JPH1041625A - Manufacturing method of multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a short circuit due to intrusion of a plating solution and to prevent oozing due to insufficient contact, by forming inner layer lines of an inner layer wiring board, when the inner layer wiring board is formed, excluding a gap in the inner layer lines of a specified range corresponding to the positions where they cross perpendicularly outer layer lines formed when wiring formation is performed on a lamination-bonded member, so that the specified range of the line gap is omitted. SOLUTION: A holed metal foil 3 with adhesive is superposed on an inner layer wiring board 4 so that an insulating resin adhesive layer 31 is in constant with the inner layer wiring board, and a plastic sheet 2 is inserted between a mirror board and a lamination member, and is heated and pressed to be bonded. After the bonding, the sheet 2 is peeled off from the lamination member, then holes are formed for connecting through-holes, plating 8 is carried out with electroless copper plating solution, and a wiring 9 is formed so that it crosses inner layer lines perpendicularly by selectively removing unnecessary copper foil. At that time, a range of line gap of 0.2-1.0mm is omitted so that the intrusion of a plating solution is prevented, a short circuit is prevented, and generation of scattering of light, oozing due to insufficient contact, etc., can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As electronic devices have become lighter, thinner, smaller, and more sophisticated, wiring boards have been required to have higher densities. For this reason, wiring boards have been multi-layered to increase the number of wiring layers, finer wiring to increase the wiring capacity in the same layer, and finer connection holes for connection between layers. However, with the increase in density, the number of connection holes required increases, and in the conventional through holes, the number of holes increases, and the area where the through holes cannot be wired to layers other than the required layers increases. For this reason, there is a problem that the wiring capacity cannot be sufficiently increased. Therefore, as a method for solving such a problem, a multilayer wiring board having an IVH (interstitial via hole) structure for connecting only necessary layers has been proposed.

For example, as shown in FIG. 3A, a double-sided copper-clad laminate in which a through hole is formed, a plating is performed in the hole, and wiring is formed by etching, is used as an inner wiring board 104 or an outer wiring board 102. Use the required number of
As shown in FIG. 3 (b), it is laminated with the prepreg 103 to form a multilayer, and thereafter, as shown in FIG. 3 (c), a through hole is made in a necessary portion, and the inner wall of the through hole is made conductive by plating. As shown in FIG. 3 (d), a method for manufacturing a wiring board having an IVH structure by forming wiring on the outermost layer is known. This method has a problem that since the number of steps and the number of plating times are large, the conductor in the outer layer becomes thick, and it is difficult to form fine wiring at the time of the last wiring formation.

Therefore, in order to solve these problems,
A hole is made in advance on a metal foil with an adhesive in which a B-stage adhesive layer is formed on a metal foil, and the laminate is adhered to an inner wiring board on which wiring has been formed, and a through hole is made as necessary, and a conductor is formed in the hole. And a method of manufacturing a multilayer wiring board having an IVH by etching away unnecessary copper foil is disclosed in
No. 196,862.

[0005]

However, Japanese Patent Application Laid-Open No.
No. 96862 discloses a method of completely filling a wiring portion of an inner wiring board with an adhesive layer of a metal foil with an adhesive,
It is necessary to minimize the exudation of the resin into the hole, which leads to unevenness of the substrate surface after lamination and bonding, in order to minimize the resin flow in the adhesive layer. Occasionally, the plating resist or the etching resist does not follow the surface irregularities of the substrate, and many circuit defects have occurred due to the penetration of the plating solution or the etching solution.

The present invention provides a method for manufacturing a multilayer wiring board with an IVH, which has a good yield and excellent production efficiency.

[0007]

SUMMARY OF THE INVENTION A method of manufacturing a multilayer wiring board according to the present invention comprises the steps of: a. A step of producing an inner wiring board; b. Perforating a metal foil with an adhesive comprising a metal foil and an insulating resin adhesive layer, c. A step of laminating and bonding the inner wiring board and the metal foil with adhesive between a laminating jig and a laminate with a sheet that flows plastically in a laminating step; d. Forming a wiring on the laminated adhesive, in the method for manufacturing a multilayer wiring board comprising the steps of: forming an inner layer line of the inner wiring board formed in the step a corresponding to a position orthogonal to the outer layer line formed in the step d; Line gap 0.2-1.0m
It is characterized in that it is formed avoiding the range of m.

