JPH1197842A - Manufacture of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a printed wiring board, which is of high density and reliability and corrosion resistance of which are superior by a method, wherein a conductor layer is formed on the inner wall of a through-hole formed so as to cross a dividing line in such a way that the dividing line is excluded. SOLUTION: First, a through-hole is opened in an insulating board 1. In succession, resist layers are formed on parts in which wiring patterns 3 on the surface and the rear of every block are not required and on a part, in which a conductor layer 4 on the inner wall of the through-hole formed so as to cross a dividing line, is not required. Then, plated layers are formed on both faces of the board 1 and on a part which is not covered with the resist layers on the inner wall surface of the through hole. As a result, wiring patterns 3 are formed respectively on the surface and the rear of every block, and the conductor layer 4 which connects the respective wiring patterns 3 is formed on the inner wall of the through-hole, so as to cross the dividing line in such a way that the dividing line is excluded. Then, surface protective layers are executed to the insulating board 1, the wiring patterns 3, the conductor layer 4 and the like. Lastly, the insulating board 1 is cut along the dividing line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board having a high density and excellent reliability and corrosion resistance.

[0002]

2. Description of the Related Art Conventionally, an insulating substrate 1 having a through hole 8 is divided into blocks by a plurality of vertical and horizontal dividing lines 7, and a wiring pattern 3 of a target printed wiring board is formed on the front and back surfaces of each block. A plate is formed and connected between the wiring patterns 3 on both sides via the conductor layer 4 formed entirely on the inner wall of the through hole 8 (see FIG. 3), and after performing a surface protection treatment, This board is cut along a dividing line 7 with a cutting tool such as a press, a router, a slicer or the like to obtain a printed wiring board (see FIG. 4. In the drawing, the surface of the conductor layer and the wiring pattern is subjected to surface protection treatment. In order to clearly show the situation, a broken portion is provided.).

In the above method, in order to increase the density of the printed wiring board, some of the through holes 8 are formed so as to straddle the dividing lines 7 and are shared by the wiring patterns 3 of adjacent blocks. .

[0004]

However, according to the conventional method, since the conductor layer 4 is formed entirely on the inner wall of the through hole 8 formed so as to straddle the dividing line 7, the through hole 8 is formed. In the semicircular notch 2 obtained on the outer end face of the printed wiring board by cutting along the dividing line 7, defects such as burrs, burrs, frays, and rubs occur in the conductor layer 4, and the printed wiring board is The reliability was inferior to those not cut at the through hole 8.

The surface of the conductor layer 4 is subjected to a surface protection treatment to form a solder resist layer 5, a solder leveler layer 6, and the like. The inner wall of the through hole 8 formed so as to extend over the dividing line 7. Since the conductor layer 4 is entirely formed in the semicircular cutout 2 obtained by cutting the through hole 8 along the dividing line 7 at the outer end face of the printed wiring board, The conductor layer 4 under the surface protection treatment layer such as the solder resist layer 5 and the solder leveler layer 6 was exposed, and the printed wiring board was inferior in corrosion resistance as compared with the one not cut by the through hole 8.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a method for manufacturing a printed wiring board having high density and excellent in reliability and corrosion resistance.

[0007]

In order to achieve the above-mentioned object, the present invention provides an insulating substrate having a through hole divided into a plurality of vertical and horizontal dividing lines, and the object is provided on the front and back surfaces of each block. The wiring patterns of the printed wiring board to be formed are respectively formed, and the wiring patterns on both sides are connected via a conductor layer formed on the inner wall of the through hole, and some of the through holes are formed so as to straddle the dividing line and are adjacent to each other. In a method of manufacturing a high-density printed wiring board by manufacturing a board shared by wiring patterns of matching blocks, performing a surface protection treatment, and cutting the board along the dividing lines, The conductor layer was formed on the inner wall of the through hole formed so as to straddle, except on the dividing line.

Further, in the above configuration, the conductor layer is formed on the periphery of the opening on the front surface and the back surface of the through hole formed so as to straddle the dividing line, except on the dividing line.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a printed wiring board according to the present invention will be described in detail.

