JPH0738498B2 - Method for manufacturing printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a method of forming a conductor wiring pattern in a method of manufacturing a printed wiring board used for an electronic computer, an electronic device, etc., in which a panel plating layer plated on a copper-clad laminated substrate is plated. A first resist pattern having an opening for forming a conductor wiring thereon is formed, and an opening having a pattern width smaller than the pattern width of the opening is formed in the opening of the first resist pattern. A second resist pattern different from the one resist pattern is formed. Then, using the second resist pattern as a mask, a thick copper plating layer is formed on the exposed surface in the opening having a small pattern width, the second resist pattern is removed, and the first resist pattern is used as a mask. A solder plating layer is plated on the top and side surfaces of the plating layer. After that, the first resist pattern is removed, and the panel plating layer and the copper foil are patterned by a selective etching method using the solder plating layer as a mask, whereby a conductor having a high pattern accuracy in which overhang due to side etching is significantly reduced. The wiring pattern can be easily formed.

[Industrial application field]

The present invention relates to a method for manufacturing a printed wiring board used in an electronic computer, an electronic device or the like, and more particularly to a method for forming a conductor wiring pattern with good pattern accuracy on the printed board in which overhang due to side etching is reduced. is there.

Conventionally, printed wiring boards used in electronic computers and electronic devices have been miniaturized with electronic components to achieve high-density packaging, and the wiring density is also increased accordingly, so that conductor wiring patterns are further miniaturized. There is a tendency. Therefore, when forming a conductor wiring pattern, there is a need for a method capable of easily forming a fine conductor wiring pattern with good pattern accuracy by preventing overhang due to side etching that reduces the pattern accuracy. .

[Conventional technology]

Conventionally, as a method of forming a conductor wiring pattern on a copper-clad laminated board, as shown in FIG. 2 (a), the copper-clad laminated board 11 has a panel copper plating layer 13 plated on the copper foil 12 surface. The resist film 14 is applied.

Next, as shown in FIG. 2 (b), the resist film 14 is patterned to form a resist pattern 15 having an opening 15a for forming a conductor wiring, and then the opening is formed as shown in FIG. 2 (c). A copper plating layer 16 is plated on the area surface exposed from the portion 15a, and then a solder plating layer 17 is plated on the surface.

Thereafter, as shown in FIG. 2D, the resist pattern 15 is dissolved and removed, and the solder plating layer 17 is used as a metal resist mask to expose the panel plating layer 13 portion and the copper foil 12 portion immediately thereunder. Is removed by etching with, for example, an alkaline etching solution.
A conductor wiring pattern 18 is formed as shown in FIG.

[Problems to be solved by the invention]

By the way, in the above-described conventional method for forming the conductor wiring pattern 18, the portion of the panel copper plating layer 13 exposed to the surroundings using the solder plating layer 17 as a metal resist mask and the portion of the copper foil 12 immediately thereunder are patterned by a chemical etching method. Therefore, not only the side surface of the panel copper plating layer 13 portion and the copper foil 12 portion immediately therebelow to be etched, but also the thick copper plating layer 16 side surface is dissolved and eroded by side etching, and the solder plating layer 17 is a side surface. An overhang occurs when it overhangs in the direction.

The pattern width of the conductor wiring pattern 18 formed by such an overhang is partially thinned, and there is a drawback that the electric resistance increases or a disconnection occurs. Further, the solder plating layer 17 portion which is bulged in the lateral direction due to the overhang is easily removed by the pretreatment process of the subsequent solder resist coating, and the solder plating layer is dropped in the solder resist coating process, and the dropped solder fillet is the conductor wiring. It was a cause of a short circuit between them.

In order to solve the above-mentioned conventional drawbacks, the present invention uses a mask pattern formed of two kinds of photoresists for forming a conductor wiring pattern, and when plating a solder plating layer on a thick copper plating layer, By covering the side surface of the thick copper plating layer with the solder plating layer as well, overhang due to side etching is prevented from occurring, and a new printed wiring board that can easily form a conductor wiring pattern with good pattern accuracy without solder fillet It is intended to provide a manufacturing method.

[Means for solving problems]

In order to achieve the above object, the present invention forms a first resist pattern having an opening for forming a conductor wiring on a panel plating layer plated on a copper foil surface of a copper-clad laminated substrate, and the first resist At least the opening of the pattern is filled with a second resist film different from the first resist, and the second resist film in the opening is patterned to a pattern width smaller than the pattern width of the opening to obtain a pattern width. Forming a second resist pattern having a small opening. Next, using the second resist pattern as a mask to form a thick copper plating layer on the surface exposed from the opening, the second resist pattern is removed, and the first resist pattern is used as a mask to form the copper plating layer. A solder plating layer is plated on the top and side surfaces.

Then, the first resist pattern is removed, and the panel plating layer and the copper foil are patterned in the selective etching direction using the solder plating layer as a mask to form a conductor wiring pattern.