The present inventors have conducted intensive studies and as a result, found that the gap between the line of the inner layer wiring board and the line which is perpendicular to the outer layer line is 0.
When the thickness is 2 to 1.0 mm, the plating or etching resist used for forming the substrate surface and the outer layer does not follow the substrate surface, so that the plating solution or the etching solution easily enters the gap, and a short circuit occurs when the plating solution enters. However, the inventor has found that the breakage of the circuit occurs when the etchant enters, and the present invention has been accomplished. It has also been found that the unevenness of the surface makes it difficult for the printing negative used for forming the resist to follow, and that light scattering and insufficient adhesion cause bleeding and the like, thereby causing circuit defects. From this, the gap between the lines of the inner layer wiring is designed to be 0.2 to 1.0 m
By designing so as to avoid the range of m, these problems can be prevented. If the line gap is less than 0.2 mm, the gap is filled with resist,
Further, it is difficult to pick up the unevenness of the inner layer and no defect is generated. If the line gap exceeds 1.0 mm, a gap that can be followed by the resist can be secured, and the surface unevenness becomes gentle, so that no circuit defect is generated. .

As the inner wiring board used in the present invention, any one can be used as long as it can be used for a normal wiring board.

As the metal foil used for the adhesive-attached metal foil comprising the metal foil and the insulating resin adhesive layer of the present invention, a copper foil or an aluminum foil can be used. Among them, a copper foil used for a normal wiring board is preferable. It is preferable to use a material that is roughened for adhesion to the insulating resin adhesive layer. Regarding the thickness, a thickness of 5 μm to 70 μm used for a normal wiring board can be used. When a high wiring pattern accuracy and a high wiring density are required, it is preferable to use a thinner wiring as possible. For this metal foil, a composite foil having a carrier layer that can be physically or chemically peeled off and removed before wiring formation can be used.When using the thin metal foil, the one supported by the carrier can be used. If used, the handleability of the metal foil is high, which is preferable. Examples of the copper foil supported by such a carrier include a copper foil using aluminum as a carrier which has been subjected to a treatment that facilitates peeling at the interface, and a first copper layer / intermediate layer having a thickness of 3 to 7 μm. As a nickel-phosphorus layer / carrier having a thickness of 0.1 to 0.3 μm, a composite metal foil or the like including a second copper layer having a thickness of 30 to 40 μm can be used.

For the insulating resin adhesive layer, an epoxy resin having excellent properties such as heat resistance, mechanical properties, electrical properties, and chemical resistance is suitable for a multilayer wiring board requiring high properties. . When using a resin mainly composed of a high-molecular-weight epoxy polymer as the insulating resin adhesive of the metal foil with the adhesive, it maintains a certain degree of flexibility after curing without a flexibilizing agent or modification,
Further, the resin viscosity can be kept high even during heating during lamination bonding, which is suitable for the purpose of the present invention.

In the resin mainly composed of the high-molecular-weight epoxy polymer, the blending equivalent ratio of the bifunctional epoxy resin and the halogenated bifunctional phenol is set to epoxy group / phenol hydroxyl group = 1 / 0.9 to 1.1, Heated and polymerized in the presence of a catalyst to produce a film having a molecular weight of 100,000
Using a high-molecular-weight epoxy polymer and a crosslinking agent, a thermosetting epoxy resin having a polyfunctional epoxy resin as a component, the varnish-like thermosetting epoxy resin is applied to a roughened surface of a copper foil, and heated. An epoxy resin layer may be formed directly on a copper foil in a semi-cured state, or the thermosetting epoxy resin may be applied on a film substrate to form a film, and then laminated with the copper foil.

(Composition of thermosetting epoxy resin) The compounding equivalent ratio of the bifunctional epoxy resin and the halogenated bifunctional phenol used in the present invention is set to epoxy group / phenol hydroxyl group = 1 / 0.9 to 1.1. A polymer having a molecular weight of 100,000 having a film-forming ability heated and polymerized in the presence of a catalyst.
The above-mentioned high-molecular-weight epoxy polymer and cross-linking agent, the thermosetting epoxy resin composition comprising a polyfunctional epoxy resin as a constituent component, a high-molecular-weight epoxy polymer having a film-forming ability and a cross-linking agent, a polyfunctional epoxy resin as a constituent And

(High Molecular Weight Epoxy Polymer) The high molecular weight epoxy polymer having a film forming ability is a so-called high molecular weight epoxy polymer having a weight average molecular weight of 100,000 or more, and comprises a bifunctional epoxy resin and a halogenated difunctional resin. The phenols were prepared by adjusting the blending equivalent ratio of the bifunctional epoxy resin and the bifunctional phenol to epoxy group / phenolic hydroxyl group = 1.
/0.9-1.1, boiling point 130 ° C. in the presence of a catalyst
It is obtained by heating and polymerizing at a reaction solids concentration of 50% by weight or less in the amide-based or ketone-based solvent described above.

