JPH10224036A - Build-up printed wiring board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the surface of an insulation layer from directly contacting a strong alkali plating liquid on electroless copper plating treatment by forming a metal plating film on the roughening surface of the insulation layer by oxidation electroless metal plating treatment. SOLUTION: In a copper-clad lamination plate 10, a copper foil 12 is laminated on both surfaces of an insulation substrate, thus forming a first circuit pattern. An alkali development type photosensitive insulation resin is applied to the inner surface of the copper-clad lamination plate 10 and is dried and cured properly, thus forming an insulation layer 30. Then, after the surface roughening, oxidation electroless nickel plating treatment is performed, thus forming a nickel plating film 50. The thickness of the nickel plating film 50 is determined by considering that the roughening surface of the insulation layer 30 does not directly contact a strong alkali plating liquid on later-process electroless copper plating treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a build-up printed wiring board, and more particularly to a technique for improving the adhesion between an insulating layer made of an alkali developing type photosensitive insulating resin and a conductive circuit.

[0002]

2. Description of the Related Art In a method of manufacturing a multilayer printed wiring board, there is known a build-up method in which a circuit pattern and an insulating layer are sequentially stacked on at least one surface of an insulating substrate. In this build-up method, the surface of the insulating layer is chemically polished and roughened in order to improve the adhesion between the insulating layer made of insulating resin and the conductor circuit.

FIG. 2 is a view showing a process of manufacturing a multilayer printed wiring board by this build-up method. In FIG. 2, reference numeral 10 denotes a copper-clad laminate, which is an insulating plate (laminate) obtained by stacking a sheet (prepreg) impregnated with a resin on a reinforcing substrate such as paper or glass fiber, and subjecting the sheet to pressure and heat treatment. The copper foil 12 is attached to both sides or one side. Here, a glass cloth impregnated with an epoxy resin, for example, NEM
A standard FR-4 double-sided copper-clad laminate is used. An appropriate first circuit pattern is formed on the copper foils 12 by a known photoetching method. Then, a photosensitive insulating resin, for example, an epoxy acrylate resin is applied to both surfaces of the copper-clad laminate 10 to form an insulating layer 30. The laminate 32 thus obtained is placed in a low-temperature constant-temperature bath, dried except for the volatile organic solvent contained in the solvent of the resin, and the film quality is appropriately cured (FIG. 2A).

Next, a photomask 34 having a via hole pattern printed thereon is closely attached to the surface of the laminated body 32, or is positioned slightly away from the photomask 34 to perform alignment to obtain light of an appropriate wavelength (usually, ultraviolet (UV) light). (FIG. 2B). As a result, the insulating layer 30 under the via hole pattern is not cured, and the insulating layer 30 other than the via hole pattern is cured.

[0005] Then, by developing with a developer of an alkaline solvent to remove the uncured portion (soluble portion), the photomask 3
Small holes 36 corresponding to the pattern of the via holes baked on No. 4, that is, small holes 36 for via holes are formed (FIG. 2C).

Next, in order to improve the adhesion between the second conductor layer formed on the surface of the insulating layer 30 and the insulating layer 30, the surface of the insulating layer 30 is chemically polished to roughen the surface of the insulating layer 30. Become ((D) of FIG. 2). Next, an electroless copper plating process is performed on the roughened surface of the insulating layer 30 to form a first copper plated layer 38. A baking process is performed to improve the adhesion between the first copper plating layer 38 and the resin layer 30. ((E) of FIG. 2). Next, electrolytic copper plating is performed on the surface of the first copper plating layer 38 to form the second copper plating layer 42. ((F) of FIG. 2). Thus, the second conductor layer 44 including the first copper plating layer 38 and the second copper plating layer 42 on the insulating layer 30
Is formed, and a via hole 40 is formed.

An appropriate second circuit pattern can be formed on the second conductor layer 44 on the surface by a photoetching method or the like. The same procedure can be repeated to increase the number of layers.

[0008]

By roughening the surface of the insulating layer as described above, it is possible to manufacture a build-up printed wiring board with improved adhesion between the insulating layer and the second conductor layer. However, there is a problem that the adhesion strength between the insulating layer and the second conductor layer of the build-up printed wiring board manufactured by this method is 0.8 kg / cm or less, and the adhesion reliability is not sufficient. The present invention has been made to solve the above problems, and provides a build-up printed wiring board including a metal plating film formed by performing an acidic electroless metal plating process on a roughened surface of an insulating layer. Is a first object, and a second object is to provide a manufacturing method thereof.

[0009]

The present invention focuses on performing electroless copper plating after roughening the surface of the insulating layer 30 by chemical polishing, and on the fact that the insulating layer 30 is of an alkali developing type. It was done. That is, since the electroless copper plating treatment is performed in a strongly alkaline plating solution of PH12 to PH13, the roughened surface of the insulating layer 30 is eroded by the strongly alkaline plating solution at the same time as the deposition of the plating, and the roughened surface is roughened. Is generated, and the adhesion strength is reduced. Therefore, the insulating layer 3
The roughened surface of No. 0 was subjected to an acidic electroless metal plating treatment to form a metal plating film. This metal plating film is used as a protective film to prevent the roughened surface from directly contacting the strongly alkaline plating solution during the electroless copper plating treatment.

