JP4412864B2 - Manufacturing method of double-sided flexible circuit board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a double-sided flexible circuit board characterized by processing of an insulating base material by a resin etching or plasma etching method and a method of forming a hole for conduction for forming a through-hole conduction part.
[0002]
[Prior art]
When manufacturing a double-sided flexible circuit board using a double-sided copper-clad laminate, first, a mask layer for drilling and grooving the insulating base material from the first conductor layer by a laser processing method is formed. . Therefore, the mask layer is used to form holes and grooves on both sides of the insulating base material by laser drilling and groove processing. Next, conductive treatment and plating are performed, and a conductive layer formed by plating is formed after the conductive treatment. Then, double-sided circuit wiring pattern processing is performed to obtain a double-sided flexible circuit board.
[0003]
[Problems to be solved by the invention]
Conventionally, flexible circuit boards have been required to be flexible when mounted or after mounting. Furthermore, the elastic modulus of the circuit board also affects the power consumption of the assembly after mounting, such as a circuit board intended for connection to a product and a magnetic head that require flexibility to improve mountability. Therefore, for circuit boards that require flexibility after mounting, the insulation base material itself of the copper clad laminate, which is the material, must be reviewed, and it has a relatively high priority over other requirements. It was low and often had to be compromised.
[0004]
Even in the actual case, a thin copper clad laminate has a drawback that it is more difficult and costly than a thick handle in the manufacturing process. Although there is a report on a method for applying a groove for improving mountability by laser processing, there is no report on a method for simply and efficiently performing groove processing.
[0005]
[Means for Solving the Problems]
The present invention provides a method for manufacturing a double-sided flexible circuit board for suitably solving the above-mentioned conventional problems.
For this purpose, in the method for manufacturing a double-sided flexible circuit board according to the present invention, a conductive material necessary for conducting the conductive layers on both sides of the insulating base material by subjecting the insulating base material to plasma etching or wet etching. A technique is adopted in which a through hole and a non-through groove for improving flexibility are formed at the same time, then a through hole conducting portion is formed in the conducting hole, and then a required circuit wiring pattern is formed. .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be further described below with reference to the illustrated embodiments. FIG. 1 is a manufacturing process diagram of a double-sided flexible circuit board according to an embodiment of the present invention.
[0007]
In order to manufacture a double-sided flexible circuit board, first, a double-sided copper clad laminate having a conductor layer 2 and a conductor layer 3 on both sides of an insulating base material 1 is prepared as shown in FIG.
[0008]
Therefore, as shown in FIG. 2 (2), the conductor layers 2 on both sides are provided so that the required holes 6 and the groove holes 7 are respectively provided in the portions where the conduction holes are formed and the portions where the insulating base material 1 is thinly formed. , 3 are etched to form conductor layers 4 and 5 serving as mask layers. Here, it is sufficient to form the groove hole 7 for forming the non-penetrating groove in one of the conductor layers 4 and 5 as shown in the figure.
[0009]
Next, using the conductor layers 4 and 5 as the mask layer, the insulating base material 1 is drilled from both sides by plasma etching means until the conduction hole penetrates, and the conduction hole as shown in FIG. 8 and a non-penetrating groove 9 are formed simultaneously.
[0010]
Therefore, as shown in FIG. 4 (4), the resist layer 10 is formed in the region of the insulating base material 1 exposed in the groove 9 which is a region where it is not necessary to form the through-hole conducting portion and the most region of the conductor layer 5, respectively. 11 is formed.
[0011]
Next, by conducting a conductive treatment and plating the entire surface, the conductive layers 4 and 5 on the front and back sides are electrically connected as shown in FIG. Thereafter, after the resist layers 10 and 11 are peeled off, a double-sided flexible circuit board can be obtained by performing a patterning process to form a required circuit wiring pattern 13 as shown in FIG.
[0012]
