JP2007189216A - Method of manufacturing multilayer wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a multilayer wiring board, by which an adhesion between an insulating layer and a conductor circuit in the multilayer wiring board to carry out a face-down packaging of a semiconductor chip can be improved, a peeling between the conductor circuit and the insulating layer during a processing process can be reduced, and a fine wiring can be formed. <P>SOLUTION: The method of manufacturing the multilayer wiring board comprises the steps of: forming the insulating layer including a porosity inorganic filler on a front surface of a circuit board composed of an insulating substrate in which the conductor circuit is formed; and exposing the porosity inorganic filler on a front surface of the insulating layer by oxidizing roughening liquid. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multilayer wiring board.

In recent years, multilayer wiring boards using a build-up method in which insulating layers and conductor layers are alternately stacked on a circuit board have attracted attention because they can improve the wiring density, and can be used as a roughening agent as an insulating layer on the circuit board. There is a method for producing a multilayer wiring board in which an epoxy resin composition containing a soluble spherical inorganic filler is applied, heat-cured, then irregularities are formed on the surface of the insulating layer with a roughening agent, and a conductor layer is formed by plating (for example, , See Patent Document 1). A semi-additive method is widely known as a method for forming fine wiring. In the semi-additive method, a via hole for interlayer connection is formed on an insulating substrate, followed by a roughening process on the surface of the insulating layer, followed by an electroless plating process as a base, and a non-circuit forming portion is protected by a plating resist. Next, the circuit forming portion is electroplated to form a circuit, the resist is removed, and then the electroless plating layer of the non-circuit forming portion is removed by soft etching to form a conductor circuit on the insulating layer. In the semi-additive method, the conductor circuit is formed by soft etching the electroless plating layer in the non-circuit forming portion. Therefore, the smaller the surface roughness of the insulating layer, the more advantageous for the fine wiring.
Japanese Patent Laid-Open No. 7-304931

Currently, multilayer wiring boards for face-down mounting of semiconductor chips are required to improve high-frequency characteristics, further miniaturize wiring of conductor circuits, and lower the linear expansion coefficient of insulating layers. Furthermore, it is essential to mix an inorganic material in the insulating layer. However, when a spherical inorganic filler soluble in the roughening agent is mixed into the insulating layer, the adhesion between the insulating layer and the conductor circuit can be obtained, but there are places where the roughening agent locally increases the irregularities on the surface of the insulating layer. Arise. By forming a conductor layer of fine wiring at a place where the unevenness is locally increased, a short circuit between patterns and a defect of the conductor circuit occur due to the progress of local etching to the place.
On the other hand, when a spherical inorganic filler insoluble in the roughening agent is mixed, a conductor circuit is formed on the spherical inorganic filler exposed on the surface of the insulating layer by the roughening agent during the formation of fine wiring, so that a sufficient anchor effect is obtained. However, there is a problem in that the conductor circuit and the insulating layer in the processing process are separated due to poor adhesion between the insulating layer and the conductor circuit.

  The present invention has been made in view of the above problems, and improves the adhesion between the conductor circuit and the insulating layer of the multilayer wiring board for face-down mounting of the semiconductor chip, and the conductor circuit and the insulating layer during the processing step. It is an object of the present invention to provide a method for manufacturing a multilayer wiring board that can reduce peeling and form fine wiring.

Such an object is achieved by the present invention described in the following [1] to [4].
[1] A step of forming an insulating layer containing a porous inorganic filler on the surface of a circuit board made of an insulating substrate on which a conductor circuit is formed,
A method for producing a multilayer wiring board, comprising the step of exposing the porous inorganic filler to the surface of the insulating layer with an oxidizing roughening solution.
[2] A step of forming an insulating layer containing a porous inorganic filler on the surface of a circuit board composed of an insulating substrate on which a conductor circuit is formed,
Forming a via hole in the insulating layer;
Exposing the porous inorganic filler to the surface of the insulating layer and the inner wall of the via hole with an oxidizing roughening solution;
Forming an electroless copper plating layer on the insulating layer surface and the inner wall of the via hole;
Forming a plating resist on the surface of the electroless copper plating layer;
A process of thickening copper on the non-plated resist-formed surface by electrolytic copper plating,
Removing the plating resist and removing the electroless copper plating layer in the plating resist forming portion;
A multilayer wiring board manufacturing method characterized by repeating the steps in this order.
[3] The surface roughness (Ra) obtained by exposing the porous inorganic filler of the insulating layer to the surface of the insulating layer and the inner wall of the via hole with the oxidizing roughening solution is 0.4 μm or less [1] or [ [2] The method for producing a multilayer wiring board according to item [2].
[4] The above-mentioned [1], wherein the insulating layer contains a cyanate resin and / or a prepolymer thereof, an epoxy resin substantially free of halogen atoms, and a phenoxy resin substantially free of halogen atoms. The manufacturing method of the multilayer wiring board in any one of thru | or [3].

