proceeding the reaction in a tack-free state or higher.

By using the undercoating agent of the present invention, the black processing conventionally required for a multilayer printed wiring board can be eliminated. Therefore, it is expected that the number of man-hours spent for quality control in the black processing step and the production cost are reduced, and the absence of black processing does not cause a halo phenomenon, so that high-density wiring can be easily achieved. Furthermore, since the undercoat layer is formed on the upper surface of the circuit-processed copper-clad laminate, the circuit pattern gap can be filled with resin in advance, so that bubbles remain even when prepregs are stacked and laminated. It can be molded without causing it to form. Accordingly, the amount of resin of the prepreg and the fluidity during heating have been changed depending on the residual ratio of the copper foil in the inner layer circuit, but this is no longer necessary. That is, since the thickness accuracy does not depend on the residual ratio of the copper foil in the inner layer circuit, it is possible to use only a small number of types of prepregs, so that the prepregs can be stored and managed in a small variety.

Further, the time required for filling the etched portion of the inner layer copper foil of the prepreg becomes unnecessary. Conventionally, since it is necessary to secure time for defoaming, the heating rate is 2 to 5 ° C /
The press time was 140 minutes or more because the time was set to 1 minute. However, in the present invention, the heating time can be increased to 6 to 15 ° C./min. As a result, the manufacturing cost is greatly reduced, and the man-hours spent on quality control and inventory control are also significantly reduced.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

Example 1 100 parts by weight of diglycidyl ether bisphenol A (epoxy equivalent: 925) was dissolved in 120 parts by weight of butyl cellosolve acetate. 5.9 parts by weight of 4,4'-diaminodiphenyl ether (1 equivalent to the epoxy resin) was added thereto, and the mixture was easily dissolved by stirring. Further, 2,4-diamino-6
{2′-undecylimidazole- (1 ′)} ethyl-
0.5 parts by weight of s-triazine, 80 parts by weight of hydrophobically treated calcium carbonate having an average particle diameter of 1.2 μm, 20 parts by weight of ultrafine silica R-972 (manufactured by Nippon Aerosil Co., Ltd.)
After adding 1 part by weight of γ-glycidoxypropyltrimethoxysilane, the mixture was kneaded with a three-roll mill. Defoaming was performed with a vacuum defoamer at a degree of vacuum of 3 mmHg for 5 minutes to obtain an undercoat agent.

Next, the substrate thickness is 0.1 mm and the copper foil thickness is 35 μm.
The surface of the glass-epoxy double-sided copper-clad laminate was polished and soft-etched to remove the rust-preventive treatment, and then processed by etching. Usually, black processing is performed after this circuit processing, but the black coating is not applied, and the undercoat agent is screen-printed on one side of the inner circuit board.
After heating at 0 ° C. for 5 minutes to make it tack-free, an undercoat agent was applied to the opposite surface in the same manner.
Heat drying at 20 ° C for 20 minutes.

Further, a 100 μm thick FR-4 prepreg (EI-6765, manufactured by Sumitomo Bakelite Co., Ltd.) impregnated with an epoxy resin and dried is superposed on both sides of the dried undercoat agent one by one. Then, a copper foil having a thickness of 18 μm was stacked one by one on the upper surface, and the material was heated and cured by a vacuum press at a maximum temperature of 170 ° C. for 80 minutes including temperature rise and cooling to obtain a multilayer printed wiring board. .
The characteristics were evaluated, and the results are shown in Table 1. Since no oxidation treatment was applied to the inner circuit board, no halo phenomenon occurred when through-hole plating was performed.

(Examples 2 to 9) A multilayer printed wiring board was prepared in the same manner as in Example 1 except that the resin composition of the undercoat agent was changed as shown in Table 1, and the characteristics were evaluated. . Table 1 shows the respective resin compositions and evaluation results. As in the first embodiment, no halo phenomenon occurs.

[0025]

[Table 1]

C11Z: 2-undecylimidazole C11ZA: 2,4-diamino-6 {2'-undecylimidazole- (1 ')} ethyl-s-triazine C11Z.CN: 1-cyanoethyl- 2-undecylimidazole

(Comparative Example 1) 4,4'-Diaminodiphenyl ether was blended with 1 equivalent (5.9 parts by weight) to the epoxy resin, and 2-ethyl-4-methyl was used as an imidazole compound as a curing accelerator. An undercoat agent was obtained in the same manner as in Example 1 except that imidazole was used.
Hereinafter, a multilayer printed wiring board was manufactured in the same manner as in the example. Table 2 shows the evaluation results of the characteristics. No halo phenomenon occurred as in the example.

