JP4252227B2 - Manufacturing method of double-sided flexible circuit board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a double-sided flexible circuit board capable of easily forming a minute through-hole conductive layer required for a fine and high-definition double-sided flexible circuit board.
[Prior art and its problems]
Conventionally, in the process of manufacturing a flexible circuit board having a fine circuit wiring pattern, a copper-clad plate with a thin copper foil is expensive, so for a copper foil on a surface that requires a fine circuit wiring pattern, A technique for reducing the thickness of the copper foil by a half-etching process is employed.
[0002]
For this reason, when fine circuit wiring is required on both sides of the substrate, a half-etching process for the copper foils on both sides is required.
[0003]
FIG. 2 is a process diagram showing a manufacturing method of a double-sided flexible circuit board for forming fine circuit wirings by a conventional method. As shown in FIG. A double-sided copper-clad plate having a second conductive layer 22 on the other side is prepared.
Therefore, as shown in FIG. 2B, the thin first conductive layer 23 and the second conductive layer 24 formed by thin etching the first conductive layer 21 and the second conductive layer 22 are formed.
[0004]
Next, the half-etched first conductive layer 23 and second conductive layer 24 are etched to form the required openings 25 and 26 as shown in FIG. Make it work.
[0005]
Therefore, after a conductive hole 27 is formed in the insulating layer 20 as shown in FIG. 4 (4) by a method such as plasma etching or wet etching on the metal mask, the conductive layer 27 is electrically conductive such as chemical plating. Through-hole plating such as electrolytic treatment and electrolytic plating is performed to form a through-hole conductive layer 28 as shown in FIG.
[0006]
Finally, a method of obtaining a double-sided flexible circuit board by performing predetermined circuit wiring processing by a conventional method is employed.
[0007]
However, in this conventional manufacturing method, in order to form a minute through-hole conductive layer required for a fine and high-definition circuit board, a high degree of alignment accuracy is required, and an expensive apparatus or special device is required. There is a problem that productivity is lowered due to the necessity of a jig and the like and the time required for alignment.
[0008]
[Means for Solving the Problems]
Therefore, in the method for manufacturing a double-sided flexible circuit board according to the present invention, one of the conductive layers provided on both sides of the insulating layer is half-etched and formed on the conductive layer on the other side of the insulating layer. After forming the conduction hole in the insulating layer by applying means such as laser processing, plasma etching, wet etching, etc. to the insulating layer using the opening, and protecting the one conductive layer, At the same time that half etching of the conductive layer is performed, a method of forming a conductive hole by etching and removing the one conductive layer exposed at the bottom of the conductive hole is employed.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be further described below with reference to the illustrated embodiments. FIG. 1 is a process diagram illustrating a method of manufacturing a double-sided flexible circuit board according to an embodiment of the present invention.
[0010]
First, as shown in FIG. 1 (1), a suitable insulating layer 1 has a first conductive layer 2 such as a copper foil on one side and a similar second conductive layer 3 on the other side. Prepare a laminate.
[0011]
Therefore, as shown in FIG. 2B, the second conductive layer 3 is etched to a desired thin thickness by a half-etching method to form a thin second conductive layer 4.
[0012]
Next, as shown in FIG. 3 (3), the first conductive layer 2 is etched to form a required opening 5, thereby causing the first conductive layer 2 to function as a metal mask layer. .
[0013]
Next, as shown in FIG. 4 (4), using the metal mask layer, the conduction hole 6 is formed in the insulating layer 1 by a technique such as laser processing, plasma etching or wet etching for the insulating layer 1 exposed in the opening 5. , Thereby exposing the thin second conductive layer 4 to the bottom thereof.
[0014]
Therefore, as shown in FIGS. 5 (5) and (6), after the second conductive layer 4 that has been half-etched is protected with a resist layer 7 such as a dry film resist, the metal mask layer side, i.e., the first By performing a half-etching process from the conductive layer 2 side, the first conductive layer 2 is half-etched to form a thin first conductive layer 8 and a thin second conductive layer exposed at the bottom of the conduction hole 6 is formed. The conductive layer 4 is removed by etching to form a conduction hole 9.
[0015]
Next, as shown in FIG. 7 (7), after the resist layer 7 is peeled off, the through-hole plating conductive layer 10 is formed with respect to the conductive hole 9 by a conductive treatment by a technique such as chemical plating and an electrolytic copper plating technique. Form.
[0016]
As a result, the through-hole conductive layer can be formed by a technique such as laser processing, plasma etching, or wet etching without forming a mask layer on both sides. Finally, a desired circuit wiring pattern is formed by a conventional method. A double-sided flexible circuit board can be manufactured.
[0017]
【The invention's effect】
According to the present invention, in the manufacturing process of the double-sided flexible circuit board, the first conductive layer functioning as a metal mask having a required opening only on one surface of the insulating layer is formed, and then the opening is formed. A conductive hole is formed in the insulating layer located at the portion, the second conductive layer on the other surface exposed at the bottom of the conductive hole is removed by etching, and a half-etching process is simultaneously performed on the first conductive layer. The method is adopted.
[0018]
Therefore, a double-sided flexible circuit board having a fine circuit wiring pattern provided with a minute through-hole conduction portion without using expensive equipment or a special jig is not required. It can be obtained inexpensively and stably.
[0019]
Further, if the present invention is employed in the method for forming the outer shape of the circuit board, it becomes possible to process the outer shape of the high-definition circuit board and to manufacture a precise circuit board.
[Brief description of the drawings]
FIG. 1 is a process diagram showing a method of manufacturing a double-sided flexible circuit board according to the present invention.
FIG. 2 is a process diagram showing a method of manufacturing a double-sided flexible circuit board according to a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insulating layer 2 1st conductive layer 3 2nd conductive layer 4 Thin 2nd conductive layer 5 Opening part 6 Conductive hole 7 Resist layer 8 Thin 1st conductive layer 9 Conductive hole 10 Through-hole conductive layer

Claims (1)

Half-etching one conductive layer of the conductive layer provided on both sides of the insulating layer, using a required opening formed in the conductive layer on the other side of the insulating layer to form a conduction hole in the insulating layer, Next, after protecting the one conductive layer, half-etching is performed on the conductive layer on the other side, and at the same time, the one conductive layer exposed at the bottom of the conduction hole is removed by etching to form a conduction hole. A method for producing a double-sided flexible circuit board, comprising:

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