JPH08316632A - Method for manufacturing multilayer wiring board - Google Patents

Abstract

PURPOSE: To reduce the amount of exudation of an insulation adhesion material by overlapping a film-shaped material drilled on an inner-layer circuit substrate and further overlapping a cushion material on it. CONSTITUTION: A film-shaped material drilled on an inner-layer circuit substrate is overlapped so that a circuit substrate and an insulation adhesion layer are in contact, further a cushion material is overlapped on it to achieve flow behavior due to heating, and heating and pressurization are performed for lamination in one piece, thus causing the cushion material to flow from a connection part where a sheet-shaped reinforcing material is drilled to block a hole part and hence reducing the amount of exudation of the insulation adhesion material and hence reducing the hole diameter for connecting layers. Also, since the amount of flow of the cushion material is small at a part where the sheet-shaped reinforcing material is not drilled, the recess and projecting parts of the inner- layer copper foil can be flattened by the insulation adhesion material and improving surface smoothness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer wiring board.

[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. A method for forming a via hole is being studied. As an example of this, a base material consisting of an insulating adhesive layer and a copper foil, in which holes for interlayer connection are preliminarily drilled, is laminated on the inner layer circuit board, and the circuit on the inner layer circuit board and the copper foil of the base material are electrically connected. How to connect to is known.

Further, Japanese Patent Laid-Open No. 2-62095 discloses that
A method of laminating an adhesive sheet having almost no resin flow on a copper foil having a reinforcing material, laminating the laminated sheet on an inner layer board on which a circuit is formed, and forming IVH is described. It is described that NC hole drilling can be performed without causing breakage.

[0004]

By the way, a base material consisting of an insulating adhesive layer and a copper foil, which is preliminarily provided with holes for interlayer connection, is laminated on an inner layer circuit board, and the circuit on the inner layer circuit board and the base material are In the method of electrically connecting the copper foil, if the fluidity of the insulating adhesive layer is increased, it is possible to fill the space between the conductors of the inner layer circuit and improve the insulation characteristics between the circuits, but it also flows to the holes for interlayer connection. , There is a problem that it may block the hole,
If the fluidity of the insulating adhesive layer is reduced, the resin that flows in the interlayer connection holes will be reduced, but the problem that the insulating characteristics between the circuits will deteriorate occurs. In addition, the unevenness of the inner layer circuit appears on the surface layer, and when the outer layer circuit is processed, the resist does not adhere to the concave portion during etching resist film lamination or etching resist ink screen printing, and many defects such as circuit breakage occur, so the outer layer circuit However, there is a problem that the forming property of the Thus, it is difficult to improve the circuit filling property and the interlayer connection reliability at the same time.

Therefore, the inventors of the present invention have proposed, in Japanese Patent Application No. 6-16504, to laminate and adhere by using a cushion material which becomes fluid when heated. It was found that there is a drawback that the unevenness of the surface becomes large because the followability of the adhesive layer to the inner layer copper foil circuit is improved. In particular, it was difficult when the inner copper foil thickness was large or when the interlayer connection hole diameter was small. Also, when using a thin copper foil for the outer layer circuit, the rigidity of the copper foil is low, so the copper foil is stretched during stacking, making it easier to follow the inner layer copper foil circuit and making it easier for the surface irregularities to increase. It was found that it was difficult to obtain sufficient surface smoothness.

Further, in the method described in Japanese Patent Application Laid-Open No. 2-62095, it is necessary to use an adhesive sheet having almost no resin flow, the filling property of the inner layer circuit is not sufficient, and voids are likely to occur. There was a problem.

It is an object of the present invention to provide a method for manufacturing a multilayer wiring board which does not use glass cloth and which can simultaneously satisfy interlayer connection reliability and surface smoothness. To do.

[0008]

The method for manufacturing a multilayer wiring board according to the present invention comprises: a. A film-like material in which a relatively fluid insulating insulating layer is formed on one side of a copper foil, and a sheet-like reinforcing material made of metal or organic material that can be removed by peeling, etching, etc. is formed on the other side. Step of making a hole in a predetermined position b. On the inner layer circuit board, the perforated film-like material is overlaid so that the circuit board and the insulating adhesive layer are in contact with each other, and a cushioning material that becomes fluid by heating is overlaid thereon and heated. Process of pressure and lamination integration c. Step of removing sheet-like reinforcing material d. A step of electrically connecting the circuit on the inner layer circuit board and the copper foil of the film-shaped material through a hole provided in the film-shaped material from which the sheet-shaped reinforcing material is removed e. The method is characterized by having a step of processing a copper foil of a film material to form a circuit.

This film-shaped material can also be produced by laminating a copper foil obtained by applying an insulating adhesive material to a copper foil and a metal sheet or an organic material sheet,
It can also be manufactured by applying an insulating adhesive material to the copper foil side of a copper foil on which a metal sheet or an organic material sheet is formed.

