JPH057095A - Manufacture of shielding plate for multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To provide a manufacturing method, wherein the manufacturing process of a shielding plate is further simplified compared to a conventional manufacturing process and it is made possible to solve effectively also various troubles at the time of manufacture of a printed wiring board, of the shielding plate for multilayer printed wiring board use. CONSTITUTION:Reduced pressure system roll laminators for laminating respectively bonding agents 6 with a copper foil on both surfaces of internal layer circuit boards 3 are shown in a vacuum box 13 and these laminators respectively unwind the bonding agents 6 with a copper foil from small wound rolls 7a and 7b made by winding continuous bonding agents 6 with a copper foil in a roll-form and respectively laminate the bonding agents 6 on both surfaces of the boards 3 while the bonding agents 6 are made to insert between heating rolls 8a and 8b under a reduced pressure (100Torr or lower and preferably 40Torr or lower).

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 shield board for a multilayer printed wiring board, and more particularly to a method for manufacturing a shield board for manufacturing a multilayer printed wiring board.

[0002]

2. Description of the Related Art Conventionally, a multilayer wiring board obtained by a subtractive method is one in which a plurality of conductive circuits are laminated via an insulating layer and is used as an electric product or other parts. As shown in FIG. 7, the method of manufacturing the wiring board is such that the inner layer circuit board 3 having the circuits 2 provided on both surfaces of the insulating substrate 1 has the glass epoxy prepreg 4 as shown in FIG.
(Prepreg made by impregnating glass fiber with epoxy resin)
By disposing the copper foil 5 via the prepreg and then curing and molding the prepreg 4, a shield plate for a wiring board as shown in FIG. 9 can be obtained. A circuit is formed on this copper foil by an etching process, and a multilayer (in this case, 4
Layer) It is common to manufacture printed wiring boards.

The shield plate for a multilayer printed wiring board shown in FIG. 9 has a state in which copper foils 5 are arranged on the entire outermost both surfaces of the multilayer printed wiring board before etching the outermost circuit. Shows. However, when a shield board for a wiring board is manufactured in this manner, a press is used under high temperature and high pressure (for example, 170 ° C.) in order to flow the glass-epoxy prepreg and remove air remaining between the circuits.
Since the molding is carried out at 40 ° C. and 40 kg / cm ² ), the manufacturing process becomes complicated, and residual strain occurs in the obtained wiring board, especially in the inner layer circuit, which is a problem.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, therefore, as disclosed in JP-A-2-58897, an adhesive with a copper foil is applied to an inner layer circuit board under reduced pressure. The applicant of the present application has filed a method for manufacturing a printed wiring board in which layers are successively laminated and cured on August 25, 1988.

In this manufacturing method, since the curing method is a method of applying pressure at a relatively low pressure, the residual strain is small, but the process is still complicated. Further, acrylonitrile-butadiene rubber (NBR), which is basically inferior in electric insulation, is used in the structure of the above invention. That is, since the pressure is applied in the curing step, a certain amount of NBR must be added in order to suppress the fluidity of the resin at the time of curing, so the electrical insulation is not good. On the other hand, of course, it can be cured under normal pressure, but since NBR is added in a certain amount, even if it is roll-laminated under reduced pressure, the surface of the shield plate, that is, the copper foil surface, may be damaged due to the convex portion of the inner layer circuit. It has poor smoothness, and when manufacturing a printed wiring board by etching after that, it floats when the resist film is bonded and the etching solution enters, or the coating residue remains when the resist is applied with a screen plate. As a result, a circuit failure or burr is likely to occur when drilling a hole, which causes a problem such as a printing failure.

The present invention has been devised in view of such conventional problems, further simplifies the manufacturing process as compared with the conventional invention, and effectively solves various problems in manufacturing a printed wiring board. It is an object of the present invention to provide a method for manufacturing a shield plate for a multilayer printed wiring board that enables the above.

[0007]

In order to achieve the above object, the present invention provides a long copper foil by coating a long copper foil with a resin composition containing a thermosetting resin and a polymer as main components. It is a gist to form a laminated adhesive and form a laminated body by continuously roll laminating the adhesive with a copper foil on an inner layer circuit board under reduced pressure, and curing the laminated body under normal pressure. is there.

