JPH11204942A - Manufacture of multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient manufacturing method of a high-density multilayer wiring board which can facilitate formation of a fine conductor pattern. SOLUTION: A laser beam is projected onto the organic film surface of an adhesive-applied metal foil 5 which has an insulating adhesive layer 3 provided on one side of a metal foil 2 and a separable organic film 4 provided on the surface of the insulating adhesive layer, thereby forming a hole reaching to the metal foil at a position where electric connection between layers is to be made, fills the hole with a conductive paste 7, and the conductive paste is semi-cured. Then, the organic film 4 is separated, and the adhesive-applied metal film 5 is placed over the surface of an inner layer circuit board 1 in such a way that the hole in the adhesive-applied metal foil, which is filled with the conductive paste, is aligned with the connection portion of an inner layer circuit of the inner layer circuit board, and they are pressed and heated into a laminate. Then, the outer metal foil is made thinner in the widthwise direction and the unnecessary portion of the metal foil is etched out, thus forming a conductive pattern.

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 With the miniaturization, high performance, and multifunctionality of electronic equipment, multilayer printed wiring boards have been required to have higher densities. In order to satisfy these requirements, the thickness between layers is reduced, the wiring is miniaturized, the diameter of interlayer connection holes is reduced, and an interstitial via hole (hereinafter, referred to as IVH) that connects only conductors between adjacent layers. ) And the like, and the IVH is also being reduced in diameter.

[0003] In order to form a multilayer wiring, a plurality of circuit layers and an interlayer insulating layer between them are collectively overlapped, pressurized and heated to be laminated and integrated, and a hole is formed at a necessary portion for connection. A build-up multilayer wiring board that forms an interlayer insulating layer on a circuit, forms a circuit thereon, and provides a hole at a necessary place, and sequentially forms a circuit layer and an insulating layer, and so on. There is.

[0004] A general process of this build-up multilayer wiring board is as follows. A thermosetting resin is formed in a through hole of an inner layer circuit board having a plated through hole and an inner layer circuit formed thereon by a silk screen printing method or the like. Fill it completely so that it is completely covered, and after heating and curing, remove the resin protruding from the holes by polishing or the like, apply a thermosetting resin, overlay copper foil, heat cure to form an insulating layer, and connect. After removing the copper foil at the location and selectively removing the insulating layer at the removed location, a hole for interlayer connection is provided, and the inner wall of the hole for interlayer connection is metallized by plating or the like, and then the surface is removed. Is formed by etching or the like. Thereafter, if necessary, the same steps as described above are repeated to form an insulating layer and a circuit layer, whereby a required multilayer circuit can be formed.

[0005]

However, in the above-described method, when the inner wall of the hole for interlayer connection is metallized by plating or the like, the copper foil on the surface is also plated, and the conductor forming the circuit is It becomes thicker by the thickness of the plating, and when forming the circuit by etching the circuit conductor on the surface,
There is a problem that it is difficult to form fine wiring. Also,
Since the portion of the hole for interlayer connection is recessed, when further multilayering, it is necessary to fill the recess once with a filling resin or the like before forming an insulating layer between the layers, it is necessary to smooth out,
There was also a problem that the process became complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily forming a fine conductor pattern and efficiently producing a high-density multilayer wiring board.

[0007]

A method of manufacturing a multilayer wiring board according to the present invention comprises the following steps. a. An insulating adhesive layer is provided on one side of the metal foil, and a laser is applied to the organic film surface of the adhesive-attached metal foil provided with a peelable organic film on the surface of the insulating adhesive layer. Making a hole to reach the metal foil at the point where the electrical connection is made. b. Filling the holes with a conductive paste to bring the conductive paste into a semi-cured state; c. The step of peeling the organic film. d. On the surface of the inner circuit board, the metal foil with the adhesive prepared in step c is aligned so that the hole filled with the conductive paste of the metal foil with the adhesive overlaps the connection point of the inner layer circuit of the inner circuit board. A process of stacking, stacking and integrating by heating under pressure. e. Removing the outer metal foil in the thickness direction to make it thinner; f. A step of forming a conductor pattern by etching away unnecessary portions of the metal foil thinned in step e.

