JP2000174434A - Manufacture of circuit substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide with high positional accuracy a method for manufacturing a circuit substrate which can accurately make fine through-holes for positioning of the substrate. SOLUTION: A circuit wiring pattern 3 is formed on one surface of a flexible insulating base material 1, and an isolated conductor piece 4 is formed together with the pattern 3, so as not to be connected to the pattern 3 and to cover sites corresponding to through-holes to be made in a positional relation with connecting terminal parts 9 of the pattern 3. Then, an opening 7 for the through- holes is made simultaneously as with the formation of openings 6 for the formation of connecting terminal parts 9 of the pattern 3, and subsequently the conductor piece 4 is removed in a final step to made the required through-holes.

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 circuit board capable of forming a fine through-hole provided for alignment of a circuit board or the like with high positional accuracy and high accuracy.

[0002]

2. Description of the Related Art In a certain type of flexible circuit board, for example, a required circuit wiring pattern 21 is formed on one surface of a flexible insulating base material 20 as shown in FIG. A connection terminal portion 22 is formed such that one end is joined to a part of the circuit wiring pattern 21 and the other end is exposed through the flexible insulating base material 20. A surface treatment layer 24 is formed on the exposed surface by plating means using a member having high corrosion resistance such as gold, and the surface of the circuit wiring pattern 21 is protected by using an insulating film or resin on an outer surface of a predetermined region. A layer 23 is formed, and a surface treatment layer is formed on the exposed surface of the circuit wiring pattern 21 by plating means using a highly corrosion-resistant member such as gold to be another connection terminal. 25, and in the positional relationship with the connection terminal portion 22 described above. Flexible insulation base - is a predetermined portion of the scan material 20 has those provided with through-holes 26, the through hole 26
Is used for positioning the circuit board.

[0003] With the increase in the density and miniaturization of the circuit board as described above, the through-hole 26 provided for alignment of the circuit board and the like is also required to be miniaturized, and high precision and high density are required. ing. As a means for forming such a through hole 26, generally, a mechanical processing method such as a drill or a mold is used.

[0004]

However, when the above-described through-hole is formed, as shown in FIG. 3, in the final step of manufacturing the above-mentioned flexible circuit board, a point indicated by an arrow is formed using a drill, a mold or the like. If a through-hole is formed in such a manner, it is extremely difficult to ensure the positional accuracy between the through-hole and the connection terminal portion 22. Such a problem of positional accuracy becomes more remarkable as the through holes and the connection terminal portions 22 become finer and have higher densities.

In order to improve the positional accuracy between the through hole and the connection terminal portion 22, for example, as shown in FIG. 4, at a halfway stage after forming the circuit wiring pattern 21 and the surface protection layer 23, as shown in FIG. It is advantageous to form the through-hole 26 simultaneously with the opening 27 for forming the connection terminal 22. In this method, the through-hole 26 is formed in the step for forming the surface treatment layer 24 and the like. Problems such as spillage of chemicals occur, which is an obstacle.

As a method of solving such a problem, for example, a method of closing a through hole provided in advance by filling a suitable member or the like can be considered. In this method, such a through hole is made finer and provided at a high density. In such cases, adoption is extremely difficult, and even if it is possible, an increase in manufacturing cost is inevitable.

The present invention provides a method of manufacturing a circuit board capable of forming a fine through-hole provided for alignment of the circuit board with high positional accuracy and high accuracy while solving the above-mentioned problems. To provide.

[0008]

Therefore, in the method of manufacturing a circuit board according to the present invention, a required circuit wiring pattern is formed on one surface of a flexible insulating base material, and the circuit board is formed. A conductor piece isolated so as to cover a corresponding portion of a through hole to be provided in a positional relationship with a connection terminal portion of the circuit wiring pattern without being connected to the wiring pattern is connected to the circuit wiring pattern. After forming an opening for forming the through-hole at the same time as forming an opening for forming a connection terminal portion of the circuit wiring pattern, the conductor piece is removed in a final step. The through hole is formed.

Here, in the step, one end is connected to the circuit wiring pattern by plating means at one end of the opening for forming a connection terminal of the circuit wiring pattern, and the other end is flexible. Forming the connection terminal portion so as to be exposed on the conductive insulating base material, and forming a surface treatment layer having high corrosion resistance on the exposed surface of the connection terminal portion before the conductor piece removing step. The opening can be formed by laser processing means, chemical etching means, or photolithography means.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a manufacturing process diagram of a flexible circuit board having a through hole formed according to the present invention;
First, as shown in (1) of the figure, use of a flexible copper-clad laminate or use of a material having a conductive layer on one side of a suitable flexible insulating base material by sputtering means or the like is possible. A flexible insulating base material 1 having a conductive layer 2 on one surface is prepared.

Therefore, as shown in FIG. 2B, a required circuit wiring pattern 3 is formed by etching means for the conductive layer 2 and, at the same time, a portion corresponding to a position where a through hole to be described later is to be formed is covered. An isolated land-shaped or lid-shaped conductor piece 4 which is not connected to the circuit wiring pattern 3 or the like is formed. Then, a surface protection layer 5 is appropriately formed in a predetermined region on the outer surface of the circuit wiring pattern 3.

