JPH10335829A - Multilayered wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute drilling with a prescribed condition by forming conductor layers on the surface of an insulating resin layer and holes by an additive method and electrically connecting the circuit conductor pattern of a wiring board and the conductor layers in via holes. SOLUTION: A graphitization is executed on the surface of the conductor layer 6, and a copper oxide layer is formed. Then, a processing for chemically reducing the copper oxide layer into metallic copper is executed and the insulating resin layer 3 is stacked. The hole whose diameter is smaller than that of the via hole is formed in the same position as the via hole 15 by the irradiation with a laser and the hole reaching the conductor layer 6 is formed in the other position. Then, smearing in the holes is executed, and copper is deposited by a semi-additive method and a conductor layer 7 and via holes 13 and 16 are formed. In the multilayered wiring board which is thus generated, the drilling of the small diameter is easy and wiring density 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 via holes 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. The method using a drill has problems such as a large hole diameter, it is very difficult to complete the drilling in the middle of a multilayer wiring board having a thin conductive layer and an insulating layer, and a simultaneous drilling of the conductive layer and the insulating layer. In the method using a laser, there is a problem that it is very difficult to control the drilling of the laminated conductor layer and insulation layer, and the interior conductor layer and interior insulation layer. 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 having through holes and via holes for connecting conductive layers and a method for manufacturing the same, comprising: laminating an insulating resin layer on a wiring board on which a circuit conductive pattern is formed; A hole reaching the circuit conductor pattern is formed in the insulating resin layer, and a conductor layer is formed on the surface and the hole of the insulating resin layer by an additive method, and the circuit conductor pattern and the conductor layer of the wiring board are formed. Are electrically connected in a via hole. Provided is a multilayer wiring board and a method for manufacturing the same, which is an easy-to-control processing step capable of only drilling holes in the outermost insulating resin layer, using a laser having a relatively weak energy, and drilling holes under certain conditions. It is.

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 sectional view showing one embodiment of a multilayer wiring board and a method for manufacturing the same according to the present invention. FIG. 2A is a cross-sectional view of a wiring board in which a through hole is formed. FIG. 2B is a cross-sectional view in which an insulating resin layer is laminated on a wiring board and holes are formed by a laser. FIG. 2C is a cross-sectional view in which a conductor layer and a via hole are formed in the insulating resin layer formed in FIG. 2B by an additive method.
FIG. 2D is a cross-sectional view in which an insulating resin layer is further laminated on FIG.

A multilayer wiring board and a method of manufacturing the same according to the present invention are shown in FIGS. 1 and 2 in which an insulating resin is provided on one or both sides of a wiring board in which a circuit conductor pattern 5 composed of a conductor layer is formed on a core resin layer 1. The layer 2 is laminated by a method known per se, and holes 12 and 15 are formed in the insulating resin layer 2 by using a laser (a circuit conductor pattern (conductor) of a wiring board located under the insulating resin layer. Layer), via holes 12 and 15 electrically connected to the conductor circuit pattern 5 (conductor layer) and formation of the conductor layer 6 on the surface of the insulating resin layer 2 by an additive method. To produce a multilayer wiring board.

Further, if desired, an insulating resin layer 3 is laminated,
Holes 13 and 16 are formed in the insulating resin layer 3 by using a laser, and the via holes 13 and 16 and the conductor layer 7 are formed by an additive method to form a multilayer wiring board having a larger number of layers. it can. Further, by repeating the same operation, a multilayer wiring board having more layers can be produced.

The additive method in the multilayer wiring board and the method of manufacturing the same according to the present invention is a method of manufacturing a printed wiring board in which a conductive pattern is formed by selectively depositing a conductive material on an insulating substrate by, for example, electroless plating. is there. For example, there is a full additive method in which a hole is formed in an insulating substrate, a circuit pattern pattern is formed by a plating resist, and a wiring pattern is formed only on the hole wall and the front and back surfaces of the insulating substrate by electroless copper plating. Also, holes are formed in the insulating substrate, an electroless copper plating layer is deposited on the entire surface (hole walls and front and back), a circuit pattern pattern is formed by a plating resist, and then electroless copper plating and / or electrolytic copper plating is performed again. Then, there is a semi-additive method in which the plating resist is peeled off, and the first electroless copper plating layer is removed by quick etching to form a wiring pattern. There is also a method in which holes are formed in an insulating substrate, electroless copper plating and electrolytic copper plating are applied to the entire surface, and a circuit is formed on the copper plating layer.

The thickness of the conductor layer deposited by the additive method in the multilayer wiring board and the method of manufacturing the same according to the present invention is not particularly limited, but is preferably 0.5 to 50 μm. More preferably, it is 1 to 40 μm. Particularly preferably, it is 3 to 20 μm.

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. Resins mainly composed of one type. Further, these resins are preferably ultraviolet curable resins and thermosetting resins. Particularly preferred are thermosetting resins. The insulating resin layer is made of glass, aramid,
An insulating resin obtained by impregnating a resin with a nonwoven fabric such as paper, porous polytetrafluoroethylene, or quartz, or a woven fabric may be used. In addition, resin beads, alumina powder,
Organic or inorganic fillers such as titanium oxide powder and calcium carbonate powder may be filled.

