JP2000091749A - Multilayer wiring board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent interlaminar blistering halfway through travel to the substrate surface-layer part and wiring board surface-layer part of a multilayer wiring board by providing a non-through hole for discharging gases being accumulated inside the wiring board toward the outside of the wiring board. SOLUTION: A glass epoxy copper-clad laminate with a catalyst is used for a glass epoxy copper-clad laminate 1 and an inner-layer circuit conductor 2 where an empty hole 9 is provided at a circuit conductor part at a part with a large inner-layer conductor area. Then, an insulation layer 3 is formed at the inner-layer circuit conductor 2. After that, a dot-shaped empty hole part for laser punching being provided at the circuit conductor part in a part with a large inner-layer conductor area and a part with a large inner-layer conductor area is punched by a laser to form a non-through hole 7 reaching the inner-layer circuit conductor 2 or feeding through the inner-layer circuit conductor 2 with the carbon dioxide gas laser. In this case, the outer-layer surface end face of the non-through hole 7 needs not always be in contact with the outer-layer circuit conductor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer wiring board and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a multilayer wiring board, gas, water vapor, and the like accumulated in the wiring board are cured by resist ink curing or by heating the wiring board such as soldering and reflow soldering. It moves to the surface layer of the wiring board, and is discharged to the outside of the wiring board from a portion having no circuit conductor. In particular, if there is a place where the conductor area of the inner layer circuit conductor and the outer layer circuit conductor is large, and they overlap vertically via the insulating layer,
The gas, water vapor, and the like accumulated in the inside of the wiring board have no discharge port, and therefore expand at the interface between the inner layer circuit conductor and the insulating layer, which is inside the wiring board, and cause interlayer swelling.

Conventionally, as described above, the gas generated in the heat treatment step of the multilayer wiring board is formed by removing a 0.5 to 2.0 mm diameter in the circuit conductor portion where the conductor area of the inner layer circuit conductor and the outer layer circuit conductor is large. The gas is vented from this hole as a non-conductive portion by providing a dot-shaped hole.

[0004]

The gas, water vapor and the like accumulated inside the wiring of the multilayer wiring board move to the surface layer of the base material and the surface layer of the wiring board by heat treatment, but the metal conductor area is large. Gas and water vapor cannot be completely discharged to the outside of the wiring board only by the non-conductor part which is a hole provided in the place, and the multi-layer wiring board moves to the surface layer of the base material and the wiring board. Interlayer blisters may occur on the way.

[0005]

In the present invention, in order to solve the above-mentioned problem, that is, gas accumulated in the wiring of the multilayer wiring board is discharged to the outside of the wiring board to prevent blister between layers. Therefore, in the circuit conductor portion where the conductor area of the inner layer circuit conductor or the outer layer circuit conductor is large, the inner layer circuit conductor may reach from the outside of the multilayer wiring board or penetrate the inner layer circuit conductor, that is, inside the wiring board. A non-through hole for discharging the stored gases to the outside of the wiring board is provided. The above-mentioned non-penetrating hole is a non-penetrating hole in which a metal conductor is not formed on the hole wall surface by electroless plating, electroplating or the like, and the base material and the insulating layer on the hole wall surface are exposed.

A non-through hole extending from the outside of the multilayer wiring board to the inner layer circuit conductor or a non-through hole penetrating the inner layer circuit conductor transfers gas accumulated inside the wiring board to the surface layer of the wiring board. Even if the hole has the same diameter as the conventional dot-shaped hole, the hole surface area is large without moving gradually, and the gas reaches or penetrates the inner layer circuit conductor inside the wiring board, so that gas can be easily vented. A multilayer wiring board characterized in that a non-through hole in which a base material or an insulating layer is exposed on a wall surface of a non-through hole is provided in a circuit conductor portion where an area of an inner layer circuit conductor or an outer layer circuit conductor is large. .

In a method for manufacturing a multilayer wiring board, a step of forming an inner layer circuit conductor, a step of forming an insulating layer and an adhesive layer on the inner layer circuit conductor, and a step of forming an outer layer circuit conductor on the adhesive layer And forming a non-through hole exposing a base material and an insulating layer on a hole wall surface for discharging gas accumulated inside the wiring board not intended for electrical conduction to the outside of the wiring board. And a method for manufacturing a multilayer wiring board.