FIG. 2 is a manufacturing process diagram of a double-sided flexible circuit board according to another embodiment of the present invention. In this method, a single-sided copper-clad laminate having a conductor layer 21 on one surface of an insulating base material 20 as shown in FIG. 1 (1) is used, and as shown in FIG. First, a resist layer 22 is formed on the entire exposed surface 20.
[0013]
Therefore, as shown in FIG. 3 (3), the required hole 25 and the groove hole 26 are respectively provided in the portion where the conduction hole is formed and the portion where the insulating base material 1 is thinly formed as in the above embodiment. In addition, a resist layer 23 to be a mask layer is formed by processing the resist layer 22, and the conductor layer 21 is etched to form a conductor layer 24 to be a mask layer. Here, it is sufficient to form the groove hole 26 for forming the non-penetrating groove on the surface side of the insulating base material 20 as shown in the figure.
[0014]
Next, using the resist layer 23 and the conductor layer 24 as a mask layer, the insulating base material 20 is drilled from both sides by plasma etching means until the conduction hole is penetrated, and is guided as shown in FIG. The through hole 27 and the non-penetrating groove 28 are formed simultaneously.
[0015]
Therefore, as shown in FIG. 5 (5), the resist layer 29, the region of the insulating base material 20 exposed in the groove 28 which is a region where it is not necessary to form the through-hole conducting portion and the most region of the conductor layer 24, respectively. After forming 30, the conductive hole 27 is electrically conductive and plated on the entire surface in the same manner as in the above embodiment, thereby electrically connecting the front and back plating layers and the conductor layer 24 to each other. A double-sided flexible circuit board is manufactured in the same manner as described above by forming a hole conducting portion and then peeling off both resist layers 29 and 30 and performing a patterning process to form a required circuit wiring pattern. Can do.
[0016]
【The invention's effect】
According to the method for manufacturing a double-sided flexible circuit board according to the present invention, formation and bending of a conduction hole for conducting a conductive layer on both sides when resin etching is performed on an insulating base material of a double-sided copper-clad laminate. Since it is possible to simultaneously improve the mountability, improve the mountability, and process the groove for suppressing the power consumption of the assembly after mounting, the cost can be reduced as compared with the case where these are processed individually.
[0017]
By etching from both sides, the difference between the maximum diameter and the minimum diameter in one hole can be made smaller even when the opening diameter of the same mask layer is used than when etching is performed from one side.
[0018]
Therefore, it is possible to open a hole having a smaller hole diameter, and a hole diameter of 50 μm or less, for example, a hole diameter of 30 to 40 μm, which is a size that can be processed only by laser processing, can be processed.
[0019]
Further, the processing of the groove can be controlled from about half the thickness of the insulating base material to penetrate through the insulating base material, so that the processing depth can be selected in accordance with the required characteristics at the time of mounting or after mounting.
[0020]
In addition, since the bent shape of the circuit board can be defined in, for example, a Z-shape or a U-shape by predetermining the surface to be grooved, it is possible to obtain higher mountability than when the elastic modulus of the entire circuit board is low. it can.
[Brief description of the drawings]
FIG. 1 is a manufacturing process diagram of a double-sided flexible circuit board according to an embodiment of the present invention.
FIG. 2 is a manufacturing process diagram of a double-sided flexible circuit board according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Insulation base material 2 Conductor layer 3 Conductor layer 4 Conductor layer used as a mask layer 5 Conductor layer used as a mask layer 6 Hole 7 Groove hole 8 Conductive hole 9 Groove 10 Resist layer 11 Resist layer 12 Through-hole conductive part 13 Circuit wiring pattern

Claims (1)

A plasma etching process is performed on the insulating base material to simultaneously form a conductive hole necessary for conducting the conductive layers on both sides of the insulating base material and a non-penetrating groove for improving flexibility, and then the conductive base material. A method of manufacturing a double-sided flexible circuit board, wherein a through-hole conducting portion is formed for a through hole, and then a required circuit wiring pattern is formed.

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