JP2000185385A - Laminated sheet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing laminated sheet with good moldability and thickness accuracy, and a laminated sheet to be produced by the method. SOLUTION: A laminated sheet is produced by arranging a combined material 4 constituted by laminating a plurality of prepregs between opposed metal foils 2 to press all of them while passing a current through the metal foils 2 to mold the whole under heating and pressure. The temp. rising speed of a resin until 8-15 min is elapsed from a point of time when the temp. of the resin reaches temp. between 130-160 deg.C after the start of heating is set to 0.5-1.5 deg.C/min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminate having good thickness accuracy and good formability, and a laminate used for producing a printed wiring board.

[0002]

2. Description of the Related Art A metal foil-clad laminate used for processing a printed wiring board or the like is a set of a plurality of prepregs stacked (or a set of a prepreg stacked on an inner circuit board). ), A metal foil such as a copper foil is laminated on one or both sides to form a combined material, and a plurality of the combined materials are made of SUS
There is a method of manufacturing by performing multi-stage hot press molding in which a combination block is formed by laminating through a plate such as a plate, arranging the combined block between hot plates, and heating and pressing with a hot plate to laminate and form. Was common.

However, in this method, it is difficult to sufficiently heat the prepreg disposed in the inner layer of the combination block, and it is difficult to uniformly heat the prepregs of the respective combination materials stacked in multiple stages. As a result, there is a possibility that the quality of the formed laminate, such as the formability and plate thickness, may vary. Therefore, in recent years, in order to uniformly heat each combination material in the combination block, a method of connecting a power supply to the metal foil and energizing the metal foil to generate heat in the metal foil (hereinafter, referred to as “heating”). Direct current heating method ").

FIG. 1 shows an example of this. First, a long metal foil 2 is used, and the metal foil 2 is folded and bent in a plurality of layers, and a plurality of folded metal foils 2 are provided between the opposed metal foils 2. By alternately sandwiching a set of combination members 4 and a plurality of mirror-surface plates 5 having electrical insulation,
A laminated block 8 composed of a plurality of metal foils 2 bent in a meandering shape, a plurality of electrically insulating mirror-surface plates 5 stacked in multiple stages, and a plurality of sets of combination materials 4 is manufactured. Combination material 4
Are formed as a set of a plurality of prepregs 1 (or as a set of a prepreg 1 and an inner wiring board 3). When the laminated block 8 is set between the pressure plates 6 and the power supply 7 is connected to both ends of the metal foil 2 and the metal foil 2 is energized while being pressed by the pressure plate 6, the metal foil 2 is heated by Joule heat. Heat is generated, and the prepreg 1 of each combination material 4 is heated by the generated heat to perform molding.

According to the direct current heating method, the prepreg 1 of each combination 4 can be directly heated using the metal foil 2 as a heat source, so that the prepreg 1 of each combination 4 stacked in multiple stages is heated. Variations in temperature can be suppressed, and variations in quality of the metal foil-clad laminate can be suppressed.

[0006]

However, even with the direct current heating method as described above, it is not possible to completely prevent a slight variation in the heating temperature from occurring, and therefore, the moldability of the formed laminate deteriorates. In addition, variations in plate thickness occur.

That is, conventionally, when a laminated plate is formed by heating and pressurizing, the resin once in the prepreg, as shown in FIG. 3, is used regardless of the multi-stage hot press method or the direct current heating method. Is rapidly heated to a temperature at which the viscosity of the resin starts to decrease, and then heated at a constant heating rate of about 1.5 to 4.5 ° C./min. At this time, the viscosity of the resin reaches the minimum viscosity. Thereafter, the temperature rises due to a thermosetting reaction. As described above, the melt viscosity of the resin in the prepreg temporarily decreases and then rapidly increases. Therefore, even if the temperature of the combination material 4 is slightly different, the resin flow of the resin in the prepreg varies and the resin is formed. This causes variations in the moldability and plate thickness of the laminated plate.

[0008] The present invention has been made in view of the above points, and an object of the present invention is to provide a method of manufacturing a laminate that can be manufactured with high moldability and plate thickness accuracy, and to provide a laminate manufactured by this method. It is the purpose.

[0009]

According to a first aspect of the present invention, there is provided a method for manufacturing a laminated board, comprising: placing a combination material formed by laminating a plurality of prepregs between opposed metal foils;
A method for manufacturing a laminated board in which pressing and pressurizing the metal foil 2 to apply heat and pressure are performed, and from the time when the resin temperature reaches any temperature between 130 and 160 ° C. after the start of heating, It is characterized in that the rate of temperature rise of the resin until elapse of up to 15 minutes is 0.5 to 1.5 ° C./min.

