JPH1187922A - Manufacture of multilayered wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture of a multilayered wiring board, capable of raising the density of wiring, without the use of a special insulation material and without the need of considerable equipment investment. SOLUTION: This manufacture is provided with processes for laminating an insulating adhesive layer 2 and a conductor metallic foil 1 in the order on the surface of an inner layer sheet 4, where an inner layer circuit 3 is formed, pressing, heating and integrating them, forming an opening part 5 by etching and removing the conductor metallic foil 1 at a part for forming an IVH(interstitial via hole) 9, jointing a film 81 for plating resist, irradiating the opening part 5 formed on the conductor metallic foil 1 and the periphery with a laser beam 6 from the above of the film 81 for the plating resist, opening a non-through hole 11 until the inner layer circuit 3 is exposed from the insulating adhesive layer 2, applying a catalyst 7 for plating at least to the insulating adhesive layer 2 on the inner wall of the non-through hole 11, performing plating 13 at the part without the film 81 for the plating resist, removing the film 81 for the plating resist, etching and removing the unwonted parts of the conductor metallic foil 1 and forming an outer layer wiring 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an interstitial via for connecting only adjacent layers.
The present invention relates to a method for manufacturing a multilayer wiring board having a hole (hereinafter, referred to as IVH).

[0002]

2. Description of the Related Art Conventionally, in a multilayer wiring board, as a method of electrically connecting layers, a method of metal plating after forming a through hole has been mainly used. However, in this method, a wiring prohibition region due to a through hole is present in all layers, which is an obstacle to high density. In recent years, a method using an IVH for connecting only adjacent layers has been put into practical use. I have. As described in Japanese Patent Application Laid-Open No. 148590/1992, a photosensitive insulating layer is formed on the surface of an inner circuit board, and a photoconductive insulating layer is formed on the insulating layer on the surface of the substrate where interlayer connection is to be performed. There is a method in which a non-through hole is formed by a lithographic method, the hole and the substrate surface are metal-plated, and a conductor on the substrate surface is formed by etching a circuit (photo via method).

Further, as described in Japanese Patent Publication No. 4-3637, a metal foil and an insulating adhesive are layered and adhered on the surface of an inner circuit board, and a portion of the substrate surface where the interlayer connection is to be performed is performed. There is also a method of forming a hole in a metal layer by an etching method, further making a non-through hole with a laser or the like, plating the hole and the substrate surface with a metal, and then forming a circuit on a conductor on the substrate surface by an etching method (laser drilling method). .

[0004]

Problems to be Solved by the Invention Japanese Patent Laid-Open No. 4-14859
According to the method described in Japanese Patent Publication No. 0, the insulating layer is required to have many characteristics such as photolithography, insulation, adhesion to a plated metal, and ability to form a coating film on a substrate. Few satisfy the requirements, and cannot be performed only with the current equipment, and some capital investment is required. For example, in order to achieve both insulating properties and photolithographic properties, if a material system having a small number of polar groups is selected, in the photolithographic process development, solvent development must be adopted, and chlorine-based solvents cannot be used from the viewpoint of environmental protection. Therefore, a completely explosion-proof device using a flammable solvent is required. In addition, 4-3
In the method described in Japanese Patent No. 637, the thickness of a metal layer serving as a conductor circuit is large because metal plating is further performed on a metal foil. When a circuit is formed by an etching method, there is a limit to miniaturization of a circuit. is there.

It is an object of the present invention to provide a method for manufacturing a multilayer wiring board capable of increasing the wiring density without using a special insulating material and without requiring a large capital investment.

