JPH10335831A - Multilayered wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily secure flatness and to form the wiring pattern of fine pitches by applying conductor ink to a pattern layer, where through-holes are carved, applying plating catalytic agent to the upper part of a result object which is hardened and stacked after silk screening and executing nonelectrolytic plating. SOLUTION: A photosensitive insulating layer 3 is formed on a metallic substrate 1, where a resin layer 2 is formed and a photo mask is insulated on it. It is exposed and developed, and the pattern layer where through-holes are carved in recessed forms is formed. Then, a conductive ink is applied to the pattern layer, it is silk-screened and hardened. Then, the wiring pattern 5 is formed, the process is repeated, and the layers are stacked. The result object to which plating catalytic agent is applied is non-electrolytically plated, and the wiring pattern 6 of the uppermost layer is formed. As a result, flatness in the uppermost part is superior, and the wiring pattern of fine pitches can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board and a method of manufacturing the same. on Boa
rd), BGA (Ball Grid Array),
The present invention relates to a multilayer printed wiring board that can be used for a chip carrier of a highly functional composite semiconductor package such as an MCM (Multi Chip Module) and a method of manufacturing the same.

[0002]

2. Description of the Related Art In a semiconductor package, a chip carrier having various materials and structures is required in accordance with multi-layer, multi-layer, high-performance, and multi-functional chips.
As a result, a multilayer PCB in which a through hole is formed for each layer has been manufactured.

[0003] However, such a method of manufacturing a multilayer PCB is not only composed of complicated steps requiring considerably high technology, but also has a low reliability and a high manufacturing cost, and is therefore inferior in practical use.

[0004] The usual method of manufacturing a multilayer PCB is performed by an etching technique. This is a method in which copper foil is laminated on a material substrate, each layer is manufactured by etching the copper foil to form a through hole, and then laminated. But,
According to this method, the number of working steps increases, and the problem of environmental pollution due to excessive use of the etching solution is serious. Also,
Since high-reliability materials must be selected to ensure reliability, manufacturing costs increase.

Another method is to produce a multilayer PCB by plating each layer with electroless copper. This method is useful for securing flatness and providing fine pitch,
It is difficult to put into practical use because it takes too much production time and cost.

[0006]

A technical problem to be solved by the present invention is to provide a method of manufacturing a multilayer PCB which can easily secure a flatness, can form a fine pitch wiring pattern, and has a low manufacturing cost. That is.

Another technical problem to be solved by the present invention is to provide a multi-layer PCB applicable to a highly functional composite semiconductor package.

[0008]

Means for Solving the Problems The technical problems of the present invention are:
a) forming a photosensitive insulating layer on a material substrate; b)
Exposing and developing the photosensitive insulating layer to form a pattern layer in which through holes are inscribed; c) applying a conductive ink to the pattern layer, performing a silk screen, and then curing; d) E) repeating steps a) -c) and laminating the desired number of layers;
Applying a plating catalyst on top of the resulting product; f)
Forming the wiring pattern of the uppermost layer by electroless plating the resulting product of the step e).

Another technical object of the present invention is achieved by a multilayer PCB manufactured according to the above manufacturing method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in detail.

In the method of manufacturing a multilayer PCB according to the present invention, the material substrate is not particularly limited as long as it can be used in this field, such as metal, ceramic, and resin.

Among them, metal is preferable as a material substrate because metal can improve reliability because heat stability, heat release property and the like are improved, and can also reduce production cost. Therefore, in order to use it as a material substrate, it is required to treat the surface with a resin layer.

Further, a through hole may be formed by drilling or punching a material substrate. At this time, when the material substrate is a metal substrate, after the formation of the through hole, the resin layer should be formed not only on the substrate surface but also on the inner wall of the through hole.

Next, a photosensitive insulating material is coated on the material substrate, and is exposed and developed using a photomask to form a pattern layer in which the through-holes are formed in a concave shape. A wiring pattern is formed by applying a silk screen printing method and embedding an intaglio through hole with conductive ink.

In the silk screen printing method, a portion to be coated with ink is intaglio-printed using photolithography, and then ink is charged into the concave portion to form a squeegee (sq.
a method for forming a pattern by extruding the ink while applying pressure to the ink. This method is a method that can form a pattern more easily than a normal electroplating or electroless plating method.

By repeating the steps from forming the photosensitive insulating layer to silk-screening the conductive ink several times, a desired number of layers are laminated.

However, the uppermost wiring pattern is not formed by the silk screen method. If the uppermost wiring pattern is formed by a silk screen method using conductive ink, the viscosity of the conductive ink causes a round phenomenon in which edges are not formed at right angles but rounded. Therefore, there is a problem that a sufficient degree of flatness cannot be secured during wire bonding, which makes it difficult to form a fine-pitch wiring.

Therefore, the uppermost wiring pattern is formed by electroless plating. That is, a wiring pattern is formed by applying a plating catalyst to the uppermost layer and performing electroless copper plating. Since the flatness can be obtained by applying the electroless plating method in this manner, it is easy to form a fine-pitch wiring pattern.

However, since the electroless plating is a process which requires much time and cost, if the pattern thickness of the uppermost layer exceeds about 1 μm, the electroless plating and the electroplating should be performed sequentially. Thus, a wiring pattern can be formed. In other words, electroless plating is performed up to about 0.1-0.2 μm, electroplating is further performed, and after obtaining a desired thickness, exposure, development, and etching are performed to form a wiring pattern.

