JPH07202434A - Production of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To form a blind via hole in which the plating thickness of outer layer is minimized while preventing layer exfoliation. CONSTITUTION:A through hole 2 is made previously through the outer layer material, i.e., a copper clad laminate 1, of a multilayer printed wiring board and a wiring pattern 3 is formed on the inner layer surface side. A dry film resist 18 is laminated on the inner layer surface of the outer layer material and exposed with scattering light from the outer layer surface side thus exposing the dry film resist 18 only at the through hole 2 part. It is then developed and an inner layer material 8, previously applied with an arbitrary wiring pattern, is laminated on the outer layer material 6 through a glass cloth 7 impregnated with a thermosetting semicured resin before hot press. The through hole of the multilayer printed wiring board is then processed and plasma processing is effected in order to remove the dry film resist 18 left on the inner layer face side of the outer layer material 6 before a copper plating layer is applied. Finally, a wiring pattern is formed on the surface of outermost layer thus producing a multilayer printed wiring board having a blind via hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a multilayer printed wiring board having a blind via hole suitable for surface mounting.

[0002]

2. Description of the Related Art Recently, with the further increase in the density of multilayer printed wiring boards, a multilayer printed wiring board having a blind via hole 13 having a non-penetrating structure as shown in FIG. 9 has been put into practical use. Since the blind via hole 13 does not penetrate the wiring surface of the inner layer of the multilayer printed wiring board, the degree of freedom of wiring accommodated in the inner layer is large and the number of wirings is also increased. As a method for manufacturing this blind via hole, there is used a method in which a drilling process is performed from the surface of the laminated multilayer printed wiring board or a non-through hole reaching the multilayer substrate by laser light irradiation is performed, and then a plating treatment is performed. . Further, for example, Japanese Patent Laid-Open No. 2-49
As shown in Japanese Patent No. 494, there is also a method of using an outer layer plate having a through hole formed therein.

That is, first, a through hole 2 is formed by drilling or the like at an arbitrary position of a copper clad laminate 1 which is an outer layer material of a multilayer printed wiring board as shown in FIG.
As shown in (b), copper plating is performed to obtain electrical continuity between the outer layer surface and the inner layer surface immediately below, to form a copper plating layer 5 (FIG. 6).
(B)). Next, a wiring pattern is formed. In this case, the dry film resist 4 is formed on the outer layer surface side of the outer layer material.
And a photosensitive solder resist 15, which is a permanent resist of a photocurable resin, is laminated on the inner layer surface side. The solder resist 15 is exposed and developed into a predetermined pattern with a photomask or the like, and the exposed copper plating layer 5 is removed by etching. Further, the dry film resist 4 on the outer layer surface is peeled off to obtain the outer layer material 6 in a form in which the inner layer surface side of the through hole 2 is covered with the photosensitive solder resist 15 as shown in FIG. 6 (e). The outer layer material 6 thus formed and the inner layer material 8 in which an arbitrary pattern is formed by a normal method are laminated with the thermosetting semi-curable resin-impregnated glass cloth 7 interposed therebetween, and the pressing die 9 is placed above and below. A multilayer printed wiring board 11 is obtained by sandwiching them and performing heat-pressure molding between the hot plates 10 of the laminating press (FIG. 7). afterwards,
Through holes 16 are formed in the multilayer printed wiring board 11 by drilling or the like (FIG. 8A), and copper plating is performed to obtain conduction between the outermost layers to form a copper plating layer 12 (FIG. 8B). .
Further, the wiring pattern 17 on the outer layer surface is formed by the subtractive method or the additive method to obtain a multilayer printed wiring board having the blind via holes 13 (FIG. 9).

[0004]

According to the conventional method for manufacturing a multilayer printed wiring board having a blind via hole as described above, the photosensitive solder resist is left on the entire wiring pattern on the inner layer side of the outer layer material. Since the layers are laminated, the adhesion between the layers is reduced, and there is a risk of delamination due to thermal stress during component mounting.

Further, when the outer layer material is provided with through holes and then copper plating is performed to obtain conduction between the outer layer surface and the inner layer surface immediately below the outer layer surface, the conductor thickness of the outermost layer surface is the through hole of the multilayer printed wiring board. Since the copper plating is thick even after the perforation, the thickness of the copper plating increases, which causes a problem in forming a thin wire in the outer layer wiring pattern.

[0006]

Means for Solving the Problems A step of forming through holes in an outer layer material constituting a multilayer printed wiring board in advance, a step of forming a wiring pattern on the inner layer surface side of the outer layer material, and an inner layer surface side of the outer layer material. A step of laminating a dry film resist on the outer layer surface, a step of exposing and exposing only the through-hole portion from the outer layer surface side, and a step of exposing the outer layer material to a predetermined inner layer material via a thermosetting semi-curable resin impregnated glass cloth. Combined heating and pressure molding process, removing the dry film resist left in the through hole portion on the inner layer surface side of the outer layer material, forming a through hole in the multilayer printed wiring board, and performing copper plating When,
A method of manufacturing a multilayer printed wiring board, comprising a step of forming an outer layer wiring pattern.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings.

1 to 5 illustrate each step of a method for manufacturing a multilayer printed wiring board according to an embodiment of the present invention.