[0006]

A method of manufacturing a multilayer wiring board according to the present invention is characterized in that the method of manufacturing a multilayer wiring board having an IVH 9 for connecting only adjacent layers includes the following steps. . a. 1 (a), an insulating adhesive layer 2 and a conductive metal foil 1 are superposed in this order on a surface of an inner substrate 4 on which an inner circuit 3 is formed, and integrated by pressing and heating; b. . As shown in FIG. 1B, a step of forming an opening 5 by etching and removing the conductive metal foil 1 at a location where an IVH 9 for electrically connecting the conductive metal foil 1 and the inner layer circuit 3 is formed, c. As shown in FIG. 1C, a step of attaching a plating resist film 81 to the surface of the conductive metal foil 1 in which the openings 5 are formed, d. As shown in FIG. 1D, a plating resist film 81 is formed around the opening 5 formed in the conductive metal foil 1 and the periphery thereof.
Irradiate a laser beam 6 from above to the insulating adhesive layer 2,
Drilling a non-through hole 11 until the inner layer circuit 3 is exposed, e. As shown in FIG. 1E, at least the non-through hole 1
1 a step of applying a plating catalyst 7 to the insulating adhesive layer 2 on the inner wall; f. As shown in FIG. 1 (f), a step of performing plating 13 on a portion where there is no plating resist film 81, g. 1g, a step of removing the plating resist film 81, h. As shown in FIG. 1H, an unnecessary portion of the conductive metal foil 1 is removed by etching to form an outer wiring 10.

[0007] Multilayering is possible as follows. a. A step of laminating the insulating adhesive layer 2 and the conductive metal foil 1 on the surface of the inner layer substrate 4 on which the inner layer circuit 3 is formed in this order, and pressing and heating to integrate them; b. IV for electrically connecting conductive metal foil 1 and inner layer circuit 3
A step of etching and removing the conductive metal foil 1 at locations where H9 is to be formed to form openings 5; c. Attaching a plating resist film 81 to the surface of the conductive metal foil 1 in which the openings 5 are formed, d. The opening 5 formed in the conductive metal foil 1 and its surroundings are irradiated with a laser beam 6 from above the plating resist film 81 so that the non-through hole 11 is formed in the insulating adhesive layer 2 until the inner layer circuit 3 is exposed. Opening step, e. At least the insulating adhesive layer 2 on the inner wall of the non-through hole 11
Applying a plating catalyst 7 to the substrate, f. A step of performing plating 13 on a portion where there is no plating resist film 81; g. Removing the plating resist film 81, h1. Forming a first outer layer wiring by etching and removing unnecessary portions of the conductive metal foil 1; j. Step a to Step h1 are repeated a required number of times to perform Step a to Step h.

In step a, instead of stacking the insulating adhesive layer 2 and the conductive metal foil 1 on each other, an insulating adhesive layer 12 with a conductive metal foil in which these are integrated can be used.

[0009] Further, the following steps are added, and
4 can also be provided at the same time. A step of drilling the through hole 14 in the step c or the step d; a step of applying the plating catalyst 7 to the inner wall of the through hole 14 in the step e; and a plating of the inner wall of the through hole 14 in the step f. Step 13. Further, in step d, if the plating resist film 81 around the through hole 14 is removed, a multilayer wiring board having the through hole 14 as shown in FIG. 2 can be obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(Step a) The conductive metal foil 1 used in the present invention can be used as long as wiring can be formed by an etching method, and a copper foil is generally preferred. Further, the thickness of the metal foil is preferably as thin as possible to form fine wiring,
When the copper foil is a single layer, the thickness is preferably 9 μm to 18 μm from the viewpoint of handleability. Also, the line / space is 50 μm /
When forming an extremely fine wiring of less than 50 μm,
The thickness of the copper foil is desirably thinner. In such a case, a composite foil comprising an ultrathin copper foil of 3 to 9 μm and a reinforcing layer of the ultrathin copper foil is used. After the lamination under pressure and heat, the reinforcing layer is peeled off or removed by etching. An example of the peelable composite foil is a peelable copper foil (trade name, manufactured by Furukawa Circuit Foil Co., Ltd.) composed of a 70 μm thick copper foil and a 9 μm ultra-thin copper foil. As a material capable of removing the reinforcing layer by etching, there is a composite foil (manufactured by Mitsui Kinzoku Kogyo Co., Ltd.) which removes an aluminum foil obtained by combining an aluminum foil with a 5 μm ultra-thin copper foil by etching.