Further, according to the present invention, a resin composition containing a thermosetting resin and a polymer as a main component is coated on a long releasable film to form an adhesive layer, and the adhesive layer is formed. A long copper foil is attached to form a long copper foil adhesive, and the copper foil adhesive is continuously roll laminated to the inner layer circuit board under reduced pressure to form a laminate. The gist of the invention is to cure under normal pressure.

At the time of roll lamination under the reduced pressure, 50
The viscosity of the adhesive when it comes into contact with a roll heated from 140 ° C to 140 ° C is preferably 10 to 10 ³ poise, and the thickness of the adhesive layer of the adhesive with copper foil is the inner layer circuit board inside thereof. It is preferable that the thickness of the circuit is twice or more. The configuration of the present invention will be described below with reference to the accompanying drawings. The same components as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. FIG. 1 shows a pressure reducing roll laminator for laminating an adhesive 6 with a copper foil as shown in FIG. 2 on both surfaces of an inner layer circuit board 3 in a pressure reducing box 13, and this pressure reducing roll laminator has a long length. The adhesive 6 with the copper foil is unwound from the small rolls 7a and 7b in which the adhesive 6 with the copper foil is wound into a roll, and is applied to both surfaces of the inner layer circuit board 3 under reduced pressure (10
Lamination is performed by inserting the heating rolls 8a and 8b at 0 torr or less, preferably 40 torr or less).

Reference numerals 9a and 9b in FIG. 1 denote rolls for winding the film 10, and both surfaces of the inner layer circuit board 3 in the state where the film 10 is bonded to the adhesive 6 with copper foil as shown in FIG. Only the film 10 unnecessary when laminating the adhesive 6 with a long copper foil on the roll is taken up by rolls 9a and 9b.
It was made to be wound around. Further, the configuration of the present invention will be described in detail. The adhesive 6 with copper foil comprises an adhesive layer 11 and a copper foil 5, and the thermosetting resin constituting the adhesive layer 11 is an epoxy resin or a modified epoxy. resin,
BT resin, imide-modified epoxy resin, acrylic resin, polyimide resin or the like, or a mixture thereof, which is a thermosetting resin usually used as a printed wiring board.

The polymer is NBR, NBR having a functional group capable of reacting with a thermosetting resin, a polyester resin, or an acrylic polymer, and may be one or two.
Use more than one seed. In addition, a thermosetting resin curing agent, a curing accelerator, and a filler are used. If necessary, these raw materials are dispersed and dissolved in an organic solvent such as methyl ethyl ketone, ethyl acetate or toluene to obtain a resin composition.

By coating the long copper foil 5 with the resin composition having the above-mentioned structure and drying the solvent to form the adhesive layer 11 having a uniform thickness, as shown in FIG. The adhesive 6 with a long copper foil is manufactured. As another method of obtaining the adhesive 6 with a copper foil, the resin composition is coated on the above-mentioned long film 10 having releasability, and the solvent is dried to obtain an adhesive layer 1 having a uniform thickness.
It is also possible to produce 1 and then bond the adhesive layer 11 to the long copper foil 5 to manufacture.

Adhesive 6 with copper foil thus obtained
Is a long roll, and is therefore easy to handle and has a length of several tens to several hundreds of meters.
a and 7b. Next, a method of laminating the long adhesive 6 with copper foil on both surfaces of the inner layer circuit board 3 under reduced pressure will be described.

For example, a decompression box 13 as shown in FIG.
The adhesive 6 with copper foil is set inside and above the heating rolls 8a and 8b, and the inner layer circuit board 3 is inserted between the heating rolls 8a and 8b to laminate the adhesive 6 with copper foil. The heating of the heating rolls 8a and 8b lowers the viscosity of the adhesive layer 11, and the pressure of the heating rolls 8a and 8b increases together with the inner layer circuit board 3.
Necessary for pouring adhesive between the circuits.

However, too much heating rolls 8a, 8b
If the heating temperature is too high, the adhesive will flow too much and the circuit 2
It becomes impossible to maintain the thickness as an insulating layer between the copper foil 5 and the copper foil 5, or it flows out to the periphery of the circuit board to stain the roll. If the copper foil 5 has a thickness of 70 μm, for example, 1
There is no problem up to 40 ° C., but if it is 35 μm, wrinkles may occur in the copper foil, so 50 ° C. to 140 ° C., preferably 80 ° C. to 120 ° C. are preferable.