As the sheet-like reinforcing material, a metal foil or an organic material sheet having a high elastic modulus at high temperature can be used.
Examples of the metal foil include metal foils such as copper and aluminum, those coated with an adhesive or the like, or those produced by plating a copper foil with a dissimilar metal. For example,
Peelable electrolytic copper foil made of aluminum foil and copper foil (trade name, manufactured by Furukawa Circuit Foil Co., Ltd.) and described in JP-A-5-206599, the surface of which has a roughness suitable for adhesion with a resin. A first copper layer to be a circuit, a second copper layer having sufficient strength as a metal layer as a whole, and a thickness of 0.04 to 4 provided between the first copper layer and the second copper layer. There is CCT foil (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a metal foil for a printed wiring board, which is composed of a nickel-phosphorus alloy layer having a thickness of 1.5 μm. As the organic material sheet, organic material sheets such as polyimide, polyethylene terephthalate, polypropylene, polyvinylidene chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, polyacrylonitrile, polyamide, and cellophane can be used.

The composition of the insulating adhesive layer that can be used in the present invention is an epoxy resin adhesive, an acrylic modified resin system,
Alternatively, a polyimide resin adhesive or the like can be used. The insulating adhesive layer needs to be in an A-stage shape or a B-stage shape. Regarding fluidity, the resin flow is converted into an area change rate under the conditions of 170 ° C./15 MPa / 10 minutes from the coated state. Therefore, it is preferable to use an adhesive material in the range of 0.2 to 5.0%. If it is less than 0.2%, the space between the conductors of the inner layer circuit is not sufficiently filled, and if it exceeds 5.0%, the resin exudation effect of the cushion material is not sufficient, and resin exudation is large. As a result, the reliability of interlayer connection decreases, which is not preferable. Further, if the fluidity is too large, the film thickness between layers is greatly reduced, and the insulation reliability is reduced, which is not preferable. Examples of such an insulating adhesive material include AS-300.
0 (manufactured by Hitachi Chemical Co., Ltd.).

Further, this insulating adhesive layer may be composed of two or more layers having different curing states in order to balance the circuit filling property and the amount of the adhesive oozing out. In order to have such a structure of two or more layers, a varnish is applied as a coating film first layer on a copper foil, and this is heat-cured to a B or C stage state, and a coating film second layer is formed thereon. Can be achieved by coating and heat-curing it to the A or B stage state under conditions milder than the above heat-curing. Alternatively, as the first layer of the coating film, a flexible substrate or the like or a layer having a low fluidity containing a high molecular weight rubber, a phenoxy resin, a high molecular weight epoxy resin, a high molecular weight epoxy resin or the like as a main component is used, and the second coating film is formed on the layer. It can also be achieved by applying a layer and heat-curing it in the A or B stage state. In the present invention, the A, B, and C stages indicate the degree of curing of the insulating adhesive material, and the A stage is in a substantially uncured and non-gelled state and has a total curing heat value of 0 to 20. %, The B stage is a state of slightly hardening and gelling, and the heat generation of 20 to 60% of the total curing heat value is finished, and the C stage is a considerably hardened state. Is in a gelled state, and the heat generation of 60 to 100% of the total curing heat value is finished. As a method of applying varnish to a copper foil or film in forming this insulating adhesive layer, there are a bar coater, a lip coater, a roll coater, etc. Any method may be used as long as it can be applied.

When mounting an electronic component having a large amount of heat generation, an inorganic filler such as alumina, silica or aluminum nitride can be added to the insulating adhesive layer, and the addition amount is within 50% by volume. Is preferred. This added amount is
Although the heat dissipation improves as the amount increases, on the other hand, the fluidity of the adhesive sheet decreases and the adhesiveness between the copper foil and the adhesive sheet decreases, so if the addition amount exceeds 50% by volume, sufficient solder heat resistance reliability is obtained. Can't get

Next, for drilling the base material, one to four base materials are used.
It is possible to stack about 0 sheets and make holes at once. The larger the number of stacked sheets, the better the work efficiency is, but it is not preferable to stack 40 sheets or more because problems such as variations in hole diameter and burrs occur. Next, the method for laminating and bonding is not particularly limited, but pressing, vacuum pressing, or the like can be used. Also, by using the above sheet-shaped reinforcing material,
This has the effect of improving workability in the alignment process during the stacking work. In particular, when the copper foil is thin, the workability may be deteriorated due to warping of the copper foil with an insulating adhesive material, but this is effective. The thickness of the sheet material is 1
It is preferably about 0 μm to 200 μm. Further, if the thickness of these sheet-like reinforcing materials is less than 10 μm, the effect of surface smoothing decreases, which is not preferable. Again 200μ
If the thickness exceeds m, flow of the cushioning material is impeded, and as a result, the exudation of the resin is not suppressed, and the exudation amount of the resin becomes large, which is not preferable. For example, the hole diameter is 2
When the thickness is 00 μm, the thickness of the sheet-like reinforcing material is appropriately about 50 μm.