[0008] The thickness of the metal foil thinned in the step e is 1 to 1
It is preferably in the range of 0 μm, and if it is less than 1 μm, it cannot be roughened in order to improve adhesion with the resin,
If it exceeds 0 μm, high-density wiring cannot be formed.

The metal foil used in the step (a) is composed of a copper layer having a roughness suitable for bonding to a resin and also serving as a circuit, and a carrier layer having sufficient strength for handling as a whole metal layer. Using a composite metal foil from which two layers can be easily peeled off, the carrier layer can be peeled and removed in the step e in which the outer metal foil is thinned in the thickness direction.

The metal foil used in the step (a) has a roughness suitable for bonding with a resin and has a circuit of 1 to 9 μm.
A first copper layer having a thickness of 10 μm and a second copper layer having a thickness of 10 to 150 μm having sufficient strength for handling as a metal layer as a whole.
Copper layer and the thickness provided between the two layers is 0.04
Using a composite metal foil composed of a nickel-phosphorus alloy layer of about 1.5 μm, in step e, a step of thinning the outer metal foil in the thickness direction, a step of removing only the carrier layer, and a step of removing only the nickel-phosphorus alloy layer. May be removed.

The metal foil used in the present invention includes a copper foil, a nickel foil, an aluminum foil and the like. If the metal foil is thin, the rigidity is low, and the non-through hole is likely to be displaced during lamination under pressure and heat, so that a certain thickness is required.
Also, by applying the insulating adhesive layer to the metal foil,
When manufacturing a metal foil and an insulating adhesive layer, or when affixing a separately manufactured insulating adhesive layer and a metal foil, it is necessary that the handleability of the metal foil be easy, and from these points, The thickness of the metal foil before heat and pressure integration with the wiring board on which the inner layer circuit is formed should be at least 1
Preferably it is 2 μm or more.

Further, a copper layer having a roughness suitable for bonding to a resin and having a thickness of 1 to 9 μm, which can be used in place of the metal foil, and which serves as a circuit, and a metal layer as a whole can be used. 10-150μ thickness with sufficient strength
Commercially available metal foils composed of an m carrier layer include a peelable copper foil (Furukawa Circuit Foil Co., Ltd., trade name) composed of a 70 μm thick copper foil and a 9 μm ultra-thin copper foil.

Similarly, a first copper layer having a roughness suitable for bonding to a resin and having a thickness of 1 to 9 μm, which can be used in place of the metal foil and serves as a circuit, A 10-150 μm thick second copper layer having sufficient strength for handling as a metal layer and a 0.04-1.5 μm thick nickel-phosphorus alloy layer provided between the two layers. The composite metal foil uses a metal layer having a chemical removal condition different from that of the circuit conductor for removing the carrier.

The insulating adhesive layer used in the present invention contains epoxy or polyimide as a component. Commercially available ones include an epoxy-based adhesive having a high molecular weight epoxy polymer having a molecular weight of 100,000 or more as a main component. MCF-3000E (Hitachi Kasei Kogyo Co., Ltd.), a film, GF-35 as an epoxy system with added deformable rubber
00 (Hitachi Chemical Industry Co., Ltd., trade name); AS-2500 (Hitachi Chemical Industry Co., Ltd.) as a polyimide type; 0.1 μm to 6 μm in diameter and about 5 μm to 1 in length
MCF-6000E (Hitachi Kasei Kogyo Co., Ltd.) as an epoxy-based adhesive film in which a fibrous substance having a thickness of 1 mm is dispersed in an epoxy resin.

