JPH09186457A - Production of laminate having inner layer circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a laminate having an inner layer circuit where the difference of thickness is small between a laminate having an inner layer circuit produced at a position touching a hot plate and a laminate having an inner layer circuit produced at a position not touching the hot plate. SOLUTION: A prepreg comprising a basic material impregnated with a thermosetting resin is laminated on a board provided with a circuit and more than two such laminates are laminated and hot pressed by means of hot plates. The ratio of melt viscosity at 130 deg.C is set at 1:1.2-1.5 between the prepreg in a laminate touching the hot plate and the prepreg in a laminate not touching the hot plate.

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 laminated board containing an inner layer circuit, which is used for manufacturing a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, a laminated board with an inner layer circuit has a substrate on which a circuit is formed as an inner layer substrate, a prepreg is laminated on the inner layer substrate, and a metal foil is further arranged on the outermost layer of the prepreg as required. It is manufactured by stacking and sandwiching the stacked product between hot plates to heat and press. In addition, in order to improve productivity, a plurality of the above-mentioned laminates are laminated with a mold interposed therebetween, and the plurality of laminates are sandwiched between hot plates and heated and pressed once. In addition, a method for obtaining a large number of laminated boards with inner circuit is also used. These prepregs used for the inner layer circuit-containing laminated plate have a resin amount required to fill the recesses of various shapes existing between the circuits formed on the surface of the inner layer substrate with resin, compared to the resin amount required. A resin having an excessively large amount of resin is generally used with a margin, and a resin having a good fluidity when heated is used so that air bubbles do not remain in the recess.

As electronic devices have become more sophisticated in recent years, the plate thickness accuracy required for laminated plates with inner layer circuits has become extremely high. However, in the case of a method in which a plurality of laminates as described above are sandwiched between hot plates and heat-pressed, there is a large variation in plate thickness, which may result in defects, which lowers the yield and poses a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and its purpose is to impregnate a substrate on which a circuit is formed and a base material with a thermosetting resin. A method for producing a laminated board with an inner layer circuit, comprising laminating prepregs to form a laminated body, stacking three or more laminated bodies to form a laminated body, sandwiching the laminated body between hot plates, and heating and pressurizing the laminated body. In, there is provided a method for producing a laminated plate with an internal layer circuit, in which a difference in plate thickness between the laminated plate with an internal layer circuit produced at a position in contact with the hot plate and the laminated plate with an internal layer circuit produced at a position not in contact with the hot plate is small. Especially.

[0005]

According to a first aspect of the present invention, there is provided a method of manufacturing a laminated board with an inner layer circuit in which a circuit-formed substrate and a prepreg having a base material impregnated with a thermosetting resin are laminated. In the method for producing a laminated board with an inner layer circuit, the laminated body is formed by stacking three or more laminated bodies to form a laminated body, and sandwiching the laminated body between hot plates to heat and pressurize the laminated body. Melt viscosity at 130 ° C. of a prepreg (hereinafter referred to as a first prepreg) used for a laminate in contact with a hot plate, and a laminate other than the laminate in contact with the hot plate among the laminates in the laminate. The ratio of the melt viscosity of the prepreg used (hereinafter referred to as the second prepreg) at 130 ° C. is
1: 1.2 to 1.5.

According to a second aspect of the present invention, there is provided a method for producing a laminated board having an inner layer circuit, wherein the prepreg is a glass cloth impregnated with an epoxy resin composition. Is characterized in that.

According to a third aspect of the present invention, there is provided a method for producing an inner layer circuit-containing laminated sheet according to the second aspect, wherein the first prepreg and the second prepreg have a melt viscosity at 130 ° C. , 300 to 800 poise.

The term "contact with the hot plate" in the present invention includes not only the direct contact between the laminated body and the hot plate, but also the case of interposing a mold, a heat cushioning material, a cushion material or the like therebetween. .

In order to solve the above-mentioned problems, the inventors have conducted various studies, and as a result, due to the difference in the positional relationship (distance) between the prepreg and the hot plate, a difference in the temperature rising rate of the prepreg occurs, and the temperature increase thereof occurs. It was found that the difference in the fluidity of the thermosetting resin due to the difference in speed is one of the causes of the variation in the plate thickness. Therefore, the inventors have found a manufacturing method in which the difference in the fluidity of the thermosetting resin of the prepreg is reduced even if there is a difference in the rate of temperature rise, and solved the problem.

According to the present invention, the melt viscosity of the first prepreg is made smaller than the melt viscosity of the second prepreg by a specific ratio, so that the difference in the resin flow between the first prepreg and the second prepreg is reduced and the plate thickness is reduced. To reduce the variation.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a laminated board with an internal circuit according to the present invention comprises laminating a prepreg in which a base material is impregnated with a thermosetting resin on a circuit-formed substrate, and further, if necessary, the outermost layer thereof. A metal foil or a release film is laminated on the above to form a laminated body, and the laminated body is intervened with a mold if necessary.
A laminate is formed by stacking one or more sheets, and the laminate is sandwiched between hot plates and heated and pressed to manufacture.