As the cushioning material used for lamination, paper, rubber sheet, silicone rubber sheet, various film materials such as polypropylene, polyethylene, polyvinylidene chloride, and fluorine-containing materials such as polytetrafluoroethylene are used. Can be used. Also, paper, rubber,
A plurality of various thermoplastic films can be used in combination. The required thickness of the cushion material needs to be appropriately set depending on the film thickness of the insulating adhesive material, the stacking temperature, the pressure, and the like.

For the interlayer connection, a method using conductive paste, plating, soldering, wire bonding or the like can be used.

[0017]

According to the method for manufacturing a multilayer wiring board of the present invention, the cushion material flows from the connection portion where the sheet-shaped reinforcing material is perforated and closes the hole, so that the amount of seeping-out of the insulating adhesive material is reduced. Therefore, it is possible to reduce the hole diameter for the interlayer connection. In addition, since the flow amount of the cushion material is small in the portion where the sheet-shaped reinforcing material is not perforated, the unevenness of the inner layer copper foil can be flattened by the insulating adhesive material, and the surface smoothness can be improved. did it. Further, according to the present invention, the insulating adhesive material and the sheet-shaped reinforcing material can be punched together, and compared to the method in which the insulating adhesive material and the sheet-shaped reinforcing material are punched and then overlapped with each other, there is less displacement and the cost required for punching is less It is preferable in terms.

[0018]

【Example】

Example 1 (1) A copper foil having a thickness of 18 μm and a film thickness after drying of 70 μm
Epoxy resin adhesive is applied so that
Dry at 10 ° C for 10 minutes to prepare a copper foil with an insulating adhesive material. The resin flow rate of this insulating adhesive material was 0.3%. (2) A polyethylene terephthalate pressure-sensitive adhesive sheet (film thickness 70 μm) is further laminated on the above-mentioned copper foil with insulating adhesive material. (3) A hole having a diameter of 0.2 mm is drilled at a portion of the above-mentioned copper foil with an insulating adhesive material where interlayer connection is to be performed. (4) As a cushioning material, a polyethylene film having a thickness of 150 μm is used on the side of the copper foil with an insulating adhesive material, and a punched insulating adhesive material copper foil and a circuit board having a copper foil circuit thickness of 18 μm are added by a press. Pressure / heating (laminating temperature 170
(° C, pressure 30 kgf / cm, 1 hour), and laminated and integrated. (5) Polyethylene terephthalate adhesive sheet (film thickness 7
0 μm) is peeled off. (6) The copper foil surface is polished, washed, and pre-plated. (7) Copper plating is used to connect layers between the upper and lower circuits. (8) Remove unnecessary portions of the copper foil on the surface by etching,
Form a circuit.

Example 2 A copper foil having a thickness of 18 μm was coated with an epoxy resin adhesive as the first layer of the coating film so that the film thickness after drying was 70 μm, dried at 150 ° C. for 10 minutes, and coated. As the second layer of the film, an epoxy resin adhesive is applied so that the total thickness of the first layer and the second layer after drying is 140 μm, and dried at 130 ° C. for 10 minutes to produce a copper foil with an insulating adhesive material. A wiring board was formed in the same manner as in Example 1 except that. The resin flow rate of the second layer of the coating film at this time was 0.3%.

Example 3 (1) Thickness 79 μm (first layer 70 μm, second layer 9 μm)
Peelable electrolytic copper foil (trade name, manufactured by Furukawa Circuit Foil Co., Ltd.) is coated with an epoxy resin adhesive so that the film thickness after drying is 70 μm, and dried at 130 ° C. for 10 minutes, with an insulating adhesive material Make a copper foil. The resin flow rate of this insulating adhesive material was 0.3%. (2) A hole having a diameter of 0.2 mm is drilled in a portion of the above-mentioned copper foil with an insulating adhesive material where an interlayer connection is to be made. (3) As a cushioning material, a polyethylene film having a film thickness of 150 μm is used on the side of the copper foil with an insulating adhesive material, and a punched insulating adhesive material copper foil and a circuit board having a copper foil circuit thickness of 18 μm are pressed. Pressure / heating (laminating temperature 170
(° C, pressure 30 kgf / cm, 1 hour), and laminated and integrated. (4) Strip the first layer of copper foil. (5) Copper plating is used to connect layers between the upper and lower circuits. (6) By removing unnecessary portions of the copper foil on the surface by etching,
Form a circuit.