First, a through hole 2 having a diameter of 0.15 mm is formed at an arbitrary position in advance by drilling or the like in a copper clad laminate 1 having a plate thickness of 0.1 mm which is an outer layer material of a multilayer printed wiring board (see FIG. 1 ( a)). Next, an arbitrary wiring pattern 3 is formed by a subtractive method or the like only on the side surface to be the inner layer surface of the outer layer material (FIG. 1D). After forming the wiring pattern,
A dry film resist 18 is laminated on the inner layer surface side. The dry film resist is, for example, "MVA of Asahi Kasei"
A series "is used. The laminating pressure is 5.0 to 7.0 kg / cm2, which is 1.5 to 2 times the normal pressure, and the laminating speed is 0.5 to 1.0 m / min. As a result, the dry film resist 18 is laminated so as to be embedded in the through holes as shown in Fig. 2 (a), and an adhesive force sufficient to withstand the pressure during lamination can be obtained. 160 m
The outer layer surface side of the outer layer material is exposed at j / cm, and the dry film resist 18 on the inner layer surface side is exposed through the through holes 2. At this time, since the scattered light is used, the dry film on the inner layer side is exposed wider by about 0.01 mm in diameter than the diameter of the through hole 2 of 0.15 mm. Then Na ₂
By developing with an aqueous solution of CO ₃ 1% (temperature: 30 ° C.) for about 35 seconds, as shown in FIG. 2 (b), the inner surface of the through hole 2 is covered with a dry film resist 18. The outer layer material 6 is obtained. The outer layer material 6 thus formed and the inner layer material 8 having a thickness of 0.15 mm and having an arbitrary pattern formed thereon are combined with a prepreg having a thickness of 0.1 mm as shown in FIG. The cured resin-impregnated glass cloths are laminated on each other by several sheets. Further, as shown in FIG. 3 (a), it is sandwiched between the upper and lower sides of a pressing die 9, and the temperature is 150 to 300 ° C. and the pressure is 10 to 40 kgf / cm between the hot plates 10 of the laminating press.
Multilayer printed wiring board 1
1 is obtained.

After the multilayer printed wiring board 11 is integrally formed, a through hole 16 having a diameter of 0.3 mm is formed by drilling or the like (FIG. 3B). Further, as shown in FIG. 4, the dry film resist 18 applied to the inner layer surface side of the outer layer material by plasma treatment is removed, and conduction is established between the outermost layer of the multilayer printed wiring board and the outermost layer and the inner layer immediately below. 20μ to get
A copper plating layer 12 of about m is formed (FIG. 5A). After that, the wiring pattern 17 on the outermost layer surface is formed by a subtractive method, an additive method, or the like (FIG. 5B).

[0011]

As described above, according to the present invention, the wiring pattern on the inner layer surface side of the outer layer material is formed, the dry film resist is laminated again, and then the dry film resist is applied to the portion of any through hole. By forming only the layer, it is possible to prevent delamination due to a decrease in adhesion between layers. Further, according to the present invention, by exposing the dry film resist laminated on the inner layer side through the through holes from the outer layer side, the lids can be formed on all the through holes without using a mask film.

Further, since copper is plated in the through holes of the outer layer material by performing copper plating after drilling the through holes of the multilayer printed wiring board, the number of times of plating can be minimized. As a result, the copper plating thickness of the outermost layer is suppressed, and a fine wiring pattern can be formed.

[Brief description of drawings]

1 to 5 are sectional views showing the manufacturing steps in order of manufacturing steps for explaining a manufacturing method according to an embodiment of the present invention.

6 to 9 are cross-sectional views showing in order of manufacturing steps for explaining a conventional method for manufacturing a printed wiring board.

[Explanation of symbols]

 1 Copper Clad Laminate 2 Through Hole 3 Wiring Pattern 4 Dry Film Resist 5 Copper Plating Layer 6 Outer Layer Material 7 Thermosetting Semi-Cured Resin Impregnated Glass Cloth 8 Inner Layer Material 9 Press Mold 10 Hot Plate 11 Multilayer Printed Wiring Board 12 Copper Plating layer 13 Blind via hole 14 Through hole 15 Photocurable solder resist 16 Through hole 17 Wiring pattern 18 Dry film resist

Front page continuation (72) Inventor Seiichi Inoue 5-7-1 Shiba, Minato-ku, Tokyo NEC Corporation

Claims (2)

[Claims] 1. A step of forming through holes in an outer layer material constituting a multilayer printed wiring board in advance, a step of forming a wiring pattern on the inner layer surface side of the outer layer material, and a dry film resist on the inner layer surface side of the outer layer material. Of the outer layer surface, a step of exposing and developing only the portion of the through hole exposed from the outer layer surface side, a step of heating and pressurizing the outer layer material in combination with a predetermined inner layer material via a prepreg, A step of removing the dry film resist left in the through hole portion on the inner layer surface side, a step of forming a through hole in the laminated member, a step of conducting conductive layer plating, and a step of forming an outer layer wiring pattern. A method for manufacturing a multilayer printed wiring board, comprising: 2. The method for producing a multilayer printed wiring board according to claim 1, wherein the prepreg is a thermosetting semi-cured resin-impregnated glass cloth.