JPH09153661A - Wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to simply and efficiently manufacture a wiring board excellent in low profile by forming recesses in chip components on a multilayer wiring board having via holes or in places of installation of board securing screws. SOLUTION: Insulating adhesive is applied to the copper foil to form insulating adhesive layers with the copper foil. The adhesive surfaces of such insulating adhesive layers with copper foil are superposed in such a manner that they are in contact with inner circuits, and they are laminated and integrated by application of heat and pressure. The insulating adhesive layer of the obtained laminated board is selectively etched and removed to form recesses. Further, the entire surface of the workpiece is subjected to electroless plating, and the unnecessary copper foil is selectively etched and removed to obtain this wiring board. The recesses can be formed by removing the outermost wiring layer and the insulating layer supporting the wiring layer, and the inner circuits exposed in the recesses and the circuit in the outermost layer can be connected with each other by plating.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a wiring board and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, multilayer wiring boards have been made higher in density and thinner, and a method for manufacturing a multilayer wiring board without using glass cloth has been studied. A so-called interstitial for connecting only adjacent wiring layers. Via hole (hereinafter IVH
That. ) Are being studied. That is, the thickness of the insulating layer is suppressed by not using glass cloth, and the wiring area of the circuit layers other than the connection layer is increased by connecting only the adjacent wiring layers. It is a thing. A wiring board having such a via hole is disclosed in JP-A-58-58.
As described in Japanese Patent Laid-Open No. 64097 and Japanese Patent Laid-Open No. 4-148590, and as shown in FIG. 2, a multilayer wiring board having a plurality of insulating layers, a plurality of wiring layers, and via holes for connecting at least adjacent wiring layers. Is listed.

Further, an insulating resin layer and a metal layer are further formed on the inner layer circuit, and a portion of the metal layer where a via hole is formed is selectively removed by etching, and the exposed portion is exposed. A method of chemically etching the insulating resin layer to metallize the inner wall of the hole to form a via hole is disclosed in JP-A-4-148590 and JP-A-5-259.
No. 649, etc. Of these, JP-A-5
JP-A-259649 describes that an alkali-soluble resin is used as an insulating resin and an alkali is used as a chemical etching liquid. JP-A-4-148590 discloses an insulating resin manufactured by Ciba-Geigy. It is described that a photosensitive epoxy resin Probimer 52 is used and a developer DY90 (mixed solution of propylene carbonate, cyclohexanone and gammabutyrolactone) manufactured by Ciba-Geigy is used as a chemical etching solution.

[0004]

By the way, recently,
There is an increasing demand for thinner electronic devices such as video cameras and notebook computers, and they have via holes as described in Japanese Patent Application Laid-Open No. 58-64097. Multi-layer wiring boards are no longer available.

An object of the present invention is to provide a wiring board excellent in thinning and a method for manufacturing such a wiring board simply and efficiently.

[0006]

A wiring board according to the present invention is a multilayer wiring board having a plurality of insulating layers, a plurality of wiring layers, and via holes for connecting at least adjacent wiring layers. On the mounting part of the fixing screw,
It is characterized by having a recess.

In such a wiring board, a copper foil is coated with an insulating adhesive, and an insulating adhesive layer with a copper foil is preliminarily provided with holes at the portions where the recesses are to be formed. The adhesive side of the adhesive layer is laminated so as to contact the inner layer circuit side, and heat and pressure are applied to laminate and integrate, and electroless plating is performed on the entire surface of the laminate in which the laminate is integrated to selectively remove copper foil at unnecessary locations. It can be manufactured by etching away.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Further, the adhesive surface of an insulating adhesive layer with a copper foil, which is obtained by applying an insulating adhesive to a copper foil, is laminated so as to be in contact with the inner layer circuit side, and is heated and pressed to be laminated and integrated. By selectively etching away the insulating adhesive layer at the place where the concave portion of the laminated integrated laminate is formed, and further performing electroless plating on the entire surface, and selectively removing the copper foil at unnecessary places by etching Can also be manufactured.

As shown in FIG. 1, the recess of the present invention can be formed by removing the outermost wiring layer and the insulating layer supporting it, and the inner layer circuit exposed in the recess and the outermost layer can be formed. Circuits can be connected by plating.

The insulating adhesive layer with a copper foil obtained by applying an insulating adhesive to the copper foil used in the present invention is an electrolytic copper foil or a rolled copper foil generally used in a printed wiring board or a multilayer wiring board. An ultra-thin copper foil, a three-layer copper foil having Ni in the center can be used. In this insulating adhesive, the compounding equivalence ratio of the bifunctional epoxy resin and the halogenated bifunctional phenol is set to epoxy group / phenolic hydroxyl group = 1: 0.9 to 1.1, and heated to polymerize in the presence of a catalyst. A thermosetting epoxy adhesive film containing a halogenated high molecular weight epoxy polymer having a molecular weight of 100,000 or more, a cross-linking agent, and a polyfunctional epoxy resin having the above film-forming ability can be used. Also,
A thermosetting epoxy adhesive resin insulating layer using a brominated phenoxy resin can be used instead of the halogenated high molecular weight epoxy polymer.

