JP3335945B2 - Manufacturing method of multilayer printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a multilayer printed wiring board in which an outer layer of a copper foil sheet with a resin is roll-laminated on an inner circuit board having circuit wiring.

[0002]

2. Description of the Related Art Conventionally, when manufacturing a multilayer printed wiring board, a prepreg sheet obtained by impregnating a glass cloth base material with an epoxy resin and semi-curing is laminated on an inner circuit board having circuit wiring, and an outer layer is further formed thereon. After laminating the copper foil for use, a shield board is formed by heating and molding with a hot plate press to form a shield substrate, and a process of forming an outer layer circuit by drilling, plating and etching in the shield substrate is performed. However, this process requires a long time because hot press molding is performed using a hot plate press, and high-cost equipment such as a hot plate press and the use of glass cloth for prepreg sheets require multi-layer printed wiring boards. It is difficult to make the interlayer thickness extremely thin, and the manufacturing cost is high.

[0003] In recent years, in order to solve these problems, a technique of a multilayer printed wiring board by a build-up method that does not perform integral molding by heating using a hot plate press and does not use glass cloth as an interlayer insulating material has attracted attention. .

A method of manufacturing a multilayer printed wiring board by a build-up method includes a method of forming a multilayer circuit wiring by alternately applying and plating a photosensitive insulating resin on an inner circuit board, and a method of forming a resin on the inner circuit board. A method has been proposed in which a laminated copper foil sheet is roll-laminated and a multilayer circuit is formed by plating and etching.

The present invention relates to a method of manufacturing a multilayer printed wiring board by roll laminating a resin-coated copper foil sheet on an inner circuit board (hereinafter referred to as a roll lamination method).

Japanese Patent Application Laid-Open Nos. 9-293988 and 11-46063 disclose a method of manufacturing a multilayer printed wiring board by a roll lamination method. Through
A technique is disclosed in which copper foil with an epoxy resin-based resin is simultaneously laminated on both sides of an inner circuit board. In these techniques, the surface hardness of the hot roll is not particularly specified. Japanese Patent No. 2803579 discloses that a conductive paste is filled into a through-hole of a prepreg sheet such as aramid-epoxy resin, and then a metal roll is coated with a metal roll lining both sides of the prepreg sheet with heat-resistant silicon rubber having a rubber hardness of 70 degrees. A method for forming a substrate with a double-sided metal foil by heating and pressing is disclosed.

Japanese Patent Application Laid-Open No. 6-155584 discloses a case in which a metal foil to be a conductor circuit or the like is laminated by a pair of rolls on the surface of an insulating base material having an opening for forming an electronic component mounting substrate. The surface of the roll on the side of the metal foil to be laminated is formed of a material (hard silicon rubber or fluororesin) that is softer than the insulating base material and harder than the surface of one roll on the surface of the metal center member, and the other roll surface A technique has been disclosed in which is made softer than the insulating base material and is formed of a material (normal silicone rubber) softer than the surface of the one roll. In this technique, the roll surface hardness of the surface on which the metal foil is not laminated is soft, so that the soft roll material penetrates into the opening during lamination to prevent the metal foil from sinking into the opening.

Japanese Patent Application Laid-Open No. Hei 7-245480 discloses a method in which copper foil with a thermosetting insulating adhesive is laminated on both surfaces of an inner circuit board with a pair of same-type hard rolls arranged vertically and then simultaneously and integrally thermoset. Is disclosed.

FIG. 5 shows the above-mentioned prior art JP-A-7-24.
FIG. 4 is a schematic cross-sectional view of the arrangement of an inner layer circuit board and a roll laminator at the time of roll lamination for explaining a method of manufacturing a multilayer printed wiring board by a roll lamination method disclosed in Japanese Patent Application Laid-Open No. 5480 and Japanese Patent Application Laid-Open No. 11-46063. According to FIG. 5, first, a liquid undercoat material (not shown) is screen-printed on the inner circuit board 1 and the inner circuit (not shown) is completely covered by using a coating device such as a roller coater or a curtain coater. And apply it. At this time, the undercoat material is in an uncured state. Next, the inner layer circuit board 1 is transported between the hard rollers 9 arranged above and below the roll laminator by the transport roller 5.
And a copper foil sheet 3a with an epoxy resin is laminated on the surface of the inner circuit board 1 at a temperature of 100 to 130C. Next, by performing a heat treatment at a temperature of 140 to 180 ° C., the undercoat material and the epoxy resin (thermosetting insulating adhesive) of the copper foil sheet 3 a are simultaneously heated and integrally cured to firmly adhere to each other to form a multilayer printed wiring board. Is formed.

