JPH10335824A - Multilayered wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute drilling with a prescribed condition and to set wiring density to be high by forming the hole of a large diameter in a connection desiring place with a through-hole and/or a via hole, formed on a wiring board and electrically connecting conductor layers via the hole. SOLUTION: This wiring board constituted of the through-hole 11 and the circuit of the conductor layer 2 is generated in an insulating resin layer 1, a graphitization is executed, and a resin body with a copper foil 3 is stacked. Copper plating is executed on the surface of a copper foil 5a and the inner wall side of the hole 13 and the via hole 13, which is electrically connected with the conductor layers 5 and 2, is formed. Next, the hole whose diameter is larger than the via hole is formed above the via hole 13 by the irradiation with a laser. The via hole 14 which is electrically connected with the conductor layers 6 and 5 is formed, and a circuit pattern is formed. In the multilayered wiring board which is thus generated, drilling work is easy and the reliability of electrical connections is 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. Also,
Since the positions of the lower and upper holes and / or via holes are different from each other, a large area is required for connection. The dimension A in FIG. 2 (approximately twice as large as one piece) becomes four times the square of a single land. A multilayer wiring board and a method of manufacturing the same according to the present invention are to solve these difficulties of the drilling process and to increase the wiring density.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a multilayer wiring board having through holes and via holes for connecting conductive layers and a method of manufacturing the same, comprising the steps of forming an insulating resin layer and a conductive layer on a wiring board having through holes and / or via holes formed therein. A hole having a diameter larger than the diameter of the through hole and / or the via hole is formed at a desired position of connection between the laminated conductor layer and the insulating resin layer with the through hole and / or the via hole formed in the wiring board. And electrically connecting the through-hole and / or the via-hole of the wiring board and the laminated conductor layer through the hole, and merely forms a hole in the outermost conductor layer and the insulating resin layer. By providing a multi-layered wiring board with high wiring density and easy control, which can be drilled under conditions, and a method of manufacturing the same. That.

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 (without drilling a conductor layer of a wiring board located below the insulating resin layer), and the hole is formed by an electroless plating method or an electrolytic plating method. Via holes for electrically connecting the conductor layers are formed, and a wiring pattern is formed by an etching method to form a multilayer wiring board. Further, if desired, an insulating resin layer and a conductor layer are laminated, and a hole is formed by a laser,
Electrical connection is made, a wiring pattern is formed, and a multilayer wiring board having more layers can be produced.

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.

In the multilayer wiring board and the method for manufacturing the same according to the present invention, the holes in the laminated conductor layer and insulating resin layer are formed by using a hole having a diameter larger than the diameter of the through hole and / or via hole formed in the lower layer. It is formed by. The holes are formed at the same positions as the through holes and / or via holes formed in the lower layer (via-on-via method). The holes formed in this manner are formed by melting, vaporizing, decomposing, or the like the resin in the laminated conductor layer and insulating resin layer and the resin in the through hole and / or via hole formed in the lower layer using a laser.

Compared with the conventional method of forming through holes and / or via holes at different positions in the lower layer and the upper layer, the via-on-via method does not increase the land area due to the formation of the through holes and / or via holes. Wiring density can be increased. When the positions of the holes in the lower layer and the upper layer are different, the land width (A) is about twice that of the via-on-via method as shown in FIG. 2, and the area is about four times when the land is round.

Since laser is irradiated to form a hole having a large diameter, the resin existing on the inner surface of the lower through hole and / or via hole is removed cleanly, and the lower conductive layer is exposed. The conductor layer and the lower conductor layer can be completely and easily electrically connected.

The land to be formed is not limited in shape and size, but is preferably a fine land formed by laser processing for high density, for example, from 1 mm to 1 mm.
0.03 mm. More preferably, 0.7 mm ~
It is 0.05 mm. Particularly preferably, 0.5 mm or more
0.1 mm.

The surface treatment of the conductor layer to be perforated by a laser is not particularly limited, but the surface of the conductor layer is subjected to a treatment having a high absorption rate of laser energy, or the conductor layer is previously 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 treatment with metal oxides containing nickel oxide, copper oxide, iron oxide, etc. as a main component, treatment with dyes such as Congo red and methyl violet, and pigments such as carbon. Can be illustrated.