In order to preliminarily form a hole in a portion where a concave portion is to be formed, punching with a tooth mold is most suitable for a large area or a complicated shape portion. With a circular shape, drilling can also be applied. Laser processing is also possible if the circuit specifications or the removal of carbide can be done in a post process where insulation degradation due to carbonization is not a problem.

The cushion press method is not essential for stacking the adhesive surface of the copper foil-insulating insulating adhesive layer so as to contact the inner layer circuit side and heating and pressurizing to laminate and integrate the layers. It is optimal in that it substantially suppresses the resin flow of the insulating adhesive layer. If the resin flow of the insulating adhesive layer has substantially negligible characteristics or has negligible recess design specifications, the end plate pressing method is also possible. Cushion materials include Tedra (trade name of DuPont) and T
PX film (Mitsui Petrochemical Industry Co., Ltd., trade name)
It is possible to use a combination of a heat-resistant release film such as and a thermoplastic film such as polyethylene and polypropylene. Further, a water-soluble thermoplastic film such as Nobon (manufactured by Chisso Corporation, trade name) film can also be used.

To carry out electroless plating on the entire surface of the laminated and integrated laminated plate, thick electroless plating such as CC-41 can be used. When electroless plating and electrolytic plating are used in combination, a base electroless copper plating such as CUST-201 (manufactured by Hitachi Chemical Co., Ltd., trade name) or an electroless plating solution CC-41 (Hitachi Chemical Co., Ltd.) (Product name)
It is possible to use thick electroless copper plating. As the electrolytic copper plating, copper sulfate plating or copper pyrophosphate plating can be used.

It is a general technique for printed wiring boards to selectively remove copper foil at unnecessary portions by etching. The copper foil can be removed by etching by exposing, developing and etching with a dry film. Any of ferric chloride, cupric chloride and alkali can be used as the etching solution,
A dry film suitable for each can be used. It is also possible to cut and remove the copper foil with an NC router.

Further, the insulating adhesive layer of the copper foil coated with an insulating adhesive is laminated so that the adhesive surface of the copper foil is in contact with the inner circuit side, heated and pressed to be laminated and integrated, and the laminated and integrated. In order to selectively remove the insulating adhesive layer at the location where the concave portion of the laminate is to be formed by etching, it is necessary to have selective etching properties between the resin of the inner layer circuit board and the resin of the insulating adhesive layer,
Concentrated sulfuric acid is invincible. When the insulating adhesive compounded with the above-mentioned high molecular weight epoxy polymer is used, the epoxy substrate, the polyimide substrate system substrate and the BT substrate are prepared by immersing the insulating adhesive in an etching solution composed of an amide solvent, an alkali metal compound and an alcohol solvent. Selective etching is obtained on the substrate, and the insulating resin layer can be etched.

[0016]

【Example】

Example 1 As shown in FIG. 3A, an etching resist was formed on both surfaces of a copper-clad laminate E-67 (manufactured by Hitachi Chemical Co., Ltd.), and a copper foil exposed from the etching resist was removed. A chemical etching solution mainly composed of ferric chloride / hydrochloric acid was sprayed and selectively removed by etching to prepare an inner layer circuit board. Next, as shown in FIG. 3B, the thickness is 18 μm.
A copper varnish of AS-3000 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is an insulating adhesive in which a high molecular epoxy polymer is characteristically blended, is applied to the copper foil with an applicator, and 1
After drying at 30 ° C. for 10 minutes, as shown in FIG. 3 (c), a hole is formed by a numerical control type drill machine in the semi-cured state of the insulating adhesive layer with copper foil where the recess is to be formed. Open
As shown in FIG. 3 (d), the adhesive surface of the copper foil-insulated insulating adhesive layer is laid so as to contact the inner layer circuit side of the inner layer circuit board, as shown in FIG. 3 (e). As shown in FIG. 3 (f), necessary portions of the laminated plate are integrated by heating and pressurizing under the conditions of a holding temperature of 175 ° C., a holding time of 45 minutes, and a pressure of 2.5 MPa. A hole to be a through hole is formed in the plate, and as shown in FIG. 3 (g), the laminated plate is formed in a CC-41 plating solution (Hitachi Chemical Co., Ltd., trade name) at 70 ° C. for 18 hours. Under the conditions, electroless plating is performed, and as shown in FIG. 3 (h), an etching resist is formed on the surface of the copper foil, and unnecessary portions of the copper foil exposed from the etching resist are selectively etched. After removal, a wiring board was manufactured. The recess of this wiring board had a depth of 0.05 mm, a width of 0.5 mm, and a length of 1.0 mm, as shown in FIG. The place where the screw was fastened was a recess having a diameter of 1.5 mm and a depth of 0.10 mm.

