JPH10335825A - Multilayered wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute drilling with a prescribed condition by electrically connecting more than three conductor layers, without matching the relative positions of the adjacent conductor layers of a through-hole and/or via holes. SOLUTION: A wiring board constituted of a through-hole 1 and the circuit of a conductor layer 2 is generated in an insulating resin layer 1 and resin body with a copper foil 3 is stacked. Copper plating is executed on the surface of copper foil 5a and the inner wall side of the holes, and via holes 12 and 16 which electrically connect the conductor layers 5 and 2 are formed. A graphitization is executed on the surface of the copper foil of a conductor layer 6, holes are formed in positions which do not match with the positions of the via holes 12 and 16 formed by the irradiation with a laser, via holes 13 and 17 which electrically connect the conductor layers 6 and 5 are formed and a circuit pattern is formed. In a multilayered wiring board which is thus generated, drilling work is easy and the reliability of electrical connections is also high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the formation of through holes, via holes and the like in a multilayer wiring board.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of electronic equipment, the conductor width, conductor gap, through hole, via hole and the like of a multilayer wiring board have been developed in order to reduce the size, density, and weight of a copper-clad multilayer wiring board. Miniaturization and small diameter are required. Of these requirements, the through hole and the via hole are processed and formed from the surface of the multilayer wiring board on which the through hole is laminated.

[0003] For example, a through hole is drilled from the surface of a laminated multilayer wiring board by a drill, and a hole is partially drilled by a drill. For example, through holes and non-through holes are formed by laser from the surface of the laminated multilayer wiring board.

[0004]

However, the conventional method for forming a hole in a multilayer wiring board as described above has a problem in the manufacturing process. In the method using a drill, there are problems such as a very large hole diameter, and a very difficult drilling process for completing the drilling in the thickness direction of a multilayer wiring board having a thin insulating layer. In the method using a laser, it is very difficult to control the processing conditions of the laser in the drilling process for different layers of the material to be drilled for the laminated conductor layer and the insulating resin layer, and for the inner conductor layer and the interior insulating resin layer. There's a problem. It is an object of the present invention to solve the difficulties of these drilling steps.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a multilayer wiring board comprising three or more conductive layers having through holes and via holes for connecting conductive layers, and a method of manufacturing the same. The via holes and / or the through holes connecting the conductive layers B and / or the via holes are adjacent to each other in the conductive layer A and the conductive layer B, and the relative positions of the conductive layers A and B are not the same, and electrical connection is made between three or more conductive layers; An object of the present invention is to provide a multi-layer wiring board which can be easily formed by only repeating a step of forming a hole in an outermost conductor layer and an insulating resin layer and can be formed under certain conditions, and a method of manufacturing the same.

Hereinafter, a multilayer wiring board and a method of manufacturing the same according to the present invention will be described in detail. FIG. 1 is a cross-sectional view illustrating a multilayer wiring board and a method for manufacturing the same according to an embodiment of the present invention. FIG. 1A is a cross-sectional view of a wiring board in which a through hole is formed. FIG. 1B is a cross-sectional view showing a process of laminating an insulating resin layer and a conductor layer on a wiring board. FIG.
(C) is a sectional view in which via holes are formed in the insulating resin layer and the conductor layer laminated in (b). FIG. 1 (d) is (c)
FIG. 4 is a cross-sectional view in which an insulating resin layer and a conductor layer are laminated on each other, and a via hole is further formed.

As shown in FIG. 1, a multilayer wiring board and a method of manufacturing the same according to the present invention perform perforation as required on a wiring board serving as a core board, and employ a known method such as a subtractive method or an additive method. A wiring pattern is formed by a method, an insulating resin layer and a conductor layer are laminated on one or both surfaces of the wiring board by a method known per se, and a through hole and / or a via hole of the wiring board are formed on the conductor layer and the insulating resin layer. Hole is formed by using a laser at a position that does not coincide with the position (without drilling a conductor layer of a wiring board located below the insulating resin layer), and an electroless plating method is applied to the hole. Then, a via hole for electrically connecting the conductive layers is formed by an electrolytic plating method, and a wiring pattern is formed by an etching method to form a multilayer wiring board. Furthermore,
If necessary, an insulating resin layer and a conductor layer are laminated, a hole is formed by laser at a position that does not coincide with an adjacent through hole and / or via hole, an electric connection is made, a wiring pattern is formed, and a multilayer wiring having a larger number of layers is formed. A substrate can be created. The positions of the through holes and / or via holes formed in the non-adjacent delamination layers may or may not match.