The bifunctional epoxy resin may be any compound as long as it has two epoxy groups in the molecule, such as bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, Examples include aliphatic chain epoxy resins. These compounds can have any molecular weight. Some of these compounds can be used in combination. Further, components other than the bifunctional epoxy resin may be included as impurities.

The halogenated bifunctional phenol may be any compound as long as the compound is substituted with a halogen atom and has two phenolic hydroxyl groups, such as hydroquinone, resorcinol and monocyclic bifunctional phenol. Catechol, bisphenol A which is a polycyclic bifunctional phenol, bisphenol F, naphthalene diols,
Bisphenols, and halides such as alkyl group-substituted products thereof. These compounds can have any molecular weight. Some of these compounds can be used in combination. Further, components other than the halogenated bifunctional phenols may be contained as impurities.

The catalyst may be any compound having a catalytic ability to promote an ether reaction between an epoxy group and a phenolic hydroxyl group. Examples thereof include alkali metal compounds, alkaline earth metal compounds, imidazoles, and the like.
Organic phosphorus compounds, secondary amines, tertiary amines, quaternary ammonium salts and the like. Among them, an alkali metal compound is the most preferred catalyst, and examples of the alkali metal compound include sodium, lithium and potassium hydroxide,
Examples include halides, organic acid salts, alcoholates, phenolates, hydrides, borohydrides, amides and the like. These catalysts can be used in combination.

The reaction solvent is preferably an amide or ketone solvent, and the amide solvent has a boiling point of 13%.
There is no particular limitation on dissolving the epoxy resin and phenols as raw materials at 0 ° C. or higher, but, for example, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N,
N-dimethylacetamide, N, N, N ', N'-tetramethylurea, 2-pyrrolidone, N-methyl-2-pyrrolidone, carbamic acid ester and the like. These solvents can be used in combination. Further, it may be used in combination with other solvents typified by ketone solvents, ether solvents and the like. Examples of the ketone-based solvent include cyclohexanone, acetylacetone, diisobutylketone, holon, isophorone, methylcyclohexanone, and acetophenone.

As for the conditions for synthesizing the polymer, the blending equivalent ratio of the bifunctional epoxy resin and the halogenated difunctional phenol is as follows: epoxy group / phenolic hydroxyl group = 1 / 0.9 to
1.1. The polymerization reaction temperature is preferably from 60 to 150 ° C. If the temperature is lower than 60 ° C, the polymerization reaction becomes extremely slow. If it exceeds 150 ° C, side reactions increase and the polymer does not linearly increase in molecular weight. The solid content concentration during the polymerization reaction using a solvent may be 50% by weight or less, and more preferably 30% by weight or less.

Thus, a so-called high molecular weight epoxy polymer having a film forming ability and a molecular weight of 100,000 or more can be obtained. As a crosslinking agent for this high-molecular-weight epoxy polymer, a mask isocyanate obtained by masking (blocking) an isocyanate with a compound having another active hydrogen, in which the reactivity of the crosslinking agent is easily controlled and the storage stability of the varnish is easily ensured. It is preferably used.

The isocyanate may be any as long as it has two or more isocyanate groups in the molecule, for example, hexamethylene diisocyanate masked with a masking agent such as phenols, oximes and alcohols. Examples thereof include diphenylmethane diisocyanate, isophorone diisocyanate, and tolylene diisocyanate. In particular, isophorone diisocyanate and tolylene diisocyanate masked with phenols for improving the heat resistance of the cured product are preferable. The amount of the crosslinking agent is such that the isocyanate group is 0.1 to 1.0 equivalent to 1.0 equivalent of the alcoholic hydroxyl group of the high molecular weight epoxy polymer.
It is preferable to make it equivalent.