What is important here is that the melt viscosity of the adhesive when passing through the heating roll is in the range of 10 to 10 ³ poises. If it is less than 10 poise, the adhesive layer 11 will flow too much when passing through the heating roll, and the thickness of the insulating layer cannot be maintained, or the adhesive layer 11 will flow to the surroundings, causing a problem. When it exceeds 10 ³ poises, the fluidity is slightly reduced, and the circuit 2 of the inner circuit board 3
Unevenness occurs on the surface of the laminated body 12 in which the adhesive 6 with copper foil is laminated by spreading out the convex part of No. 3, that is, the surface of the copper foil. In the subsequent curing step, these irregularities are cured under normal pressure, for example, in an oven, and therefore remain on the surface of the shield plate X as they are.

As described above, since the unevenness causes various problems in the post-process, the height difference of the unevenness needs to be 10 μm or less, and more preferably 5 μm or less. In order to fall within this viscosity range, the compounding ratio of the thermosetting resin and the polymer in the resin composition is approximately a weight ratio, where the polymer is NBR and rubber such as acrylic rubber, the thermosetting resin / polymer is 97 / 3 to 90/10, and when the polymer is a thermoplastic polymer, liquid rubber or liquid polymer, the range is 97/3 to 50/50.

Further, the thickness of the adhesive must be at least twice the height of the circuit of the inner layer circuit board. If the thickness is less than twice, the difference in height of the unevenness on the surface of the copper foil is 10 μm or more as in the above case, which causes a problem. The laminate obtained by laminating the adhesive 6 with copper foil on both surfaces of the inner circuit board 3 under reduced pressure is then heated and cured under normal pressure (atmospheric pressure).

This step may be performed by continuously passing through an oven 14 having a certain length as shown in FIG. 4 to be cured, and then cut into a regular length, or as shown in FIG. It may be cut into pieces and placed in an oven. The curing temperature is a temperature at which the thermosetting resin can be sufficiently cured, and is usually 150 to 230 ° C. Although the curing time depends on the temperature, it is usually 30 minutes to 3 hours. In this way, it is possible to manufacture the shield plate X for a multilayer printed wiring board in which the copper foils 5 are attached to both surfaces as shown in FIG.

This shield plate X can be obtained as a multilayer printed wiring board by subjecting the surface copper foil 5 to an etching treatment by a conventional subtractive method. Next, Table 1 shows Examples and Comparative Examples of the present invention.

[0021] In addition, Table 1 shows Examples 1 to 3 and Comparative Examples 1 and 2 described later.
Other properties of are shown. Example 1 A resin composition prepared by dissolving a thermosetting resin, a polymer, a curing agent, and a filler in methyl ethyl ketone in the formulation shown in Table 1 was applied to a copper foil (thickness 35 μm, width 500 mm, length 100 m). After coating and drying, thickness 70
An adhesive 6 with a copper foil having an adhesive layer 11 of μm was obtained.
A polyethylene film 10 as shown in FIG. 3 was stuck on the adhesive layer 11, cut into a length of 50 m and wound up into a small roll. The melt viscosity of the adhesive at 100 ° C. was 10 poise.

Next, as shown in FIG. 1, the decompression box 1
Two small-sized take-up rolls 7a and 7b were placed on the roll laminator installed in No. 2 and the inner layer circuit board 3 was placed from both sides at a position where they could be attached via the adhesive layer 11. Also, just before bonding, useless polyethylene film 1
The take-up rolls 9a and 9b are arranged so that 0 can be peeled off and the roll can be automatically taken up.

After decompressing the decompression box 13 to a vacuum degree of 40 Torr and setting the surface temperature of the laminating roll to 100 ° C., the inner layer circuit board was fed at a feed rate of 0.5 m / min and the roll pressure was 1 kg / cm. 35 μm high inner circuit board (500 m
An adhesive with a copper foil was attached from both sides of m × 333 mm). The inner layer circuit board 3 was continuously placed in the decompression box 13 with a space of 1 cm to obtain a laminate 12 in which the copper foil adhesive 6 was bonded. As shown in FIG. 4, the laminated body 12 is cured as it is through a curing oven (200 ° C.) having a length of 10 m to cure the adhesive, and then the copper foil 5 in the portion between the inner layer circuit boards 3 is made to have a predetermined length. It cut and obtained the shield plate X of a fixed length.