As the resin of the insulating adhesive layer 2 used in the present invention, a resin such as a phenol resin, an epoxy resin, and a polyimide resin can be used. The insulating adhesive layer 2 is laminated on the inner substrate 4 by applying pressure and heat, and then is irradiated with a laser beam 6 to form a hole for interlayer connection. When included in the layer 2, the time required for laser processing becomes long and the productivity becomes extremely low.
It is desirable not to include inorganic fibers having a length greater than the diameter of the hole to be drilled. The insulating adhesive layer 2 contains epoxy or polyimide as a component. For example, AS-3000E (Hitachi Chemical Industries, Ltd.) is used as an epoxy adhesive film containing a high-molecular-weight epoxy polymer having a molecular weight of 100,000 or more as a main component. Co., Ltd., trade name). There is GF-3500 (trade name, manufactured by Hitachi Chemical Co., Ltd.) as an epoxy-based adhesive film to which modified rubber is added. AS-2500 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is available as a polyimide-based adhesive film. As an epoxy-based adhesive film in which a fibrous substance having a diameter of 0.1 to 6 µm and a length of about 5 to 100 µm is dispersed in an epoxy-based resin, AS-
6000E (trade name, manufactured by Hitachi Chemical Co., Ltd.). These insulating adhesive layers 2 are obtained by applying a varnish obtained by dissolving a thermosetting resin in a solvent on a peelable film, and then drying the solvent. The thickness of the insulating adhesive layer 2 is related to the thickness of the inner circuit 3, and it is necessary that the thickness be at least equal to or greater than the thickness of the inner circuit 3 from the viewpoint of the filling property of the inner circuit 3. When the thickness of the inner layer circuit 3 is 12 μm, the thickness is about 25 μm. If the thickness of the inner layer circuit 3 is as thin as about 5 μm,
The inner layer circuit 3 can be filled even with about 10 μm.
Generally, the thickness of the insulating adhesive layer 2 is 10 to 500 μm.
Range.

An insulating adhesive layer 12 with a conductive metal foil integrated with the conductive metal foil 1, which can be used instead of overlapping the conductive metal foil 1 and the insulating adhesive layer 2, is provided on the surface of the conductive metal foil 1. A film obtained by applying an insulating adhesive to the above-mentioned peelable film is attached, and then the film is peeled off. The peelable film is
An organic film is preferable, and the organic film to which the adhesive is applied needs to have heat resistance at this heating temperature in order to remove the solvent by drying after application. Such organic films include polyethylene terephthalate,
Polypropylene, 4-methylpentene 1 polymer, polyfluoroethylene, and the like can be used. The thickness of these films is 5 μm or more, and a certain thickness is required from the viewpoint of handleability. From this point, the desirable thickness is 1
0 to 70 μm.

The insulating adhesive layer 12 with the conductive metal foil
Can also be obtained by directly applying a varnish obtained by dissolving an insulating adhesive resin in a solvent to a metal foil. As such a material, for example, there is MCF-3000 (trade name, manufactured by Hitachi Chemical Co., Ltd.) as an epoxy-based adhesive film with a copper foil containing a high molecular weight epoxy polymer having a molecular weight of 100,000 or more as a main component. An epoxy adhesive film with a copper foil in which a fibrous substance having a diameter of 0.1 to 6 μm and a length of about 5 to 100 μm is dispersed in an epoxy resin, MCF
-6000E (trade name, manufactured by Hitachi Chemical Co., Ltd.).

As the inner layer substrate 4 used in the present invention, an epoxy-based, phenol-based, or polyimide-based single-sided copper-clad laminate containing a paper base or a glass base can be used. In addition, a double-sided copper-clad laminate made of these base materials and resin is used.
Using these base materials, the inner layer circuit 3 is formed by using an etching method or both plating and etching. In addition, a substrate obtained by forming a conductive pattern on an epoxy-based, phenol-based, or polyimide-based substrate including a paper substrate or a glass substrate by an additive method can also be used. In addition, a metal substrate, a ceramic substrate, or the like having a conductive pattern formed on the surface thereof can also be used.
When the inner layer substrate 4 is a double-sided circuit board having a circuit formed on both sides thereof, a double-sided circuit board filled with a conductive paste or an insulating resin is used for the interlayer connection hole.