When the laminated body is sandwiched between heating plates and heated,
Since the temperature rise of each laminate is heated by the heat transfer from the hot plate, the rise rate is deviated according to the distance from the hot plate. This difference in the rising speed of the temperature causes a particularly large difference between the laminate in contact with the hot plate and the second laminate from the adjacent heat plate. It should be noted that sandwiching the laminated body between the hot plates is not only sandwiched so that the laminated body and the hot plate are in direct contact with each other, but also a thermal buffering material used to reduce the difference in temperature rising speed as much as possible, Paper or the like that imparts cushioning properties may be sandwiched so that air bubbles do not remain in the recesses between the circuits.
Also in this case, generally, the largest difference in the ascending speed occurs between the laminate in contact with the hot plate and the above-mentioned second laminate.

The prepreg used in the present invention is obtained by impregnating a base material with a thermosetting resin and semi-curing it. This semi-cured thermosetting resin is easy to handle because it loses its viscosity once it is heated and the resin flows when it is heated, and the resin does not flow when it is heated, because it is semi-cured during lamination. In addition, since it has a certain degree of fluidity during heating and pressurizing and molding, air bubbles are less likely to remain in the recesses between the circuits, and it is generally used. Of the characteristic values representing the fluidity during heating, 1
The minimum viscosity value measured when heated to 30 ° C is 13
Melt viscosity at 0 ° C., which is measured using a flow tester or the like. Further, when the same kind of resin is used, the melt viscosity also represents the degree of curing of the thermosetting resin, and the resin having a small melt viscosity is compared with the resin having a large melt viscosity,
It indicates that the degree of curing is low and the time to cure is long.

The prepreg used in the present invention has a ratio of the melt viscosity of the first prepreg at 130 ° C. to the melt viscosity of the second prepreg at 130 ° C. of 1: 1.2 to 1.5.
As a result, the difference in resin flow between the first prepreg and the second prepreg is reduced, and the variation in plate thickness is reduced. As a method for obtaining prepregs having different melt viscosities,
It can be easily obtained by changing the heating temperature, the heating time, etc. when manufacturing the prepreg.

When the ratio of the melt viscosity of the first prepreg at 130 ° C. to the melt viscosity of the second prepreg at 130 ° C. is less than 1.2, the effect of improving the variation in plate thickness cannot be obtained. If it exceeds 5, the viscosity of the first prepreg becomes too low, which causes a problem of large variation in plate thickness.

When a plurality of prepregs having different melt viscosities are used in one laminate, the average value obtained by multiplying the weight ratio of the plurality of prepregs is taken as the melt viscosity of the laminate.

The resin used for the substrate and prepreg of the present invention may be an epoxy resin type, a phenol resin type, a polyimide resin type, an unsaturated polyester resin type, a polyphenylene ether resin type, etc., such as a single substance, a modified substance or a mixture thereof.
All thermosetting resins can be used. The epoxy resin composition is preferable because of its excellent electrical characteristics and heat resistance.
In the case of an epoxy resin composition, a melt viscosity at 130 ° C. of about 150 to 2000 poise is generally used, but in order to improve the plate thickness and prevent bubbles from remaining in the recesses between circuits, 300-800 poise is preferred. Further, as the substrate to be impregnated with resin, inorganic fibers such as glass and polyester, polyamide, polyacrylic, organic fibers such as polyimide, woven fabric of natural fibers such as cotton,
Nonwoven fabric, paper, etc. can be used. In addition, inorganic fibers such as glass cloth are preferable because they have excellent heat resistance and moisture resistance. A circuit made of metal is formed on both sides or one side of the substrate, and as the metal forming the circuit, copper, aluminum, brass, nickel or the like alone, alloy, composite metal foil and copper, nickel, solder It is possible to use a metal deposited by plating such as.

[0018]

【Example】

Example 1 Tetrabromobisphenol A type epoxy resin having an epoxy equivalent of 500 [manufactured by Dow Chemical Co.,
Product name DER511] 80 parts by weight and epoxy equivalent is 1
20 parts by weight of a phenol novolac type epoxy resin [trade name: Epicoat 154, manufactured by Yuka Shell Epoxy Co., Ltd. 80], 2.5 parts by weight of dicyandiamide, and 0.1 parts by weight of 2-methylimidazole were mixed and mixed. A resin composition was obtained.