(Comparative Examples 2 to 6) A multilayer printed wiring board was produced in the same manner as in Example 1 except that the resin composition of the undercoat agent was changed as shown in Table 2, and the characteristics were evaluated. . Table 2 shows the respective resin compositions and evaluation results. No halo phenomenon occurred as in the example.

(Comparative Example 7) An inner layer circuit board was produced in the same manner as in the Examples and Comparative Examples except that no undercoat agent was applied and oxidation treatment was carried out, thereby producing a multilayer printed wiring board. . Table 2 shows the evaluation results of the characteristics. The halo phenomenon occurs due to the oxidation treatment.

Comparative Example 8 A multilayer printed wiring board was prepared in the same manner as in Comparative Example 5, except that the inner surface circuit board was subjected to an oxidation treatment (black treatment) on the circuit surface. Table 2 shows the evaluation results of the characteristics. The halo phenomenon occurs due to the oxidation treatment.

[0031]

[Table 2] DDDDM: 4,4'-diamino-3,3'-diethyl-
5,5'-dimethyldiphenylmethane 2E4MZ: 2-ethyl-4-methylimidazole

(Measurement method) Formability: circular etched part with a diameter of 20 mm (A)
After preparing a multilayer printed wiring board using an inner circuit board having 100 pieces, etching the surface copper foil, observing the presence or absence of voids in A, and determining the void generation rate (%) from the number of voided A. I asked. 2. Interlayer adhesion: A multilayer printed wiring board was prepared by the method described in the Examples or Comparative Examples except that an inner layer circuit board having a circuit only on one side was used, and the inner layer circuit board and the prepreg were peeled off. The peel strength was determined, and the result was defined as interlayer adhesion. 3. Moisture absorption solder heat resistance: PCT treatment of multilayer printed wiring board (125 ° C, 0.5 hours) and solder bath at 260 ° C
After immersion for 2 seconds, the presence or absence of blisters was observed.

(Evaluation Criteria) Evaluation was made according to the evaluation criteria shown in Table 3.

[Table 3]

[0034]

According to the method for manufacturing a multilayer printed wiring board of the present invention, the adhesion between the copper foil and the undercoat agent is excellent by using the specific undercoat agent as described above. Therefore, the black processing, which has been required for manufacturing a conventional multilayer printed wiring board, becomes unnecessary. Therefore, since the halo phenomenon does not occur, high-density wiring can be easily achieved, and further, the man-hours spent for quality control in the black processing step can be reduced,
It is expected that production costs will be reduced. In addition, since an undercoat agent is applied in advance to bury the steps in the inner circuit, there are no air bubbles in the gaps between the circuits, and voids are generated even without long-time pressurization by a conventional vacuum press. Without doing so, good moldability can be obtained.
At the same time, it is not necessary to change the type of prepreg according to the residual copper foil ratio of the inner circuit, so that the manufacturing time of the multilayer printed wiring board can be significantly reduced. In addition, it is expected that the road to the automation of the prepreg set, which requires a huge amount of man-hours at present and is performed manually, will be opened.

Claims (3)

[Claims] 1. A method for producing a multilayer printed wiring board, comprising laminating a prepreg obtained by impregnating a thermosetting resin on a base material and drying the substrate on a circuit-processed single-sided or double-sided copper-clad laminate, and laminating and forming the circuit. On the circuit surface of the processed copper-clad laminate, (1) an epoxy resin, (2) an aromatic polyamine having an ether bond or an ether bond and a sulfone bond as a curing agent, and (3) 2-one as a curing accelerator. Undercoat containing at least one of decyl imidazole, 1-cyanoethyl-2-undecylimidazole and 2,4-diamino-6- {2'-undecylimidazole- (1 ')} ethyl-s-triazine as an essential component After applying and drying the agent, the epoxy resin is impregnated into the base material, and the dried prepregs are overlapped and laminated and pressed. Method of manufacturing the plate. 2. An epoxy resin having an average epoxy equivalent of 45
2. The method for producing a multilayer printed wiring board according to claim 1, wherein the epoxy resin is a bifunctional linear epoxy resin having a terminal number of 0 or more and 6000 or less. 3. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the copper-clad laminate processed with a circuit is not subjected to an oxidation treatment.