According to the present invention, a first object is to provide an insulated substrate having a first circuit pattern formed on at least one surface thereof in a build-up printed wiring board, and to be laminated on the first circuit pattern. An insulating layer, a metal plating film formed by performing an acidic electroless metal plating process on the insulating layer, and a second circuit pattern formed on the metal plating film. This is achieved by a build-up printed wiring board.

A second object of the present invention is to provide a method of manufacturing a build-up printed wiring board, comprising: a. Forming an insulating layer by laminating an alkali-developing photosensitive insulating resin on the copper-clad laminate on which the first circuit pattern is formed; b. Roughening the surface of the insulating layer; c. Subjecting the roughened surface of the insulating layer to acidic electroless metal plating to form a metal plating film; d. This is achieved by a method of manufacturing a build-up printed wiring board, characterized in that a copper plating layer is formed by performing copper plating on the metal plating film.

[0012]

FIG. 1 is a diagram showing one embodiment of a method of manufacturing a build-up printed wiring board according to the present invention.
In this embodiment, a nickel plating film is formed by performing an acidic electroless nickel plating process to protect the roughened surface of the insulating layer.

First, a copper-clad laminate 10 similar to that used in FIG. 2 is prepared. This is a copper foil 1 on both sides of the insulating substrate
2 to form a first circuit pattern. An insulating layer 30 is formed on both surfaces of the copper-clad laminate 10 by applying an alkali-developable photosensitive insulating resin, for example, an epoxy acrylate-based resin, and drying and appropriately curing the resin (FIG. 1A). )). Steps (A) to (D) are the same as the steps shown in FIG. 2, and thus the same portions are denoted by the same reference characters and description thereof will not be repeated.

The difference from the step of FIG. 2 is that, after the surface roughening in the step (D), an acidic electroless nickel plating treatment is performed to form a nickel plating film 50 (FIG. 1 (E)). . The thickness of the nickel plating film 50 is intended to prevent the roughened surface of the insulating layer 30 from coming into direct contact with the strong alkaline plating solution during electroless copper plating in the subsequent step. It is determined in consideration of the fact that etching can be sufficiently performed at the time of photoetching for forming a two-circuit pattern. As a plating solution for this acidic electroless nickel plating treatment, for example, PH4-5
With nickel chloride, 30 g / l, sodium hypophosphite 10 g / l, sodium citrate 10 g / l
A plating solution containing liters is used.

Subsequently, similarly to FIGS. 2E and 2F,
An electroless copper plating process is performed on the surface of the nickel plating film 50, and then a baking process is performed after forming the first copper plating layer 38 ((F) in FIG. 1), and the surface of the first copper plating layer 38 is electrolytically processed. A copper plating process is performed to form a second copper plating layer 42 (FIG. 1G). Thus, the first copper plating layer 3
8. A second conductor layer 44 composed of the second copper plating layer 42 is formed, and a via hole 40 is formed. Note that an appropriate second circuit pattern can be formed on the second conductor layer 44 on the surface by a photoetching method or the like. The same procedure can be repeated to increase the number of layers.

In the build-up printed wiring board thus obtained, the adhesion strength between the insulating layer and the conductor layer is 1.2 k.
g / cm or more, and sufficient adhesion as a multilayer printed wiring board could be secured. The acidic electroless metal plating after the surface roughening of the insulating layer is not limited to nickel, but may be nickel alloy (Ni-Co-P), chromium, or the like.

[0017]

According to the first aspect of the present invention, as described above, a metal plating film is formed on a roughened surface of an insulating layer by an acidic electroless metal plating process. Sometimes, the surface of the insulating layer does not come into direct contact with the strong alkaline plating solution. For this reason, the roughened surface is not eroded by the alkaline plating solution, so that the unevenness of the surface does not occur. Therefore, the adhesion between the insulating layer and the conductor layer is improved, and the excellent reliability of the adhesion strength of 1.2 kg / cm or more is obtained. It is possible to provide a built-up printed wiring board having a predetermined length. Claim 2
According to the invention, a method of manufacturing the build-up printed wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a method for manufacturing a build-up printed wiring board according to the present invention.

FIG. 2 is a view showing a manufacturing process of a multilayer printed wiring board by a conventional build-up method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Copper-clad laminated board 12 Copper foil 30 Insulating layer 34 Mask film 36 Photo via hole small hole 38 1st copper plating layer 40 Via hole 42 2nd copper plating layer 50 Nickel plating film

Claims (2)

[Claims] 1. A build-up printed wiring board, comprising: an insulating substrate having a first circuit pattern formed on at least one surface; an insulating layer laminated on the first circuit pattern; A build-up printed wiring board comprising: a metal plating film formed by performing an acidic electroless metal plating process; and a second circuit pattern formed on the metal plating film. 2. A method for manufacturing a build-up printed wiring board, comprising: a. Forming an insulating layer by laminating an alkali-developing photosensitive insulating resin on the copper-clad laminate on which the first circuit pattern is formed; b. Roughening the surface of the insulating layer; c. Subjecting the roughened surface of the insulating layer to an acidic electroless metal plating treatment to form a metal plating film; d. A copper plating process is performed on this metal plating film to form a second
A method for manufacturing a build-up printed wiring board, comprising forming a conductor layer.