JPS63305589A - Forming method for printed wiring part - Google Patents

Abstract

PURPOSE:To make a wiring part of a desired pattern formable uniformly and in high density, by forming a specific photoresist layer as well as a photoresist layer formed in a desired wiring pattern and next performing an etching process when a conductive foil is etched in a wiring pattern shape. CONSTITUTION:A first photoresist layer 3 with a desired wiring pattern is formed on a conductive foil 2 stuck on an insulation layer 1, and a second photoresist layer 4 is formed in the vicinity of the layer 3 part which corresponds to the conductive film 2 and is subject to operation of large side etching. A nearly patterned conductive foil 5 corresponding to the layer 3, and a conductive foil 6 corresponding to the layer 4, are formed during formation of this etching pattern, and the conductive foil 6 is provided with the operation of large side etching so as to become thinner. As the etching process proceeds more, the foil 6 disappears, and a wiring part 7 with a desired wiring pattern can be obtained almost at the same time. Hence etching operation of an unavailingly large side can be avoided to uniformly form a high density printed wiring part 7.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method of forming a printed wiring section.

[Summary of the invention]

The present invention provides a method for forming a printed wiring section in which, when etching a conductive foil into a wiring pattern, etching is performed after forming a specific photoresist layer in addition to the photoresist layer formed in the desired wiring pattern. This makes it possible to form wiring portions in a desired pattern with high density and uniformity.

[Conventional technology]

2. Description of the Related Art As electronic devices having various printed wiring sections become smaller and lighter, there is an increasing demand for higher density printed wiring sections. This printed wiring part is, for example, the wiring part of a sheet coil,
It is formed as an external lead electrode wiring part of an IC component, a wiring part of other printed wiring boards, etc. Printed wiring is generally formed by etching a conductive foil into a desired high-density pattern. When etching conductive foil into a high-density pattern, in order to suppress side etching and increase the etching speed in the thickness direction, for example, the spray pressure of the etching solution is increased to increase the impact force, or the etching solution is applied to the target object. Methods such as applying it for a long time and constantly applying fresh etching solution are used.

[Problem that the invention seeks to solve]

It is extremely difficult to form uniform high-density printed wiring by any of the conventional methods.

For example, as shown in FIG. 4, when a photoresist layer 8 having a high-density wiring pattern for a sheet coil is formed on a copper foil 2 bonded to an insulating layer 1, the outermost (right end in the drawing)
There is a large space outside the photoresist layer 8 located at the photoresist layer 8 compared to the space between each photoresist layer 8 . copper foil 2
When etching is performed, the copper foil portions corresponding to the photoresist layers 8 other than the rightmost photoresist layer 8 are formed into uniform wiring portions 7, but the copper foil portions corresponding to the rightmost photoresist layer 8 have significant side edges. Since the etching action is applied from the right side, the wiring part 9 is formed to have an abnormal side etching part 10 which is narrower than the wiring part 5.

Therefore, a problem arises in that it is difficult to route the printed wiring section obtained in this way according to the same pattern rule.

It is an object of the present invention to provide a method for forming uniform printed wiring, particularly high density printed wiring.

[Means for solving problems]

The object of the present invention is to provide a method for forming a printed wiring part comprising forming a photoresist layer on a conductive foil adhered to an insulating layer, etching the conductive foil, and removing the photoresist layer. a first photoresist layer in which the resist layer is formed in a desired wiring pattern;
This is achieved by a method of forming a printed wiring section characterized in that the second photoresist layer is formed in the vicinity of a first photoresist layer section corresponding to a conductor foil section that is susceptible to a large side etching effect.

The conductor foil portions that are susceptible to large side etching effects include, for example, the outermost wiring portion in the high-density wiring pattern of a sheet coil and the outermost wiring portion of the high-density electrode wiring portion drawn to the outside of an RC component. Refers to the part of the conductor foil adjacent to the space larger than the space between each wiring part.

The second photoresist layer is formed such that the conductor foil portion corresponding to the second photoresist a disappears by the etching process when the conductor foil portion of the desired wiring pattern corresponding to the first photoresist layer is formed by the etching process. It is preferable to form the That is, the conductor foil portion corresponding to the second photoresist layer exists as a dummy pattern during the etching process, serving to protect the conductor foil portion that is disadvantageously susceptible to large side etching effects.

A second photoresist layer is formed adjacent to the first photoresist layer, preferably at a distance equal to the distance between each first photoresist layer.

〔Example〕

Examples of the present invention are shown below.

1, a first photoresist layer 3 having a desired wiring pattern and a first photoresist layer 3 having a desired wiring pattern are deposited on a copper N2 having a thickness of about 35 μm bonded to a glass-epoxy resin insulation N1 having a thickness of about 0.5 μm. A second photoresist layer 4 was formed separated from the first photoresist layer 3 by the distance between each resist layer 3. Each first photoresist layer 3 has a width of about 100 μm and is formed at intervals of about 20 μm, and each second photoresist layer 4 has a width of about 80 μm.

Next, the two portions of the copper foil were etched with an etching solution at 45°C for 30 seconds at a spray pressure of 4 kg/cm''.

The etching solution was FeCIz concentration 28-40%, II
An aqueous solution containing 5% cI tH and a small amount of surfactant was used. During this etching process, first, as shown in FIG. Been formed. Copper foil layer 6 is another copper foil layer 5
It is narrowed due to the side etching effect which is larger than the main part.

As the etching process further progressed, the wiring section 7 having the desired wiring pattern was obtained almost at the same time as the copper foil layer 6 disappeared. The thickness of this wiring part 7 is 30 to 35 meters! m (Figure 1C). Finally, the remaining first photoresist layer 3
was removed (Fig. 1D).

The wiring portion 7 thus obtained is usually subjected to electroplating.

In order to make it easier to understand the arrangement of the first photoresist layer 3 and the second photoresist layer 4 in this example, FIGS. 2 and 3 show examples of forming the lead electrode wiring portions of sheet coils and IC components, respectively. For each photoresist layer 3.4 is shown.

〔Effect of the invention〕

As described above, according to the present invention, the undesirably large side etching effect, which has been a problem in the prior art, can be avoided, and a high-density printed wiring portion can be uniformly formed.

[Brief explanation of the drawing]

1A to 1D are cross-sectional views showing the steps of an embodiment of the present invention, FIGS. 2 and 3 are plan views showing the first and second photoresist layers of the embodiment, and FIG. FIG. 2 is a cross-sectional view showing a process according to a conventional method. In addition, in the symbols used in the drawings, 1.--..--m-.--insulating layer 2-.-.
····························Copper foil 3····················· 1st photoresist layer 4····················································································································. Second photoresist layer 7 --- wiring section.

Claims (1)

[Claims] A method for forming a printed wiring section comprising forming a photoresist layer on a conductive foil adhered to an insulating layer, etching the conductive foil, and removing the photoresist layer, wherein the photoresist layer is formed into a desired wiring pattern. A first photoresist layer formed in a shape, and a second photoresist layer formed in the vicinity of a portion of the first photoresist layer corresponding to a portion of the conductor foil that is susceptible to large side etching effects. A method of forming a printed wiring section.