The conditions for laminating the insulating adhesive layer 2 and the conductive metal foil 1 on the inner layer substrate 4 in this order and applying pressure and heat to the resin depend on the resin used.
At a heating temperature range of 0 ° C., the pressure is generally in the range of 1 to 50 MPa.

(Step b) Opening 5 provided in conductive metal foil 1
The hole diameter is not particularly limited, and the smaller the hole diameter is, the better from the viewpoint of increasing the density of the substrate. However, the hole diameter is preferably 50 μm or more in consideration of the processability in the etching method, the plating coverage, and the like.

(Step c) A film with an adhesive is adhered as a plating resist film 81 to the surface of the conductive metal foil 1 in which the openings 5 are formed as described above. The film to be used is desirably a film such as polyethylene, polypropylene, or polyester which is not easily attacked by an acid or alkali solution in a later step. For film, for example, H
There is a -5310 film (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is preferably stuck using a hot roll laminator.

(Step d) Examples of the laser light to be applied to the opening 5 from above the plating resist film 81 include an excimer laser and a carbon dioxide laser, but a resin layer other than the conductive metal foil 1 is selectively formed. A carbon dioxide laser that is easy to process, has a fast processing speed, and is easy to maintain is preferable. In laser drilling, by irradiating a laser beam having a beam diameter larger than the diameter of the opening 5, a hole having the same diameter is formed in the insulating adhesive layer 2 at the same place as the opening 5 of the conductive metal foil 1. The non-through hole 11 can be opened until the inner layer circuit 3 is exposed, and the plating resist film 8 is formed.
A hole can be drilled in the periphery including the opening 5 in 1. Since the laser processing conditions at this time vary depending on the type of the insulating adhesive layer, the optimum conditions are experimentally selected in advance.

(Step e) The plating catalyst 7 to be applied to the insulating adhesive layer 2 on the inner wall of the non-through hole 11 is formed by depositing fine metal particles generally called seeding,
A method for forming a conductive film, for example, DE 38068
As described in JP-A-84C1, after adsorbing a monomer consisting of a 5- or 6-membered heterocyclic group having nitrogen or sulfur as a heteroatom to a resin portion in a hole portion, polymerizing with a oxidizing agent. To form a conductive polymer layer. In the present invention, since only the inner wall of the hole and the vicinity of the hole are plated, the latter method that can use electroplating that can be processed in a short time in a short time is preferable. Also, in order to increase the adhesion strength between the plating catalyst 7 and the metal plating and the resin layer inside the hole and improve the reliability of the connection portion, the surface of the resin layer inside the hole is oxidized before the plating catalyst application step. A desmear process can be added.

(Step f) Plating 13 is applied to the drilled portion, and an IVH 9 for connecting the inner layer circuit 3 and the conductive metal foil 1 is formed.
The method for forming is not particularly limited,
Electroless plating or electroplating performed on a normal printed board can be applied.

[0021]

【Example】

Example 1 As the insulating adhesive layer 12 with a conductive metal foil, a copper foil having a thickness of 12
MCF-3000E (trade name, manufactured by Hitachi Chemical Co., Ltd.), an epoxy-based adhesive film having a resin layer thickness of 50 μm, a resin layer thickness of 50 μm, and a high molecular weight epoxy polymer having a molecular weight of 100,000 or more. 0.2mm thick
To prepare an epoxy-based single-sided copper-clad laminate having been subjected to circuit processing.
Next, these are superimposed and heated under pressure at a pressure of 2.5 MPa and a temperature of 170 ° C. for 60 minutes to produce a multilayer wiring board. The opening 5 having a diameter of 0.1 mm is formed in the copper foil layer on the surface by etching. Was formed. Next, a polyethylene film H-5310 with an adhesive (trade name, manufactured by Hitachi Chemical Co., Ltd.) was attached to the surface of the multilayer wiring board with a laminator.
Next, a carbon dioxide gas laser is set to a diameter of 0.1
A non-through hole 11 reaching the inner layer circuit 3 of the inner layer substrate 4 by irradiating a wide range of mm was formed. Next, as a plating catalyst 7, a DMS-E treatment solution (trade name, manufactured by Brassberg Oberflechentichnik GmbH) was applied to the insulating adhesive layer 2 of the non-through hole 11. A conductive film was formed. Next, 1 is placed inside and around the non-through hole 11.
Electroplating was performed at a thickness of 2 μm, and the plating resist film 81 was peeled off. Further, an etching resist was newly formed, exposed and developed using a mask pattern in the shape of the outer layer wiring 10, and an outermost layer circuit was formed by an etching method to produce a two-layer substrate.

