KR19980084566A - Multilayer printed circuit board and its manufacturing method - Google Patents

Abstract

The present invention comprises the steps of a) preparing a material substrate; b) forming a photosensitive insulating layer on the material substrate; c) exposing and developing the photosensitive insulating layer to form a pattern layer having a through hole engraved therein; d) applying conductive ink to the pattern layer, silk screening and curing; e) repeating steps b) -d) to stack as many layers as desired; f) applying a plating catalyst to the pattern layer of the uppermost part; And g) forming a circuit pattern by electroless plating the pattern layer of the uppermost layer, and a multilayer printed circuit board manufactured according to the manufacturing method. The method is easy to manufacture and inexpensive to manufacture, and the multilayer PCB obtained by this method has an advantage in that the flatness of the uppermost layer on which the component or chip is to be mounted is excellent and a fine pitch circuit pattern can be formed.

Description

Multilayer printed circuit board and its manufacturing method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed circuit board and a method for manufacturing the same, and more particularly, through holes are formed in each layer, and a flatness is secured so that COB (Chip on Board) and BGA (Ball Grid Array) are provided. The present invention relates to a multilayer printed circuit board and a method of manufacturing the same, which can be used for a chip carrier of a highly functional complex semiconductor package such as a multi chip module (MCM).

In semiconductor packages, as the chips are multi-layered, composited, highly functionalized, and multi-functional, chip carriers also need to have a variety of materials and structures, leading to the manufacture of multilayer PCBs having through holes formed in each layer.

However, the manufacturing method of such a multilayer PCB is not only made of a complicated process requiring a very high technology, but also very difficult to secure reliability and high manufacturing cost, which is not practical.

A conventional multilayer PCB manufacturing method is made by an etching technique. This is a method of laminating a copper foil on a material substrate, etching the same, forming a through hole, manufacturing each layer, and then laminating it. However, according to this method, the number of steps in the manufacturing process increases, and the problem of environmental pollution due to excessive use of the etching solution is also serious. In addition, manufacturing costs are increased because a material having high reliability must be selected to secure reliability.

Another method is to manufacture a multilayer PCB by electroless copper plating each layer. This method is useful for securing flatness and providing fine pitch, but it is difficult to put to practical use because of excessive manufacturing time and cost.

The technical problem to be achieved by the present invention is to provide a multi-layer PCB manufacturing method that is easy to secure flatness, can form a circuit pattern of fine pitch, and low manufacturing cost.

Another object of the present invention is to provide a multilayer PCB that can be applied to a highly functional complex semiconductor package.

1 is a cross-sectional view sequentially illustrating a manufacturing process of a multilayer printed circuit board according to the present invention.

<Explanation of symbols for main parts of drawing>

1 ... metal substrate 2 ... resin layer

3 ... photosensitive insulating layer 4 ... through hole

5, 6 ... circuit pattern

Technical problem of the present invention is a) preparing a material substrate; b) forming a photosensitive insulating layer on the material substrate; c) exposing and developing the photosensitive insulating layer to form a pattern layer having a through hole engraved therein; d) applying conductive ink to the pattern layer, silk screening and curing; e) repeating steps b) -d) to stack as many layers as desired; f) applying a plating catalyst to the pattern layer of the uppermost part; And g) selectively electroless plating the pattern layer of the uppermost layer.

Another technical problem of the present invention may be achieved by a multilayer PCB manufactured according to the manufacturing method of the present invention.

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

Among them, the metal is preferable as a material substrate because the thermal stability, heat dissipation, and the like are improved, thereby increasing the reliability and reducing the manufacturing cost. However, when metal substrates are used, the surface of the substrate should be blackened.

The material substrate may be drilled or punched to form a through hole, if necessary. In the case of a metal substrate, the surface of the material substrate should be blackened to the inner wall of the through hole formed after drilling or punching.

Next, a photosensitive insulating material is coated on the blackened material substrate and exposed and developed using a photomask to form a pattern layer through which a through hole is recessed. Silk-screen printing is applied to fill the indented through-holes with conductive ink to form circuit patterns.

The silk screen printing method is a method of forming a pattern by engraving a portion to be applied with ink using photolithography, pouring ink into the engraved portion and pushing the ink with a squeegee. This method is a method which can form a pattern easily compared with normal electroplating or electroless plating.