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 formed as described above, are used for forming a hole having a diameter larger than that of the lower through hole and / or the via hole. The removal of the insulating resin inside is complete, the reliability of the electrical connection is high, the land of the through hole and / or the via hole is not wide, and the wiring density is high.

[0017]

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 was formed in a copper-clad double-sided board obtained by laminating a copper foil 2a having a thickness of 18 μm on both sides of an epoxy resin 1, and plated copper 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. 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 both sides of the wiring board (FIG. 1 (b)) and laminated (pressure 25 kg, temperature 1).
80 degrees, 120 minutes).

Next, a circular blackening process smaller by 20 μm than the laser irradiation diameter was formed on the surface of the copper foil 5a at the position where the hole for forming the via hole 13 was formed.

Next, the multilayer wiring board is positioned and set on the processing table of the carbon dioxide laser device, and the laser (pulse width 2) is set.
5 μs, a frequency of 100 Hz) to form a 0.1 mm hole 13 in the copper foil 5 a and the insulating resin layer 4.

Next, the inside of the hole 13 is subjected to a smear treatment by a potassium permanganate method, and the surface of the copper foil 5a and the inner wall surface of the hole 13 are plated with copper to electrically connect the conductor layers 5 and 2 to each other. A connected via hole 13 was formed, and a circuit pattern was formed by a photoetching method. The land formed in the via hole 13 was a 0.4 mm round shape. (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 surface of the copper foil of the conductive layer 6 was subjected to blackening treatment, and a hole 14 having a diameter larger than the via hole 13 and having a diameter of 0.2 mm was formed above the via hole 13 by laser irradiation. The hole 14 also removed the insulating resin inside the via hole 13. Next, the inside of the hole was smeared and plated with copper to form a via hole 14 electrically connected to the conductor layer 6 and the conductor layer 5, and a circuit pattern was formed by a photoetching method. Land of via hole 14 is 0.4
mm round. (Fig. 1 (d))

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

The multilayer wiring board thus manufactured is
Drilling was easy, the reliability of electrical connection was high, and the land of the through hole and / or via hole was hardly widened.

(Embodiment 2) A circular carbon black laser apparatus was used without performing a circular blackening process smaller than the laser irradiation diameter in the embodiment 1 by 20 μm, and an ultraviolet laser apparatus (N
d: A multilayer wiring board was manufactured in substantially the same manner as in the manufacturing process of Example 1 except that a hole was formed by changing to a solid UV laser using a wavelength of 355 μm of YAG.

The multilayer wiring board manufactured in this manner is easy to control the laser, has no damage to the conductor layer, is easy to drill a small diameter hole, and the insulating resin layer is chemically changed by the laser. Since it was raised and decomposed and removed, it did not carbonize, there was no carbon residue problem, the wiring density was high, the interlayer adhesion was good, and the reliability of electrical connection was high.

[0029]

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 are perforated, so that the control is easy. Especially in drilling by laser, the hole stops at the next conductor layer,
Due to the hole having a larger diameter than the through hole and / or the via hole in the lower layer portion, it is possible to cover the positional deviation and make an electrical connection. Further, since the laser drilling is performed at the same position as the lower layer through hole and / or via hole, it can be formed without increasing the area occupied by the through hole and / or via hole. It is possible to provide a multilayer wiring board and a method of manufacturing the same, which eliminate the difficulty of processing steps such as the above.

[0030]

[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. FIG. 2 is a cross-sectional view according to a conventional method.

[0031]

[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 13 via hole 13 14 via hole 14

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[Procedure amendment]

[Submission date] July 22, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Added

[Correction contents]

FIG. 2

Claims (1)

[Claims] 1. A multilayer wiring board having through holes and via holes for connecting conductive layers and a method of manufacturing the same.
An insulating resin layer and a conductor layer are laminated on a wiring board having a through hole and / or a via hole formed thereon, and a desired connection position of the laminated conductor layer and the insulating resin layer with the through hole and / or the via hole formed on the wiring board is provided. Forming a hole having a diameter larger than the diameter of the through hole and / or the via hole, and electrically connecting the through hole and / or the via hole of the wiring board and the laminated conductor layer through the hole. A multilayer wiring board and a method of manufacturing the same.