JPH104270A - 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 to be secured by a method wherein, after the circuit surface of a circuit-made copper clad lamination board is coated with a specific under coat agent to be dried up, prepregs made of epoxy resin impregnated and dried up on a substrate are overlapped to be laminate-pressed on the board. SOLUTION: After the circuit surface of a circuit made copper clad lamination board is coat-dried up with an under coat agent comprising essential components such as an epoxy, aromatic polyamine having ether coupling as a hardener, calcium carbonate with the surface thereof made hydrophobic by saturated fatty acid, a coupling agent, etc., as an inorganic filler, prepregs made of epoxy resin impregnate-dried up on a substrate are overlapped to be laminate-pressed. Through these procedures, satisfactory adhesion between the inner layer circuit copper foil and the coat can be secured by the combination of end two functional normal chain type resin in a specific molecular weight, a specific aromatic polyamine and the calcium carbonate made hydrophobic as well as ultrafine particle silica also made hydrophobic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a multilayer printed wiring board, generally, a so-called black treatment is performed on a circuit surface of an inner circuit board on which circuit processing is performed on both surfaces or one surface, After roughening the circuit surface, one or more prepregs obtained by applying, impregnating, and drying a thermosetting resin on a base material are laminated, and a metal foil is further laminated on the upper surface thereof, followed by heating and pressing. The purpose of the black treatment is to obtain good adhesion with the prepreg, and since the inner layer circuit and the prepreg that have not been subjected to the black treatment have almost no adhesion at all, the black treatment is an essential technology. there were. However, this technology is based on an oxidation phenomenon caused by chemical treatment of the copper foil of the inner circuit board. Basically, it is very difficult to control the process, and furthermore, a great deal of equipment investment and running costs are required. You. In addition, copper oxide has weak acid resistance,
In addition, it has been pointed out that problems are liable to occur during multilayer molding, drilling, and through-hole plating due to low physical strength.

Japanese Patent Application Laid-Open No. Sho 53-132772 discloses a method for manufacturing a multilayer printed wiring board in which a resin layer is formed on the circuit surface of an inner-layer copper-clad laminate processed by a circuit as disclosed in the present invention.
JP-A-60-62194, JP-A-63-10879
In any 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 relates to a multilayer printing method in which a prepreg impregnated with a thermosetting resin on a substrate and dried is superimposed on one or both surfaces of a circuit-processed copper-clad laminate and laminated and pressed. In the method for manufacturing a wiring board, (1) an epoxy resin, (2) an aromatic polyamine having an ether bond or an ether bond and a sulfone bond as a curing agent,
(3) As an inorganic filler, calcium carbonate whose surface is hydrophobized with a saturated fatty acid, a coupling agent, or the like; and (4) As an inorganic filler, an ultrafine silica which has been hydrophobized as an essential component. The present invention relates to a method for manufacturing a multilayer printed wiring board, in which a coating agent is applied, and further, a base material is impregnated with an epoxy resin and dried, and prepregs are stacked and laminated and pressed.

Hereinafter, the present invention will be described in detail. An object of the present invention is, as described above, to improve the adhesion between the inner layer circuit copper foil surface and the undercoat agent, thereby making it possible to eliminate the need for black processing of the inner layer circuit copper foil. It is to provide a method. The present inventor has conducted intensive studies on the composition of the undercoat agent.As a result, not only when the black treatment was performed, but also when the black treatment was not performed,
The combination of an epoxy resin, particularly a terminal bifunctional linear epoxy resin having a certain molecular weight, a specific aromatic polyamine, hydrophobized calcium carbonate, and hydrophobized ultrafine silica, allows the inner layer circuit copper foil to be formed. It has been found that sufficient adhesion and heat resistance can be ensured.

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.

As for the aromatic polyamine, when the adhesion to raw copper not subjected to black treatment is taken into consideration, when an aromatic polyamine having an ether bond or an ether bond and a sulfone bond is used as a curing agent, Adhesion is improved by about 10 to 20% as compared with. 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. As the above-mentioned aromatic polyamine, 4,4′-diaminodiphenyl ether, bis [4- (4-aminophenoxy) phenyl] ether, 4,4′-bis (4-
Examples thereof include aminophenoxy) biphenyl, 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 inner layer peel strength required for practical use of epoxy resin multilayer printed wiring boards (FR-4 grade etc.) is generally 0.5k.
It is said to be N / m, and the peel strength of the inner layer not subjected to black treatment was at a practically minimum level by using an epoxy resin having an average epoxy equivalent of 450. If the average epoxy equivalent exceeds 6000, the peel strength of the inner layer not subjected to the black treatment is 1.1 kN / m, which is a sufficient level, but the necessary moisture absorption heat resistance is not exhibited. This is probably because the epoxy groups, which are cross-linking sites, are too far apart. In the present invention, as a filler, the surface thereof is saturated fatty acid, calcium carbonate hydrophobized with a coupling agent and the like, and by blending ultrafine silica hydrophobized, solder heat resistance and Since the interlayer adhesion is improved, epoxy resins having a smaller molecular weight can be used.