According to a second aspect of the present invention, there is provided a method for manufacturing a laminated board according to the first aspect, further comprising the steps of: starting the heating, when the resin temperature reaches any temperature between 130 to 160 ° C. the pressure of up to a 1 kg / cm ² or less, the pressure between the time that the resin temperature reaches any temperature between 130 to 160 ° C. until passage 8-15 minutes 9~15k
g / cm ² .

According to a third aspect of the present invention, in addition to the first or second aspect, the method for producing a laminate is characterized in that the heat and pressure molding is performed in a reduced pressure atmosphere of 50 mmHg or less. Things.

A laminated plate according to a fourth aspect of the present invention is manufactured by the method according to any one of the first to third aspects.

[0013]

Embodiments of the present invention will be described below.

The prepreg 1 is obtained by impregnating a thermosetting resin varnish into a glass cloth base material made of a woven or nonwoven glass fiber cloth and then drying the glass cloth base material. Is prepared as a product impregnated with. It is preferable that the resin impregnation rate of the prepreg 1 be 40 to 70%.

The thermosetting resin varnish for producing the prepreg 1 needs a resin composition prepared by blending a curing agent and the like with a thermosetting resin such as an epoxy resin, a polyimide resin, and a polyphenylene ether resin. The prepreg 1 is preferably prepared by dissolving the resin component in a solvent in accordance with the formula (1), wherein the resin component has a melt viscosity of 1,000 to 5,000 poise at 130 to 160 ° C. when the prepreg 1 is prepared.

The specific composition of the above thermosetting resin varnish will be exemplified.

As the epoxy resin varnish, a brominated bisphenol A type epoxy resin 10 having an epoxy equivalent of 500 is used.
0 parts by weight, 11 parts by weight of a cresol novolac type epoxy resin having an epoxy equivalent of 220, 2.5 parts by weight of dicyandiamide, and 0.1 part by weight of 2-ethyl-4-methylimidazole were added to an epoxy resin resin composition obtained. 30 parts by weight of methyl ethyl ketone, dimethylformamide 20
Parts by weight, and 10 parts by weight of dimethylcellosolve can be used.

As the polyphenylene ether resin composition, 100 parts by weight of a bisphenol A type epoxy resin having an epoxy equivalent of 190, polyphenylene ether (for example, PPE manufactured by Nippon General Electric Co., Ltd.) in benzoyl peroxide and bisphenol A, and toluene solvent 15 parts by weight of a modified polyphenylene ether obtained by performing a redistribution reaction by heating at 90 ° C. for 60 minutes at
To an epoxy resin composition obtained by blending 6 parts by weight of dicyandiamide, 30 parts by weight of methyl ethyl ketone, 20 parts by weight of dimethylformamide, and 1 part of dimethylcellosolve 1
A polyimide resin composition obtained by blending 0 parts by weight with 30 parts by weight of methyl ethyl ketone, 20 parts by weight of dimethylformamide, and 10 parts by weight of dimethylcellosolve can be exemplified.

As the polyimide resin varnish, 100 parts by weight of dimethylmethane maleimide as bismaleimide and 3 parts of diaminodiphenylmethane as polyarene are used.
One obtained by mixing 0 parts by weight and 70 parts by weight of dimethylacetamide as a solvent and heating and reacting at 80 ° C. for 3 hours with stirring.

In forming a laminate using the prepreg 1 obtained as described above, a plurality of prepregs 1 are laminated or the prepreg 1 is laminated on an inner wiring board 3 on which a circuit is formed. Combined material 4
It is arranged between the opposing metal foils 2, and is pressed and formed by heating and pressing by applying electricity to the metal foils 2. In the conventional multi-stage hot press, since the heating temperature is not uniform, forming shavings are generated, so forming is difficult. In this manner, the metal foil 2 is laminated on the prepreg 1,
In the method of manufacturing a laminate by energizing the metal foil 2 to cause the metal foil 2 to generate heat, molding is easy.

