JPH04221887A - Manufacture of multilayer printed circuit board - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a multilayer printed circuit board which improves a laminating step of a copper foil on an inner layer material, improves operability of the foil for a surface layer at the time of associating in the laminating step, and prevents a defect of the surface layer after laminating. CONSTITUTION:In a step of laminating a multilayer printed circuit board formed by causing a copper foil for a surface layer to adhere to the surface of an inner layer material 1 formed with a conductive wiring pattern on a base material through a prepreg 2, superposing an intermediate plate 4 to become a jig on the copper foil for the surface layer, and heating/pressurizing the plate 4 through a mold 5, an electrolytic copper foil 6 previously formed in a predetermined thickness on the plate 4 by an electrolytic copper plating is used as the copper foil for the surface layer, the foil 6 formed on the plate 4 is superposed on the prepreg 2, and the plate 4 is peeled from the foil 6 after heating/- pressurizing through the mold 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multilayer printed wiring board, and more particularly to an improvement in the process of laminating copper foil to an inner layer material. 2. Description of the Related Art In recent years, as electronic devices have become more multifunctional and smaller, there has been an increasing demand for printed wiring boards used in these devices to have more layers and higher density. For this reason, there is a growing tendency for the wiring patterns of the surface circuits of printed wiring boards to become finer, and it is desired to develop means for preventing surface layer defects (for example, dents, etc.) that occur during lamination processing.

0002

2 is a diagram showing a conventional manufacturing process, in which FIG. 2(a) is an exploded cross-sectional view before lamination, and FIG. 2(b) is a cross-sectional view after lamination. In order to make the explanation of the configuration and operation easier to understand, the same parts are denoted by the same reference numerals throughout the drawings, and their repeated explanation will be omitted. In both figures (a) and (b), 1 is an inner layer material formed by forming a conductive wiring pattern 1a on the surface of the substrate (this figure shows an example with wiring patterns on both sides of the substrate), and 2 is A prepreg consisting of a semi-cured sheet made by impregnating a base material such as glass cloth or paper with a controlled insulating resin varnish and drying it,
It has the function of adhering and hardening the members overlapping on both sides by heat/pressure treatment. 3 is a copper foil for the surface layer, which is adhered to the surface of the inner layer material via the prepreg 2, and then a wiring pattern is formed on the surface of the copper foil according to a required procedure to form the layers of a multilayer printed wiring board. Reference numeral 4 denotes an intermediate plate made of stainless steel or the like which serves as a jig during the heating/pressure treatment, and the surface thereof is kept smooth and is used without adhesion of dust. 5 is a mold, which is placed facing each other on both upper and lower surfaces, and is heated/
It forms part of a press mechanism that performs pressure treatment. As shown in FIG. 2(a), each member is precisely overlapped using positioning pins, etc., and then placed between molds 5 and subjected to heating/pressure treatment to be hardened and molded as shown in FIG. 2(b). After this, the copper foil for the surface layer is formed into a wiring pattern via the required processing steps. Commercialized as a multilayer printed wiring board.

0003

In the conventional method for manufacturing multilayer printed wiring boards, the copper foil 3 for the surface layer and the intermediate plate 4 of the jig are treated as separate objects during the assembly work during lamination. However, minute dust, foreign matter, etc. may enter between the surface layer copper foil 3 and the intermediate plate 4 during assembly work, causing surface layer defects (for example, dents, etc.) after lamination. Therefore, surface layer defects generated during lamination pose a problem during surface circuit formation, resulting in problems such as short circuits and gap defects due to copper residue.

The present invention was made in view of the above-mentioned conventional problems, and is capable of improving the handling of copper foil for the surface layer during assembly work in the lamination process, and preventing defects in the surface layer after lamination. The purpose of this invention is to provide a method for manufacturing a multilayer printed wiring board.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention, as shown in FIG. A copper foil 3 for the surface layer is pasted through the copper foil 3 for the surface layer, an intermediate plate 4 serving as a jig is stacked on the surface of the copper foil 3 for the surface layer, and the intermediate plate 4 is sandwiched between the molds 5 and heated/pressurized. In the lamination process of the multilayer printed wiring board formed by
As shown in FIG. 1, an electrolytic copper foil 6 is formed on the surface of the intermediate plate 4 to a required thickness by electrolytic copper plating in advance.
The electrolytic copper foil 6 formed on the intermediate plate 4 is stacked on the prepreg 2, and the intermediate plate 4 is separated from the electrolytic copper foil 6 after being sandwiched between molds 5 and heated/pressurized. .