It is necessary that the peelable organic film can be easily processed by a laser used for making a non-penetrating hole, and an organic film is preferable, and polyethylene terephthalate, polypropylene, poly-4-
Methylpentene-1, polyfluoroethylene, polyethylene, polyvinyl chloride and the like can be used.

A laser is used for drilling a non-through hole. Examples of the laser include an excimer laser and a carbon dioxide laser, and a carbon dioxide laser is preferred from the viewpoint of processing speed and processing cost.

As the conductive paste to be filled into the holes, a thermosetting conductive paste in which conductive particles such as metal particles, a conductive organic substance, and carbon are mixed, or a conductive paste in which ultraviolet curing is combined with thermosetting is used. , Also metal particles,
A thermoplastic conductive paste mixed with conductive particles such as a conductive organic substance and carbon can be used.

The inner layer circuit board used in the present invention may be an epoxy-based, phenol-based, or polyimide-based double-sided metal-clad laminate containing a paper substrate or a glass substrate, or a single-sided metal-clad laminate composed of these substrates and a resin. Laminated boards can be used, and these substrates can be used to etch unnecessary portions of copper foil, or to the required locations of epoxy, phenol, or polyimide substrates, including paper and glass substrates. A conductor pattern is formed using an additive method of forming a circuit by plating only. In addition, a metal substrate, a ceramic substrate, or the like having a conductive pattern formed on the surface thereof can also be used.

The inner circuit board and the metal foil with an adhesive filled with the conductive paste in the holes are aligned with the holes filled with the conductive paste at the positions where the inner circuit of the inner circuit board is connected. Pressure heating depends on the resin used, but the heating temperature is in the range of 160 ° C to 280 ° C,
The pressure is in the range of 0.1 to 15 MPa.

When a composite metal foil composed of a first copper layer, a second copper layer and a nickel-phosphorus alloy layer is used,
Using a solution containing chlorine ions, ammonium ions, and copper ions (hereinafter referred to as an alkaline etchant), only the second copper layer can be removed, and the solution is added to a solution containing nitric acid and hydrogen peroxide as main components. An organic acid having a carboxyl group as an agent, and a ring member being immersed in an aqueous solution containing a heterocyclic compound containing nitrogen in the form of -NH-, -N =, or spraying such an aqueous solution, Nickel-
Only the phosphorus alloy layer can be removed.

Further, the entire surface of the metal foil is uniformly formed with a thickness of 1 to 10 mm.
In order to perform etching to μm, it is preferable to use a sulfuric acid / hydrogen peroxide-based SE-07 solution (Mitsubishi Gas Chemical Co., Ltd., trade name) or the like as an etchant.

[0022]

Embodiment 1 An embodiment of a multilayer printed wiring board according to the present invention will be described below. Step a: Glass cloth-epoxy resin impregnated double-sided copper-clad laminate MCL-E-6 having a substrate thickness of 0.6 mm and a copper foil thickness of 18 μm
Drilling and electroless plating using 79 (trade name, manufactured by Hitachi Chemical Co., Ltd.) to form a circuit by a normal subtraction method, and then filling the hole with a thermosetting resin by a silk screen printing method As CCR-
506 (Asahi Chemical Laboratory Co., Ltd., trade name) was applied, and after heating and curing, the resin protruding from the holes was removed by polishing to obtain an inner circuit board 1 as shown in FIG. 1 (a).