Then, the obtained resin composition was impregnated into glass cloth [manufactured by Asahi Schwebel, product number 1550] and dried at 150 ° C. to have a thickness of 0.15 mm, resin content of 45% by weight, and 130 ° C. A prepreg A having a melt viscosity of 420 poises was obtained. Further, the same resin composition was impregnated in the same glass cloth, and then dried at 150 ° C. with the above prepreg A by changing the drying time to obtain a thickness of 0.
A prepreg B having a resin content of 15 mm, a resin content of 45% by weight, and a melt viscosity at 130 ° C. of 600 poise was obtained.

Further, a copper foil (thickness: 35 μm) of a double-sided copper clad laminate (FR-4 type) having an insulating layer thickness of 0.2 mm was etched to obtain a circuit-formed substrate having a residual copper rate of about 50%.

Next, two prepregs A each serving as a first prepreg are laminated on both sides of the obtained substrate, and a copper foil having a thickness of 35 μm is arranged on both outer sides of the prepregs A and laminated to form a laminate Y.
I got In addition, two prepregs B each as a second prepreg were laminated on both sides of the obtained substrate, and a copper foil having a thickness of 35 μm was arranged on both outer sides of the prepreg B to laminate them to obtain a laminate Z. Next, eight laminates Z were laminated with a 1 mm mold interposed therebetween, and a laminate Y was laminated on both outer sides thereof with a 1 mm mold interposed therebetween. Was formed.

The laminated body was sandwiched by a hot plate through a 1 mm mold and kraft paper, and heated and pressurized at a temperature of 170 ° C. for 0.4 minutes for the first 30 minutes and thereafter at 3.9 MPa for 120 minutes, Ten copper clad laminates with inner layer circuits were obtained.
In this case, the ratio of the melt viscosity of the first prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.4.

(Example 2) Drying was performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Ten copper clad laminates with an inner layer circuit were obtained in the same manner as in Example 1 except that prepreg C having a melt viscosity at 130 ° C. of 480 poise was obtained, and prepreg C was used instead of prepreg A. Obtained. In this case, the ratio of the melt viscosity of the first prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C was 1: 1.3.
Becomes

(Example 3) Drying was performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Prepreg D having a melt viscosity of 640 poises at 130 ° C. was obtained, and the prepreg D was dried by changing the drying time to have a thickness of 0.15 mm and a resin content of 45% by weight.
Prepreg E having a melt viscosity of 800 poise at 0 ° C., using prepreg D in place of prepreg A, and prepreg E in place of prepreg B
Ten copper clad laminates with inner layer circuits were obtained in the same manner as in Example 1 except that was used. In this case, the first
The ratio of the melt viscosity of the prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.3.

(Embodiment 4) Drying is performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Prepreg E having a melt viscosity of 800 poises at 130 ° C. was obtained, and the prepreg E was dried by changing the drying time to have a thickness of 0.15 mm and a resin content of 45% by weight.
Prepreg F having a melt viscosity of 560 poise at 0 ° C., using prepreg F in place of prepreg A, and prepreg E in place of prepreg B
Ten copper clad laminates with inner layer circuits were obtained in the same manner as in Example 1 except that was used. In this case, the first
The ratio of the melt viscosity of the prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.4.

(Embodiment 5) Drying is performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Prepreg G having a melt viscosity of 400 poises at 130 ° C. was obtained, and the prepreg G was dried by changing the drying time to have a thickness of 0.15 mm and a resin content of 45% by weight.
Prepreg H having a melt viscosity of 500 poise at 0 ° C., prepreg G used in place of prepreg A, and prepreg H in place of prepreg B
Ten copper clad laminates with inner layer circuits were obtained in the same manner as in Example 1 except that was used. In this case, the first
The ratio of the melt viscosity of the prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.3.

(Example 6) Drying was performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Prepreg I having a melt viscosity of 350 poise at 130 ° C. was obtained, and the prepreg I was dried by changing the drying time to have a thickness of 0.15 mm and a resin content of 45% by weight.
Same as Example 1 except that prepreg H having a melt viscosity at 500 ° C. of 500 poise was obtained, prepreg I was used instead of prepreg A, and prepreg H was used instead of prepreg B. As a result, 10 copper clad laminates with inner layer circuits were obtained. In this case, the ratio of the melt viscosity of the first prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.4.