[0008]

FIG. 4 shows a comparative example 2 of a four-layered wiring board having a structure in which interlayer blistering is most likely to occur in a four-layer wiring board for a comparative experiment on the occurrence of interlayer blistering in a multilayer wiring board. FIG. 3 is a cross-sectional view of the layer wiring board, and FIG.
FIG. 1 is a cross-sectional view of a four-layer wiring board in which dot-shaped holes according to the prior art are provided in a four-layer wiring board. FIG. FIG. 2 is a cross-sectional view showing a process in which a non-through hole is provided for discharge to the outside of the board. FIG. 2 is a cross-sectional view of a six-layer wiring board according to the present invention.

First, a description will be given with reference to FIG. Glass /
The four-layer wiring board in which the inner layer circuit conductor 2, the insulating layer 3, and the outer layer circuit conductor 5 in which both surfaces of the epoxy copper-clad laminate 1 are all copper foil, and the entire outer layer circuit conductor 5 is also copper foil is Comparative Example 2. It is a multilayer wiring board.

Next, as a comparative example 1, as shown in FIG.
According to the prior art, a four-layer wiring board is prepared in which a dot-shaped hole 9 having a diameter of 1.0 mm is provided in the inner layer circuit conductor 2 having a large conductor area and a dot-shaped hole 9 having a diameter of 1.0 mm in the outer layer circuit conductor 5. .

A four-layer wiring board according to the present invention will be described with reference to FIG. As shown in FIG.
As the epoxy copper-clad laminate 1, a glass-epoxy copper-clad laminate containing a catalyst (trade name of Hitachi Chemical Co., Ltd .: M
Using CL-E168), the inner layer circuit conductor 2 having a dot-shaped hole 9 having a diameter of 1.0 mm in the circuit conductor portion having a large inner layer conductor area as shown in FIG. Form.

Next, as shown in FIG. 1 (c), the inner layer circuit conductor 2 is subjected to an oxidation-reduction treatment and a primer treatment, and then is screen-printed, curtain-coated, dipped or the like to a thickness of about 5 mm.
An insulating layer 3 of 0 μm is formed. This time, after applying and drying an insulating ink of HR-3, a trade name of Hitachi Chemical Polymer Co., Ltd. by a screen printing method, applying an epoxy resin-based adhesive layer 4 to a trade name of HA-21, a trade name of Hitachi Chemical Polymer Co., Ltd.
After being formed by FC, a dry film for plating resist (trade name of Hitachi Chemical Co., Ltd .: S
R-3000), a plating resist is formed by a photographic method, and then electroless copper plating is performed to form a predetermined outer layer circuit conductor 5 having 9 dot-shaped holes for laser drilling. I do.

Next, as shown in FIG. 1 (d), a dot-shaped hole for laser drilling provided in a circuit conductor at a location where the outer conductor area is large or a location where the inner conductor area is large is carbonated. A non-through hole 7 that reaches or penetrates the inner layer circuit conductor 2 with a gas laser (trade name: LAVIA-600 of Sumitomo Heavy Industries, Ltd.)
Is perforated with a laser. The non-through hole 7 for venting gas inside the wiring board is formed with a metal conductor by metal plating or the like on the wall surface of the non-through hole 7 in order to efficiently release gas, water vapor, etc. to the outside of the multilayer wiring board 10. Better not.
Further, the tip of the non-through hole 7 according to the present invention is not necessarily at the end of the inner layer circuit conductor 2 but at the substantially middle portion of the insulating layer 3 or the glass or the like.
The base material may be a substantially intermediate portion of the base material portion of the epoxy copper-clad laminate 1 or a non-through hole 7 </ b> A that stops at the insulating layer.