When the smoothness of the copper foil surface of this shield plate X was measured with a surface roughness meter, the difference H in height of the unevenness shown in FIG. 6 was 3 μm even at the largest difference, and
The cross section was observed, and the distance L between the insulating layer between the inner layer circuit and the copper foil 5 on the outer side was kept at least 40 μm, which was not a problematic level. Example 2 A resin composition having the composition shown in Table 1 was prepared in the same manner as in Example 1, and a copper foil 5 (thickness 18 μm, width 500 m
m, length 100 m) and after drying,
Adhesive 6 with copper foil having an adhesive layer 11 having a thickness of 180 μm
Got Polyethylene film 1 on the adhesive layer 6
0 was attached, cut into a length of 50 m and wound up into a small roll. The melt viscosity of this adhesive at 100 ° C is 1
It was 0 ² poise.

Next, as in the first embodiment, it is placed in the decompression box 13, decompressed to a vacuum degree of 20 Torr, the surface temperature of the laminating roll is set to 100 ° C., and then the feed rate of the inner layer circuit board 3 is 2.0 m. / Min, roll pressure 2 kg / cm, and circuit height 70 μm. Adhesive 6 with copper foil from both sides of inner layer circuit board 3
Pasted together. The inner layer circuit board 3 was continuously placed in a decompression box with a space of 1 cm to obtain a laminated board 12 to which the copper foil adhesive 6 was attached. As shown in FIG. 5, when the laminate 12 comes out of the decompression box 13, the laminate 12 is cut into regular lengths, and each of them is cut into a curing oven 14 (170 ° C.).
Then, the adhesive was cured to obtain a shield plate.

When the smoothness of the copper foil surface of this shield plate X was measured by a surface roughness meter, it was 4 μm even at the largest difference, and the distance between the insulating layers was at least 90 μm.
m, and sufficient insulation could be maintained. [Example 3] A resin composition having the composition shown in Table 1 was prepared in the same manner as in Example 1, and a copper foil 5 (thickness: 35 µm, width: 500 m) was prepared.
m and length 100 m) and dried, to obtain an adhesive 6 with a copper foil having an adhesive layer with a thickness of 70 μm.
The polyethylene film 10 was stuck on the adhesive layer 11, cut into a length of 50 m and wound up into a small roll. The melt viscosity of this adhesive at 120 ° C. was 10 ³ poise.

Next, as in Example 1, the sheet was placed in the depressurization box 13, depressurized to a vacuum degree of 10 Torr, the surface temperature of the laminating roll was set to 120 ° C., and then the feed rate of the inner layer circuit board was 1.5 m / m. Min, roll pressure 4kg / cm, circuit height 3
An adhesive 6 with a copper foil was attached from both sides of the 5 μm inner layer circuit board. Then, the adhesive was cured in the same manner as in Example 2 to obtain a shield plate X. Similarly, when the smoothness was measured with a surface roughness meter, it was 5 μm even at the largest difference, and the distance between the insulating layers was kept at least 75 μm, and there was no problem. [Comparative Example 1] A resin composition having the composition shown in Table 1 was obtained in the same manner as in Example 1. Similarly, the copper foil 5 having a thickness of 35 μm was coated. However, the thickness after drying is 70 μm.
It is not possible to obtain sufficient film forming properties to apply an adhesive to
There was a large variation in the thickness of the adhesive layer 11, and crater-like dents and the like were also found in the appearance. 100 ℃ of this adhesive
The melt viscosity at was 5 poises. Then, an adhesive with copper foil was attached to both sides of the inner layer circuit board under reduced pressure and cured in the same manner as in Example 1 to obtain a shield plate X.

At the time of laminating, there was a problem that the adhesive resin flows out and adheres to the laminating roll due to its low melt viscosity. Further, although there was no problem with the smoothness of the shield plate X, the distance between the insulating layers was only about 15 μ at the lowest, which was a concern for insulation. [Comparative Example 2] A resin composition having the composition shown in Table 1 was obtained in the same manner as in Example 1. A copper foil was coated in the same manner as in Example 3 and dried to obtain a small winding roll. 1 of this glue
The melt viscosity at 20 ° C. was 5 × 10 ³ poise.