[0006]

[Operation] In the present invention, as shown in FIG. 1(b), an electrolytic copper foil is deposited on one side of the intermediate plate 4 in advance to a required thickness by electrolytic copper plating treatment, and this is deposited as is as shown in FIG. 1(c). After forming the laminate, the intermediate plate 4
is configured to be peeled off from the electrolytic copper foil 6. As a result, the surface layer copper foil is formed between the surface of the intermediate plate 4 in a dust-free state for plating precipitation, and can be laminated while being protected, resulting in a multilayer printed wiring board with no surface layer defects. Manufacturable.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing the manufacturing process of the present invention, and (a) shows a state where the intermediate plate 4 has been subjected to cleaning treatment in order to perform electrolytic plating treatment. Note that the intermediate plate 4 is a thin plate made of stainless steel or the like with a smooth surface so that the deposited electrolytic copper foil can be easily peeled off. (b) shows a state in which electrolytic copper foil 6 is deposited to a required thickness on one side of intermediate plate 4 as a result of electrolytic plating. In (c), prepregs 2 are stacked on both sides of the inner layer material 1, and an electrolytic copper foil 6 is placed on the surface of each prepreg 2.
The intermediate plate 4 is positioned so as to face each other, and the molds 5 are installed vertically. (d) shows the state in which the intermediate plate 4 is peeled off from the electrolytic copper foil 6 after forming a multilayer board by sandwiching the state in (c) using the molds 5 and performing heating/pressure treatment. , the description of the intermediate plate 4 and the mold 5 is omitted. The intermediate plate 4 side of the electrolytic copper foil 6 deposited on the smooth surface of the intermediate plate 4 is formed into a so-called glossy surface, and the opposite surface is a roughened surface due to the plating action. Therefore, the prepreg 2 can be in close contact with the roughened surface of the electrolytic copper foil 6, and the intermediate plate 4
Its adhesion to the electrolytic copper foil 6 is weak and can be easily peeled off.

[0008] The above explanation has been made for a multilayer printed wiring board with four layers, but in the case of a multilayer printed wiring board with more than four layers, electrolytic copper foil should be formed on both sides of the intermediate boards other than the top and bottom. It is necessary to do so. Alternatively, the surface circuits may be formed on the intermediate plate in advance and then laminated, thereby omitting the surface layer forming step.

[0009]

As is clear from the above description, according to the present invention, surface defects in the laminate can be prevented, and defects such as residual copper in the formation of surface circuits are eliminated, so that pattern refinement and yield improvement are effective.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the manufacturing process of the present invention.

FIG. 2 is a diagram showing a conventional manufacturing process.

[Explanation of symbols]

1 Inner layer material 1a Wiring pattern 2 Prepreg 3 Copper foil for surface layer 4 Intermediate plate 5 Mold 6 Electrolytic copper foil

Claims (1)

[Claims] Claim 1: Copper foil for the surface layer is attached to the surface of the inner layer material formed by forming a conductive wiring pattern on the surface of the base material through a prepreg, and the surface of the copper foil for the surface layer is cured. In the lamination process of a multilayer printed wiring board, which is formed by stacking intermediate plates that serve as ingredients, sandwiching the intermediate plates between molds, and applying heat/pressure, the copper foil for the surface layer is applied to the surface of the intermediate plate (4). Using an electrolytic copper foil (6) that has been previously formed to a required thickness by electrolytic copper plating, the electrolytic copper foil (6) formed on the intermediate plate (4) is stacked on the prepreg (2), and the mold (
5) A method for producing a multilayer printed wiring board, which comprises peeling the intermediate plate (4) from the electrolytic copper foil (6) after heating/pressurizing the intermediate plate.