JP2002353616A - Method of manufacturing flexible double-sided circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a flexible double-sided circuit board which has circuit wiring patterns on both faces of a flexible insulation base material, with the circuit wiring pattern on one face being a fine one, and which has fine via hole or through hole continuity parts at specified places of the circuit wiring patterns on the front and the rear faces. SOLUTION: A continuity layer 2 formed on one face of the insulation base material 1 is formed with openings 3 at the places where holes for continuity are to be formed, and a resist layer 5 having openings 4 at the places corresponding to the openings 3 is formed on the outer surface of the insulation base material 1. After removing the insulation base material 1 existing in the openings 3 and 4 to form holes 6 for continuity, a conductivity layer 7 including the through holes is formed on the entire surface including the holes 6 for continuity by a plating means. Then, the continuity layer 7 and the conductive layer 2 are etched by an etching means into a specified circuit wiring pattern 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flexible circuit board having a circuit wiring pattern on both sides of a flexible insulating base material and a fine circuit wiring pattern on one side. The present invention relates to a method for manufacturing a flexible double-sided circuit board having fine via-holes or through-hole conductive portions at required positions in circuit wiring patterns on the front and back sides.

[0002]

2. Description of the Related Art A conventional flexible double-sided circuit board having a through-hole conductive portion is formed by forming a required circuit wiring pattern on both surfaces of a flexible insulating base material such as a polyimide film by a photo-etching means for copper foil or the like. Through holes for through holes formed by drilling or the like including a flexible insulating base material are provided for required portions in the circuit wiring patterns on both surfaces, and the inner wall of the holes and the circuit wiring on both surfaces are provided. By forming a through-hole conductive layer on the upper surface of the pattern by plating means including electroless plating, an interconnecting structure is formed with respect to a required portion of the circuit wiring pattern on both surfaces.

On the surfaces of the circuit wiring patterns on both sides, a surface protection film can be formed by applying an adhesive to a surface protection layer except for necessary portions such as the through-hole conducting portions and the like to form a surface protection layer. . Such a surface protective layer can be formed by other ordinary coating means such as a printing method using an insulating resin or an insulating paint depending on the use conditions and the like.

To manufacture such a flexible double-sided circuit board, a double-sided metal-clad laminate having a conductive layer such as a copper foil on both sides of a flexible insulating base material such as a polyimide film is prepared. A through hole for a through hole is formed at a location by means such as drilling.

Next, a through-hole conductive layer is formed on the inner wall of the through hole and the upper surface of both conductive layers by plating means including electroless plating, and then the conductive layer is subjected to an etching treatment to obtain a desired circuit wiring. A manufacturing method of forming a pattern and, if necessary, forming a surface protective layer is employed.

When a via-hole conducting structure is employed in place of the through-hole conducting portion, a double-sided metal having a conductive layer such as a copper foil on both sides of a flexible insulating base material such as a polyimide film is first used. An open laminate is prepared, and an opening is formed at a required position by etching the conductive layer.

Next, the insulating base material exposed at the opening is
The hole for conduction is formed by removing using a resin etching technique, a plasma etching technique, a laser processing technique, or the like.

Next, the conductive layer is etched at the stage of forming a plated layer on the bottom, side walls, and the surface of the conductive layer of the conductive hole by a conductive treatment such as electroless plating and an electrolytic plating technique. A manufacturing method is employed in which a desired circuit wiring pattern is formed by performing a treatment, and a surface protective layer is formed as necessary.

[0009]

According to the flexible double-sided circuit board having the conventional structure as described above, the conductive portion formed by the through-hole or via-hole conductive layer for conducting the circuit wiring patterns on the front and back sides is formed by: Since it is also formed on the surface of the circuit wiring pattern, the thickness of the entire circuit wiring pattern becomes considerably thick, which hinders the formation of a fine circuit wiring pattern.

For example, for a copper foil having a thickness of 17.5 μm,
Chemical plating with a thickness of 6 μm is applied, and a further 10
When a via hole or a through-hole conductive layer is formed by performing electroplating of ２０20 μm, the thickness of the entire circuit wiring pattern is 30.5-43.5 μm. Therefore, if the width of the circuit wiring pattern that can be formed is assumed to be 2.5 times the conductor thickness, the width of the circuit wiring pattern becomes as large as about 76.25 to 108.75 μm.
It becomes difficult to form fine circuit wiring patterns at high density.

[0011]

SUMMARY OF THE INVENTION The present invention provides a method of manufacturing a flexible double-sided circuit board for suitably solving the above problems.

For this purpose, in the present invention, a single-sided metal-clad laminate having a first conductive layer on one surface of an insulating base material is used, and the first conductive layer is provided with a conductive hole forming position. While forming an opening, on the surface of the insulating base material, a resist layer having an opening at a position corresponding to the opening formed in the conductive layer is formed, and the insulating base material is subjected to a chemical etching process from both sides or A conductive hole is formed in the insulating base material by a plasma etching process, and a plating film is formed on a side wall portion of the conductive hole, the surface of the insulating base material, and the first conductive layer, and includes a through hole. A method of manufacturing a flexible double-sided circuit board having steps of forming a second conductive layer, performing an etching process on the first conductive layer and the second conductive layer, and forming a circuit wiring pattern is employed. Is done.