The conductor layer in the multilayer wiring board and the method of manufacturing the same according to the present invention is not particularly limited, but is preferably a metal foil such as copper, stainless steel, nichrome, tungsten and aluminum. More preferably, it is a metal foil of copper or stainless steel. Particularly preferred are a rolled copper foil and an electrolytic copper foil, and the electrolytic copper foil is more excellent in adhesion and adhesion to an insulating resin. The thickness of the metal foil is not particularly limited, but is preferably 0.5 to 50 μm. More preferably, it is 1 to 40 μm. Particularly preferably, 3 to 20 μm
It is. The metal foil having such a thickness is flexible and easily laser-processed and etched.

The insulating resin layer in the multilayer wiring board and the method of manufacturing the same according to the present invention is not particularly limited, but is preferably at least one of epoxy, polyimide, polyester, phenol, polyphenylene ether, polyphenylene oxide, bismaleimide triazine and the like. Resins mainly composed of one type. The insulating resin layer may be an insulating resin obtained by impregnating a nonwoven fabric such as glass, aramid, paper, porous polytetrafluoroethylene, or quartz, or a woven fabric with a resin. The insulating resin layer may be filled with an organic or inorganic filler such as resin beads, alumina powder, titanium oxide powder, and calcium carbonate powder.

[0010] In the multilayer wiring board and the method of manufacturing the same according to the present invention, the formation of holes in the laminated conductor layer and insulating resin layer does not coincide with the position of the through hole and / or via hole formed in the lower layer between adjacent layers. Is formed by melting, vaporizing, decomposing, etc. by laser.

Although the shape and dimensions of the land to be formed are not particularly limited, it is necessary that the land in the lower layer has at least holes formed in the upper layer. Preferably, at least the land width of the layer to be connected is equal to or larger than the hole diameter, and
Circular, elliptical, square, rhombic, and tiers whose dimensions are less than or equal to the sum of the hole diameters of the lower and upper layers and less than or equal to the sum of the hole diameters plus 2.0 mm. Drop, other deformation, etc. More preferably, the length of the land is 0.05 m in the sum of the hole diameters of the lower layer and the upper layer.
The above-mentioned shape or the like having a size equal to or larger than m and equal to or smaller than a size obtained by adding 2.0 mm to the sum of the hole diameters. Particularly preferably, the land width of the layer to be connected is equal to or larger than the hole diameter and equal to or smaller than 0.6 mm plus the hole diameter, and the length of the land is equal to or larger than the sum of the hole diameters of the lower layer and the upper layer plus 0.05 mm. The above-mentioned shape or the like having a size equal to or less than a size obtained by adding 1.0 mm to the sum of the hole diameters.

The surface treatment of the conductor layer to be perforated by a laser is not particularly limited, or the surface of the conductor layer may be subjected to a treatment having a high absorption rate of laser energy, or the conductor layer may be preliminarily perforated. Is preferred. Particularly preferably, the surface of the conductor is subjected to a treatment having a high laser energy absorption rate. Treatments with high laser energy absorption include nickel oxide, copper oxide, iron oxide,
Examples of such treatment include a treatment with a metal oxide whose main component is a dye, such as Congo Red and methyl violet, and a treatment with a pigment such as carbon.

As the type of laser, a carbon dioxide laser,
An Xe laser, an excimer laser, a YAG laser, an Ar laser, an ultraviolet laser and the like can be exemplified. Laser energy can be changed by the conductor layer and the insulating resin layer.

The multilayer wiring board and the method of manufacturing the same according to the present invention, which are manufactured as described above, use a laser to form a through hole and / or a via hole at a position that does not coincide with the position of a through hole and / or a via hole in an adjacent lower layer. The drilling process can be performed under the same conditions, and the reliability of the electrical connection is high.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a multilayer wiring board and a method of manufacturing the same according to the present invention will be described below. The multilayer wiring board and the method of manufacturing the same according to the present invention are not limited to the following embodiments.