(Polyfunctional epoxy resin) The polyfunctional epoxy resin may be any compound as long as it has two or more epoxy groups in the molecule. For example, a phenol novolak type epoxy resin and a cresol novolak type epoxy resin Resins, phenol-type epoxy resins such as resole-type epoxy resins and phenolic glycidyl ethers such as bisphenol-type epoxy resins, alicyclic epoxy resins, epoxidized polybutadiene, glycidyl ester-type epoxy resins, glycidylamine-type epoxy resins, isocyanurate-type Epoxy resin, flexible epoxy resin, etc., any epoxy resin may be used, especially phenolic epoxy resin, or a mixture of phenolic epoxy resin and polyfunctional epoxy resin,
It is preferable for improving heat resistance. The amount of the polyfunctional epoxy resin is preferably 20 to 100 parts by weight based on 100 parts by weight of the high molecular weight epoxy polymer. Also,
Since this polyfunctional epoxy resin works as an adhesive component and a resin flow during molding, it can be adjusted to an appropriate amount by the thickness of the inner copper foil and the density of the circuit. These polyfunctional epoxy resins may be used alone or in combination of two or more.

(Additive) It is preferable to use a curing agent and a curing accelerator for the polyfunctional epoxy resin. Examples of epoxy resin curing agents and curing accelerators include novolak type phenol resins, dicyandiamide, acid anhydrides, amines, imidazoles, phosphines, and the like. Further, these may be used in combination. Further, it is preferable to add a silane coupling agent since the adhesion of the epoxy resin layer, particularly the adhesion to the copper foil, is improved. As the silane coupling agent to be added, epoxy silane, amino silane, urea silane and the like are preferable.

(Coating) The mixture having such a composition is diluted with a solvent and applied to the surface of a copper foil. The coating method at this time can be performed by a blade coater, a rod coater, a knife coater, a reverse roll coater, a lip coater, a die coater, or the like. After application,
It is dried at 30 to 150 ° C. for 2 to 30 minutes to obtain a semi-cured state.

The step of piercing the metal foil with the adhesive is as follows.
It is possible to use a numerically controlled drill machine or press die used when manufacturing a normal wiring board.

As the sheet plastically flowing in the laminating step of the present invention, a resin mainly composed of a polyethylene resin, a polystyrene resin, a vinyl acetate resin, a copolymer thereof or the like can be used. The thickness of the sheet plastically flowing in the laminating step may be any thickness as long as the cushion effect can be obtained, and is preferably in the range of 30 μm to 2 mm. If the viscosity decrease at the temperature at the time of laminating is sufficiently large, 30 to 200 μm
Is enough. If it is less than 30 μm, there is no cushioning effect, and if it exceeds 2 mm, not only the price of the sheet plastically flowing in the laminating step becomes high, but also the heat transfer from the hot plate to the laminate decreases. The sheet that plastically flows in the laminating step may be a two-layer sheet formed by simultaneously extruding a sheet that plastically flows in the laminating step and a release film, or a three-layer structure that combines the above two types of materials. Sheets can also be used.

After laminating and bonding, the plastically flowing sheet is physically peeled and removed in the laminating step, as in the case of manufacturing a normal wiring board. It is performed by opening, taking out the laminate, and manually dismantling the end plate or cushion.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are described below.
This will be specifically described with reference to examples.

[0029]