In the multilayer wiring board and the method for manufacturing the same according to the present invention, the holes are formed in the laminated insulating resin layer by using a laser having an arbitrary diameter as compared with the diameter of the through hole and / or via hole formed in the lower layer. Can be formed. The hole is formed at the same position as the through hole and / or via hole formed in the lower layer (via / hole).
(On-via method) or at a different position. The holes formed in this manner are formed by melting, vaporizing, and decomposing the laminated insulating resin layer with a laser, exposing the lower conductive layer. Via holes are completely and easily formed by the electrical connection by the additive method.

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.

[0014]

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.

(Example 1) First, a through-hole 11 was formed in a copper-clad double-sided board in which a copper foil 5a having a thickness of 18 µm was laminated on both sides of a core resin layer 1 in which a glass nonwoven fabric was impregnated with an epoxy resin. 5a and plated copper 5b in the through hole 11.
Was deposited, and a circuit conductor pattern 5 was formed by a photo-etching method. Thus, a wiring board including the through holes 11 and the circuit conductor pattern 5 in the core resin layer 1 was prepared. 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.
(A)

Next, an ultraviolet-curable epoxy resin was applied to the wiring substrate and irradiated with UV to form an insulating resin layer 2 of about 50 μm.

Next, the wiring board on which the insulating resin layer 2 is laminated is positioned and set on a processing table of a carbon dioxide laser apparatus, and a laser (pulse width 25 μs, frequency 100 Hz) is set.
To the insulating resin layer 2 to form a hole 12,
A hole 15 of about 0.2 mm was drilled. (Figure 2
(B))

Next, the insides of the holes 12 and 15 are smeared by the potassium permanganate method, and the semi-additive method (the surface of the insulating resin layer and the hole walls are activated with palladium chloride, A copper electroless plating layer is formed on the entire surface by reduction, a plating resist (plating mask) is applied to the insulating resin layer, a pattern pattern is formed, and copper having a thickness of about 12 μm is formed in the via hole and the pattern pattern by electrolytic plating. , The plating resist was peeled off, and the entire surface was subjected to quick etching to remove the electroless plating layer.)
Copper was deposited in the holes 12 and 15 to form a conductor layer 6 having a circuit pattern pattern and via holes 12 and 15 connected to the circuit conductor pattern 5. (Figure 2
(C))

Next, a blackening treatment was performed on the surface of the conductor layer 6 to form a copper oxide layer, and then a treatment for chemically reducing the copper oxide layer to metallic copper was performed, and an insulating resin layer 3 was further laminated.

Next, the via holes 15 are irradiated by laser irradiation.
Of the diameter smaller than the diameter of the via hole 15 by about 0.1
A hole 16 of mm was formed. (The hole 16 is a via hole 1
A hole was formed in the insulating resin inside 5 and the conductor layer 6 was exposed. In addition, a hole 13 of about 0.1 mm reaching the conductor layer 6 was formed at another position (FIG. 2D). next,
Smear treatment was performed inside the holes, and copper was deposited by a semi-additive method to form conductor layers 7, via holes 13, and via holes 16. (Fig. 1)

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

The multilayer wiring board thus manufactured is
Laser control was easy, small-diameter drilling was easy, wiring density was high, interlayer adhesion was good, and electrical connection reliability was high.

(Embodiment 2) The carbon dioxide gas laser device in Embodiment 1 is replaced with an ultraviolet laser device (wavelength of Nd: YAG 35
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 5 nm.

The multilayer wiring board thus manufactured is
Laser control is easy, there is no damage to the conductor layer, small-diameter drilling is easy, and the insulating resin layer undergoes a chemical change by the laser and is decomposed and removed. There was no residue problem, the wiring density was high, the interlayer adhesion was good, and the reliability of electrical connection was high.

[0025]

In the multilayer wiring board and the method of manufacturing the same according to the present invention, holes are formed in the insulating resin layer by a laser with relatively low power and easy to control, and holes are formed in the next conductive layer. There is an effect of stopping, and since the circuit is formed by the additive method, the reliability of the electrical connection is high.
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.

[0026]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a multilayer wiring board and a method for manufacturing the same according to the present invention.

FIGS. 2 (a), (b), (c) and (d) are cross-sectional views schematically showing the 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]

 DESCRIPTION OF SYMBOLS 1 Core resin layer 2 Insulating resin layer 2 3 Insulating resin layer 3 5 Circuit conductor pattern 5a Copper foil layer 5b Copper plating layer 6 Conductor layer 6 7 Conductor layer 7 11 Through hole 12 Via hole 12, Hole 12 13 Via hole 13, Hole 13 15 via hole 15, hole 15 16 via hole 16, hole 16

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 is laminated on the wiring board on which the circuit conductor pattern is formed, a hole reaching the circuit conductor pattern is formed in the insulating resin layer by a laser, and a conductor is formed on the surface of the insulating resin layer and the hole by an additive method. A multilayer wiring board and a method of manufacturing the multilayer wiring board, wherein a layer is formed, and the circuit conductor pattern and the conductor layer of the wiring board are electrically connected to each other through a via hole.