[0010]

FIG. 6 is an enlarged sectional view of a main part of a multilayer printed wiring board manufactured by the conventional roll lamination method. Reference numeral 1 denotes an inner circuit board, 2 denotes an inner circuit, and 3 denotes an outer layer. Copper foil 4 indicates a build-up insulating layer made of an undercoat material and an epoxy resin (thermosetting insulating adhesive). It can be seen that on the surface of the outer layer copper foil 3, the convex surface of the surface of the inner layer circuit 2 is transferred, and the surface shows an irregular shape.

[0011] The following problems are caused by the transfer of irregularities to the surface of the outer copper foil of the multilayer printed wiring board manufactured using the roll lamination method of the prior art described above. (1) When a multilayer printed wiring board (hereinafter, referred to as a substrate) laminated with an outer layer copper foil is drilled in a stacked manner, a gap is formed between the substrates, and a burr is formed on the substrate and a defect is generated in a corner portion of a through hole. However, it was not possible to drill holes by stacking substrates, and drilling work was performed one by one, resulting in an increase in the cost of drilling. (2) In the circuit forming step of the outer layer after the roll lamination, complete contact between the photomask film and the substrate cannot be performed, and in the step of exposing and printing the circuit on the photoresist, light leakage due to insufficient adhesion of the photomask film may occur. In such a case, defects such as circuit loss, disconnection, and short circuit are likely to occur, and it has been difficult to form a high-precision, high-density circuit having a fine wire circuit.

It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board which has solved the above-mentioned problems in the conventional roll lamination method.

[0013]

According to a method of manufacturing a multilayer printed wiring board of the present invention, a copper foil sheet with a thermosetting resin is roll-laminated on both sides of an inner circuit board coated with an undercoat material, and a shield laminate is formed. In the method for manufacturing a multilayer printed wiring board for forming a board, the thermosetting resin-coated copper foil is disposed on both surfaces of the inner circuit board so as to be vertically offset from each other, and a soft roller disposed opposite to the hard roller. Roll lamination is performed by applying heat and pressure.

As the soft roller, a metal core may be made of JI.
A roller lined with silicone rubber or fluorine rubber having an S rubber hardness of 55 to 90 degrees can be used,
In addition, a roller made of titanium metal, aluminum or an aluminum alloy can be used as the hard roller.

In the structure of the present invention, the soft roller acts in the same manner as the action of improving the resin embedding property of kraft paper in the outer layer laminating step using the ordinary laminating press of a multilayer printed wiring board. It works in the same way as a head plate that rolls a substrate in a plane. As a result, in the present invention, in the roll lamination of the copper foil with the thermosetting resin for the outer layer, the transfer of the unevenness of the inner layer circuit board to the surface of the outer layer copper foil can be prevented.

In the configuration of the present invention, a release sheet is interposed between the hard roller facing the soft roller to which the inner circuit board enters and the inner circuit board during the roll lamination, The surface of the inner layer circuit board can be prevented from being damaged and the inner layer circuit board can be maintained horizontally, and the smoothness of the outer layer copper foil surface can be further improved.

[0017]

Next, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view of the arrangement of an inner layer circuit board and a roll laminator during roll lamination for describing a method for manufacturing a multilayer printed wiring board according to a first embodiment of the present invention. FIG.
FIG. 2 is an enlarged cross-sectional view of a main part of the shield laminate manufactured by the roll lamination method in FIG. 1. In FIG. 1,
In the roll laminator, only the roller portion is displayed, and a heating device and a pressure adjusting device for the soft roller are omitted.

In FIG. 1, reference numeral 1 denotes desired substrate properties,
This is an inner circuit board on which an inner layer circuit (not shown) is formed so as to have electrical characteristics, and an undercoat material (not shown) is applied on the entire surface. Reference numeral 3a denotes a copper foil sheet with an epoxy resin in a semi-cured state in which a thermosetting resin of an epoxy resin is applied to the surface of the copper foil. Reference numeral 5 denotes a transport roller for the inner layer circuit board 1, and reference numerals 8a and 8b denote an upper soft roller and a lower soft roller, respectively, for laminating a resin-coated copper foil sheet 3a of a roll laminator. Reference numerals 9a and 9b are disposed so as to face the upper soft roller 8a and the lower soft roller 8b. When the resin-attached copper foil sheet 3a is laminated on the inner circuit board 1 with the upper soft roller 8a and the lower soft roller 8b, the inner layer circuit is formed. An upper hard roller and a lower hard roller for holding the other surface of the substrate, respectively.