The curing accelerator for improving the curability of the undercoat agent is not particularly limited, but an imidazole compound and a phosphine compound are preferably used. Examples of the imidazole compound include 2-methylimidazole, 2-ethyl-4-methylimidazole,
-Phenyl-4-methylimidazole, 2,4′-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)] ethyl-s-triazine, 2-methylimidazole / isocyanuric acid adduct, 2-methylimidazole / trimellitic acid adducts and the like, and phosphine-based compounds include triphenylphosphine and triphenylphosphine phenol salts, and more preferably, 2-undecylimidazole and 1-cyanoethyl-.
2-undecylimidazole or 2,4-diamino-6
-{2'-Undecylimidazolyl- (1 ')} ethyl-s-triazine can be used alone or in combination. The amount of the curing accelerator based on 100 parts by weight of the epoxy resin is preferably 0.2 to 0.9 parts by weight. If the addition amount exceeds 0.9 parts by weight, the curing speed is too fast to deteriorate the moldability, and the solder heat resistance and the interlayer adhesion after moisture absorption are not compatible, or both properties are deteriorated. On the other hand, if the addition amount is less than 0.2 parts by weight, the heat resistance becomes insufficient due to insufficient curing, and the adhesiveness also decreases.

The calcium carbonate used in the present invention, whose surface has been hydrophobized with a saturated fatty acid, a coupling agent or the like, can improve both the solder heat resistance and the adhesion. The hydrophobic treatment is necessary so as not to dissolve into acids such as etching and plating performed during the circuit processing step. The compounding amount per 100 parts by weight of the epoxy resin is 30 to 160.
Parts by weight are preferred. If the amount is less than 30 parts by weight, the effect of improving the heat resistance is insufficient. If the amount exceeds 160 parts by weight, the adhesiveness is reduced, and the appearance after moisture absorption treatment is particularly deteriorated, and peeling may occur. In particular, the best characteristics are obtained in the range of 40 to 100 parts by weight. About the average particle size,
The range of 0.7 to 1.8 μm is preferred. If the thickness is less than 0.7 μm, manufacturing costs are high, and the viscosity of the undercoat agent increases, the amount of the solvent increases, and the appearance after application and drying on a circuit-processed substrate tends to deteriorate, because the viscosity of the undercoat agent increases and the amount of the solvent increases. Not usually used because it is. In addition, 1.8μ
When the average particle size exceeds m, the effect of improving the solder heat resistance and the adhesion is reduced.

Next, the ultrafine silica particles subjected to the hydrophobic treatment will be described. Hydrophobized ultrafine silica refers to SiOH, which is usually present on the surface of particles, and is further converted to a methyl group.
Hydrophobized by a method such as covering with a hydrophobic group such as an ethyl group. The secondary aggregation is small, the dispersibility is good, and the heat resistance due to poor dispersion is less likely to be reduced. It is particularly preferable for improving the moisture absorption heat resistance. The amount of the ultrafine silica is preferably 5 to 30 parts by weight based on 100 parts by weight of the epoxy resin. If the amount is less than 5 parts by weight, the effect of the compounding is small, and if the amount is more than 30 parts by weight, the viscosity of the undercoat agent is increased, so that the amount of the solvent needs to be increased and the heat resistance also decreases. Average particle size is 1
It is preferably from 0 to 19 nm, more preferably from 12 to 16 n
m. In this range, a sufficient heat resistance improving effect is exhibited.

When the above composition is applied to the inner circuit board, the viscosity can be adjusted 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.

Depending on the method of application, an inorganic filler may be added for the purpose of imparting thixotropy and solder heat resistance, in addition to calcium carbonate and ultrafine silica which have been subjected to hydrophobic treatment. For example, aluminum hydroxide, hydrated silica, alumina, antimony oxide, barium titanate, calcium sulfate, mica, silica, silicon carbide, talc, titanium oxide, quartz, zirconium oxide, zirconium silicate, boron nitride, carbon, graphite, etc. As an example, those subjected to a hydrophobic treatment are more favorable.

A coupling agent can be added to improve the adhesion to copper or the adhesion to an inorganic filler.
As the coupling agent, a silane coupling agent, a titanate coupling agent, an aluminum chelate coupling agent and the like can be used. For example, chloropropyltrimethoxysilane, vinyltrichlorosilane, γ-glycidoxypropyltrimethoxy Silane, γ-mercaptopropyltrimethoxysilane, N-β- (aminoethyl)
-Γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, isopropyltriisostearoyl titanate, isopropyltrimethacrylate titanate, isopropyltri (dioctylphyrophosphate) titanate, isopropylisostearoyldi (4-aminobenzoyl) titanate, etc. Is exemplified.

It is also possible to add a silicone-based antifoaming agent, an acrylic-based antifoaming agent, a fluorine-based surfactant or the like for the purpose of defoaming or defoaming. Furthermore, it is generally known that toughness is very effective for improving the peeling strength with a copper foil. For example, terminal carboxyl-modified butadiene acrylonitrile rubber (CTBN manufactured by Ube Industries, Ltd.), epoxy-modified polybutadiene rubber and the like can be added. However, it should be noted that a large amount of the compound tends to decrease heat resistance. .

