JP4010684B2 - Circuit board manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a circuit board capable of forming a fine through hole provided for alignment of a circuit board with high positional accuracy and high precision.
[0002]
[Prior art]
For example, in a certain form of a flexible circuit board, a required circuit wiring pattern 21 is formed on one surface of a flexible insulating base material 20 as shown in FIG. 2, and the circuit wiring pattern is formed. A connection terminal portion 22 is formed so that one end is joined to a part of 21 and the other end is exposed through the flexible insulating base material 20, and a gold is formed on the exposed surface of the connection terminal portion 22. The surface treatment layer 24 is formed by a plating means using a highly corrosion-resistant member such as a surface protection layer 23 using an insulating film or resin on the outer surface of a predetermined area of the circuit wiring pattern 21. Then, a surface treatment layer 25 is formed on the surface of the exposed portion of the circuit wiring pattern 21 by a plating means using a member having high corrosion resistance such as gold to be another connection terminal portion, Further, in the positional relationship with the connection terminal portion 22, the flexible insulating base is used. The predetermined portion of the scan material 20 has those provided with through-holes 26, the through hole 26 is used for alignment or the like of the circuit board.
[0003]
By the way, with the increase in density and miniaturization of the circuit board as described above, the through-hole 26 provided for the alignment of the circuit board is also miniaturized, and high precision and high density are required. As a means for forming such a through hole 26, a mechanical processing technique such as a drill or a mold is generally used.
[0004]
[Problems to be solved by the invention]
However, when forming a through-hole as described above, if a through-hole is formed at a location indicated by an arrow using a drill or a mold in the final step of manufacturing the flexible circuit board as shown in FIG. 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 conspicuous as the through-holes and the connecting terminal portions 22 become finer and have a higher density.
[0005]
Therefore, as a method for improving the positional accuracy between the through hole and the connection terminal portion 22, for example, in the middle stage after the circuit wiring pattern 21 and the surface protective layer 23 are formed as shown in FIG. Although it is advantageous to form the through hole 26 simultaneously with the opening 27 for forming the terminal portion 22, in this method, the through hole 26 surrounds the chemical solution in the process for forming the surface treatment layer 24 and the like. Problems such as troublesomeness.
[0006]
As a method of solving such a problem, for example, a method of closing a through-hole provided in advance by filling with an appropriate member is conceivable. However, in this method, when such a through-hole is miniaturized and provided at a high density, Is extremely difficult to adopt, and even if possible, an increase in manufacturing cost is inevitable.
[0007]
The present invention provides a method of manufacturing a circuit board capable of forming a fine through hole with high positional accuracy with high accuracy while solving the above problems. It is.
[0008]
[Means for Solving the Problems]
Therefore, in the method for manufacturing a circuit board according to the present invention, a required circuit wiring pattern is formed on one surface of the flexible insulating base material and connected to the circuit wiring pattern. In addition, an isolated conductor piece is formed together with the circuit wiring pattern so as to cover the corresponding portion of the through hole to be provided in the positional relationship with the connection terminal portion of the circuit wiring pattern, and the circuit wiring pattern -After forming the opening for forming the connection terminal portion of the lead, the opening for the through hole is formed, and then the conductor piece is removed in the final step to form the through hole. .
[0009]
Here, in the step, one end is joined to the circuit wiring pattern by the plating means in the opening for forming the connection terminal portion of the circuit wiring pattern, and the other end is connected to the flexible insulating board. A step of forming the connection terminal portion so as to be exposed on the metal material, and forming a surface treatment layer having high corrosion resistance on the exposed surface of the connection terminal portion before the step of removing the conductor piece. Further, the opening can be formed by laser processing means, chemical etching means or photolithography means.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a manufacturing process diagram of a flexible circuit board having through holes formed according to the present invention. First, as shown in FIG. A material having the conductive layer 2 on one surface of the flexible insulating base material 1 is prepared by using a material having a conductive layer on one surface of the flexible insulating base material by sputtering means or the like.
[0011]
Therefore, as shown in FIG. 2 (2), the required circuit wiring pattern 3 is formed by etching means for the conductive layer 2, and at the same time, the circuit wiring is covered so as to cover a portion corresponding to a position where a through-hole to be described later is formed. An isolated land-like or lid-like conductor piece 4 that is not connected to the pattern 3 or the like is formed. Then, a surface protective layer 5 is appropriately formed in a predetermined region on the outer surface of these circuit wiring patterns 3.