Step b: A thin copper layer 2a of peelable copper foil (Furukawa Circuit Foil Co., Ltd., trade name), which is a composite metal foil 2 composed of a thin copper foil 2a having a thickness of 9 μm / a carrier copper layer 2b having a thickness of 70 μm.
In the surface of the thermosetting resin varnish of the following composition, 3
A 0 vol% aluminum borate whisker is mixed, stirred, coated with a knife coater, and dried at 150 ° C. for 10 minutes to form a half-cured thermosetting resin layer 3 having a thickness of 50 μm. As a peelable organic film 4 on the surface of No. 3, a metal foil 5 with an adhesive was prepared by bonding a polyethylene terephthalate film having a thickness of 15 μm with a roll laminator as shown in FIG. 1B. (Composition of thermosetting resin varnish) Bisphenol A novolak epoxy resin 100 parts by weight (Epoxy equivalent: 200) Bisphenol A novolak resin 60 parts by weight (hydroxyl equivalent: 106) Curing agent, curing accelerator: 2-ethyl-4-methylimidazole 0.5 part by weight (diluent) Methyl ethyl ketone ........... 100 parts by weight

Step c: Organic film 4 of metal foil 5 with adhesive prepared in step b
Surface, carbon dioxide impact laser drilling machine L-50
0 (product name, manufactured by Sumitomo Heavy Industries, Ltd.), frequency = 150 Hz, voltage 20 kV, pulse energy = 85
Under the condition of mJ and the number of shots = 7 shots, a laser beam was irradiated to remove the resin at the place where the interlayer connection was performed.
As shown in (c), a hole having a diameter of 0.15 mm reaching the copper foil was formed.

Step d MP-200V (manufactured by Hitachi Chemical Co., Ltd., trade name) is printed and filled as a conductive paste 7 on the surface of the organic film 4 on the metal foil 5 with an adhesive formed with holes,
The conductive paste 7 was left in a semi-cured state as shown in FIG.

Step e As shown in FIG. 1E, the polyethylene terephthalate film as the organic film 4 was peeled off.

Step f: Metal foil 5 with adhesive filled with conductive paste 7 in hole
Are laminated on both sides of the inner circuit board 1, and the pressure is 2.94 MPa,
Laminated and integrated at a temperature of 175 ° C for 90 minutes.
As shown in (f), a laminate 9 was obtained.

Step g The composite metal foil carrier 2b on the surface of the laminate was peeled off to expose a thin copper foil 2a as shown in FIG. 1 (g).

Step h Subsequently, a dry film Photek HK-425 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is placed on the thin copper foil 2a.
An etching resist was formed, and a portion exposed from the etching resist was etched. As shown in FIG. 1 (h), a predetermined conductor pattern was formed to obtain a multilayer wiring board 10.

Embodiment 2 An embodiment of the multilayer printed wiring board according to the present invention will be described below. Step a As shown in FIG. 2A, an inner circuit board 1 was manufactured in the same manner as in step a of Example 1.

Step b: First copper layer 11a having a thickness of 5 μm / nickel-phosphorus alloy layer 11b having a thickness of 0.2 μm / second copper layer 1 having a thickness of 15 μm
On the surface of the first copper layer of the composite metal foil 11 made of 1c, a thermosetting resin varnish having the same composition as in Example 1 was applied with 30 v
ol% of aluminum borate whiskers are mixed and stirred,
Apply with a knife coater, dry at 150 ° C for 10 minutes,
A copper foil with an adhesive having a half-cured thermosetting resin layer 3 having a thickness of 50 μm is prepared, and a 15 μm-thick organic film 4 is peelable on the surface of the thermosetting resin layer 3.
2 m of polyethylene terephthalate film was attached by a roll laminator to produce a metal foil 5 with an adhesive as shown in FIG. 2 (b).

Step c A carbon dioxide impact laser drilling machine L-500 was applied to the surface of the organic film of the metal foil 5 with an adhesive prepared in the step b.
(Sumitomo Heavy Industries, Ltd., trade name) frequency = 1
50Hz, voltage 20kV, pulse energy = 85m
J, a laser beam was irradiated under the condition of the number of shots = 7 shots, and the resin at the portion for establishing interlayer connection was removed.
As shown in (c), a hole having a diameter of 0.15 mm reaching the copper foil was formed.