In one embodiment of the process for manufacturing a printed wiring board according to the present invention, first, an insulating substrate cut to a predetermined size and having, for example, copper foil laminated on both surfaces is prepared. Insulation materials include paper base phenolic resin, paper base epoxy resin, synthetic fiber cloth base epoxy resin, glass cloth / paper composite base epoxy resin, glass cloth / glass nonwoven composite base epoxy resin, glass cloth base Epoxy resin and the like.

Next, a through hole is formed in the insulating substrate.
At this time, the insulating substrate is divided into blocks by a plurality of vertical and horizontal dividing lines, and some of the through holes are formed so as to straddle the dividing lines. The through holes formed so as to straddle the dividing lines are shared by wiring patterns formed in adjacent blocks.
Note that the above dividing line may be a virtual line without actually drawing. As a method of opening a through hole, there is a drill or the like.

Subsequently, a plating layer of copper or the like is formed on each copper foil and on the inner wall surface of the through hole by electroless plating, electrolytic plating, or the like.

Next, a portion to be left as a wiring pattern on the front surface and the back surface of each block and a portion to be left as a conductor layer connecting between the wiring patterns on the inner wall of a through hole formed so as to straddle the dividing line are etched. A resist layer is provided. The part to be left as the conductor layer on the inner wall of the through hole formed so as to straddle the dividing line is
This is a part excluding the parting line.
For a 6 mm through hole, a width of about 0.1 to 0.3 mm is excluded. As the etching resist layer, a general etching resistant material is used.

Next, portions of the plating layer and the copper foil not covered with the etching resist layer are removed by etching.
In this step, an appropriate etching agent, for example, an alkaline etching solution such as ammonium persulfate, ammonium, or ammonium chloride, or an acidic etching solution such as cupric chloride, ferric chloride, a mixed solution of chromic acid / sulfuric acid, or a mixed solution of hydrogen peroxide / sulfuric acid is used. An etching solution or the like is used.

Further, by removing the etching resist layer, a desired wiring pattern of a printed wiring board is formed on the front and back surfaces of each block, and each wiring pattern is formed on an inner wall of a through hole formed so as to straddle the dividing line. A conductor layer connecting the wiring patterns is formed except on the dividing line. In this step, an appropriate release agent, for example, an organic solvent such as methylene chloride, glycol ether, a mixed solvent thereof, or a mixed solution thereof with an aqueous alkali solution such as sodium hydroxide or potassium hydroxide is used.

Next, a surface protection treatment is performed on the insulating substrate 1, the wiring pattern 3, the conductor layer 4, and the like. For example, a solder resist layer 5 is partially formed on the insulating substrate 1, the wiring pattern 3, and the conductor layer 4, and the solder leveler layer 6 is formed on portions of the wiring pattern 3 and the conductor layer 4 that are not covered with the solder resist layer 5. Form.

Finally, by cutting this board along the dividing lines, a large number of high-density printed wiring boards can be obtained. Examples of the cutting means include a die press, a router, and a slicer.

As described above, according to the method of manufacturing a printed wiring board of the present invention, the board having the conductor layer formed on the inner wall of the through hole except for the parting line is cut along the parting line. 4 is not contacted, and only the insulating substrate 1 is cut (see FIG. 1). Therefore, in the notch 2 on the outer end surface of the printed wiring board obtained by cutting the through hole,
Defects such as burrs, burrs, frays, and rubs do not occur on the conductor layer 4 formed on the inner wall. Further, the conductor layer 4 under the surface protection treatment layer such as the solder resist layer 5 and the solder leveler layer 6 is not exposed from the cut surface.

Further, the present invention is not limited to the embodiment in which the conductor layer on the inner wall of the through hole is patterned using the etching resist layer described above. For example, the conductor layer on the inner wall of the through hole is patterned using the plating resist layer. It can also be patterned.

Specifically, first, an insulating substrate cut to a predetermined size is prepared. Note that no copper foil is laminated on both surfaces of the insulating substrate.

Next, through holes are formed in the insulating substrate in the same manner as in the method using the etching resist layer.