According to the method of the present invention, there is an advantage that flatness is ensured, components or chips are easily mounted, and a fine-pitch wiring pattern can be formed. In addition, it has excellent reliability, is easy in the manufacturing process, and has a low manufacturing cost.

Hereinafter, the present invention will be described in more detail with reference to FIGS.

1 to 8 are cross-sectional views showing a method of manufacturing a multilayer PCB according to an embodiment of the present invention step by step.
This is a case where a metal substrate is used as a material substrate.

First, a resin layer forming process for forming a resin layer 2 on a metal substrate 1 is performed (FIG. 1).

The metal substrate is a highly reliable substrate having excellent heat stability and heat release properties. However, since it is a conductor, its surface must be treated with a resin layer to provide insulation. The through hole may be formed by drilling or punching the metal substrate before the resin layer forming process.In this case, the resin layer forming process should be performed not only on the surface of the metal substrate but also on the inner wall of the through hole. is there.

Next, after forming the photosensitive insulating layer 3 on the metal substrate 1 on which the resin layer forming process has been performed (FIG. 2), a photomask is placed on the photosensitive insulating layer 3 and exposed and developed. Is performed to form a pattern layer in which the through holes 4 are cut in a concave shape (FIG. 3).

Subsequently, a conductive ink is charged in the pattern layer, and the screen layer is cured after being silk-screened to form a wiring pattern 5 (FIG. 4).

A series of steps from the step of forming the photosensitive insulating layer to the step of forming the wiring pattern are repeated, and a desired number of layers are laminated (FIGS. 5 and 6).

Next, in order to form the uppermost wiring pattern, a plating catalyst is applied on the resultant product (FIG. 7).

Next, the resulting product coated with the plating catalyst is subjected to electroless plating to form the uppermost wiring pattern 6 (FIG. 8).

However, since the electroless plating is a process that requires a considerable amount of time and cost, when the wiring pattern 6 of the uppermost layer is to be formed to a predetermined thickness, for example, 1 μm or more, it is approximately 0.1-m. After performing electroless plating to 0.2 μm or less, electroplating is performed to obtain a wiring pattern having a desired thickness. As a result, manufacturing time and manufacturing cost can be reduced.

[0031]

According to the manufacturing method of the present invention, the manufacturing process is easy and the manufacturing cost is low. The multilayer PCB obtained by this method has excellent flatness of the uppermost layer on which components and chips are mounted, and There is an advantage that a fine pitch wiring pattern can be formed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a procedure of a manufacturing process of a multilayer printed wiring board according to one embodiment of the present invention.

FIG. 2 is a sectional view showing a procedure of a manufacturing process of the multilayer printed wiring board according to one embodiment of the present invention.

FIG. 3 is a sectional view showing a procedure of a manufacturing process of the multilayer printed wiring board according to one embodiment of the present invention.

FIG. 4 is a sectional view showing a procedure of a manufacturing process of the multilayer printed wiring board according to one embodiment of the present invention.

FIG. 5 is a sectional view showing a procedure of a manufacturing process of the multilayer printed wiring board according to one embodiment of the present invention.

FIG. 6 is a sectional view showing a procedure of a manufacturing process of the multilayer printed wiring board according to one embodiment of the present invention.

FIG. 7 is a sectional view showing a procedure of a manufacturing process of the multilayer printed wiring board according to one embodiment of the present invention.

FIG. 8 is a sectional view showing a procedure of a manufacturing process of the multilayer printed wiring board according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal substrate 2 Resin layer 3 Photosensitive insulating layer 4 Through-hole 5 Wiring pattern 6 Uppermost wiring pattern

Claims (8)

[Claims] 1. a) forming a photosensitive insulating layer on a material substrate; b) exposing and developing the photosensitive insulating layer to form a pattern layer in which a through hole is engraved; c). Applying a conductive ink to the pattern layer, curing after applying a silk screen, d) repeating the steps a) to c), and laminating a desired number of layers; e) the step d) Applying a plating catalyst to the upper portion of the resulting product; and f) electroless plating the resulting product of step e) to form an uppermost wiring pattern. Plate manufacturing method. 2. The method according to claim 1, wherein the material substrate is a metal substrate, a resin substrate, or a ceramic substrate. 3. The method according to claim 2, further comprising performing a resin layer forming process for forming a resin layer on the surface of the material substrate before the step a) when the material substrate is a metal substrate. 3. The method for producing a multilayer printed wiring board according to item 1. 4. The method of claim 1, further comprising, before the step a), punching or drilling the material substrate to form a through hole. 5. The method according to claim 3, further comprising the step of forming a resin layer on a surface of the material substrate and an inner surface of the through hole after the step of forming the through hole when the material substrate is a metal substrate. 3. The method for producing a multilayer printed wiring board according to item 1. 6. The method according to claim 1, wherein in the step (f), the thickness of the uppermost wiring pattern is 1 μm or less. 7. If the thickness of the uppermost wiring pattern exceeds 1 μm in step f, electroless plating is performed until the uppermost wiring pattern has a thickness of 0.1 μm-0.2 μm. 2. The method according to claim 1, wherein the wiring pattern having a thickness exceeding this is formed by electroplating. 8. A multilayer printed wiring board manufactured according to any one of the first to seventh manufacturing methods.