(Embodiment 7) Drying is performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Prepreg E having a melt viscosity of 800 poises at 130 ° C. was obtained, and the prepreg E was dried by changing the drying time to have a thickness of 0.15 mm and a resin content of 45% by weight.
Prepreg J having a melt viscosity at 1000 ° C. of 1000 poise was obtained, prepreg E was used instead of prepreg A, and prepreg J was used instead of prepreg B.
Ten copper clad laminates with inner layer circuits were obtained in the same manner as in Example 1 except that was used. In this case, the first
The ratio of the melt viscosity of the prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.25.
Becomes

(Embodiment 8) Drying is performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Prepreg K having a melt viscosity of 700 poise at 130 ° C. was obtained, and the prepreg K was dried by changing the drying time to have a thickness of 0.15 mm and a resin content of 45% by weight.
Prepreg J having a melt viscosity at 1000 ° C. of 1000 poise was obtained, prepreg K was used instead of prepreg A, and prepreg J was used instead of prepreg B.
Ten copper clad laminates with inner layer circuits were obtained in the same manner as in Example 1 except that was used. In this case, the first
The ratio of the melt viscosity of the prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.4.

(Comparative Example 1) 10 was carried out in the same manner as in Example 1 except that prepreg A was used for all the prepregs.
A copper clad laminate with an inner layer circuit was obtained. In this case,
The ratio of the melt viscosity of the first prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.

(Comparative Example 2) 10 was carried out in the same manner as in Example 1 except that prepreg B was used for all the prepregs.
A copper clad laminate with an inner layer circuit was obtained. In this case,
The ratio of the melt viscosity of the first prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C is 1: 1.

(Comparative Example 3) Drying was performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Ten inner-layer circuit-containing copper clad laminates were obtained in the same manner as in Example 1 except that prepreg L having a melt viscosity at 130 ° C. of 540 poise was obtained, and prepreg L was used instead of prepreg A. Obtained. In this case, the ratio of the melt viscosity of the first prepreg at 130 ° C and the melt viscosity of the second prepreg at 130 ° C was 1: 1.1.
Becomes

(Comparative Example 4) Drying was performed by changing the drying time,
Thickness is 0.15mm, resin content is 45% by weight,
Ten copper clad laminates with an inner layer circuit were obtained in the same manner as in Example 1 except that prepreg I having a melt viscosity at 130 ° C. of 350 poise was obtained, and prepreg I was used instead of prepreg A. Obtained. In this case, the ratio of the melt viscosity of the first prepreg at 130 ° C. and the melt viscosity of the second prepreg at 130 ° C. is 1: 1.7.
Becomes (Evaluation) The thickness variation and the formability of the copper clad laminates with inner layer circuits obtained in Examples 1 to 8 and Comparative Examples 1 to 4 were evaluated. The variation in plate thickness is obtained by measuring 10 copper clad laminates with inner layer circuits using a micrometer at 6 points each, and averaging the 6 points as the thickness of each copper clad laminate with inner layer circuits. The average of each of the two sheets manufactured at the position in contact with the hot plate and the other eight sheets was obtained, and the difference was defined as the variation in sheet thickness. The formability was evaluated by visually inspecting the presence or absence of air bubbles in the recesses between the circuits by etching the entire 10 copper foils of the outermost layer.

The results are shown in Table 1, and it was confirmed that Examples 1 to 8 were smaller in variation in plate thickness than Comparative Examples 1 to 4 and were good. Further, as for moldability, Example 1 having a melt viscosity at 130 ° C. in the range of 300 to 800 poises
6 were better than those of Examples 7 and 8.

[0035]

[Table 1]

[0036]

According to the method for manufacturing a laminated board with an inner layer circuit of the present invention, in order to reduce the difference in resin flow between the first prepreg and the second prepreg, the method for manufacturing a laminated board with an inner layer circuit according to the present invention The difference in plate thickness between the laminated plate with an inner layer circuit manufactured at a position in contact with the plate and the laminated plate with an inner layer circuit manufactured at a position not in contact with the heating plate becomes small.

According to the method for manufacturing a laminated board with an inner layer circuit according to a third aspect of the present invention, in addition to the above effects, bubbles are less likely to remain in the recesses between the circuits.

Claims (3)

[Claims] 1. A laminated body is formed by laminating a circuit-formed substrate and a prepreg in which a base material is impregnated with a thermosetting resin,
In the method for producing a laminated board with an inner layer circuit, which is produced by stacking three or more of the laminated bodies to form a laminated body, and sandwiching the laminated body between hot plates to heat and pressurize the laminated body, The melt viscosity of the prepreg used for the laminate in contact with the hot plate at 130 ° C., and the prepreg 130 used for the laminate other than the laminate in contact with the hot plate among the laminates in the laminate.
The method for producing a laminated board with an inner layer circuit, characterized in that the ratio of melt viscosities at ° C is 1: 1.2 to 1.5. 2. The method for producing a laminated board with an inner layer circuit according to claim 1, wherein the prepreg is a glass cloth impregnated with an epoxy resin composition. 3. The melt viscosity at 130 ° C. of the prepreg used for the laminate in contact with the hot plate and the prepreg used for laminates other than the laminate in contact with the hot plate is 300 to 800 poises. A method for producing a laminated board with an inner layer circuit according to the description.