(Embodiment 1) First, a through hole 11 is formed in a copper-clad double-sided board in which an 18 μm-thick copper foil 2a is laminated on both sides of an epoxy resin 1, and plated copper is formed on the copper foil surface and the inner wall surface of the through hole. 2b was deposited, and a circuit pattern was formed by a photo-etching method to prepare a wiring board including the circuit of the through hole 11 and the conductor layer 2 in the insulating resin layer 1 (epoxy resin 1). Thereafter, the wiring substrate was subjected to a blackening process to form a copper oxide layer, and then subjected to a process of chemically reducing the copper oxide layer to metallic copper. FIG. 1 (a)

Next, a resin body 3 with a copper foil (about 12 μm thick with an insulating resin layer 4 (epoxy resin) of about 50 μm attached)
m copper foil 5a) was placed and aligned on the wiring substrate (FIG. 1B) and laminated (pressure 25 kg, temperature 180).
Degree, 120 minutes).

Next, a circular blackening process smaller than the laser irradiation diameter by 20 μm was formed on the surface of the copper foil 5a at the positions where the holes for the via holes 12 and the via holes 16 did not coincide with the through holes 11.

Next, the multilayer wiring board is positioned and set on the processing table of the carbon dioxide laser apparatus, and the laser (pulse width 2) is set.
Irradiation (5 μs, frequency 100 Hz) was performed to form holes 12 and 16 of 0.1 mm in the copper foil 5 a and the insulating resin layer 4. The holes 12 and the holes 16 thus formed reached the conductor layer 2, and the surface of the exposed conductor layer 2 was glossy.

Next, the inside of the holes 12 and 16 is smeared by the potassium permanganate method, and the surface of the copper foil 5a and the inner wall surfaces of the holes 12 and 16 are plated with copper. Via holes 12 and 16 were formed by electrically connecting the conductor layer 5 and the conductor layer 2, and a circuit pattern was formed by a photoetching method.
(Fig. 1 (c))

Next, after the surface of the conductor layer 5 was subjected to a blackening treatment to form a copper oxide layer, the copper oxide layer was subjected to a chemical reduction treatment to metallic copper, and a resin body with a copper foil was further laminated.

Next, the entire surface of the copper foil of the conductive layer 6 was subjected to blackening treatment, and 0.1 mm holes 13 and 17 were formed at positions not coincident with the positions of the via holes 12 and 16 by laser irradiation. . (The distance between the centers of the holes 12 and 13 and the holes 16 and 17 was 0.3 mm.) Then, the inside of the holes was subjected to a smearing treatment and subjected to copper plating to electrically connect the conductor layers 6 and 5 to each other. Via holes 13 and 17 were formed, and a circuit pattern was formed by a photoetching method. (Fig. 1 (d))

Next, a resist for protecting the wiring conductor on the surface was printed, dried, and cured except for the soldered area, to produce a multilayer wiring board.

The multilayer wiring board thus manufactured is
Drilling is easy and the reliability of electrical connection is high only by forming via holes under the same conditions. Hole 11, hole 1
2. Since holes are formed in zigzag like holes 13, the area occupied by through holes and / or via holes is small and the wiring density is high.

[0025]

In the multilayer wiring board and the method of manufacturing the same according to the present invention, the outermost conductor layer and the insulating resin layer in the manufacturing process of each layer are perforated, control is easy, and the through hole, It is possible to provide a multilayer wiring board which eliminates the difficulty of a processing step of forming a via hole and has a high wiring density and a method of manufacturing the same.

[0026]

[Brief description of the drawings]

1 (a) to 1 (d) are cross-sectional views showing steps of an embodiment of a multilayer wiring board and a method of manufacturing the same according to the present invention.

[0027]

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating resin layer 1 2 conductor layer 2 2a copper foil 2a 2b plated copper 2b 3 resin body with copper foil 4 insulating resin layer 4 5 conductor layer 5 5a copper foil 5a 6 conductor layer 6 11 through hole 11 12 via hole 12 13 via hole 13 16 Via hole 16 17 Via hole 17 A Conductor layer A B Conductor layer B

Claims (1)

[Claims] 1. A multilayer wiring board comprising three or more conductor layers having through holes and via holes connecting between conductor layers and a method of manufacturing the same, wherein the through holes and / or via holes connecting the conductor layers A and the conductor layers B are connected. A multilayer wiring board and a method of manufacturing the same, characterized in that the relative positions of the through hole and / or via hole between the adjacent conductor layers (A) and (B) do not match, and three or more conductor layers are electrically connected. .