  According to the method for manufacturing a multilayer wiring board of the present invention, it is possible to provide a multilayer wiring board in which the size of the irregularities on the surface of the insulating layer can be made smaller than before, the adhesion strength between the conductor circuit and the insulating layer is excellent, and fine wiring can be formed.

The best mode for carrying out the present invention will be described below with reference to FIG.
First, the insulating layer 103 is formed on the circuit substrate 102 on which the conductor circuit 101 is formed on the insulating substrate 100 (FIG. 1 (1)) (FIG. 1 (2)). The circuit board used in the present invention is not particularly limited as long as it can be used as a printed wiring board substrate. For example, what formed the conductor circuit by the well-known subtractive method on both surfaces of the copper clad laminated board which impregnated thermosetting resin to base materials, such as glass cloth, is mentioned.

The insulating layer 103 is a resin composition containing a resin and a porous inorganic filler.
As the porous inorganic filler of the resin fat composition, agglomerated inorganic fine particles or a sintered inorganic material powder can be used. As inorganic fine particles, silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), zeolite, titanium oxide (TiO ₂ ), aluminum nitride (AlN), silicon carbide (SiC), silicon nitride ( Si ₃ N ₄ ), barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), calcium titanate (CaTiO ₃ ), aluminum borate, boronite, calcium carbonate, lead oxide, tin oxide, cerium oxide, calcium oxide , Trimanganese tetroxide, magnesium oxide, cerium zirconate, calcium silicate, zirconium silicate, ITO, titanium silicate, porous glass and the like, and inorganic material powders include silica (SiO ₂ ), alumina (Al ₂ O _3). ) Etc. , It can be used alone or in combination. Among these, silica using abundant use records for fillers in the field of electronic devices is preferable. The porous inorganic filler is insoluble in the oxidizing roughening solution.

Moreover, in order for the surface roughness (Ra) of the insulating layer when the porous inorganic filler is exposed on the surface of the insulating layer to be 0.4 μm or less, the porous inorganic filler is an aggregate of inorganic fine particles, and the average The particle size is preferably 100 nm or more and 5 μm or less. When the average particle size is 100 nm or less, the depth of penetration of the electroless copper plating into the irregularities on the surface of the porous inorganic filler is shallow, and no improvement in adhesion with the electroless copper plating is observed. When the average particle size is 5 μm or more, Ra becomes 0.4 μm or more when the porous inorganic filler is removed from the surface of the insulating layer. In the semi-additive method in which a conductive circuit is formed by soft etching of the electroless copper plating layer in the non-circuit forming part, if the surface roughness is rough, the amount of soft etching increases and the electroless copper plating layer is etched more than the conductive circuit. Since the contact area with the insulating layer is reduced and the wiring is peeled off in the manufacturing process, it is difficult to form fine wiring.
The content of the porous inorganic filler is preferably 40% by weight or more, more preferably 60% by weight with respect to the resin composition used for the insulating layer in order to reduce the linear expansion coefficient of the insulating layer and increase the elastic modulus. % Or more.

  Silica may be subjected to surface treatment with a silane coupling agent. As the silane coupling agent, various materials such as epoxy silane, amino silane, and vinyl silane can be used. By using such surface-treated silica, the interfacial adhesion between the porous inorganic filler and the resin matrix can be adjusted.

  As a method for forming the insulating layer 103, there are a method in which a liquid resin composition is applied by a method such as roll coal or curtain coating, a method in which a liquid is formed and laminated together, a method in which pressure lamination pressing is performed by sandwiching between end plates. Can be mentioned. The resin composition used for the insulating layer 103 is not only provided with plating solution resistance, heat resistance and insulation, but also needs to expose a porous inorganic filler in order to form irregularities on the surface of the insulating layer.