As a method for applying the undercoat agent, 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, depending on the application method, it is necessary to adjust the reactive diluent, the type of solvent, the type of inorganic filler, the particle size, and the amount of compounding. .

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 undercoat agent of the present invention, it is possible to eliminate the need for the black treatment conventionally required for a multilayer printed wiring board. 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 few types of prepregs.

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.

[0022]

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: 475) was dissolved in 120 parts by weight of ethyl carbitol. There 4,
5.9 parts by weight of 4'-diaminodiphenyl ether (1 equivalent to the epoxy resin) was added, and the mixture was easily dissolved by stirring. Further, 2,4-diamino-6- {2′-
Undecyl imidazolyl- (1 ′)｝ ethyl-s-triazine 0.5 part by weight, calcium carbonate hydrophobized with saturated fatty acid having an average particle size of 1.2 μm (NCC-1010 manufactured by Nitto Powder Chemical Co., Ltd.) 80 parts by weight, average particle size 18
After adding 20 parts by weight of ultrafine silica R-972 (manufactured by Nippon Aerosil Co., Ltd.) and 1 part by weight of γ-glycidoxypropyltrimethoxysilane, the mixture was kneaded with a three-roll mill. 3mmHg by vacuum deaerator
Degassing was performed for 5 minutes at a degree of vacuum of, 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. Normally, black processing is performed after circuit processing. However, the black processing is not performed, 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, apply an undercoat agent to the opposite surface in the same manner,
The resultant was dried by heating at 0 ° 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 superimposed one on each side of the dried undercoat agent. 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 10) A multilayer printed wiring board was produced in the same manner as in Example 1 except that the composition of the undercoat agent was changed as shown in Table 1, and the characteristics were evaluated. Table 1 shows the compositions and evaluation results.
As in the first embodiment, no halo phenomenon occurs.

[0027]

[Table 1] * C11Z * A: 2,4-diamino-6- {2'-undecylimidazolyl- (1 ')} ethyl-s-triazine

Comparative Examples 1 to 8 Laminates were prepared and evaluated in the same manner as in Example 1 except that the composition of the undercoat agent was changed as shown in Table 2. Table 2 shows the compositions and evaluation results.

(Comparative Example 9) 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 10 A multilayer printed wiring board was manufactured in the same manner as in Comparative Example 5, except that the inner surface circuit board was subjected to oxidation treatment (black treatment) on the circuit surface. Table 2 shows the evaluation results of the characteristics.
Shown in The halo phenomenon occurs due to the oxidation treatment.

[0031]

[Table 2] DDDDM: 4,4'-diamino-3,3'-diethyl-
5,5'-Dimethyldiphenylmethane Filler A: Aluminum hydroxide, Filler B: Barium sulfate, Filler C: Calcium carbonate, Filler W: Wollastonite (None of them is hydrophobized)

(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. Outline punching property: A portion 30 to 40 mm from the outer periphery of the multilayer printed wiring board was punched out in a straight line, and the peeling of the undercoat layer was measured. 3. Adhesion: A multilayer printed wiring board is manufactured by the method described in the Examples or Comparative Examples except that an inner layer circuit board having a circuit only on one side is used, and the inner layer circuit board and the prepreg are peeled off. The strength was determined, and the adhesion was determined. 4. Moisture absorption solder heat resistance: PCT treatment of multilayer printed wiring board (125 ° C, 0.5 hours) and soldering at 260 ° C for 20 hours
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]

The method for producing a multilayer printed wiring board of the present invention has excellent adhesion between a copper foil and an undercoat agent.
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,
Further, reductions in man-hours spent on quality control in the black processing step and reductions in production costs are expected. 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.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C08L 63/00 NLD C08L 63/00 NLD H05K 3/38 7511-4E H05K 3/38 E

Claims (5)

[Claims] 1. A method for manufacturing a multilayer printed wiring board, comprising laminating and pressing a prepreg obtained by impregnating a thermosetting resin on a substrate and drying the substrate on a circuit-processed single-sided or double-sided copper-clad laminate. 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) an inorganic filler as a surface. After applying and drying a saturated fatty acid, calcium carbonate hydrophobized with a coupling agent and the like, and (4) an undercoating agent containing hydrophobized ultrafine silica as an essential component as an inorganic filler, the epoxy resin is dried. A method for producing a multilayer printed wiring board, comprising: laminating and pressing a prepreg impregnated and dried on a substrate. 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 calcium carbonate has an average particle diameter of 0.7.
The method for producing a multilayer printed wiring board according to claim 1 or 2, wherein the compounding amount is from 30 to 160 parts by weight based on 100 parts by weight of the epoxy resin. 4. The ultra-fine particle silica has an average particle diameter of 10 to 10.
4. The composition according to claim 1, wherein the amount is 19 nm, and the compounding amount is 5 to 30 parts by weight based on 100 parts by weight of the epoxy resin.
A method for producing the multilayer printed wiring board according to the above. 5. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the circuit-processed double-sided copper-clad laminate is not oxidized.