【Example】

(1) Preparation of Inner Layer Wiring Board MCL-E67 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a double-sided copper-clad laminate obtained by laminating copper foil on both sides of a glass cloth impregnated with epoxy resin, is unnecessary. By removing the copper foil by etching, an inner wiring board 4 having an inner wiring having a land at the IVH connection portion was produced. At this time, the line width is set to 0.2, 0.5, 1.0, 2.0 mm,
A pattern in which the gap between the lines was changed to 0.1 to 1.5 mm was formed. (2) Preparation of metal foil with adhesive A bisphenol A type epoxy resin is used as a bifunctional epoxy resin, a halogenated bisphenol A is used as a halogenated bifunctional phenol, an alkali metal compound is used as a catalyst, and a reaction solvent is used. Using an amide-based solvent, the synthesis conditions of the polymer were as follows: the blending equivalent ratio of the bifunctional epoxy resin and the halogenated bifunctional phenols was set to epoxy group / phenolic hydroxyl group = 1/1, and the polymerization reaction temperature was set to 140 ° C. A high molecular weight epoxy polymer having an average molecular weight of 100,000 or more, synthesized using a polymerization reaction with a solid content of 25% by weight, and a cross-linking agent using an isocyanate mask, and a polyfunctional epoxy resin as a resol type epoxy resin. Epoxy resin varnish AS3000 using resin
(Trade name, manufactured by Hitachi Chemical Co., Ltd.) was applied on the roughened surface of a copper foil having a thickness of 18 μm, which is
0 μm, and dried at 140 ° C. for 25 minutes to obtain a B-stage state.
A 0.15 mm diameter hole for IVH connection was drilled. (3) Laminating Adhesion As shown in FIG. 1A, the perforated metal foil with adhesive 3 produced in the step (2) is attached to the inner layer wiring board 4 produced in the step (1) by insulating. A 150 μm-thick polystyrene sheet is inserted between the end plate and the laminate as a sheet 2 that is plastically flowed in the laminating step, so that the resin adhesive layer 31 is in contact with the inner wiring board, and is inserted at 160 ° C., 3M
The laminate was bonded by heating and pressing under the conditions of Pa and 90 minutes. (4) Peeling As shown in FIG. 1B and FIG.
The head plate 1 and the sheet 2 which plastically flows in the laminating step were peeled off from the laminate. (5) Formation of Wiring After the laminate was washed with water and dried, a hole for through-hole connection was made with a drill (not shown). Then, after performing a series of pre-plating treatments such as an alkali permanganate treatment and a catalyst treatment, as shown in FIG. 1 (e), an L-59 plating solution which is an electroless copper plating solution (Hitachi Chemical Industry Co., Ltd.) (Product name), at a liquid temperature of 70 ° C. for 7 hours,
Then, unnecessary copper foil is selectively removed by etching so as to be perpendicular to the inner layer line to form a wiring 9, and a multi-layer with IVH shown in FIG. A wiring board was obtained. The defect occurrence rate is calculated by the number of places where the width of the outer layer line is narrowed to 2/3 or less of the designed value by a metallurgical microscope.
The calculation was made based on the total number of orthogonal portions between the inner layer line and the outer layer line. The number of samples was 100. As a result, as shown in FIG. 2, it was found that the defect rate was large when the line interval was in the range of 0.2 to 1.0 mm.

[0030]

As is apparent from the above description, according to the present invention, a multilayer wiring board having fine IVH can be manufactured with a high yield.

[Brief description of the drawings]

FIGS. 1A to 1F are cross-sectional views in respective steps for explaining one embodiment of the present invention.

FIG. 2 is a diagram for explaining the result of one embodiment of the present invention, showing the relationship between the interval between the inner layer lines of the inner wiring board and the defect occurrence rate of the outer layer circuit.

3 (a) to 3 (d) are cross-sectional views in respective steps for describing manufacturing steps of a conventional example.

[Explanation of symbols]

1. End plate 2. 2. Sheet that plastically flows in the lamination process Metal foil with adhesive 31. Insulating resin adhesive layer 32. Metal foil 33. Carrier 4. Inner layer wiring board 5. Laminate 6. 7. Hole for IVH Plating 9. IVH 102. Outer plate 103. Prepreg 104. Inner layer plate 105. Laminate 106. IVH hole 107. Laminate 108. Through hole 109. IVH

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kazuyuki Tazawa 1500 Oji Ogawa, Shimodate City, Ibaraki Prefecture Inside the Shimodate Plant of Hitachi Chemical Co., Ltd. (72) Inventor: Kazuhisa Otsuka, 1500 Ogawa, Oji, Shimodate-shi, Ibaraki Pref., Shimodate Research Laboratory, Hitachi Chemical Co., Ltd.

Claims (2)

[Claims] 1. A method according to claim 1, A step of producing an inner wiring board; b. Perforating a metal foil with an adhesive comprising a metal foil and an insulating resin adhesive layer, c. A step of laminating and bonding the inner wiring board and the metal foil with adhesive between a laminating jig and a laminate with a sheet that flows plastically in a laminating step; d. Forming a wiring on the laminated adhesive, in the method for manufacturing a multilayer wiring board comprising the steps of: forming an inner layer line of the inner wiring board formed in the step a corresponding to a position orthogonal to the outer layer line formed in the step d; Line gap 0.2-1.0m
A method for manufacturing a multilayer wiring board, wherein the method is formed so as to avoid the range of m. 2. The method for manufacturing a multilayer wiring board according to claim 1, wherein the insulating resin adhesive layer is a resin layer mainly composed of a high molecular weight epoxy polymer.