[Action]

In the method for forming a conductor wiring pattern of the present invention, when the solder plating layer is used as a metal resist mask to pattern the panel plating layer and the copper foil by a selective etching method, the metal resist mask has a surface of the thick copper plating layer. Of course, since the side surface is also covered, the side surface of the region to be side-etched is only the side surface of the panel plating layer and the copper foil to be patterned, and the side-etching is significantly reduced. Therefore, the overhang due to the side etching is greatly reduced, and the short circuit damage due to the solder fillet is also eliminated.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIGS. 1 (a) to 1 (g) are cross-sectional views of essential parts showing, in the order of steps, one embodiment of a method for forming a conductor wiring pattern in the production of a printed wiring board according to the present invention.

First, as shown in FIG. 1 (a), the copper foil of the copper-clad laminated substrate 11
A first resist pattern 2 having an opening 21a for forming a conductor wiring is formed by applying a first resist film on the panel copper plating layer 13 plated on the 12th surface and patterning the first resist film.
Forming a one.

Next, as shown in FIG. 1 (b), the first resist pattern is formed.
A second resist film 22, which is different from the first resist film forming the first resist pattern 21 and is not dissolved in a solvent that dissolves the first resist pattern 21, is formed in at least the opening 21a of the screen 21, for example, by screen printing. Coating (filling) by a method or the like, and then patterning the second resist film 22 in the opening 21a to a pattern width smaller than the pattern width of the opening 21a as shown in FIG. 1 (c). Second resist pattern 23 having opening 23a having a small pattern width
To form.

Then, using the second resist pattern 23 as a mask, a thick copper plating layer 24 is formed by plating on the surface exposed in the opening 23a.

Next, as shown in FIG. 1 (d), the second resist pattern 23 is dissolved and removed by a peeling wave that does not dissolve the first resist pattern 21, and then the first resist pattern 23 is removed as shown in FIG. 1 (e). Using the mask 21 as a mask, the solder plating layer 25 is screwed on the upper surface and the side surface of the copper plating layer 24.

Then, as shown in FIG. 1 (f), the first resist pattern 21 is dissolved and removed, and the solder plating layer 25 is used as a metal resist mask to select the panel plating layer 13 and the copper foil 12 with an alkaline etching solution. The conductive wiring pattern 26 is formed by mechanically etching and patterning as shown in FIG.

In such a forming method, since the panel plating layer 13 and the copper foil 12 are patterned by using the solder plating layer 25 plated on the upper surface and the side surface of the copper plating layer 24 as a metal resist mask, side etching is performed. Since the number is remarkably reduced and the overhang is also significantly reduced, it is possible to easily form the conductor wiring pattern 26 with good pattern accuracy.

In the above embodiments, an example of forming a conductor wiring pattern on a single-sided copper-clad laminated substrate has been described, but the present invention is not limited to this example, and for example, a land pattern forming step or Needless to say, the same effect can be obtained in the step of forming the conductor wiring pattern on the double-sided copper-clad laminated board or the multilayer laminated board.

〔The invention's effect〕

As is clear from the above description, according to the method for forming a conductor wiring pattern in the production of a printed wiring board according to the present invention, the side-etched area surface when forming the conductor wiring pattern is significantly reduced. Also, the overhang due to side etching is significantly reduced, a conductor wiring pattern with good pattern accuracy can be easily formed, and the short circuit damage due to the solder fillet caused by the overhang can be eliminated. .

[Brief description of drawings]

1 (a) to 1 (g) are cross-sectional views of a main part showing an embodiment of a method of forming a conductor wiring pattern in manufacturing a printed wiring board according to the present invention in the order of steps, and FIGS. 2 (a) to 2 (e). FIG. 6 is a cross-sectional view of an essential part for explaining a method of forming a conductor wiring pattern in manufacturing a conventional printed wiring board in the order of steps. 1 (a) to (g), 11 is a copper-clad laminated substrate, 12 is a copper foil, 13 is a panel copper plating layer, 21 is a first resist pattern, 21a and 23a are openings, 22
Is a second resist film, 23 is a second resist pattern, 24 is a copper plating layer, 25 is a solder plating layer, and 26 is a conductor wiring pattern.

Claims (1)

[Claims] 1. A method of forming a conductor wiring pattern (26) on a copper-clad laminated board (11), comprising a panel plating layer (13) plated on the copper foil (12) surface of the copper-clad laminated board (11). A step of applying a first resist film thereon and patterning the first resist film to form a first resist pattern (21) having an opening (21a) for forming a conductor wiring; and the first resist pattern At least the opening (21a) of (21) is filled with a second resist film (22) different from the first resist film, and the second resist film (22) in the opening 21a is filled with the second resist film (22). 21a) is patterned to a pattern width smaller than that of the second resist pattern (2a) having an opening (23a) having a small pattern width.
3) forming step and the second resist pattern (23)
Forming a copper plating layer (24) on the exposed surface of the panel plating layer (13) using the mask as a mask, removing the second resist pattern (23), and removing the first resist pattern (2).
After performing a step of forming a solder plating layer (25) on the upper and side surfaces of the copper plating layer (24) using the mask 1) and a step of removing the first resist pattern (21), the solder Using the plating layer (25) as a mask, the panel plating layer (1
A method for manufacturing a printed wiring board, which comprises sequentially removing 3) and the copper foil (12) by etching.