JP2003046225A - Method of manufacturing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a printed wiring board which is capable of ensuring pattern insulation for a wiring pattern, and improving a gap between the wiring patterns in transparency so as to improve the wiring board in part mounting density. SOLUTION: A laminate composed of a conductor layer 2 and an insulating layer 1 is used, and an interface between the layers 1 and 2 is roughened. A required wiring pattern 3 is provided to the conductor layer 2, and the roughened surface of the insulating layer 1 located at a gap G between the wiring patterns 3 is smoothed by the use of a chemical method or the like. When a smoothing operation is carried out, conductor residues 4 are removed.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print capable of securing insulation between wiring patterns and improving the transparency of a gap portion between the wiring patterns to increase the component mounting density. The present invention relates to a method for manufacturing a wiring board. 2. Description of the Related Art A conductor laminated plate having a conductor layer and an insulating layer laminated thereon has a physical / chemical interface adhesion strength to ensure the adhesion strength between the conductor layer and the insulation layer. Means to increase are adopted. As a method of physically increasing the adhesion strength, a method of increasing the contact area of the interface is used. For example, a surface of a conductor layer such as a metal foil, which is in close contact with an insulating layer before being adhered, is roughened by a physical or chemical method to increase the surface area, and a single insulating layer is adhered or insulated thereto. This is a method of casting and coating the layer. In the case of a printed wiring board in which a wiring pattern is formed using the above-described conductor laminate, the surface shape of the insulating layer exposed between the wiring patterns (hereinafter referred to as a gap) depends on the shape of the conductive layer. The shape is a replica of the sparsed shape, that is, a rough shape. [0005] If the roughened shape of the interface of the conductor laminate is too rough, a conductor residue may remain in the concave portion of the gap when a wiring pattern is formed by, for example, a chemical etching method. If the conductor residue extends between adjacent wiring patterns, the wiring pattern will be short-circuited. When the wiring pattern does not extend over the adjacent wiring pattern or is isolated from the wiring pattern, sufficient insulation between the wiring patterns may not be ensured even if the wiring pattern is not short-circuited. [0007] In order to completely remove the conductor residue between the gaps, it is necessary to perform sufficient etching for forming the wiring pattern. However, even if the upper part of the wiring pattern is protected by the etching resist, the etching is performed in the lateral direction of the etching medium. When the amount of etching is increased, etching proceeds in the horizontal direction, and the width of the wiring pattern becomes thinner. On the other hand, a rough surface of the insulating layer replicating the roughened shape of the conductor layer scatters transmitted light from a smooth surface, and thus has a problem of low transparency. In mounting electric components, image recognition is generally used for positioning components, and a circuit board having a large image contrast difference is required. In recent years, since the mounting density of electric components has been increasing, it is necessary to improve the accuracy of image recognition. Further, a technique for increasing the transmittance of the surface of the gap insulating layer has been required. Therefore, the transmittance can be improved by reducing the unevenness on the surface of the insulating layer. However, reducing the unevenness of the conductive layer and reducing the contact area at the interface between the conductive layer and the insulating layer can be achieved by removing the interface. It is not preferable because the strength is reduced and the reliability of the circuit to be miniaturized is further reduced. Therefore, according to the present invention, after forming a wiring pattern as a circuit, the roughened surface of the insulating layer in the gap portion is smoothed by using a chemical or other method, and the conductive residue is efficiently removed at the time of the smoothing. An object of the present invention is to provide a method of manufacturing a printed wiring board which can be removed and the transparency of a gap portion can be improved. [0012] For this purpose, in the method of manufacturing a printed wiring board according to the present invention, a laminated board in which the interface between a conductor layer and an insulating layer is roughened is prepared, and After forming a required wiring pattern, a method of smoothing