The method of manufacturing a laminated board will be specifically described.
For example, as shown in FIG. 1, a plurality of prepregs 1 are laminated, or a circuit is formed on a metal foil on the surface of a metal-clad laminate such as a double-sided copper-clad laminate. Alternatively, a combination material 4 is configured by arranging a plurality of prepregs 1. The thickness of the metal foil 2 such as copper foil is 6 to
Using two long pieces of 70 μm, the two metal foils 2
And an electrically insulating mirror plate which is formed by arranging a plurality of layers in a meandering manner and forming the combination material 4 between the facing metal foils 2 and forming an insulating coating on the surface of an aluminum plate. 5 are alternately arranged to form a laminated block as shown in FIG. The laminated block is set between the pressure plates 6 and a power source 7 is connected to the two metal foils 2, and the pressing by the pressure plates 6 and the energization of the metal foil 2 are performed. When the metal foil 2 is energized in this way, the metal foil 2 generates heat by Joule heat, and this heat causes the resin in the prepreg 1 of each combination material 4 to be cured by heating, thereby forming a multi-layered laminate. Things.

Preferred heating conditions for heating by energizing the metal foil 2 will be described below. As shown in FIG. 2, first, the temperature of the resin in the prepreg 1 is 7
The resin is heated at a rate of 3 to 10 ° C./min until the temperature becomes 0 to 120 ° C. to soften the resin. Subsequently, the resin is heated at a rate of 1.5 to 4.5 ° C./min until the temperature of the resin becomes 130 to 160 ° C. and the melt viscosity of the resin becomes 1000 to 5000 poise. Then, heating is performed at a heating rate of 0.5 to 1.5 ° C./min, preferably 0.7 to 1.0 ° C./min for 8 to 15 minutes. By controlling the rate of temperature rise from the time when the temperature of the resin reaches any temperature between 130 to 160 ° C., the melt viscosity of the resin becomes 1000 to 5 as shown in FIG.
The low viscosity region which is in the range of about 000 poise is 10 to 15
Minutes, and the resin flow in each prepreg 1 at this time can be kept constant. Subsequently, heating is performed at a heating rate of 1.5 to 4.5 ° C./min for 13 to 20 minutes so that the temperature of the resin becomes any temperature between 175 to 210 ° C. The curing reaction is allowed to proceed for a period of 1 minute.

Here, the pressurizing condition is such that after energization of the metal foil 2 is started, the temperature of the resin in the prepreg 1 is 130 to 16
Until the temperature reaches 0 ° C. and the heating rate is controlled to 0.5 to 1.5 ° C./min, the pressure applied to the prepreg 1 is 1 kg / cm ^2.
Below or in a non-pressurized state, the temperature of the resin is 130 to 160
° C, and while controlling the rate of temperature rise to 0.5 to 1.5 ° C / min, the pressure is increased to 9 to 15 kg / cm ² to increase the pressure until the heating is completed. 15kg / cm
It is preferable to keep the pressure at ² . By controlling the pressing conditions in this way, it is possible to pressurize to the final molding pressure when the resin in all the prepregs 1 being subjected to laminate molding is in a low viscosity state of about 1000 to 5000 poise. The resin flow in the prepreg 1 can be kept constant.

The above-mentioned heat and pressure molding is performed at 50 mmHg.
It is preferable to perform the reaction under the following reduced pressure atmosphere. In this case, a gas component generated along with the progress of the thermosetting reaction of the resin is removed, and the generation of voids in the molded laminate is suppressed. , Formability and plate thickness accuracy can be improved. The lower the pressure at this time is, the more preferable it is. However, it is considered that a practical lower limit is 10 mmHg.

The laminated board manufactured as described above can form a printed wiring board by forming a circuit by performing an etching process or the like on the metal foil 2 on the surface. Further, this printed wiring board can be applied as the above-mentioned inner wiring board to produce a multilayered board.

[0026]

The present invention will be described below in detail with reference to examples. Example 1 100 parts by weight of a brominated bisphenol A type epoxy resin having an epoxy equivalent of 500, and an epoxy equivalent of 220
An epoxy resin composition obtained by mixing 11 parts by weight of a cresol novolak type epoxy resin, 2.5 parts by weight of dicyandiamide, and 0.1 part by weight of 2-ethyl-4-methylimidazole, 30 parts by weight of methyl ethyl ketone and dimethylformamide 20 parts by weight, dimethyl cellosolve 1
The resin varnish was prepared by mixing 0 parts by weight. This resin varnish is impregnated into a 2116 type glass cloth, and
By heating and drying at 60 ° C. for 7 minutes, prepreg 1 having a resin impregnation rate of 52% was produced.