Such a surface protective layer 5 can be formed by a method of laminating an appropriate insulating film, a photolithographic means on a photosensitive insulating resin, or a laser processing means on an insulating film or an insulating resin. It can be formed as appropriate by a method of removing unnecessary regions.

Next, as shown in FIG. 3 (3), an opening 6 for forming a bump-shaped connection terminal for the circuit wiring pattern 3 and an opening for a through hole used for alignment. 7 are simultaneously formed on predetermined portions of the flexible insulating base material 1 where the circuit wiring pattern 3 and the conductor piece 4 are located.

These openings 6 and 7 are provided with flexible insulating bases.
Since they can be formed simultaneously by laser processing means, chemical etching means or photolithography means for the substrate material 1, they can be formed finely and with high mutual positional accuracy.

After such a step, as shown in FIG.
At the stage where an appropriate mask layer 8 is uniformly formed on the side where the circuit wiring pattern 3, the conductor piece 4 and the surface protection layer 5 are formed, a conductive member is formed in the opening 6 using a copper plating means or the like. Thus, a bump-shaped connection terminal portion 9 having one end joined to the circuit wiring pattern 3 and the other end exposed on the flexible insulating base material 1 can be formed.

When the bump-shaped connection terminal portions 9 are formed, the conductor pieces 4 are formed in isolation without being connected to other conductor portions such as the circuit wiring pattern 3. Piece 4
No plating member adheres to the opening 7 formed above,
Therefore, masking of the opening 7 becomes unnecessary.

Then, at the stage where the mask layer 8 is removed, as shown in FIG. 5 (5), by using gold plating means or the like on both surfaces, the exposed portions of the bump-like connection terminal portions 9 and the circuit wiring pattern are formed. The surface treatment layers 10 and 11 having high corrosion resistance can be formed at the portions exposed to the end portions and the like of the third and serving as other connection terminal portions.

In the step of forming the surface treatment layers 10 and 11 as well, since the conductor pieces 4 are formed in an isolated manner as described above, the openings 7 and the conductor pieces 4 are not subjected to plating treatment and are not masked. Is also unnecessary.

Finally, by removing the conductor piece 4 by etching as shown in FIG. 6 (6), the opening 7 is formed as a through-hole used for alignment or the like. When the conductor piece 4 is removed by etching, the other connection terminal portions at the ends of the bump-shaped connection terminal portions 9 and the circuit wiring pattern 3 are made of a highly corrosion-resistant surface such as gold. Treatment layer 10, 1
1, the exposed portions are not damaged, so that it is possible to stably produce a circuit board having a required through hole with high precision and high precision. .

[0020]

As described above, in the method of manufacturing a circuit board according to the present invention, a through hole used for positioning or the like is finely defined in a positional relationship with a connection terminal portion formed in a circuit wiring pattern. In addition, it can be formed with high positional accuracy and high accuracy.

The formation of such a through-hole can be achieved while significantly reducing a complicated masking step by forming a highly corrosion-resistant surface treatment layer of gold or the like on a connection terminal formed in a circuit wiring pattern. Since it can be performed, it is possible to form a circuit wiring pattern with a narrow pitch which could not be masked conventionally, and furthermore, it is possible to stably produce a circuit board having a required through-hole even in the case of a product having a portion which cannot be masked. .

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a circuit board according to the present invention.

FIG. 2 is a conceptual explanatory view of a circuit board having a through hole for alignment.

FIG. 3 is a view for explaining a problem when a through hole is provided by a conventional method.

FIG. 4 is a diagram similarly explaining a problem in a case where a through hole is provided by another conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible insulating base material 2 Conductive layer 3 Circuit wiring pattern 4 Conductor piece 5 Surface protective layer 6 Opening 7 Opening 8 Mask layer 9 Connection terminal 10 Surface treatment layer 11 Surface treatment layer

Claims (5)

[Claims] A circuit wiring pattern is formed on one surface of a flexible insulating base material, and is connected to the circuit wiring pattern without being connected to the circuit wiring pattern. An isolated conductor piece is formed together with the circuit wiring pattern so as to cover a corresponding portion of the through hole to be provided in a positional relationship with the terminal part, and a connection terminal part of the circuit wiring pattern is formed. Forming an opening for the through hole at the same time as forming an opening for the circuit board, and removing the conductor piece in a final step to form the through hole. 2. An opening for forming a connection terminal of the circuit wiring pattern, one end of which is joined to the circuit wiring pattern by plating means, and the other end of which is the flexible insulating base. 2. The circuit according to claim 1, further comprising: forming the connection terminal portion so as to be exposed on a material; and forming a surface treatment layer having high corrosion resistance on an exposed surface of the connection terminal portion before the step of removing the conductor piece. Substrate manufacturing method. 3. The method for manufacturing a circuit board according to claim 1, wherein said opening is formed by laser processing means. 4. The method for manufacturing a circuit board according to claim 1, wherein said opening is formed by chemical etching means. 5. The method according to claim 1, wherein said opening is formed by photolithography.