As the above-mentioned soft roller, a roller obtained by lining a metal core such as stainless steel with silicon rubber or fluorine rubber having a JIS hardness of 55 to 90 degrees can be used. In addition, a titanium or aluminum metal roller can be used as the hard roller.

Reference numeral 6 denotes a lower hard roller 9b on the front side with respect to the approaching direction of the inner circuit board 1 and an inner circuit board (lower surface).
Is a release sheet that is pressed by a take-up roller after being pressed against the release sheet, and 7 denotes a release sheet take-up roller. A fluoropolymer resin is used for the release sheet.

The release sheet 6 pressed against the surface of the inner circuit board 1 by the lower hard roller 9b has a different starting point for laminating the copper foil sheet 3a with epoxy resin on both sides of the inner circuit board 1 so that the inner circuit board is horizontally moved. And to prevent the lower hard roller 9b from scratching the inner layer circuit surface. The upper and lower arrangement of the soft roller and the hard roller in FIG. 1 may be reversed.

As shown in FIG. 1, the upper and lower soft rollers (55 to 90 degrees in hardness) and the hard rollers are displaced from each other, and the soft roller and the hard roller are arranged to face each other. Surface irregularities are flattened,
A multilayer printed wiring board (shield plate) in which the outer layer copper foil surface is flattened can be obtained.

Hereinafter, a method of laminating the resin-attached copper foil sheet 3a to the inner layer circuit board 1 will be described in detail with reference to FIGS.

First, an inner circuit board 1 having a circuit of a predetermined width is prepared by etching a copper foil of an epoxy glass base material on which a copper foil having a thickness of 18 to 35 μm is attached. Next, a thermosetting epoxy resin undercoat material having a viscosity of 10 to 20 poise is applied on the entire surface of both surfaces of the inner circuit board 1 by a screen printing method so that the thickness of the undercoat material on the inner circuit becomes 5 to
Coated to 20 μm, 10 ° C at 100 ° C
Pre-dry for ~ 20 minutes.

Next, a roll laminator having a soft roller and a hard roller shown in FIG.
Is transported by the transport roller 5 and the upper soft roller 8
a, The surface temperature of the lower soft roller 8b is 100 to 13
A resin-coated copper foil sheet 3a having a resin thickness of 40 to 100 μm is laminated on both surfaces of the inner circuit board 1 at 0 ° C. and a pressure of ^{2 to} 6 kgf / cm ² to form a shield laminate.

The copper foil thickness of the copper foil sheet with resin 3a is 12
３５35 μm. When laminating the resin-coated copper foil sheet 3a to the inner layer circuit board 1, the lower hard roller 9b which comes into contact first has a predetermined distance between the lamination start point of the epoxy resin-coated copper foil sheet 3a on the upper and lower surfaces of the inner layer circuit board. Therefore, it is necessary to consider keeping the inner layer circuit board horizontal and preventing scratches on the surface of the inner layer circuit board 1 on which the resin-coated copper foil sheet 3a is not laminated. For this purpose, the release sheet 6 is loaded into the lower hard roller 9b in FIG. 1 simultaneously with the loading of the copper foil sheet 3a with epoxy resin on the soft roller, and the lower hard roller 9
After passing through b, it is automatically wound up by the release sheet winding roller 7.

Next, the inner layer circuit board 1 on which the copper foil sheet 3a with epoxy resin is laminated is heated in a baking furnace at a temperature of 140 to 180 ° C. for 10 to 60 minutes to completely cure the epoxy resin, as shown in FIG. A shield laminate 10 having a smooth surface was obtained. Note that reference numeral 4 in FIG.
Is a build-up insulating layer, which is made of an undercoat material for an inner circuit board and a resin of a copper foil sheet with an epoxy resin. After the formation of the shield laminate 10, an outer layer circuit is formed by ordinary drilling, plating, and etching methods to manufacture a multilayer printed wiring board.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a schematic cross-sectional view of an arrangement of an inner circuit board and a roll laminator during roll lamination for explaining a method of manufacturing a multilayer printed wiring board according to a second embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of a main part of the shield laminate manufactured by the roll lamination method in FIG. In FIG. 3, the roll laminator shows only a roller portion, and a heating device and a pressure adjusting device of a soft roller and a hard roller are omitted. Further, the same reference numerals as those in FIGS. The same thing as FIG. 2 is shown.