The multilayer wiring board 10 according to the present invention comprises an inner circuit conductor 2
Is a subtractive method, and the outer layer circuit conductors 5 are patterned by a build-up method and an additive method.
A method for manufacturing a multilayer wiring board 10, characterized in that a non-penetrating non-penetrating hole 7 having no metal conductor is formed on the wall surface of a hole by a carbon dioxide gas laser after forming an outer layer circuit conductor 5. Further, the outer layer surface end face of the non-through hole 7 does not necessarily need to be in contact with the outer layer circuit conductor 5. When degassing is performed when there is a portion where the conductor area of the inner layer circuit conductor 2 is large and there is no portion where the conductor area is large in the outer layer circuit conductor 5, the end surface of the outer layer surface of the non-through hole 7 is connected to the outer layer circuit conductor 5. It is good to make settings that do not touch the FIG. 1H is a plan view showing the upper surface of the multilayer wiring board 10, in which the outer circuit conductor 5 is in contact with the outer periphery of the non-through hole 7.
There is a non-through hole 7 not in contact with the outer layer circuit conductor 5.

A six-layer wiring board according to the present invention will be described with reference to FIG. First inner layer circuit conductors 2a are formed on both surfaces of the glass / epoxy copper clad laminate 1 in a predetermined pattern by etching, and then the insulating layer 3 and the adhesive layer 4 are formed on the upper surface. Next, first predetermined electroless copper plating is performed to form a predetermined second inner layer circuit conductor 2b by an additive method. An insulating layer 3 and an adhesive layer 4 are formed on the upper surface of the second inner layer circuit conductor 2b. Next, a second outer electroless copper plating is performed to form a predetermined outer layer circuit conductor 5 by an additive method. The multilayer wiring board 10 is not used for electrical conduction by a carbon dioxide gas laser after the outer circuit conductor 5 is formed, that is, the multilayer wiring board 10 in which a non-through hole 7 for removing gas, water vapor and the like inside the wiring board is formed.

The four-layer wiring board according to the prior art of Comparative Example 1 (FIG. 3) manufactured according to the above-described contents, the four-layer wiring board in which interlayer blistering is most likely to occur in Comparative Example 2 (FIG. 4), and the wiring board according to the present invention. Table 1 shows the results of evaluating the gas release properties inside the wiring board for three types of four-layer wiring boards (FIG. 1) having a non-through hole for venting gas inside. (Evaluation method) Each multilayer wiring board is made into a 25 mm x 25 mm square test piece and floated in a 260 ° C solder bath for 5 minutes. n = 50 each.

[Table 1]

[0017]

As is clear from the comparison of the gas release properties inside the wiring board of the multilayer wiring board, the non-through hole for gas release inside the wiring board of the present invention is the same as the conventional circuit having a large conductor area. The gas venting efficiency is much better than that of a multilayer wiring board in which dot-shaped holes are provided in a conductor portion. Therefore, high quality reliability can be ensured even for a multilayer wiring board subjected to a high-temperature heat treatment.

[Brief description of the drawings]

FIG. 1 is a process sectional view and a plan view of a multilayer wiring board according to the present invention.

FIG. 2 is a sectional view of a six-layer wiring board according to the present invention.

FIG. 3 is a cross-sectional view of a conventional four-layer wiring board.

FIG. 4 is a cross-sectional view of a four-layer wiring board in which interlayer swelling is likely to occur.

[Explanation of Signs] 1: Glass-epoxy copper-clad laminate 2: Inner layer circuit conductor
DESCRIPTION OF SYMBOLS 3 ... Insulating layer 4 ... Adhesive layer 5 ... Outer layer circuit conductor 7 ... Non-through hole 9 ... Empty hole 10 ... Multilayer wiring board. Reference number P2470

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Aoki 1065 Kushita, Ninomiya-cho, Haga-gun, Tochigi Prefecture Inside Hitachi AIC Co., Ltd. F term in reference (reference) 5E338 AA03 BB19 BB28 EE31 5E346 AA43 CC32 CC41 DD23 DD33 DD45 GG15

Claims (3)

[Claims] 1. A multilayer wiring board having a non-through hole for discharging gases accumulated inside the wiring board to the outside of the wiring board. 2. The multilayer wiring board according to claim 1, wherein a non-through hole in which a base material or an insulating layer of a hole wall surface is exposed is provided in a portion of the wiring board where a circuit conductor has a large area. 3. A method for manufacturing a multilayer wiring board, comprising: forming an inner circuit conductor; forming an insulating layer and an adhesive layer on the inner circuit conductor; and forming an outer circuit conductor on the adhesive layer. And a step of forming a non-through hole for discharging gas accumulated inside the wiring board to the outside of the wiring board.