Step d MP-200V (manufactured by Hitachi Chemical Co., Ltd., trade name) as a conductive paste 7 is printed and filled from above the surface of the polyethylene terephthalate film into the hole formed in the metal foil 5 with an adhesive at 160 ° C. The conductive paste 7 was left in a semi-cured state by being left for 10 minutes as shown in FIG. 2d).

Step e As shown in FIG. 2E, the polyethylene terephthalate film as the organic film 4 was peeled off.

Step f A metal foil 5 with an adhesive filled with a conductive paste in the hole is placed on both sides of the inner circuit board 1 at a pressure of 2.94 MPa and a temperature of 1
The laminate was integrated under the conditions of 75 ° C. and 90 minutes to obtain a laminate 15 as shown in FIG.

Step g FIG. 2 (g) Only the second copper layer 11c on the surface of the laminate 15 is subjected to Process A (trade name, manufactured by Meltex Co., Ltd.) which is an alkaline etchant composed of copper chloride, ammonia and ammonium chloride. It was removed by etching.

Step h Subsequently, as shown in FIG. 2H, only the nickel-phosphorus alloy layer 11b was removed by etching with an etching solution having the following composition to expose the first thin copper layer 11a. (Etching solution composition) Nitric acid 200 g / l Hydrogen peroxide solution (35% by volume) 10 ml / l DL-apple Acid: 100 g / l Benzotriazole: 5 g / l

Step i Subsequently, an etching resist by dry film Photek HK-425 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is formed on the thin copper composition 11a, and a portion exposed from the etching resist is formed. By etching and forming a predetermined conductor pattern, a multilayer wiring board 16 was produced as shown in FIG.

Comparative Example 1 Step a As shown in FIG. 3A, an inner layer circuit board 1 was obtained in the same manner as in Step a of Example 1.

Step b MCF-3000E (trade name, manufactured by Hitachi Chemical Co., Ltd.) in which an epoxy adhesive layer having a thickness of 55 μm was provided as an insulating adhesive layer on one side of a copper foil having a thickness of 18 μm as a metal foil. ) On both sides of the inner circuit board 1 and a pressure of 2.94MP
a, laminated at a temperature of 175 ° C. for 90 minutes,
As shown in (b), a laminate 17 was obtained.

Step c An etching resist film HK is formed on both sides of the laminate 17.
-425 (trade name, manufactured by Hitachi Chemical Co., Ltd.) is laminated, an etching resist is formed, and copper in a portion for making interlayer connection is removed by etching, and as shown in FIG. did.

Step d Next, as shown in FIG. 3 (d), the copper was removed by etching using a carbon dioxide impact laser drilling machine L-500 (trade name, manufactured by Sumitomo Heavy Industries, Ltd.). = 150 Hz, voltage 20 kV, pulse energy = 85 mJ, number of shots = 7 shots, the resin was removed, the resin was removed, and a hole with a diameter of 0.15 mm reaching the inner layer was drilled.

Step e Next, as shown in FIG. 3E, a 12 μm-thick electroless copper plating 18 was applied to the surface and the inner wall of the portion to be the hole.
The thickness of the copper on the surface was 30 μm.

Step f Further, an etching resist film HK-42 is formed on the surface.
5 (manufactured by Hitachi Chemical Co., Ltd.), an etching resist was formed by photolithography, copper having a thickness of 30 μm was selectively removed by etching, and the etching resist was peeled and removed. 2), a multilayer wiring board 19 having a predetermined pattern was obtained.

As a result of testing the characteristics of the multilayer wiring board manufactured as described above, as shown in Table 1, the metal thickness to be etched by the method of this embodiment was as thin as 5 to 9 μm,
It was found that a fine pattern of a space = 30 μm / 30 μm level can be formed with high accuracy. Example 1
And in Example 2, the metal thickness up to the etching step is 7
9 μm and 20.2 μm and have sufficient thickness for handling, no wrinkles on the metal foil in the manufacturing process,
Productivity was also excellent.