Example 2 In the same manner as in Example 1, an inner layer circuit board was prepared as shown in FIG. Next, as shown in FIG. 4 (b), AS-3000 which is an insulating adhesive is applied to a copper foil having a thickness of 18 μm.
(Hitachi Chemical Co., Ltd., trade name) Film 130
The insulating adhesive layer with a copper foil was obtained by pressing at a temperature of 2 ° C. for 2 minutes. Next, as shown in FIG. 4 (c), the adhesive surface of the insulating adhesive layer with a copper foil is stacked so as to be in contact with the inner layer circuit side of the inner layer circuit board, and the pressure is 2 at 175 ° C. for 45 minutes. Under the condition of 0.5 MPa, heating and pressurizing to laminate and integrate,
A hole that will be a through hole is made with a numerically controlled drill machine at the required place of the laminated and integrated laminated plate, and the insulating adhesive layer at the place where the concave portion of the laminated plate is formed is changed to a chemical etching solution of the following composition. Immerse at 60 ℃ for 30 minutes,
It was selectively removed by etching. (Composition of chemical etching liquid) ・ N-methyl-2-pyrrolidone ・ 81% by weight ・ Potassium hydroxide ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ 2.7% by weight ・ Methyl alcohol ・ ・ ・ ・ ・ 6.3% by weight ・ Water ・ ・ ・ ・··································································· Forty-minute solution of sodium hydroxide 40 g / l and potassium permanganate 60 g / l Soak,
After smearing, it is dipped in CC-41 plating solution (Hitachi Chemical Co., Ltd., trade name) for 18 hours at 70 ° C., electroless plating is performed on the entire surface, and lamination with a vacuum roll laminator is followed by vacuum cushioning. An etching resist is formed by material pressing (130 ° C., 10 minutes), a resist image is formed by exposure and development, and unnecessary portions of the copper foil exposed from the etching resist are selectively removed by etching to form a wiring board. Created. The concave portion of this wiring board has a depth of 0.05 m as shown in FIG.
m, width 0.5 mm, length 1.0 mm. The place where the screw was fastened was a recess having a diameter of 1.5 mm and a depth of 0.10 mm.

[0018]

As described above, according to the present invention, it is possible to provide a wiring board excellent in thinning and a method of manufacturing such a wiring board simply and efficiently. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an example of a conventional wiring board with a via hole.

3 (a) to 3 (h) are cross-sectional views in each step for explaining one embodiment of the present invention.

4A to 4H are cross-sectional views in each step for explaining another embodiment of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H05K 3/46 H05K 3/46 Q

Claims (6)

[Claims] 1. A multilayer wiring board having a plurality of insulating layers, a plurality of wiring layers, and via holes for connecting at least adjacent wiring layers, wherein a recess is provided in a mounting portion of a chip component or a board fixing screw. A wiring board characterized by the above. 2. The recess is formed by removing the outermost wiring layer and the insulating layer supporting it.
The wiring board described in. 3. The wiring board according to claim 1, wherein the inner layer circuit exposed in the recess and the outermost layer circuit are connected by plating. 4. An adhesive for an insulating adhesive layer with a copper foil in which a hole is formed in advance in a place where a recess is formed in an insulating adhesive layer with a copper foil, which is obtained by applying an insulating adhesive to a copper foil. Stack the surfaces so that they contact the inner layer circuit side, heat and pressurize to laminate and integrate, and then perform electroless plating or electroless plating and electrolytic plating on the entire surface of the laminated and integrated laminate to remove unnecessary copper foil. A method of manufacturing a wiring board, characterized by selectively removing by etching. 5. The method for manufacturing a wiring board according to claim 4, wherein the insulating adhesive is a high molecular weight epoxy polymer. 6. An insulating adhesive layer with a copper foil, which is obtained by applying an insulating adhesive to a copper foil, is laminated so that the adhesive surface of the copper foil is in contact with the inner layer circuit side, and is heated and pressed to be laminated and integrated. After selectively etching away the copper foil at the place where the concave part of the laminated plate is formed, the exposed insulating adhesive layer is selectively removed by etching at the place where the copper foil is removed by etching, and further electroless plating is performed on the entire surface. The method of manufacturing a wiring board according to claim 1, 2 or 3, wherein the copper foil is selectively removed by etching at unnecessary portions.