  Polypropylene, polyethylene, polyethylene terephthalate, polymethylpentene, polyacetal, polycarbonate, acrylonitrile butadiene sulfide, styrene butadiene copolymer, polyimide, polyphenylene sulfide, liquid crystal polymer, polyether ketone, epoxy as resins that can form such an insulating layer 103 Resin, cyanate resin and / or prepolymer thereof, phenol resin, phenoxy resin, and the like may be used, and a curing catalyst may be blended. Examples of the curing catalyst include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octylate and cobalt octylate, tertiary amines such as triethylamine, tributylamine, diazabicyclo [2,2,2] octane, 2 -Phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2,4-diamino-6- [2'-methylimidazolyl] -(1 ')]-ethyl-s-triazine, 2,4-diamino-6- (2'-undecylimidazolyl) -ethyl-s-triazine, 2,4-diamino-6- [2'-ethyl- 4-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 1-benzyl-2-phenylimidazole, 2- Imidazole compounds such as til-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, phenolic compounds such as phenol, bisphenol A and nonylphenol, phenolic resin And organic acids. These can be used alone or as a mixture thereof.

Among the resin compositions, those containing a cyanate resin and / or a prepolymer thereof, an epoxy resin substantially free of halogen atoms, a phenoxy resin substantially free of halogen atoms, and a porous inorganic filler are preferable.
By containing a cyanate resin and / or a prepolymer thereof, flame retardancy can be improved. The method for obtaining the cyanate resin and / or its prepolymer is not particularly limited. For example, it can be obtained by reacting a halogenated cyanide compound with a phenol and prepolymerizing it by a method such as heating as necessary. it can. Moreover, the commercial item prepared in this way can also be used.
Although it does not specifically limit as a kind of cyanate resin, For example, bisphenol type cyanate resin, such as a novolak-type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin, tetramethylbisphenol F type cyanate resin, etc. can be mentioned. Among these, a novolak type cyanate resin is preferable. Thereby, while being able to improve heat resistance by the increase in a crosslinking density, a flame retardance can further be improved. The novolak-type cyanate resin is considered to have a high proportion of benzene rings due to its structure and easily carbonize. The novolak type cyanate resin can be obtained, for example, by reacting a novolak type phenol resin with a compound such as cyanogen chloride or cyanogen bromide. Moreover, the commercial item prepared in this way can also be used.
Here, as the novolac-type cyanate resin, for example, those represented by the following general formula (1) can be used.

  The average repeating unit n of the novolak cyanate resin represented by the general formula (1) is not particularly limited, but is preferably 1 to 10, and particularly preferably 2 to 7. When the average repeating unit n is less than the lower limit, the novolak cyanate resin has low heat resistance, and the low-mer may be desorbed and volatilized during heating. Moreover, when average repeating unit n exceeds the said upper limit, melt viscosity will become high too much and a moldability may fall.

  Although it does not specifically limit as a weight average molecular weight of the novolak-type cyanate resin shown by the said General formula (1), It can be set to 500-4,500, Preferably it is 600-3,000. If the weight average molecular weight is too small, the mechanical strength of the resulting resin may decrease, while if it is too large, the curing rate of the resin composition may increase and the storage stability may decrease. By setting it as said range, the resin composition obtained becomes the thing excellent in both balance.

  In addition, as said cyanate resin, what prepolymerized this can also be used. That is, a cyanate resin may be used alone, a cyanate resin having a different weight average molecular weight may be used in combination, or a cyanate resin and a prepolymer thereof may be used in combination. Here, the prepolymer is usually obtained by, for example, trimerizing the cyanate resin by a heat reaction or the like, and is preferably used for adjusting the moldability and fluidity of the resin composition. is there. Although it does not specifically limit as a prepolymer here, For example, what a trimerization rate is 20 to 50 weight% can be used. This trimerization rate can be determined using, for example, an infrared spectroscopic analyzer.

Although content of the said cyanate resin is not specifically limited, From a viewpoint of making the said characteristic which cyanate resin has express effectively, it can be set as 5 to 50 weight% of the whole resin composition, Preferably 10 to 40% by weight. Here, if the content of the cyanate resin is too small, the effect of increasing the heat resistance by the cyanate resin may be reduced. On the other hand, if the content is too large, the crosslinking density is increased and the free volume is increased. However, by setting the content of the cyanate resin in the above range, the effect of using the cyanate resin is excellent in the balance between the two.
Furthermore, the resin composition used in the present invention contains an epoxy resin that does not substantially contain a halogen atom, so that there is no circuit corrosion due to a halogen atom even when the temperature is higher than the glass transition temperature, and the reliability is high. improves.