In this manner, a series of steps of silk screening the conductive ink from the photosensitive insulating layer formation are repeated several times to stack as many layers as desired.

However, the top layer is not silk screened. The reason is that due to the viscosity of the conductive ink, a round phenomenon occurs in which the edges are not formed at right angles but are rounded, making it difficult to secure sufficient flatness during wire bonding, thus forming a fine pitch circuit. This is because there is a problem that is difficult.

Therefore, a plating catalyst is first applied to the uppermost layer and electroless copper plating is performed to form a pattern. By electroless plating, flatness can be obtained and it is easy to form a fine pitch circuit pattern.

However, since electroless plating is a process that requires a lot of time and cost, when the pattern thickness of the uppermost layer exceeds about 1 mu m, electroless plating and electroplating can be performed in order to form a circuit pattern. In other words, electroless plating is carried out to about 0.1-0.2 占 퐉, and then electroplating again to obtain a desired thickness, followed by etching after exposure and development to form a circuit pattern.

According to the method of the present invention, the flatness is secured, so that it is easy to load a component or a chip, and a circuit pattern of fine pitch can be formed. In addition, it is excellent in reliability, easy in the manufacturing process and low in manufacturing cost.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1.

1 is a cross-sectional view showing step by step a method of manufacturing a multilayer PCB using a metal substrate.

First, the blackening process which forms the resin layer 2 on the metal substrate 1 is performed (a of FIG. 1).

Since the metal substrate is a highly reliable substrate or conductor having excellent thermal stability, heat dissipation, etc., the surface should be blackened to provide insulation. Through holes may be drilled or punched to form through holes prior to the blackening process. In this case, the surface of the metal substrate as well as the inner wall of the through holes should be blackened.

Subsequently, a photosensitive insulating layer 3 is formed on the blackened metal substrate 1 (b of FIG. 1), and a photomask is placed on the photosensitive insulating layer 3 to expose and develop a through hole ( 4) to form a recessed pattern layer (Fig. 1c).

Next, a conductive ink is poured into the pattern layer, silkscreened, and cured to form a circuit pattern 5 (FIG. 1 d).

The series of steps from the photosensitive insulating layer forming step to the circuit pattern forming step are repeated to stack as many layers as desired (e and f in FIG. 1).

Subsequently, a photosensitive insulating layer 3 is applied to the resultant to form a top layer, and then exposed and developed to form a patterned layer, and a plating catalyst is applied to the through-holes engraved intaglio on the patterned layer (Fig. 1 g).

Subsequently, the uppermost part is electroless plated to form a circuit pattern 6 of the uppermost part (h in Fig. 1).

However, electroless plating is a time-consuming and expensive process, so if the circuit pattern 6 of the uppermost layer is to be formed thicker than a predetermined thickness, for example 1 μm, electroless plating is performed only up to 1 μm or less By plating, a circuit pattern of a desired thickness is obtained. As a result, manufacturing time and manufacturing cost can be reduced.

The manufacturing method according to the present invention is easy in the manufacturing process and the manufacturing cost is low, and the multilayer PCB obtained by this method has the advantage that the flatness of the uppermost layer where the component or chip is to be mounted is excellent and a fine pitch circuit pattern can be formed. have.

Claims (7)

a) preparing a material substrate; b) forming a photosensitive insulating layer on the material substrate; c) exposing and developing the photosensitive insulating layer to form a pattern layer having a through hole engraved therein; d) applying conductive ink to the pattern layer, silk screening and curing; e) repeating steps b) -d) to stack as many layers as desired; f) applying a plating catalyst to the pattern layer of the uppermost part; And g) electroless plating the pattern layer of the uppermost part to form a circuit pattern. The method of claim 1, wherein the material substrate is a metal substrate, a resin substrate, or a ceramic substrate. The method of claim 2, further comprising blackening the material substrate when the material substrate is a metal substrate. The method of claim 1, further comprising forming a through hole by punching or drilling the substrate. The method of claim 4, further comprising blackening the surface of the material substrate and the inner surface of the through hole when the material substrate is a metal substrate. The multilayer printed circuit board as claimed in claim 1, wherein when the thickness of the circuit pattern is formed thicker than about 0.1 μm in step g), electroplating is further performed to form a circuit pattern having a predetermined thickness. Manufacturing method. A multilayer printed circuit board manufactured according to the method of claim 1.