Example 2 As a conductive metal foil 1, a peelable copper foil (made by Furukawa Circuit Foil Co., Ltd., trade name) composed of a 70 μm thick copper foil and a 9 μm ultra-thin copper foil as a reinforcing layer, an insulating adhesive layer 2
AS-6000E (trade name, manufactured by Hitachi Chemical Co., Ltd.) as an epoxy-based adhesive film having a resin layer having a thickness of 70 μm, and as the inner substrate 4, a circuit-processed epoxy-based double-sided copper clad having a thickness of 0.2 mm. A laminate was prepared. Next, AS-6000E (trade name, manufactured by Hitachi Chemical Co., Ltd.) and peelable copper foil (trade name, manufactured by Furukawa Circuit Foil Co., Ltd.) are superimposed on both surfaces of the inner layer substrate 4 in this order, and a pressure of 2.5 MPa is applied. Pressure heating was performed at a temperature of 170 ° C. for 60 minutes to produce a multilayer wiring board. Next, a copper foil having a thickness of 70 μm as a reinforcing layer was peeled off, and an opening 5 having a diameter of 0.1 mm was formed in the copper foil layer on the surface by an etching method.
Next, a polyethylene film H-5310 with an adhesive (trade name, manufactured by Hitachi Chemical Co., Ltd.) was attached to the surface of the multilayer wiring board with a laminator. Next, a carbon dioxide laser was irradiated to a range 0.1 mm wider than the diameter of the opening 5 to form a non-through hole 11 reaching the inner circuit 3 of the inner substrate. Next, as a plating catalyst, a non-penetrating hole 11 was prepared using a DMS-E treatment solution (trade name, manufactured by Brassberg Oberflechentichnik GmbH).
A conductive film was formed on the portion of the insulating adhesive layer 2. Next, the non-through hole 11 and its surroundings were electroplated with a thickness of 12 μm, and the plating resist film 81 was peeled off. Further, a new etching resist was formed, exposed and developed by using a mask pattern in the shape of the outer wiring 10, and a circuit of the outermost layer was formed by an etching method, thereby producing a four-layer multilayer substrate.

Example 3 The substrate of Example 2 was used as the inner layer substrate 4, the insulating adhesive layer 2 and the copper foil layer were further stacked on both sides, and the same material was used for other materials, and the same steps as in Example 2 were repeated. And a six-layer multilayer substrate.

Comparative Example 1 In Example 1, after the opening 5 was formed, laser hole processing was performed without forming the plating resist film 81. Thereafter, a circuit similar to that of Example 1 was formed.

The substrates produced in the above Examples and Comparative Examples were comparatively evaluated. In the wiring pattern provided on each substrate, the wiring rule of line / space = 50 μm / 50 μm showed no short-circuit or disconnection failure in both Examples 1, 2, and 3; Many failures occurred. In addition, the test piece which connected 100 IVH in series,
When 50 cycles of a hot oil test (a cycle test in which 260 ° C. hot oil 10 seconds dipping and a 10 seconds dipping in water at room temperature were repeated), which is one of the reliability tests, were performed, the change in the resistance value of each test piece was 10%. %.

[0026]

As described above, according to the present invention, it is possible to manufacture a multilayer wiring board capable of high-density fine wiring. Further, since a non-through hole is formed by a laser, a very small diameter of 100 μm level can be processed. Furthermore, since the insulating adhesive layer can use a general insulating material used for a multilayer printed circuit board, the insulating material can be used properly according to the application.

