JPH1027958A - Manufacture of multi-layer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent poor lamination attachment caused by seepage of plastic material from ends of a plastic flow sheet, by forming a band-shaped pattern portion with a predetermined band width at the outer periphery of an inner layer wiring board which is not used as a product, and by providing a curved cut line crossing the band-shaped pattern portion. SOLUTION: An ordinary multi-layer wiring board is used as the inner wiring board. A band-shaped pattern portion with a predetermined band width is provided at the outer periphery of the inner wiring board which is not used as a product. Then a curved cut line A crossing the pattern portion is provided on the pattern portion. The cut line A is substantially square-c shaped, substantially sine-wave shaped, substantially comb shaped, or substantially saw-tooth shaped. The cut line A prevents seepage of plastic material from the plastic flow sheet at lamination process. The shape of the cut line is selected such that it is appropriate in accordance with the characteristic of adhesive used in lamination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[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. 4 (a), a double-sided copper-clad laminate having a through hole formed therein, a plating inside the hole, and wiring formed by etching is used as an inner wiring board 104 or an outer wiring board 102. Fig. 4
As shown in FIG. 4 (b), it is laminated with the prepreg 103 to form a multilayer, and thereafter, as shown in FIG. 4 (c), a through hole is formed in a necessary portion, and the inner wall of the through hole is made conductive by plating. As shown in FIG. 4 (d), a method of 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.

In this method, since the adhesive needs to sufficiently fill the circuit conductor of the inner wiring board, it is required that the adhesive has a large fluidity. Since the flow causes a reduction and a connection failure, a property that does not flow in the hole is required, and this contradictory requirement cannot be solved by simply selecting the composition of the adhesive. Therefore, as a countermeasure, by inserting a sheet or the like that plastically flows in the laminating step between the laminate and the laminating jig (end plate), this sheet material is preceded by the flow of the adhesive resin in the laminating step. Filling the inside of the hole suppresses resin exudation and also has the effect of equalizing the pressure on the surface of the laminate, so that the adhesive resin flows into the gaps between the inner wiring layers, thereby suppressing the occurrence of voids. To do so, refer to JP-A-7-22
No. 6592 proposes this.

[0006]

However, in this method, as shown in FIG. 3, in the laminating step, at the end of the inner wiring board, the plastic material of the sheet that plastically flows in the laminating step is higher than the end. Because of exudation, there is a problem that sufficient pressure is not applied and poor adhesion occurs at the end of the product.

[0007] The present invention provides a method for preventing the defective lamination adhesion at the end.

[0008]

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 resin layer mainly composed of a high molecular weight epoxy polymer and a metal foil, c. A step of laminating and bonding the inner-layer wiring board and the metal foil with adhesive between the laminating jig and the laminated adhesive with a sheet that plastically flows in the laminating step interposed therebetween; d. In a method of manufacturing a multilayer wiring board having a step of forming wiring on a laminated adhesive, as shown in FIG. 2 (a), a pattern having a fixed width is formed on an outer peripheral portion which is not a product of an inner wiring board. The present invention is characterized in that a pattern having a band shape and having a curved cut line crossing the band shape is used.

[0009] The curved cuts crossing the band-like shape are substantially U-shaped as shown in FIG. 2 (b), substantially sinusoidal as shown in FIG. 2 (c), and as shown in FIG. 2 (d). The shape may be a substantially comb-like shape or a substantially saw-tooth shape as shown in FIG. 2 (e). Such a curved cut can suppress the in-plastic material of the sheet that flows plastically in the laminating process from exuding from the end,
Adhesion failure can be prevented.

The shape and width of the cut are determined by the amount of volatile components and other characteristics of the adhesive to be laminated and bonded. The width is adjusted to be narrow when the resin flow is large, and to be wide when the resin flow is small. For example, an optimum value may be selected in advance before manufacturing.

As the inner wiring board used in the present invention, any one can be used as long as it is used for an ordinary multilayer wiring board.

The metal foil used for the adhesive-attached metal foil comprising the metal foil and the adhesive resin layer of the present invention can be a copper foil or an aluminum foil, and among them, a copper foil used for a normal wiring board is preferable. It is preferable to use one that is roughened for adhesion with the adhesive resin 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 and removed before wiring formation can be used, and when using the thin metal foil, the one supported by the carrier is 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.

The resin layer of the adhesive has heat resistance, mechanical properties,
Epoxy resins having excellent overall properties such as electrical properties and chemical resistance are suitable for multilayer wiring boards requiring high properties. When a resin mainly composed of a high molecular weight epoxy polymer is used as the resin of the metal foil with an adhesive, it retains a certain degree of flexibility after curing without a flexibilizing agent or denaturation, and also when heated during lamination bonding. The resin viscosity can be kept high and is suitable for the purpose of the present invention.

The epoxy resin layer is heated in the presence of a catalyst by setting the blending equivalent ratio of the bifunctional epoxy resin and the halogenated difunctional phenol to epoxy group / phenol hydroxyl group = 1 / 0.9 to 1.1. A varnish-like thermosetting epoxy resin using a high-molecular-weight epoxy polymer having a molecular weight of 100,000 or more having a film-forming ability and a cross-linking agent, and a polyfunctional epoxy resin as constituents. Is applied to the roughened surface of the copper foil, put into a semi-cured state by heating, an epoxy resin layer is formed directly on the copper foil, or after the thermosetting epoxy resin is applied on a film substrate and formed into a film, It can also be formed by laminating with a copper foil.