According to another manufacturing method of the present invention, a predetermined through hole is formed on a surface of the insulating base material of a single-sided metal-clad laminate having a first conductive layer on one surface of the insulating base material. A resist layer having an opening is formed, and the insulating base material exposed at the resist opening portion is removed by chemical etching or plasma etching.
After peeling the resist layer, a second conductive layer is formed on the bottom of the conductive hole, the side wall, and the surface of the insulating base material, and a circuit is formed by etching the first conductive layer and the second conductive layer. A method for manufacturing a flexible double-sided circuit board having a step of forming a wiring pattern is employed.

Here, in the conductive layer forming step, the side wall portion of the conductive hole, the surface of the insulating base material and the first conductive layer, or the bottom portion, the side wall of the conductive hole and the insulating base. After performing a conductive treatment on the surface of the material, on the insulating base material surface side, a resist layer is formed so as to expose the conductive hole and the circuit wiring pattern forming portion, and a circuit wiring pattern is formed by plating. After the formation of the through-hole conductive portion or the via-hole conductive layer for front-to-back conduction, the method of removing the resist layer and then removing the conductive layer between the circuit wiring patterns can be adopted.

Further, in the step of forming the second conductive layer, a side wall portion of the conductive hole, a surface of the insulating base material and the first conductive layer, or a bottom portion of the conductive hole, After applying a catalyst to the side walls and the surface of the insulating base material,
On the insulating base material surface side, a resist layer is formed so as to expose the conduction hole and the circuit wiring pattern formation portion, and a through hole or via hole conductive layer for front and back conduction with the circuit wiring pattern by a plating technique. Can be adopted.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the illustrated embodiments. FIG. 1 is a manufacturing process diagram of a flexible double-sided circuit board according to an embodiment of the present invention.
As shown in FIG. 1A, a single-sided metal-clad laminate having a first conductive layer 2 such as a copper foil on one surface of an insulating base material 1 is prepared.

Next, as shown in FIG. 2B, the first conductive layer 2 is subjected to an etching process to form an opening 3 at a position where a conduction hole is to be formed, and a position corresponding to the opening 3. A resist layer 5 having an opening 4 on the surface side of the insulating base material 1 is formed.

Then, as shown in FIG. 3C, a conduction hole 6 is formed from both sides by a resin etching technique or a plasma etching technique.

Then, as shown in FIG. 4 (4), the resist layer 5 is peeled off, and the side wall of the conduction hole 6 and the insulating base material 1 are removed.
A conductive layer 7 serving as a second conductive layer made of a plating film is formed on the surface of the first conductive layer 2 and the first conductive layer 2 by an electrolytic plating method following the chemical plating process.

Next, as shown in FIG. 5 (5), the first conductive layer 2 and the conductive layer 7 are subjected to an etching process using a normal photolithography method to form a circuit wiring pattern 8. A flexible double-sided circuit board in which the circuit wiring patterns 8 on the front and back are conducted by the through-hole conducting portions can be obtained.

As a method of manufacturing a flexible double-sided circuit board according to another embodiment, as shown in FIG. 2A, a first conductive layer 2 such as a copper foil is Is prepared.

Next, as shown in FIG. 2B, a resist layer 5 having an opening 4 at the position where the conduction hole is formed is placed on the insulating base material 1.
Is formed on the surface side.

Next, as shown in FIG. 3C, a conduction hole 9 whose bottom is closed by the first conductive layer 2 is formed by a resin etching technique or a plasma etching technique from one side.

Next, as shown in FIG. 4D, the resist layer 5 is peeled off, and the first side exposed on the side wall of the conduction hole 9 and the surface of the insulating base material 1 and on the bottom of the conduction hole 9 is formed. A conductive layer 10 serving as a second conductive layer made of a plating film is formed on the conductive layer 2 by a plating method following the chemical plating process.

Then, as shown in FIG. 5 (5), the first conductive layer 2 and the conductive layer 10 are subjected to an etching process by using a usual photolithographic method to form a circuit wiring pattern 11. Thus, a flexible double-sided circuit board in which the circuit wiring patterns 11 on the front and back are conducted by the via holes can be obtained.

In the above, as the means for forming the conductive layer 10, in addition to the electrolytic plating method following the above-described chemical plating, ion beam sputtering or vapor deposition of chromium or copper and electrolytic copper plating means subsequent thereto are also employed. You can do it.

Further, as another method for forming a circuit wiring pattern using a conductive layer, a semi-additive method can be used as shown in FIG. FIG. 3 shows an embodiment of a conductive structure using via holes.

In this case, a single-sided copper-clad laminate having a first conductive layer 2 such as a copper foil on one surface of an insulating base material 1 is prepared as shown in FIGS. A resist layer 5 having an opening 4 at a position where a conduction hole is formed is formed on the surface side of the insulating base material 1, and the bottom is closed with the first conductive layer 2 by a resin etching method or a plasma etching method from both surfaces. After forming the conduction holes 9, the resist layer 5 is peeled off.

