JP2581433B2 - Method for manufacturing 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 having a blind via hole suitable for surface mounting.

[0002]

2. Description of the Related Art Recently, a multilayer printed wiring board having a blind via hole 13 having a non-penetrating structure as shown in FIG. Since the blind via holes 13 do 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 also increases. As a method of manufacturing this blind via hole, a method of performing a drilling process from the surface of the laminated multilayer printed wiring board, or a method of performing a non-through hole reaching the multilayer substrate by irradiating a laser beam, and then performing a plating process or the like is used. . Further, for example, Japanese Patent Application Laid-Open No. 2-49
As shown in Japanese Patent No. 494, there is a method 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 as an outer layer material of a multilayer printed wiring board as shown in FIG.
As shown in FIG. 6B, copper plating is performed to obtain electrical continuity between the outer layer surface and the inner layer surface immediately below, thereby forming a copper plating layer 5 (FIG. 6).
(B)). Next, a wiring pattern is formed. In this case, a dry film resist 4 is formed on the outer layer 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 side. The solder resist 15 is exposed and developed into a predetermined pattern using a photomask or the like, and the exposed copper plating layer 5 is removed by etching. Further, by removing the dry film resist 4 on the outer layer surface, an outer layer material 6 in which a lid is formed with a photosensitive solder resist 15 on the inner layer surface side of the through hole 2 as shown in FIG. The outer layer material 6 formed in this manner and the inner layer material 8 having an arbitrary pattern formed by a normal method are laminated via a thermosetting semi-cured resin impregnated glass cloth 7, and the upper and lower portions of a pressing mold 9 are vertically stacked. The multi-layer printed wiring board 11 is obtained by performing a heating and pressing molding process between the hot plates 10 of the laminating press by sandwiching between them (FIG. 7). afterwards,
A through hole 16 of the multilayer printed wiring board 11 is formed 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, a wiring pattern 17 on the outer layer surface is formed by a subtractive method or an additive method, and a multilayer printed wiring board having blind via holes 13 is obtained (FIG. 9).

[0004]

According to the conventional method of manufacturing a multilayer printed wiring board having blind via holes 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 stacked, the adhesion between the layers is reduced, and delamination may occur due to thermal stress or the like at the time of component mounting.

Further, when a through hole is formed in the outer layer material and then copper plating is performed to obtain conduction between the outer layer surface and the inner layer surface immediately below the outer layer material, the conductor thickness of the outermost layer surface is limited to the through hole of the multilayer printed wiring board. Since the copper plating becomes thicker together with the copper plating even after the perforation, there is a problem that it becomes an obstacle when forming fine wires in the outer wiring pattern.

[0006]

Means for providing a through hole in an outer layer material constituting a multilayer printed wiring board, a step of forming a wiring pattern on an inner layer side of the outer layer material, and a step of forming a wiring pattern on the inner layer side of the outer layer material A step of laminating a dry film resist, a step of exposing only the through-hole portion by exposing from the outer layer surface side and developing, and a predetermined inner layer material through a thermosetting semi-cured resin impregnated glass cloth to the outer layer material. A step of performing combined heat and pressure molding, a step of removing the dry film resist left in the through hole on the inner layer side of the outer layer material, a step of forming a through hole in the multilayer printed wiring board, and a step of performing copper plating When,
A method for producing a multilayer printed wiring board, comprising a step of forming an outer layer wiring pattern.

[0007]

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

FIGS. 1 to 5 illustrate steps 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 in an arbitrary position in advance on a copper-clad laminate 1 having a thickness of 0.1 mm as an outer layer material of a multilayer printed wiring board by drilling or the like (FIG. 1 ( a)). Next, an arbitrary wiring pattern 3 is formed only on the side surface serving as the inner layer surface of the outer layer material by a subtractive method or the like (FIG. 1D). After forming the wiring pattern,
A dry film resist 18 is laminated on the inner layer side. As for dry film resist, for example, “MVA” of Asahi Kasei
Series "is used. The roll pressure at the time of lamination is 1.5 to 2 times the normal value of 5.0 to 7.0 kg / cm 2, and the laminating speed is lower than usual and the lamination is performed at 0.5 to 1.0 m / min. 2 (a), the dry film resist 18 is laminated so as to be embedded in the through-hole, and an adhesive force enough to withstand the pressure at the time of lamination can be obtained. 160m
Exposure is performed at j / cm from the outer layer side of the outer layer material to expose the dry film resist 18 on the inner layer side through the through holes 2. At this time, since the scattered light is used, the dry film on the inner layer side is exposed to a diameter of about 0.01 mm wider than the diameter of the through hole 2 of 0.15 mm. Then, Na ₂
By developing with an aqueous solution of 1% CO ₃ (temperature: 30 ° C.) for about 35 seconds, the inner surface of the through hole 2 is covered with a dry film resist 18 as shown in FIG. An outer layer material 6 is obtained. The outer layer material 6 formed in this way and the 0.15 mm thick inner layer material 8 having an arbitrary pattern formed thereon are combined with a 0.1 mm thick prepreg as shown in FIG. Lamination is performed via several glass sheets impregnated with the cured resin. Furthermore, as shown in FIG. 3 (a), it is sandwiched between the upper and lower sides of a pressing die 9, and a temperature of 150 to 300 ° C. and a pressure of 10 to 40 kgf / cm between hot plates 10 of the laminating press.
To perform multi-layer printed wiring board 1
1 is obtained.

After integrally forming the multilayer printed wiring board 11, 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 side of the outer layer material is removed by plasma treatment, and conduction between the outermost layer of the multilayer printed wiring board, and the outermost layer and the inner layer immediately below the outermost layer. 20μ to get
A copper plating layer 12 of about m is formed (FIG. 5A). Thereafter, a wiring pattern 17 on the outermost layer 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 side of the outer layer material is formed, the dry film resist is laminated again, and then the dry film resist is arbitrarily applied to the portion of the 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, lids can be formed in all the through holes without using a mask film.

Furthermore, by performing copper plating after drilling the through-holes of the multilayer printed wiring board, copper plating is simultaneously performed in the through-holes of the outer layer material, so that the number of times of plating can be minimized. As a result, the thickness of the outermost copper plating is suppressed, and a thin wiring pattern can be formed.

[Brief description of the drawings]

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copper-clad laminated board 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 Die for press 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

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Seiichi Inoue 5-7-1 Shiba, Minato-ku, Tokyo Within NEC Corporation (56) References JP-A-2-54994 (JP, A) JP-A-1 -143293 (JP, A) JP-A-51-45767 (JP, A)

Claims (2)

(57) [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 an inner layer surface side of the outer layer material, and a step of forming a dry film resist on the inner layer surface side of the outer layer material. Laminating, exposing only the portion of the through-hole exposed from the outer layer surface side, developing and exposing, combining the outer layer material with a predetermined inner layer material via a prepreg, heating and pressing, and forming the outer layer material. 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 performing conductive layer plating, and a step of forming a wiring pattern of the outer layer 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.