(Composition of thermosetting epoxy resin) The compounding equivalent ratio of the bifunctional epoxy resin and the halogenated difunctional 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 containing a polyfunctional epoxy resin as a component is an epoxy polymer having a film-forming ability, a cross-linking agent, and a polyfunctional epoxy resin as components. .

(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 is composed of 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 it has a halogen atom substituted and has two phenolic hydroxyl groups. Examples thereof include monocyclic bifunctional phenols such as hydroquinone, resorcinol, and the like. 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 bifunctional 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.

In this manner, a so-called high molecular weight epoxy polymer having a film forming ability and having 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. Examples thereof include 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) As the polyfunctional epoxy resin, any compound having two or more epoxy groups in a molecule may be used. For example, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin may be used. Phenol epoxy resin and alicyclic epoxy resin which are glycidyl ethers of phenols such as resin, resol type epoxy resin and bisphenol type epoxy resin, epoxidized polybutadiene, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, 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.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below by way of examples.

[0031]

【Example】

Example (1) Production 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 base material obtained by impregnating a glass cloth with an epoxy resin. By removing unnecessary copper foil by etching, an inner wiring board 4 having an inner wiring having a land at an IVH connection portion was produced. At this time, a pattern as shown in FIG. 2A is used, and a pattern provided on the outer peripheral portion which is not a product of the inner wiring board has a band shape having a fixed width and a curved shape crossing the band shape. 2 (d) was formed into a comb-teeth shape having a width of 10 mm, a unit of 2 mm in a direction perpendicular to the band, and a unit of 2 mm in a parallel direction of the band. (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. The average molecular weight was 50,000 to 100,0, with the solid content concentration of the polymerization reaction being 25% by weight.
Epoxy resin varnish AS using a high molecular weight epoxy polymer of No. 00, a cross-linking agent using an isocyanate as a mask, and a polyfunctional epoxy resin using a resol type epoxy resin.
3000 (manufactured by Hitachi Chemical Co., Ltd., trade name) is applied to the roughened surface of the copper foil 18 μm as the metal foil 32 so that the thickness after drying becomes 50 μm, and dried at 140 ° C. for 25 minutes. To the B-stage state, and the adhesive-attached metal foil 3
Then, a hole having a diameter of 0.15 mm for IVH connection was drilled. (3) Lamination bonding As shown in FIG. 1 (a), the perforated metal foil with adhesive 3 produced in the step (2) is applied to the inner layer wiring board 4 produced in the step (1) by a resin layer. The sheet 2 is overlapped with the inner layer wiring board 31 so as to flow plastically in the laminating step.
Then, a polystyrene sheet having a thickness of 150 μm was inserted between the end plate and the laminate, and heated and pressed at 160 ° C. and 3 MPa for 90 minutes to laminate and bond. (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. (Product name) at a liquid temperature of 70 ° C for 7 hours.
1m, and unnecessary copper foil is selectively removed by etching to form a wiring 9.
The multilayer wiring board with IVH shown in (f) was obtained.

COMPARATIVE EXAMPLE 1 In the example, the pattern formed on the outer peripheral portion of the inner wiring board which is not a product is a strip having a constant width of 10 mm and a cut having a width of 2 mm crossing the strip. A multilayer wiring board was obtained in exactly the same manner except that the shape was as shown in FIG.

(Evaluation) In the example and the comparative example, the adhesion failure of the end portion of the inner wiring board was examined. In the comparative example, the edge adhesion failure occurred in all the panels. No failure occurred.

[0034]

According to the present invention, a high-density multilayer wiring board having a lamination bonding step using a plastic flow sheet can be manufactured without defective end portions.

[Brief description of the drawings]

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

2A is a top view showing one embodiment of the present invention, FIG. 2B is an enlarged view of a portion A of FIG. 2A, and FIGS.
(E) is an enlarged view of a portion A of (a) of another embodiment of the present invention.

FIG. 3 is a top view showing a conventional example.

FIGS. 4A to 4D are cross-sectional views in respective steps for explaining a manufacturing process 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. Adhesive resin 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

Claims (6)

[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 resin layer mainly composed of a high molecular weight epoxy polymer and a metal foil, c. A step of laminating and bonding the inner-layer wiring board and the metal foil with adhesive between the laminating jig and the laminated adhesive with a sheet that plastically flows in the laminating step interposed therebetween; d. In the method of manufacturing a multilayer wiring board having a step of forming a wiring on the laminated adhesive, a pattern shape provided on an outer peripheral portion that does not become a product of the inner wiring board has a band-like shape having a certain width, and A method for manufacturing a multilayer wiring board, comprising using a pattern having a curved cut line crossing a shape. 2. The method for manufacturing a multilayer wiring board according to claim 1, wherein the curved cuts crossing the band-like shape are substantially U-shaped. 3. The method for manufacturing a multilayer wiring board according to claim 1, wherein the curved cuts crossing the strip-like shape are substantially sinusoidal. 4. The method for manufacturing a multilayer wiring board according to claim 1, wherein the curved cuts crossing the band-like shape are substantially arc-shaped. 5. The method for manufacturing a multilayer wiring board according to claim 1, wherein the cuts having a curved shape crossing the strip-like shape are substantially comb-shaped. 6. The method for manufacturing a multilayer wiring board according to claim 1, wherein the curved cuts crossing the band-like shape are serrated.