Next, as shown in FIG.
The first conductive layer 2 exposed on the side wall portion, the surface of the insulating base material 1, and the bottom of the conductive hole 9 is subjected to a chemical plating process, a sputtering process, a vapor deposition process, or the like to form a thin conductive layer 10. To form

Therefore, as shown in FIG. 4A, a resist layer 12 is formed so as to expose the conductive hole and the portion where the circuit wiring pattern is formed on the surface side of the insulating base material 1.

Then, as shown in FIG. 2B, the exposed thin film conductive layer 10 is plated to form a via hole conductive layer 14 for front and back conduction with the circuit wiring pattern 13. .

Next, as shown in FIG. 3 (3), the region of the thin conductive layer 10 exposed by stripping the resist layer 12 is removed by etching to obtain the required circuit wiring patterns 15, 1.
6 are electrically separated.

Finally, a circuit wiring pattern 17 is formed by etching the first conductive layer 2 as shown in FIG.

Here, although not shown, a circuit formation method by a full additive method by an electroless plating method using a catalyst may be employed instead of the conductive layer of the thin film.

In each of the above steps, the surface protective layer is not described. However, the steps can be appropriately performed as in the conventional case, and the outer shape processing can be appropriately performed after the above steps. I can do it.

[0036]

According to the method of manufacturing a flexible double-sided circuit board according to the present invention, a circuit on the surface side of the insulating base material is replaced by a single-sided metal-clad laminate instead of the conventional double-sided metal-clad laminate. Since the thickness of the wiring pattern can be reduced, it is easy to form a fine circuit wiring pattern, and it is possible to provide a high-density mounting board on which electronic components are mounted at a high density.

Further, since a single-sided metal-clad laminate is used, the material cost can be reduced as compared with the conventional method, and an inexpensive substrate can be provided.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of a flexible double-sided circuit board according to one embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of a flexible double-sided circuit board according to another embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of a flexible double-sided circuit board according to another embodiment of the present invention.

FIG. 4 is a manufacturing process diagram following FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulation base material 2 Conductive layer 3 Opening 4 Opening 5 Resist layer 6 Conducting hole 7 Conducting layer 8 Circuit wiring pattern

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E317 AA24 BB01 BB12 CC31 CC51 CD12 CD15 CD18 CD25 CD32 GG14 5E339 AA02 AB02 AC01 AD03 AE01 BC02 BD03 BD08 BD11 BE11 CD01 CE12 CE15 CG01 GG10

Claims (4)

[Claims] 1. A single-sided metal-clad laminate having a first conductive layer on one surface of an insulating base material, wherein an opening is formed in the first conductive layer at a position where a conduction hole is formed, and After forming a resist layer having an opening at a position corresponding to the opening formed in the conductive layer on the surface of the insulating base material, forming the conduction hole by removing the insulating base material located at the opening, A second conductive layer including a through hole is formed by forming a plating film on the side wall of the conduction hole, the surface of the insulating base material, and the first conductive layer, and then forming the first conductive layer. A method for producing a flexible double-sided circuit board, comprising the steps of performing an etching process on a layer and a second conductive layer to form a circuit wiring pattern. 2. A single-sided metal-clad laminate having a first conductive layer on one surface of an insulating base material, a resist layer having an opening at a position where a predetermined conduction hole is formed on the surface of the insulating base material. Forming a conduction hole by removing the insulating base material exposed at the opening portion of the resist layer, peeling the resist layer, and then forming a bottom portion, a side wall, and the insulating base material of the conduction hole. A method for manufacturing a flexible double-sided circuit board, comprising the steps of: forming a second conductive layer on the surface of the substrate; and performing an etching process on the first conductive layer and the second conductive layer to form a circuit wiring pattern. 3. The step of forming the second conductive layer includes the step of forming a side wall portion of the conduction hole, a surface of the insulating base material and the first conductive layer, or a bottom portion, a side wall of the conduction hole and the conductive hole. After forming a conductive treatment layer on the surface of the insulating base material, a resist layer is formed on the surface side of the insulating base material so as to expose the conductive hole and a portion where the circuit wiring pattern is formed, and plating is performed. Forming a circuit wiring pattern and a through-hole or via-hole conductive layer for front-to-back conduction, removing the resist layer, and then removing the conductive processing layer between the circuit wiring patterns is performed. Claim 1
Or the method for producing a flexible double-sided circuit board according to 2. 4. The step of forming the second conductive layer includes the step of forming a side wall portion of the conduction hole, a surface of the insulating base material and the first conductive layer, or a bottom portion, a side wall of the conduction hole and the side wall of the conduction hole. After applying a catalyst to the surface of the insulating base material, a resist layer is formed on the surface side of the insulating base material so as to expose the conductive hole and the circuit wiring pattern forming portion, and the circuit wiring pattern is formed by plating. 3. The method for producing a flexible double-sided circuit board according to claim 1, wherein the method is performed by forming a through-hole or via-hole conductive layer for front-to-back conduction.