As in the first embodiment, when the copper foil sheet 3a with epoxy resin is laminated on the internal circuit board 1 as shown in FIG. 3, the adhesion between the internal circuit board 1 and the copper foil sheet 3a with epoxy resin is checked. Inner circuit board 1 to raise
While heating the hard rollers 9a and 9b at 90 to 100 ° C. so that the surface temperature of the resin can be maintained at 70 to 95 ° C. which is the resin melting temperature of the copper foil sheet with epoxy resin 3a, the soft rollers 8 a and 8 b are heated to 100 to 100 ° C. Heated at 130 ° C,
Crimping is performed at a pressure of ^{2 to} 6 kgf / cm ² , followed by heating in a baking furnace at a temperature of 140 to 180 ° C. for 10 to 60 minutes to completely cure the epoxy resin to obtain a desired smooth surface as shown in FIG. Shield laminate 10 having
I got

In order to stably maintain the temperature of the inner circuit board 1, it is necessary to heat the entire board including the inside of the inner circuit board 1. As the hard roller, an upper hard roller (far infrared ray) having good heat conductivity is used. 9c with heater)
A lower hard roller (with a far-infrared heater) 9d was used.

In the second embodiment of the present invention, when laminating a copper foil sheet with an epoxy resin, lamination can be performed while heating the temperature of the entire inner layer circuit board to an optimum temperature. In comparison, the embedding property of the wiring circuit in the build-up insulating layer by lamination can be improved.

[0032]

According to the present invention, a multilayer printed wiring board having a smooth substrate surface can be manufactured, and the following effects can be obtained. (1) In the through-hole drilling process, drilling work can be performed by stacking multiple printed wiring boards at once, improving the work efficiency by more than three times compared to the conventional work and reducing the drill cost to 1/3 or less. Becomes (2) Since the surface of the copper foil of the outer layer is smooth, it is possible to reduce defects such as circuit defects, circuit disconnections, and circuit shorts in the circuit forming process, and it is also possible to form a fine wire circuit having a circuit width and a gap of 100 μm or less in the outer layer. Become.

[0033]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an arrangement of an inner-layer circuit board and a roll laminator during roll lamination for describing a method of manufacturing a multilayer printed wiring board according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the shield laminate manufactured by the roll lamination method in FIG.

FIG. 3 is a schematic cross-sectional view of an arrangement of an inner layer circuit board and a roll laminator at the time of roll lamination for explaining a method of manufacturing a multilayer printed wiring board according to a second embodiment of the present invention.

FIG. 4 is an enlarged cross-sectional view of a main part of the shield laminate manufactured by the roll lamination method in FIG. 3;

FIG. 5 is a schematic cross-sectional view of an arrangement of an inner layer circuit board and a roll laminator during roll lamination for explaining a method of manufacturing a multilayer printed wiring board by a conventional roll lamination method.

6 is an enlarged sectional view of a main part of the shield laminate manufactured by the roll lamination method of FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 inner circuit board 2 build-up layer 3 outer layer copper foil 3a copper foil sheet with epoxy resin 4 build-up insulating layer 5 transport roller 6 release sheet 7 release sheet take-up roller 8a upper soft roller 8b lower soft roller 9 hard roller 9a Upper hard roller 9b Lower hard roller 9c Upper hard roller (with far-infrared heater) 9d Lower hard roller (with far-infrared heater) 10 Shield laminate

Claims (7)

(57) [Claims] 1. A method for manufacturing a multilayer printed wiring board, wherein a copper foil sheet with a thermosetting resin is roll-laminated on both sides of an inner circuit board coated with an undercoat material to form a shield laminate. Roll lamination by heating and pressing a copper foil with a conductive resin on both surfaces of the inner layer circuit board, vertically displaced from each other in a horizontal direction, and a soft roller arranged opposite to a hard roller. A method for manufacturing a multilayer printed wiring board. 2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein an epoxy resin is used as a resin for the undercoat material and the copper foil sheet with the thermosetting resin. 3. The metal roller as a soft roller according to JIS.
2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein a roller lined with silicone rubber or fluorine rubber having a rubber hardness of 55 to 90 degrees is used. 4. The method according to claim 1, wherein a roller made of titanium metal, aluminum or an aluminum alloy is used as said hard roller. 5. A releasable sheet is interposed between the hard roller facing the soft roller to which the inner circuit board enters and the inner circuit board during the roll lamination according to claim 1. Manufacturing method of a multilayer printed wiring board. 6. The method for manufacturing a multilayer printed wiring board according to claim 5, wherein a hard fluororesin sheet is used as said release sheet. 7. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein said hard roller is heated to a resin melting temperature of said copper foil with thermosetting resin.