Example 4 (1) The thickness of the first copper layer is 5 μm and the thickness of the second copper layer is 20 μm, the surface of which has a roughness suitable for adhesion to resin. , CCT foil (manufactured by Hitachi Chemical Co., Ltd.), which is a metal foil made of a nickel-phosphorus alloy layer having a thickness of 0.4 μm provided between the first copper layer and the second copper layer Epoxy resin adhesive is applied so that the film thickness after drying is 70 μm, and the temperature is 130 ° C. for 10 minutes.
Dry to prepare a copper foil with an insulating adhesive material. The resin flow rate of this insulating adhesive material was 0.3%. (2) A hole having a diameter of 0.2 mm is drilled in a portion of the above-mentioned copper foil with an insulating adhesive material where an interlayer connection is to be made. (3) As a cushioning material, a polyethylene film having a film thickness of 150 μm is used on the side of the copper foil with an insulating adhesive material, and a punched insulating adhesive material copper foil and a circuit board having a copper foil circuit thickness of 18 μm are pressed. Pressure / heating (laminating temperature 170
(° C, pressure 30 kgf / cm, 1 hour), and laminated and integrated. (4) The second copper layer is removed by an etching process. (5) The nickel phosphorus alloy layer is removed by an alkali etching process. (5) Copper plating is used to connect layers between the upper and lower circuits. (6) By removing unnecessary portions of the copper foil on the surface by etching,
Form a circuit.

Comparative Example 1 The same as Example 1 except that the sheet-like reinforcing material is not used.

Comparative Example 2 The same as Example 3 except that the cushion material is not used.

Comparative Example 3 The same as Example 1 except that the sheet-shaped reinforcing material and the cushion material are not used.

Comparative Example 4 The same as Example 3 except that an adhesive sheet having a resin flow amount of 0.1% was used.

Comparative Example 5 The same as Example 3 except that an adhesive sheet having a resin flow amount of 7% was used.

The multilayer wiring board produced as described above was evaluated as follows. Table 1 shows the evaluation results.
Shown in

(Amount of Exudation) An adhesive sheet having a hole with a diameter of 0.2 m was laminated on a circuit board, and after lamination, the distance of the insulating adhesive material exuding from the hole was measured. (Void generation) Microscopic observation was conducted, and those having no voids having a diameter of more than 10 μm between the lower copper foil and the insulating adhesive material were considered good, and those having voids having a diameter of 10 μm or more were considered defective. did. (Amount of unevenness on the surface) The unevenness on the surface was measured using a surface roughness meter, and the difference in height between the convex portion and the concave portion was measured by measuring the amount of surface unevenness.

[0029]

[Table 1]

[0030]

According to the method for manufacturing a multilayer wiring board of the present invention, the unevenness of the inner layer copper foil can be flattened with an insulating adhesive material,
The surface smoothness could be improved. It has become possible to form fine wiring that improves the circuit formability of the outer layer circuit. The miniaturization of the multilayer wiring board was achieved. In addition, the defective rate was reduced. Further, although the cost of the film increases, it is not necessary to perform the positioning and the like when the press is configured, and the increase in the cost required for manufacturing is slight. Further, these methods increase the steps of laminating and peeling the sheet-shaped reinforcing material,
These can be automated and have little effect on processing time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of stacking by a conventional method.

FIG. 2 is a sectional view showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing an example of a laminated structure of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeharu Ariya 1500 Ogawa, Shimodate, Ibaraki Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Kazuhisa Otsuka 1500 Ogawa, Shimodate, Ibaraki Hitachi Chemical Co., Ltd. Company Shimodate Research Institute (72) Inventor Kazunori Yamamoto 1500 Ogawa, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Shimodate Research Institute

Claims (3)

[Claims] 1. A. Forming an A-stage or B-stage insulating adhesive layer on one surface of the copper foil, and on the other surface
Process of making a hole in a predetermined position of a film-like material on which a sheet-like reinforcing material made of a metal or an organic material that can be removed by peeling, etching, or the like is formed. B. On the inner layer circuit board, the perforated film-like material is overlaid so that the circuit board and the insulating adhesive layer are in contact with each other, and a cushioning material that becomes fluid by heating is overlaid thereon and heated. Process of pressure and lamination integration c. Step of removing sheet-like reinforcing material d. A step of electrically connecting the circuit on the inner layer circuit board and the copper foil of the film-shaped material through a hole provided in the film-shaped material from which the sheet-shaped reinforcing material is removed e. A method for manufacturing a multilayer wiring board, which comprises a step of processing a copper foil of a film material to form a circuit. 2. The multilayer wiring board according to claim 1, wherein the film-shaped material is a laminate of a copper foil having one surface coated with an insulating adhesive material and a metal sheet or an organic material sheet. Manufacturing method. 3. The film-shaped material is obtained by applying an insulating adhesive material to the copper foil side of a copper foil having a metal sheet or an organic material sheet formed thereon. The method for manufacturing a multilayer wiring board according to.