[0012]
Such a surface protective layer 5 is a region unnecessary for photolithography means for photosensitive insulating resin and laser processing means for insulating film or insulating resin, as well as a method of attaching and attaching an appropriate insulating film. It can form suitably by the method of removing.
[0013]
Next, as shown in FIG. 3 (3), an opening 6 for forming a bump-like connection terminal for the circuit wiring pattern 3 and an opening 7 for a through hole used for alignment are formed. Each of them is simultaneously formed in a predetermined portion of the flexible insulating base material 1 where the circuit wiring pattern 3 and the conductor piece 4 are located.
[0014]
These openings 6 and 7 can be formed simultaneously by laser processing means, chemical etching means or photolithography means for the flexible insulating base material 1, so that they can be finely and highly mutually positioned. Can be formed with high accuracy.
[0015]
After such a process, as shown in FIG. 4 (4), when a suitable mask layer 8 is uniformly formed on the side on which the circuit wiring pattern 3, the conductor piece 4 and the surface protective layer 5 are formed, By forming a conductive member in the opening 6 using plating means or the like, a bump-like connection in which one end is joined to the circuit wiring pattern 3 and the other end is exposed on the flexible insulating base material 1. The terminal portion 9 can be formed.
[0016]
When the bump-shaped connection terminal portion 9 is formed, the conductor piece 4 is formed in an isolated manner without being connected to other conductor portions such as the circuit wiring pattern 3. No plating member adheres to the opening 7 formed in this way, and therefore masking of the opening 7 becomes unnecessary.
[0017]
Therefore, 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 portion of the bump-like connection terminal portion 9 and the end of the circuit wiring pattern 3 are obtained. The surface treatment layers 10 and 11 having high corrosion resistance can be formed respectively at the portions that are exposed to the portions and become the other connection terminal portions.
[0018]
Even in the process of forming the surface treatment layers 10 and 11, since the conductor piece 4 is formed in isolation as described above, the opening 7 and the conductor piece 4 are not subjected to plating treatment and masking is not required. is there.
[0019]
Finally, as shown in FIG. 6 (6), the conductor piece 4 is removed by etching means, whereby 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 bump-like connecting terminal portion 9 and the other connecting terminal portion at the end of the circuit wiring pattern 3 are made of a highly corrosion-resistant surface such as gold. Since it is covered with the treatment layers 10 and 11, these exposed portions are not damaged, and thereby a stable circuit board having the required through-holes with a fine and high positional accuracy can be stably produced. Is possible.
[0020]
【The invention's effect】
As described above, in the method of manufacturing a circuit board according to the present invention, the through-hole used for alignment or the like is fine and highly accurate in the positional relationship with the connection terminal portion formed in the circuit wiring pattern. It can be formed with high accuracy.
[0021]
In addition, the formation of such a through hole can be performed while significantly reducing the complicated masking process by forming a surface treatment layer having high corrosion resistance such as gold on the connection terminal portion formed in the circuit wiring pattern. A circuit wiring pattern having a narrow pitch that cannot be masked in the prior art can be formed, and a circuit board having a required through hole can be stably manufactured even in the case of a product having a portion that 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 diagram of a circuit board having a through hole for alignment.
FIG. 3 is a diagram for explaining a problem when a through hole is provided by a conventional method.
FIG. 4 is a diagram for similarly explaining a problem in the 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 part 7 Opening part 8 Mask layer 9 Connection terminal part 10 Surface treatment layer 11 Surface treatment layer

Claims (5)

A required circuit wiring pattern is formed on one surface of the flexible insulating base material, and the position of the circuit wiring pattern with the connection terminal portion 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 the relationship, and an opening for forming a connection terminal portion of the circuit wiring pattern is formed. A method of manufacturing a circuit board, comprising: forming an opening for the through hole simultaneously with the formation, and then removing the conductor piece in a final step to form the through hole. One end of the circuit wiring pattern is connected to the circuit wiring pattern by the plating means in the opening for forming the connection terminal portion of the circuit wiring pattern, and the other end is exposed on the flexible insulating base material. The method of manufacturing a circuit board according to claim 1, further comprising: forming the connection terminal portion 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. 3. The method for manufacturing a circuit board according to claim 1, wherein the opening is formed by laser processing means. 3. The method of manufacturing a circuit board according to claim 1, wherein the opening is formed by chemical etching means. 3. The method for manufacturing a circuit board according to claim 1, wherein the opening is formed by photolithography.

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