Subsequently, a resist layer is provided on an unnecessary portion of the wiring pattern on the front and back surfaces of each block, and on an unnecessary portion of the conductor layer on the inner wall of the through hole formed so as to straddle the dividing line. The unnecessary portion of the conductor layer on the inner wall of the through hole formed so as to straddle the dividing line is a portion on the dividing line. For example, a through hole having a diameter of 0.6 mm has a width of 0.1 to 0.1 mm. It is about 0.3 mm.
As the resist layer, a plating-resistant material that does not deposit a plating layer thereon even after plating is used.

Next, a plating layer is formed by electroless plating, electrolytic plating, or the like, on both surfaces of the substrate and on the inner wall surfaces of the through holes that are not covered with the resist layer. as a result,
A wiring pattern of a target printed wiring board is formed on the front and back surfaces of each block, and a conductor layer connecting between the wiring patterns is formed on an inner wall of a through hole formed so as to straddle the dividing line except on the dividing line. It is formed.

Next, a surface protection treatment is performed on the insulating substrate 1, the wiring pattern 3, the conductor layer 4, and the like.

Finally, this board is cut along the dividing lines in the same manner as in the method using the etching resist layer, whereby a large number of high-density printed wiring boards can be obtained.

Further, the conductor layer on the inner wall of the through hole can be removed and patterned along the dividing line by a laser beam or the like without using the etching resist layer, and the method of patterning the conductor layer on the inner wall of the through hole is not particularly limited. .

In the printed wiring board shown in FIG.
The conductor layer 4 is also formed on the periphery of the notch 2 on the front and back surfaces, but the conductor layer 4 is not provided on the periphery of the notch 2 and the conductor layer 4 on the inner wall of the notch 2 and the wiring pattern 3 May be directly connected (see FIG. 2). In other words, a plate having the conductor layer 4 formed on the periphery of the opening on the front surface and the back surface of the through hole formed so as to straddle the dividing line is formed and cut off.

[0028]

The method for producing a printed wiring board according to the present invention comprises:
With the above configuration and operation, the following effects are achieved.

That is, according to the present invention, in a method for manufacturing a high-density printed wiring board, a board having a conductor layer formed on an inner wall of a through hole except for a parting line is cut along the parting line. And the conductor layer do not contact, and only the insulating substrate is cut.

Therefore, in the cutout portion on the outer end surface of the printed wiring board obtained by cutting the through hole, the conductor layer formed on the inner wall does not have defects such as burrs, burrs, frays, and rubs, and the reliability is improved. A printed wiring board having excellent properties can be obtained.

Further, in the cutout portion on the outer end surface of the printed wiring board obtained by cutting the through hole, the conductor layer under the surface protection treatment layer such as the solder resist layer and the solder leveler layer is not exposed from the cut surface, so that the corrosion resistance is reduced. An excellent printed wiring board can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view showing one embodiment of a printed wiring board obtained by a manufacturing method according to the present invention.

FIG. 2 is a partially enlarged view showing another embodiment of the printed wiring board obtained by the manufacturing method according to the present invention.

FIG. 3 is a view showing an embodiment of a board obtained by taking a large number of printed wiring boards according to the prior art.

FIG. 4 is a partially enlarged view showing one embodiment of a printed wiring board obtained by a manufacturing method according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulating board 2 Notch 3 Wiring pattern 4 Conductor layer 5 Solder resist layer 6 Solder leveler layer 7 Separation line 8 Through hole

Claims (2)

[Claims] An insulating substrate having a through hole is divided into blocks by a plurality of vertical and horizontal dividing lines, and a wiring pattern of a target printed wiring board is formed on a front surface and a back surface of each block, respectively. The board is connected through a conductor layer formed on the inner wall of the through-hole, and some of the through-holes are formed so as to straddle the dividing line, and a board shared by the wiring patterns of the adjacent blocks is produced. In the method of manufacturing a high-density printed wiring board by performing a protection process and then cutting the board along the dividing line, the inner wall of a through hole formed so as to straddle the dividing line, excluding the part on the dividing line A method of manufacturing a printed wiring board, wherein a conductive layer is formed by a conductive layer. 2. The method for manufacturing a printed wiring board according to claim 1, wherein a conductor layer is formed on the periphery of the opening on the front surface and the back surface of the through hole formed so as to straddle the dividing line, except on the dividing line.