Then, also in the same manner as in Example 3, adhesives with copper foil were attached to both sides of the inner layer circuit board under reduced pressure, and the adhesives were cured to obtain a shield plate. The smoothness of this shield plate was 12 μm at the largest difference.

[0030]

Since the present invention has the above-described structure, an embodiment of the present invention will be described below with reference to the accompanying drawings. (A). Since the adhesive with copper foil is attached to the inner circuit board under reduced pressure, no air pockets (voids) are generated inside, and the subsequent curing process is performed under normal pressure (in a normal oven) to cure the adhesive. Therefore, the adhesive does not easily flow during curing. Therefore, the distance between the inner layer circuit and the outer copper foil (distance between the insulating layers) is sufficiently maintained.

Further, since the melt viscosity of the adhesive is low, the adhesive easily enters the concave portion of the inner layer circuit when laminating under reduced pressure. As a result, the uneven portion of the inner layer circuit is not spread, and the copper foil of the shield plate is not spread. Excellent surface smoothness. (B). Also, NBR is inferior in electrical insulation when a certain amount is added.
However, since a small amount is blended as shown in Example 2, the insulating property can be used without any problem. (C). In addition, as described in the conventional invention, the NB
When the amount of R was reduced, it was feared that the adhesive strength of the adhesive to the circuit board would decrease, but since the adhesive did not flow out and a sufficient thickness was maintained, no decrease in the adhesive strength was observed. It was Therefore, from the viewpoint of productivity, since the continuous production is possible, the productivity is extremely high as compared with the conventional shield plate.

[0032]

[Brief description of drawings]

FIG. 1 is an explanatory view of a roll laminator showing a step of laminating an adhesive with a copper foil in a decompression box on both surfaces of an inner layer circuit board embodying the present invention.

FIG. 2 is a cross-sectional view of an adhesive with copper foil.

FIG. 3 is a cross-sectional view in which a film is attached to an adhesive with copper foil.

FIG. 4 is an explanatory view showing a step of cutting the laminated body that has come out of the oven into a predetermined length after the laminated body is continuously cured in the oven.

FIG. 5 is an explanatory view showing a step of curing a laminate cut into regular lengths in an oven.

FIG. 6 is an explanatory diagram when the smoothness of the copper foil surface of the shield plate manufactured according to the present invention is measured by a surface roughness meter.

FIG. 7 is a cross-sectional view of an inner layer circuit board.

FIG. 8 is a layout view of materials when manufacturing a conventional shield plate for a multilayer wiring board.

FIG. 9 is a cross-sectional view of a wiring board shield plate formed by curing a prepreg of a conventional multilayer wiring board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating substrate 2 Circuit 3 Inner layer circuit board 4 Glass / epoxy prepreg 5 Copper foil 6 Adhesive with copper foil 10 Film 11 Adhesive layer 12 Laminated body 13 Decompression box 14 Oven X Shield plate

Claims (4)

[Claims] 1. A long copper foil is coated with a resin composition containing a thermosetting resin and a polymer as a main component to form a long copper foil-attached adhesive. A method for producing a shield plate for a multilayer printed wiring board, which comprises continuously laminating an inner circuit board under reduced pressure to form a laminate, and curing the laminate under normal pressure. 2. A resin composition containing a thermosetting resin and a polymer as a main component is coated on a long releasable film to form an adhesive layer, and the adhesive layer is formed into a long copper film. A long copper foil adhesive is formed by pasting on the foil, and the copper foil adhesive is continuously roll laminated to the inner layer circuit board under reduced pressure to form a laminate, and the laminate is formed under normal pressure. A method for manufacturing a shield board for a multilayer printed wiring board, which comprises curing. 3. At the time of roll lamination under the reduced pressure, 5
The adhesive viscosity when contacting a roll heated from 0 ° C to 140 ° C is 10 to 10 ³ poise.
Or the manufacturing method of the shield board for multilayer printed wiring boards of Claim 2. 4. The method according to claim 1, wherein the thickness of the adhesive layer of the adhesive with copper foil is twice or more the thickness of the circuit of the inner layer circuit board inside the adhesive layer. A method for manufacturing a shield board for a multilayer printed wiring board according to.