Further, two prepregs 1 were stacked and copper foil having a thickness of 18 μm was stacked on both sides thereof at 170 ° C.
It was heated and pressed under a condition of 3.9 MPa for 90 minutes to produce a double-sided copper-clad laminate having a thickness of 0.2 mm.

One or a plurality of prepregs 1 similar to those used for manufacturing the inner layer wiring board 3 were arranged on both sides of the inner layer wiring board 3, thereby forming 50 sets of combined materials 4. As the metal foil 2, a long copper foil having a thickness of 18 μm was used.
The two metal foils 2 are arranged so as to face each other and bent in a plurality of layers in a meandering manner, and the combination material 4 is provided between the facing metal foils 2 and an aluminum plate (mirror) whose surface is insulated. By alternately arranging the face plates 5), a 50-layer laminated block was formed as shown in FIG. Then, the laminated block is set between the pressure plates 6 and the power source 7 is connected to the two metal foils 2. Under the atmosphere of 40 mmHg, pressing by the pressure plates 6 and energization of the metal foil 2 are performed. Thus, a laminate was obtained. Here, the heating and pressing conditions were as shown in Table 1 below.

[0029]

[Table 1]

(Embodiment 2) A laminated block constructed under the same conditions as in Embodiment 1 was set between the pressure plates 6 and a power source 7 was connected to the two metal foils 2 to obtain a pressure of 40 mmHg.
In the atmosphere described above, pressing by the pressure plate 6 and energization of the metal foil 2 were performed to obtain a laminate. Here, the heating and pressurizing conditions are as shown in Table 2 below.

[0031]

[Table 2]

Example 3 A laminated block constructed under the same conditions as in Example 1 except that the resin impregnation rate of the prepreg 1 when preparing the prepreg 1 was 58% was placed between the pressure plates 6. Set and power 7 on two metal foils 2
And pressurization by the pressure plate 6 and energization of the metal foil 2 were performed in an atmosphere of 40 mmHg to obtain a laminate. Here, the heating and pressing conditions are as shown in Table 3 below.

[0033]

[Table 3]

(Embodiment 4) A laminated block constructed under the same conditions as in Embodiment 1 was set between the pressure plates 6, and a power supply 7 was connected to the two metal foils 2 to obtain 40 mmHg.
In the atmosphere described above, pressing by the pressure plate 6 and energization of the metal foil 2 were performed to obtain a laminate. Here, the heating and pressing conditions are as shown in Table 4 below.

[0035]

[Table 4]

(Embodiment 5) A laminated block constructed under the same conditions as in Embodiment 1 was set between the pressure plates 6, and a power supply 7 was connected to the two metal foils 2 to obtain a pressure of 40 mmHg.
In the atmosphere described above, pressing by the pressure plate 6 and energization of the metal foil 2 were performed to obtain a laminate. Here, the heating and pressing conditions are as shown in Table 5 below.

[0037]

[Table 5]

(Comparative Example 1) A laminated block constructed under the same conditions as in Example 1 was set between the pressure plates 6 and a power supply 7 was connected to the two metal foils 2 to apply a voltage under normal pressure. Pressing by the pressure plate 6 and energization of the metal foil 2 were performed to obtain a laminate. Here, the heating and pressurizing conditions are as shown in Table 6 below.

[0039]

[Table 6]

(Comparative Example 2) A laminated block constructed under the same conditions as in Example 1 was set between the pressure plates 6, and a power supply 7 was connected to the two metal foils 2 to apply pressure under normal pressure. Pressing by the pressure plate 6 and energization of the metal foil 2 were performed to obtain a laminate. Here, the heating and pressurizing conditions are as shown in Table 7 below.

[0041]

[Table 7]

(Comparative Example 3) A laminated block constructed under the same conditions as in Example 1 was set between the pressure plates 6 and a power supply 7 was connected to the two metal foils 2 to obtain 40 mmHg.
In the atmosphere described above, pressing by the pressure plate 6 and energization of the metal foil 2 were performed to obtain a laminate. Here, the heating and pressurizing conditions are as shown in Table 8 below.

[0043]

[Table 8]

Comparative Example 4 A copper foil having a thickness of 18 μm was arranged on both sides of a combination material 4 constructed under the same conditions as in Example 1 to form 10 sets of laminates. A laminated block was formed by laminating via a plate, and cushion materials were arranged above and below the laminated block and set between a pair of hot plates. The laminated block was obtained by heating and pressing the laminated block with a hot platen. Here, the heating and pressing conditions are as shown in Table 9 below. In Table 9, the temperature change is indicated not by the resin temperature but by the hot platen temperature. In the case of heating with a hot platen, the prepregs 1 arranged in multiple layers are used.
This is because the temperature of the resin inside cannot be controlled uniformly.