Although it does not specifically limit as said epoxy resin which does not contain a halogen atom substantially, For example, a phenol novolak type epoxy resin, a bisphenol type epoxy resin, a naphthalene type epoxy resin, an aryl alkylene type epoxy resin etc. are mentioned. Among these, aryl alkylene type epoxy resins are preferable. Thereby, a flame retardance and moisture absorption solder heat resistance can be improved. Here, the aryl alkylene type epoxy resin refers to an epoxy resin having one or more aryl alkylene groups in the repeating unit, and examples thereof include a xylylene type epoxy resin and a biphenyl dimethylene type epoxy resin. Among these, a biphenyl dimethylene type epoxy resin is preferable. As the biphenyldimethylene type epoxy resin, for example, one represented by the following general formula (2) can be used.

  In the biphenyldimethylene type epoxy resin represented by the general formula (2), n can be 1 to 10, and preferably 2 to 5. When n is too small, the biphenyl dimethylene type epoxy resin is easily crystallized, and the solubility in a general-purpose solvent is relatively lowered, which may make handling difficult. On the other hand, if it is too large, the fluidity of the resin is lowered, which may cause molding defects. By making n into the above range, the effect of using the biphenyl dimethylene type epoxy resin is excellent in the balance between the two.

  The weight average molecular weight of the epoxy resin is not particularly limited, but is preferably 4,000 or less. More preferably, it is 500-4,000, Most preferably, it is 800-3,000. If the weight average molecular weight of the epoxy resin is too small, tackiness may occur in the metal foil with resin and the insulating sheet with base material formed using the resulting resin composition. On the other hand, if it is too large, the solder heat resistance may decrease. By making a weight average molecular weight into said range, the effect by use of an epoxy resin will be excellent in both balance.

  Although it does not specifically limit as content of the said epoxy resin, It is preferable that it is 5 to 50 weight% of the whole resin composition. More preferably, it is 10 to 40% by weight. If the content of the epoxy resin is too small, the effect of improving moisture-absorbing solder heat resistance and adhesion by the epoxy resin may be reduced. On the other hand, if the amount is too large, the content of the cyanate resin is relatively reduced, and thus the low thermal expansion property of the resulting resin composition may be lowered. By making content of an epoxy resin into said range, the effect by use of an epoxy resin will be excellent in both balance.

  Furthermore, the resin composition used in the present invention contains a phenoxy resin that does not substantially contain a halogen atom, so that the solder resin composition has adhesiveness when it is thermocompression bonded to an insulating layer provided with a conductor circuit. When the via hole for interlayer connection of the insulating layer is provided, it is opened by a laser to remove the resin residue (smear), but at that time, the resin residue can be easily removed by containing the phenoxy resin.

The phenoxy resin substantially not containing a halogen atom is not particularly limited, and examples thereof include a phenoxy resin having a bisphenol skeleton, a phenoxy resin having a novolac skeleton, a phenoxy resin having a naphthalene skeleton, and a phenoxy resin having a biphenyl skeleton. It is done. A phenoxy resin having a structure having a plurality of these skeletons can also be used. Among these, those having a biphenyl skeleton and a bisphenol S skeleton can be used. Thereby, the glass transition temperature can be increased due to the rigidity of the biphenyl skeleton.
Further, those having a bisphenol A skeleton and a bisphenol F skeleton can be used. Thereby, the adhesiveness to an inner-layer circuit board can be improved at the time of manufacture of a multilayer wiring board. Moreover, what has the said biphenyl skeleton and the bisphenol S skeleton, and what has the bisphenol A skeleton and the bisphenol F skeleton can be used together. Thereby, these characteristics can be expressed with good balance. In the case where the compound having the bisphenol A skeleton and the bisphenol F skeleton (a) and the compound having the biphenyl skeleton and the bisphenol S skeleton (b) are used in combination, the combination ratio is not particularly limited. a) :( b) = 2: 8 to 9: 1.

  Although it does not specifically limit as molecular weight of a phenoxy resin, The thing whose weight average molecular weight is 5000-70000 can be used, and it is preferable that it is 5000-50000. More preferably, it is 10,000 to 40,000. If the weight average molecular weight of the phenoxy resin is too small, the effect of improving the film forming property by the phenoxy resin may be reduced. On the other hand, when too large, the solubility of a phenoxy resin may fall. By setting the weight average molecular weight of the phenoxy resin within the above range, the effect of using the phenoxy resin is excellent in the balance between the two.

  Although it does not specifically limit as content of a phenoxy resin, It is preferable that it is 1 to 40 weight% of the whole resin composition. More preferably, it is 5 to 30% by weight. If the content of the phenoxy resin is too small, the effect of improving the film forming property by the phenoxy resin may be lowered. On the other hand, if the amount is too large, the content of the cyanate resin is relatively reduced, and thus the effect of imparting low thermal expansibility may be reduced. By making content of a phenoxy resin into the said range, the effect by use of a phenoxy resin will be excellent in both balance.

The resin composition used in the present invention may contain an imidazole compound as a curing agent. Thereby, reaction of cyanate resin or an epoxy resin can be accelerated | stimulated, without reducing the insulation of a resin composition. The imidazole compound is not particularly limited, and examples thereof include 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2, 4-diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine, 2,4-diamino-6- (2'-undecylimidazolyl) -ethyl-s-triazine, 2, 4-Diamino-6- [2′-ethyl-4-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 1-benzyl-2-phenylimidazole and the like can be mentioned. Among these, an imidazole compound having two or more functional groups selected from an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a hydroxyalkyl group, and a cyanoalkyl group is preferable, and 2-phenyl- 4,5-dihydroxymethylimidazole is preferred. By using such an imidazole compound, the heat resistance of the resin composition can be improved, and low thermal expansion and low water absorption can be imparted to the resin layer formed from the resin composition.
Although it does not specifically limit as content of the said imidazole compound, It can be 0.05-5 weight% with respect to the sum total of the said cyanate resin and an epoxy resin, Preferably it is 0.1-5 weight%, Furthermore, Preferably it is 0.1 to 3 weight%. Thereby, especially the heat resistance of a resin composition can be improved.

Furthermore, it is also possible to add a rubber component, an amino resin or the like to the resin composition. Examples of the rubber component include polybutadiene rubber, epoxy-modified polybutadiene rubber, acrylonitrile butadiene rubber having a carboxy group, methacrylonitrile butadiene rubber having a carboxy group, an acrylic rubber dispersed epoxy resin, and the amino resin includes a melamine resin, Examples thereof include amino resins such as guanamine resin and urea resin, or those obtained by alkylating these amino resins. The rubber component and the amino resin are preferably those that can be decomposed or dissolved in the oxidizing roughening solution.

Next, a via hole 105 is formed in the insulating layer 103, and in order to improve adhesion between the insulating layer and a conductor circuit formed on the surface, an oxidizing roughening solution is used to form the surface of the insulating layer 103 and the via hole 105. The porous inorganic filler is exposed on the inner wall to form the circuit board 106 in the middle of manufacturing the multilayer wiring board (FIG. 1 (3)). Examples of the method for forming the via hole 105 include UV-YAG laser processing and CO ₂ laser processing. The oxidizing roughening solution may be a roughening agent containing an oxidizing agent, and is not particularly limited. For example, a permanganate, a dichromate, a hydrogen peroxide / sulfuric acid mixed solution, a mixed solution containing an oxidizing agent such as nitric acid, and the like can be given.

Here, as a method for exposing the porous inorganic filler to the surface of the insulating layer, the circuit board 106 in the middle of the production of the multilayer wiring board is immersed in an oxidizing roughening solution, and the processing conditions (immersion time, processing temperature) are adjusted. Is possible.
Further, in order to make the surface roughness of the insulating layer surface and the inner wall of the via hole 0.4 μm or less, if the cured resin component can be decomposed or dissolved by the oxidizing roughening liquid, the degree of curing of the insulating layer 103 is increased. By adjusting by the curing temperature, the target surface roughness can be obtained.
By setting the surface roughness of the insulating layer to 0.4 μm or less, the adhesion strength between the insulating layer and the circuit on it is excellent, so fine wiring can be formed, and the insulating layer and the surface circuit layer are in close contact with each other. A multilayer wiring board having excellent strength can be obtained.

  Next, the electroless copper plating layer 107 is formed on the surface of the insulating layer 103 and the inner wall of the via hole 105 to obtain the circuit board 108 in the middle of manufacturing the multilayer wiring board (FIG. 1 (4)). The thickness of the electroless copper plating layer 107 is about 0.3 to 2 μm.

  Next, a plating resist 109 is selectively formed on the electroless copper plating layer 107 to obtain a circuit board 110 in the middle of manufacturing the multilayer wiring board (FIG. 2 (5)). As a method for forming a plating resist, a patterned plating resist can be obtained by forming a photosensitive resin on the circuit board 108 in the middle of manufacturing a multilayer wiring board, exposing and developing the photosensitive resin. Examples of the photosensitive resin include dry film types, and examples of the forming method include lamination.

Next, the electrolytic copper plating layer 111 is deposited on the electroless copper plating layer 107 where the plating resist 109 is not formed to a desired thickness by electrolytic copper plating to obtain a circuit board 112 in the middle of manufacturing the multilayer wiring board. (FIG. 2 (6)).
Next, the plating resist 109 is peeled off from the circuit board 112 in the middle of manufacturing the multilayer wiring board with an alkaline solution to obtain a circuit board 113 in the middle of manufacturing the multilayer wiring board (FIG. 2 (7)), and then exposed by peeling off the plating resist 109. The portion of the electroless copper plating layer that has been removed is removed by soft etching to obtain a multilayer wiring board 114 (FIG. 2 (8)).
By repeating the above-described steps for forming the insulating layer on the multilayer wiring board 114, a multilayer wiring board having excellent adhesion to the insulating layer of the conductor circuit and capable of forming fine wiring can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to these. In this example, the production of a porous inorganic filler and the formation of an insulating layer film containing the porous inorganic filler are first described, and then a method for producing a multilayer wiring board using them is described.

[Example 1]
<Preparation of porous inorganic filler and preparation of insulating layer film containing porous inorganic filler>
First, as inorganic fine particles, silica sol (Snowtech 30 manufactured by Nissan Chemical Industries, Ltd.) in which silica particles having an average particle diameter of 12 nm are dispersed in an aqueous solution is used, and 50 cc of water and 11 g of silica sol are used as a pore-forming agent in a beaker. In order to prevent gelation of silica sol, 10 g of KBr and nitric acid were sequentially added to a pH of about 4.0 and stirred. Next, the stirred sample was transferred to a petri dish and dried at 100 to 120 ° C. using a hot plate. The dried sample was pulverized and classified to a particle size of 70 to 300 mesh. The sample after classification is placed on a baking dish, and the temperature is raised from 20 ° C. to 600 ° C. at a rate of 3 ° C./min in a fully automatic opening and closing type tubular path (EKRO-23 manufactured by ISUZU) and held at 600 ° C. for 2 hours. And then cooled at 5 ° C./min. The fired sample was washed with hot water at 80 ° C. to dissolve and remove KBr in the fired body. Then vacuum dried to obtain a porous inorganic filler SiO ₂ skeleton of an average particle diameter of 100 [mu] m.
Next, as preparation of the resin composition for producing an insulating layer, 33 parts by weight of a novolak cyanate resin PT-60 (manufactured by Lonza Co., Ltd., number average molecular weight 560), novolak cyanate resin PT-30 (Lonza ( Co., Ltd., number average molecular weight 380) 10 parts by weight, bisphenol F type phenoxy resin Epicoat 4010P (manufactured by JER, number average molecular weight 6,000) 15 parts by weight, novolac type phenol resin HF-3 (Sumitomo Bakelite Co., Ltd.) 2) parts by weight were dissolved in methyl ethyl ketone and stirred for 10 minutes.
After stirring, 40 parts by weight of the porous inorganic filler having the SiO ₂ skeleton and surfactant as an epoxy silane coupling agent A-187 (manufactured by Nihon Unicar Co., Ltd.) were used as the porous inorganic filler having the SiO ₂ skeleton. On the other hand, a resin composition was prepared by adding 0.5 parts by weight.
This resin composition was pulverized and kneaded with three rolls with a gap of 50 μm and then 10 μm to obtain a resin composition containing a porous inorganic filler having an average particle diameter of 5 μm. This resin composition was coated on a PET film with a comma coater so that the thickness after drying was 60 μm, and an insulating layer film containing a porous inorganic filler was produced.

<Manufacture of multilayer wiring boards and substrates for adhesion strength evaluation>
A circuit board was formed on a glass cloth base epoxy resin double-sided copper-clad laminate (ELC-4785GS, manufactured by Sumitomo Bakelite Co., Ltd.) having a 12 μm thick copper foil on both sides by a subtractive method. On the circuit board, the insulating layer film containing the porous inorganic filler was vacuum-pressed (MVLP-500 / 600-IIA, manufactured by Meiki Seisakusho Co., Ltd.) for the first time at a temperature of 80 ° C. and a pressure of 0 An insulating layer was formed on both surfaces under the conditions of 0.5 MPa, 100 ° C. and 1.0 MPa for the second time, and the PET film was peeled off, followed by heating at 170 ° C. for 45 minutes.
Next, in order to form a via hole with a UV-YAG laser processing machine (manufactured by Mitsubishi Electric Corporation) and expose the porous filler on the surface of the insulating layer, the main component is used for cleaning and activating the surface of the insulating layer. Immerse in a solution of monoethylbutyl alcohol (MLB conditioner, manufactured by Rohm and Haas Electronic Materials Co., Ltd.) at a liquid temperature of 80 ° C. for 10 minutes, and then a solution mainly composed of an oxidizing roughening solution, potassium permanganate. (Solution: Rohm and Haas Electronic Materials, MLB Promoter) Soaked in sulfuric acid solution (MLB Neutizer, Rohm and Haas Electronic Materials Co., Ltd.) for 20 minutes at a liquid temperature of 80 ° C. Then, it was immersed in a liquid temperature of 40 ° C. for 5 minutes, and further washed with water and hot water.
Subsequently, using an electroless copper plating solution (print Gantt MSK-DK series manufactured by Atotech Co., Ltd.), an electroless copper plating layer having a thickness of 1.0 μm is formed on both sides, and a photosensitive dry film (Tokyo Ohka Kogyo Co., Ltd.). AR-320 manufactured by Co., Ltd. is formed on both surfaces of the electroless plating layer with a laminator, exposed and developed to form a plating resist, and electrolytic plating with a thickness of 14 μm is performed by electrolytic copper plating on the portion where the plating resist is not formed. Copper plating layers were formed on both sides.
Thereafter, the electroless copper plating layer exposed by peeling the plating resist is removed with a soft etching solution (SAC manufactured by Ebara Densan Co., Ltd.), and 100 fine wirings having a minimum L / S of 10 μm / 10 μm are obtained. The conductor circuit which has it was formed in both surfaces, and it was set as the multilayer wiring board.
Next, as a substrate for evaluation of adhesion strength, on one side of a glass cloth base epoxy resin double-sided copper-clad laminate (Sumitomo Bakelite Co., Ltd., ELC-4785GS) having a 12 μm thick copper foil on both sides, An insulating layer film containing a porous inorganic filler was formed in the same manner as described above, and a conductor layer of 35 μm in total was formed on the surface of the insulating layer, with an electroless copper plating layer of 1.0 μm and an electrolytic copper plating layer of 34 μm.
Evaluation is performed by the following method, and the evaluation results are shown in Table 1.

<Evaluation method>
1. Fine wiring formation inspection: The fine wiring (total 200 lines) formed on both surfaces of the multilayer wiring board was observed with a length measuring microscope, and the number of peeled or poorly formed parts was counted.
2. Measurement of surface roughness: After exposing the porous inorganic filler to the surface of the insulating layer of the multilayer wiring board, the surface roughness Ra of the surface of the insulating layer was measured with a laser microscope (VK-8000, manufactured by Keyence Corporation). (Unit: μm).
3. Measurement of adhesion strength: The adhesion strength test method uses the above-mentioned adhesion strength evaluation substrate, and JIS
C 6481 “Test method for copper-clad laminate for printed wiring board”

[Example 2]
<Preparation of Porous Inorganic Filler and Insulating Layer Film Containing Porous Inorganic Filler, and Production of Multilayer Wiring Board and Adhesion Strength Evaluation Substrate> Except that the content of the porous inorganic filler used in the insulating layer is 60 parts by weight In the same manner as in Example 1, an insulating layer film, a multilayer wiring board, and an adhesion strength evaluation substrate were prepared and evaluated.

[Example 3]
<Production of porous inorganic filler and insulating layer film containing porous inorganic filler, and production of multilayer wiring board and adhesion strength evaluation substrate>
As the preparation of the resin composition for producing the insulating layer, 25 parts by weight of a novolac-type cyanate resin (Lonza Japan Co., Ltd., Primaset PT-30, weight average molecular weight of about 700), biphenyldimethylene type epoxy resin (Japan) Kayaku Co., Ltd., NC-3000, epoxy equivalent 275, weight average molecular weight 2000) 24.7 parts by weight, a copolymer of phenoxy resin / biphenyl epoxy resin and bisphenol S epoxy resin, the terminal part being an epoxy group 10 parts by weight (manufactured by Japan Epoxy Resin Co., Ltd., YX-8100H30, weight average molecular weight 30000), imidazole compound (manufactured by Shikoku Chemicals Co., Ltd., Curesol 1B2PZ (1-benzyl-2-phenylimidazole)) Example 1) 0.1 part by weight was dissolved and dispersed in methyl ethyl ketone. Similarly, 40 parts by weight of the porous inorganic filler prepared and 0.2 part by weight of an epoxy silane coupling agent (GE Toshiba Silicone Co., Ltd., A-187) as a coupling agent were added and stirred for 10 minutes. A resin composition was obtained. This resin composition was pulverized and kneaded with three rolls with a gap of 50 μm and then 10 μm to obtain a resin composition containing a porous inorganic filler having an average particle diameter of 5 μm. Using this resin composition, an insulating layer film containing a porous inorganic filler was produced in the same manner as in Example 1.
Hereinafter, a multilayer wiring board and a substrate for adhesion strength evaluation were prepared and evaluated in the same manner as in Example 1.

[Comparative Example 1]
An insulating layer film containing a spherical inorganic filler instead of the porous inorganic filler used in Example 1 was produced.
<Preparation of insulating layer film containing spherical inorganic filler>
33 parts by weight of novolak-type cyanate resin PT-60 (manufactured by Lonza, Inc., number average molecular weight 560), 10 parts by weight of novolac-type cyanate resin PT-30 (manufactured by Lonza, Inc., number average molecular weight 380), bisphenol F-type phenoxy Resin Epicoat 4010P (manufactured by JER Corporation, number average molecular weight 6,000) 15 parts by weight and novolac type phenolic resin HF-3 (manufactured by Sumitomo Bakelite Co., Ltd.) 2 parts by weight were dissolved in methyl ethyl ketone. Spherical fused silica SO-25H (manufactured by Admatechs Co., Ltd., average particle size 0.5 μm) 40 parts by weight as a spherical inorganic filler and an epoxy silane coupling agent A-187 (manufactured by Nippon Unicar Co., Ltd.) as a surfactant Then, 0.5 part by weight was added to the spherical inorganic filler and stirred for 10 minutes using a high-speed stirrer to obtain a resin composition having a solid content of 60% by weight. This resin composition was coated on a PET film with a comma coater so that the thickness after drying was 60 μm, and an insulating layer film containing a spherical inorganic filler was produced.

<Manufacture of multilayer wiring boards and substrates for adhesion strength evaluation>
A multilayer wiring board and a substrate for adhesion strength evaluation were prepared in the same manner as in Example 1 except that an insulating layer film containing a spherical inorganic filler was used instead of the porous inorganic filler, and evaluated in the same manner as in Example 1.

[Comparative Example 2]
In Example 1, the step of exposing the porous filler to the surface of the insulating layer was omitted, and a multilayer wiring board and a substrate for evaluating adhesion strength were produced in the same manner as in Example 1 except that the porous inorganic filler was not exposed. Evaluation was performed in the same manner as in Example 1.

  According to the method for manufacturing a multilayer wiring board of the present invention, it is possible to provide a multilayer wiring board in which the size of the irregularities on the surface of the insulating layer can be made smaller than before, the adhesion strength between the conductor circuit and the insulating layer is excellent, and fine wiring can be formed.

It is sectional drawing for demonstrating the example of the manufacturing method of the multilayer wiring board by embodiment of this invention. It is sectional drawing for demonstrating the example of the manufacturing method of the multilayer wiring board by embodiment of this invention (continuation of FIG. 1).

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Insulating board 101 Conductor circuit 102 Circuit board 103 Insulating layer 104,106,108,110,112,113 Circuit board 105 in the middle of multilayer wiring board manufacture Via hole 107 Electroless copper plating layer 109 Plating resist 111 Electrolytic copper plating layer 114 Multilayer Wiring board

Claims (4)

Forming an insulating layer containing a porous inorganic filler on the surface of a circuit board made of an insulating substrate on which a conductor circuit is formed;
A method for producing a multilayer wiring board, comprising the step of exposing the porous inorganic filler to the surface of the insulating layer with an oxidizing roughening solution. Forming an insulating layer containing a porous inorganic filler on the surface of a circuit board made of an insulating substrate on which a conductor circuit is formed;
Forming a via hole in the insulating layer;
Exposing the porous inorganic filler to the surface of the insulating layer and the inner wall of the via hole with an oxidizing roughening solution;
Forming an electroless copper plating layer on the insulating layer surface and the inner wall of the via hole;
Forming a plating resist on the surface of the electroless copper plating layer;
A process of thickening copper on the non-plated resist-formed surface by electrolytic copper plating,
Removing the plating resist and removing the electroless copper plating layer in the plating resist forming portion;
A multilayer wiring board manufacturing method characterized by repeating the steps in this order. 3. The multilayer wiring according to claim 1, wherein the surface roughness (Ra) of the surface of the insulating layer exposed from the surface of the insulating layer and the inner wall of the via hole by the oxidizing roughening solution is 0.4 μm or less. A manufacturing method of a board. The insulating layer includes a cyanate resin and / or a prepolymer thereof, an epoxy resin substantially free of halogen atoms, and a phenoxy resin substantially free of halogen atoms. A method for producing a multilayer wiring board according to claim 1.