[Brief description of the drawings]

FIGS. 1A to 1H are cross-sectional views in each step for explaining an embodiment of the present invention, and FIG. 1A is a cross-sectional view in one step of another embodiment of the present invention. FIG.

FIG. 2 is a cross-sectional view illustrating a multilayer wiring board manufactured by a method according to still another embodiment of the present invention.

[Explanation of symbols]

1. Conductor metal foil 2. 2. Insulating adhesive layer Inner layer circuit 4. Inner layer substrate 5. Opening 6. Laser light 7. Plating catalyst 81. 8. Film for plating resist IVH10. Outer layer wiring 11. Non-through hole 12. 12. Insulating adhesive layer with conductive metal foil Plating 14. Through hole

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoyuki Urasaki 1500 Oji Ogawa, Shimodate City, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. Inside Shimodate Research Laboratory (72) Inventor ▲ Tsuru ▼ Yoshiyuki Shimodate City, Ibaraki Prefecture 1500 Ogawa, Hitachi Chemical Co., Ltd.

Claims (4)

[Claims] An IVH for connecting only adjacent layers.
A method for manufacturing a multilayer wiring board according to (9), comprising the following steps. a. A step of laminating an insulating adhesive layer (2) and a conductive metal foil (1) in this order on a surface of an inner layer substrate (4) on which an inner layer circuit (3) is formed, and pressing and heating to integrate them; b. The conductive metal foil (1) at a position where an IVH (9) for electrically connecting the conductive metal foil (1) and the inner layer circuit (3) is formed
Forming an opening (5) by etching away c. Affixing a plating resist film (81) to the surface of the conductive metal foil (1) having the openings (5) formed therein, d. The opening (5) formed in the conductive metal foil (1) and its surroundings are irradiated with a laser beam (6) from above the plating resist film (81) to apply the inner layer circuit to the insulating adhesive layer (2). Drilling a non-through hole (11) until (3) is exposed, e. Applying a plating catalyst (7) to at least the insulating adhesive layer (2) on the inner wall of the non-through hole (11); f. A step of performing plating (13) on a portion where there is no plating resist film (81); g. Removing the plating resist film (81), h. A step of forming an outer layer wiring (10) by etching and removing unnecessary portions of the conductive metal foil (1). 2. The method for producing a multilayer wiring board according to claim 1, comprising the following steps. a. A step of laminating an insulating adhesive layer (2) and a conductive metal foil (1) in this order on a surface of an inner layer substrate (4) on which an inner layer circuit (3) is formed, and pressing and heating to integrate them; b. The conductive metal foil (1) at a position where an IVH (9) for electrically connecting the conductive metal foil (1) and the inner layer circuit (3) is formed
Forming an opening (5) by etching away c. Affixing a plating resist film (81) to the surface of the conductive metal foil (1) having the openings (5) formed therein, d. The opening (5) formed in the conductive metal foil (1) and the periphery thereof are irradiated with a laser beam (6) from above the plating resist film (81) to form an inner circuit on the insulating adhesive layer (2). Drilling a non-through hole (11) until (3) is exposed, e. Applying a plating catalyst (7) to at least the insulating adhesive layer (2) on the inner wall of the non-through hole (11); f. A step of performing plating (13) on a portion where there is no plating resist film (81); g. Removing the film for plating resist (81), h1. A step of removing unnecessary portions of the conductive metal foil (1) by etching to form a first outer wiring; j. Step a to Step h1 are repeated a required number of times to perform Step a to Step h. 3. In the step (a), an insulating adhesive layer (12) with a conductive metal foil is used instead of overlapping the insulating adhesive layer (2) and the conductive metal foil (1). The method for producing a multilayer wiring board according to claim 1 or 2, wherein: 4. The method for manufacturing a multilayer wiring board according to claim 1, wherein the following steps are additionally provided, and a through hole is provided at the same time. A step of forming a through hole (14) in step c or step d; a step of applying a plating catalyst also to the inner wall of the through hole (14) in step e; and a through hole (14) in step f. A step of plating (13) also on the inner wall.