the roughened surface of the insulating layer surface in a gap portion between the wiring patterns by using a chemical or other method and removing a conductor residue at the time of the smoothing is adopted. It was done. The present invention will be further described below with reference to the illustrated embodiments. FIG. 1 is a view showing a manufacturing process of a printed wiring board according to the present invention. As shown in FIG. 1A, in order to increase the adhesion strength between the conductor layer 2 and the insulation layer 1, the conductor layer 2 and the insulation layer 1 are formed. A laminate having an interface roughened is prepared. Using this laminate as a starting material, a wiring pattern 3 as a circuit is formed as shown in FIG. For example, a liquid or film-shaped photosensitive etching resist layer is placed on the upper surface of the conductor layer 2, the resist layer is partially cross-linked by ultraviolet light or the like, and then development is performed to remove unnecessary portions of the resist. The wiring layer 3 is formed by removing the conductor layer 2 by etching. FIG. 2B shows that the surface of the insulating layer 1 is roughened as a replica of the unevenness of the roughened surface in the wiring pattern 3 which was a conductor layer. In addition, a state is shown in which the conductor layer residue 4 that cannot be completely removed by chemical etching is partially left on the roughened surface of the insulating layer 1. However, in the form of FIG. 2B, the transmitted light incident from the lower side of the figure is scattered by irregularities on the surface of the insulating layer 1 and has poor transparency. Further, in order to completely remove the conductor layer residue 4 that cannot be completely removed by etching in FIG. 2B, it is necessary to further add etching of the conductor layer.
Is thin in the width direction. Therefore, the state of FIG.
Is preferentially removed, and the roughened surface of the unevenness is smoothed as shown in FIG. In the case of a flexible copper foil circuit board, for example, Espanex (Nippon Steel Chemical Co., Ltd.), Neoflex (Mitsui Toatsu Chemical Co., Ltd.)
In such a case, the conductor layer 2 is made of copper and the insulating layer 1 is made of a polyimide resin. In this case, as a method of removing the polyimide, a method of chemically etching the polyimide can be preferably used. As the polyimide etching solution, many chemical solutions such as an alkali-hydrazine etching solution, a urea-alkali metal etching solution, and a mixed solution of an aliphatic alcohol and dimethylformamide are known. These chemicals can easily remove polyimide by etching.
The etching ability with respect to copper for forming the wiring pattern is significantly low with respect to the copper etchant, and there is little or almost no possibility that the wiring pattern 3 is made thinner than necessary. When the polyimide is removed by etching as described above, the surface of the insulating layer 1 in the gap G between the wiring patterns 3 becomes a smoothed gap 5 which is smoothed to the original unevenness, and the transmission on the surface is achieved. Since light scattering is reduced, the transparency of the polyimide is increased. Moreover, although the conductor layer residue 4 itself isolated in the concave portion is not directly etched away by this etching solution, the insulating layer polyimide around the residue 4 is removed by etching away from the polyimide surface.
It is separated from the gap G as a result. When the method for manufacturing a printed wiring board according to the present invention is adopted, the roughened surface of the insulating layer in the gap portion is smoothed by using a chemical or other method. By efficiently removing the conductor residue, the insulation between the wiring patterns can be sufficiently secured without making the wiring pattern width narrower than necessary. Further, since the transparency of the gap portion can be improved, image recognition at the time of mounting the electric component becomes easy, and the accuracy of the image recognition can be increased, so that the reliability of the component mounting can be increased. As a result, the component mounting density can be increased.

[Brief description of the drawings] FIG. 1 is a manufacturing process diagram of a printed wiring board according to the present invention. [Explanation of symbols] 1 insulating layer 2 conductor layer 3 Wiring pattern 4 residue 5 Smoothing gap G gap

Claims (1)

Claims: 1. A laminate having a roughened interface between a conductor layer and an insulating layer is prepared, and after a required wiring pattern is formed on the conductor layer, the laminate is formed in a gap between the wiring patterns. A method for manufacturing a printed wiring board, characterized in that a roughened surface of the insulating layer surface is smoothed, and a conductor residue is removed during the smoothing.