[0046]

[Table 1] Note) The evaluation of wiring formability was as follows: ：: good wiring formation, small fluctuation in wiring width ○: wiring formation possible, large fluctuation in wiring width △: partial wiring formation possible ×: wiring formation impossible

[0047]

As described above, according to the present invention, it is possible to manufacture a high-density multilayer wiring board having a fine pattern and capable of flattening a via in a process excellent in simple productivity. Become.

[Brief description of the drawings]

FIGS. 1A to 1H are cross-sectional views in respective steps of an embodiment of the present invention.

2 (a) to 2 (i) are cross-sectional views in respective steps of another embodiment of the present invention.

FIGS. 3A to 3F are cross-sectional views in respective steps of a conventional example.

[Explanation of symbols]

1. Inner layer circuit board 2,11. Composite metal foil 2a. Thin metal foil 2b. 2. carrier copper layer Thermosetting resin layer 4. Organic film 5. Metal foil with adhesive 7. Conductive paste 9, 15, 17; Laminates 10, 16,
19. Multilayer wiring board 11a. First copper layer 11b. Nickel-phosphorus alloy layer 11c. Second copper layer 18. Electroless copper plating

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoyuki Urasaki 1500 Oji Ogawa, Shimodate City, Ibaraki Prefecture Inside the Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor Kazuhisa Otsuka 1500 Oji Ogawa Shimodate City, Ibaraki Prefecture Inside Shimodate Research Laboratory (72) Inventor Toyoki Ito 1500 Ogawa, Oji, Shimodate City, Ibaraki Prefecture Inside Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor ▲ Tsuru ▼ 1500 Yoshihiro Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Industry Co., Ltd. Inside

Claims (4)

[Claims] 1. A method for manufacturing a multilayer wiring board, comprising the following steps. a. An insulating adhesive layer is provided on one side of the metal foil, and a laser is applied to the organic film surface of the adhesive-attached metal foil provided with a peelable organic film on the surface of the insulating adhesive layer. Making a hole to reach the metal foil at the point where the electrical connection is made. b. Filling the holes with a conductive paste to bring the conductive paste into a semi-cured state; c. The step of peeling the organic film. d. On the surface of the inner circuit board, the metal foil with the adhesive prepared in step c is aligned so that the hole filled with the conductive paste of the metal foil with the adhesive overlaps the connection point of the inner layer circuit of the inner circuit board. A process of stacking, stacking and integrating by heating under pressure. e. Removing the outer metal foil in the thickness direction to make it thinner; f. A step of forming a conductor pattern by etching away unnecessary portions of the metal foil thinned in step e. 2. The method according to claim 1, wherein the thickness of the metal foil reduced in step e is 1 to 1
The method according to claim 1, wherein the thickness is in a range of 0 µm. 3. A metal foil used in the step (a) comprises a copper layer having a roughness suitable for bonding to a resin and serving as a circuit, and a carrier layer having sufficient strength as a metal layer as a whole. The composite metal foil from which the two layers can be easily peeled off, and in the step e, the carrier layer is peeled off in the step of removing the outer metal foil in the thickness direction to make it thinner. 3. The method for manufacturing a multilayer wiring board according to 1 or 2. 4. A method according to claim 1, wherein the metal foil used in the step (a) is treated as a first copper layer having a thickness of 1 to 9 μm having a roughness suitable for bonding to a resin and forming a circuit, and a metal layer as a whole. A second copper layer having a sufficient strength and a thickness of 10 to 150 μm, and a middle layer between the two layers having a thickness of 0.04 to 1.
Using a composite metal foil made of a 5 μm nickel-phosphorus alloy layer, in the step e, the step of thinning the outer metal foil in the thickness direction includes the step of removing only the carrier layer and the step of removing the nickel-phosphorus alloy.
3. The method according to claim 1, wherein a step of removing only the phosphorus alloy layer is performed.