[0045]

[Table 9]

(Evaluation Test) The copper foil on the surface of each laminate obtained in each of the above Examples and Comparative Examples was removed by etching, and the exposed resin layer was observed. , Counting the number of voids in the resin layer,
The moldability was evaluated.

Further, the maximum distance of the resin flowing out from the end of each wiring board to the outside from the end face is measured.
The resin flow was evaluated.

The thickness of each wiring board was measured, and the standard deviation of the thickness was calculated.

Table 10 shows the evaluation results.

[0050]

[Table 10]

As is clear from Tables 1 to 10, in Examples 1 to 5, compared to Comparative Examples 1 to 4, wiring boards having excellent moldability and good thickness accuracy were obtained. In particular, in Examples 1 to 3 in which the final pressure was controlled to 9 to 15 kg / cm ² , a wiring board having particularly excellent formability and thickness accuracy was obtained.

[0052]

As described above, in the method for manufacturing a laminated board according to the first aspect of the present invention, a composite material formed by laminating a plurality of prepregs is arranged between opposing metal foils, pressed and pressed. A method for producing a laminated board in which heating and pressure molding is performed by energizing a metal foil, wherein 8 to 15 minutes have elapsed since the start of heating, when the resin temperature reached any temperature between 130 to 160 ° C. The rate of temperature rise of the resin until
0.5 to 1.5 [deg.] C./min to maintain a long period of time during which the resin in the prepreg used for forming the laminate is in a low-viscosity state and to keep the resin flow in each prepreg during the molding constant. , And the formability and thickness accuracy can be improved.

According to a second aspect of the present invention, there is provided a method of manufacturing a laminated board according to the first aspect, further comprising the step of: starting the heating, when the resin temperature reaches any temperature between 130 to 160 ° C. the pressure of up to a 1 kg / cm ² or less, the pressure between the time that the resin temperature reaches any temperature between 130 to 160 ° C. until passage 8-15 minutes 9~15k
g / cm ² , and can be pressurized to the final molding pressure when the resin in all of the prepregs being provided with the laminate is in a low-viscosity state. Is kept constant, moldability,
The thickness accuracy can be further improved.

According to a third aspect of the present invention, in addition to the structure of the first or second aspect, in addition to the constitution of the first or second aspect, the heat and pressure molding is performed under a reduced pressure atmosphere of 50 mmHg or less. By removing gas components generated with the progress of the thermosetting reaction of the above, it is possible to suppress the occurrence of voids in the laminated plate to be formed, and to further improve the formability and plate thickness accuracy. .

A laminate according to a fourth aspect of the present invention is manufactured by the method according to any one of the first to third aspects, and it is possible to obtain a wiring board excellent in formability and thickness accuracy. You can do it.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment of the present invention.

FIG. 2 is a graph schematically showing a change in heating conditions and a change in resin viscosity in a prepreg in the present invention.

FIG. 3 is a graph showing an outline of a change in a resin viscosity in a prepreg under heating conditions in a conventional technique.

[Explanation of symbols]

 1 Pre-preg 2 Metal foil 4 Combination material

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) H05K 3/00 H05K 3/00 R

Claims (4)

[Claims] 1. A method of manufacturing a laminated plate in which a composite material formed by laminating a plurality of prepregs is disposed between metal foils facing each other, pressed and heated and pressed by applying electricity to the metal foils. After the start of heating, the resin temperature becomes 1
The rate of temperature rise of the resin from the point when any temperature between 30 to 160 ° C. is reached until 8 to 15 minutes elapse is 0.5
A method for producing a laminate, which is performed at a temperature of 1.5 to 1.5 ° C./min. 2. After the start of heating, the resin temperature is 130 to 160.
Pressure until one of the temperatures reaches
and kg / cm ² or less, raising the pressure between the time that the resin temperature reaches any temperature between 130 to 160 ° C. until passage 8-15 minutes until 9~15kg / cm ² The method for producing a laminate according to claim 1, wherein 3. The method for producing a laminate according to claim 1, wherein the heat and pressure molding is performed in a reduced pressure atmosphere of 50 mmHg or less. 4. A laminate manufactured by the method according to claim 1. Description: