JP3048450B2 - Manufacturing method of flexible double-sided circuit wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible circuit wiring board having fine circuit wiring patterns on both sides of a flexible insulating base material. Flexible double-sided circuit wiring board that can electrically connect required parts in the screen with fine blind through-hole conductive parts
A method for producing the same.

[0002]

2. Description of the Related Art A conventional flexible double-sided circuit board having a through-hole conducting portion has the structure shown in FIG.
In the figure, a flexible insulating base such as a polyimide film is used.
Required circuit wiring patterns 32, 33 are formed on both surfaces of the material 31 by photo-etching means for copper foil or the like, and required portions of the circuit wiring patterns 32, 33 on both surfaces are acceptable. A through hole 34 for through hole formed through means such as drilling including the flexible insulating base material 31 is provided, and an inner wall of the through hole 34 and both circuit wiring patterns 32,
The upper surface of the substrate 33 is plated with plating means including electroless plating.
By forming the hole conductive layer 35, a mutual conduction structure with respect to required portions of both circuit wiring patterns 32 and 33 is formed.

In addition, the circuit wiring patterns 32 and 33 are used.
A surface protective film 37 can be formed by applying an adhesive 36 on the surface except for the necessary portions such as the through-hole conducting portions and the like to form a surface protective layer. Such a surface protective layer can be formed by other ordinary coating means such as a printing means using an insulating resin or an insulating paint depending on the use conditions and the like.

According to the flexible double-sided circuit wiring board having the conventional structure as described above, the conductive portion formed by the through-hole conductive layer 35 for making the circuit wiring patterns 32, 33 on the front and back conductive is formed. The circuit wiring pattern is formed on a land portion larger than the through hole 34 for through hole. Therefore, it is difficult to form a highly dense circuit wiring pattern around such a through-hole conducting portion.

Further, since the through-hole conductive layer 35 is also formed on the surface of the circuit wiring patterns 32 and 33, the overall thickness of the circuit wiring patterns 32 and 33 is considerably large. Therefore, it is difficult to form a fine circuit wiring pattern. For example, a copper foil having a thickness of 17.5 μm is subjected to chemical copper plating to a thickness of 3 to 6 μm, and further an electrolytic plating is applied to a thickness of 10 to 20 μm to form a through-hole conductive layer 35. In such a case, the total thickness of the circuit wiring patterns 32 and 33 is 30.5 to 43.5 μm. Therefore, if the width of the circuit wiring pattern that can be formed is set to 2.5 times the thickness of the conductor, the width of the circuit wiring pattern becomes 76.
Since it is as large as about 25 to 108.75 μm, it is difficult to form fine circuit wiring patterns at high density.

Further, when the plating solution renewability and the like in the plating process for forming the through-hole conductive layer 35 are taken into consideration, the hole diameter of the through-hole for through-hole 34 is increased. However, since the land pattern becomes large accordingly, it is difficult to increase the density of the circuit wiring pattern by forming the land pattern portion as small as possible.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a circuit wiring pattern formed with an interconnecting portion when manufacturing a flexible double-sided circuit wiring board having a structure in which front and back circuit wiring patterns are conducted by an interconnecting means. The problem of difficulty in forming a fine circuit wiring pattern due to an increase in the thickness of the circuit wiring pattern due to the conventional through-hole plating layer for conduction, as well as suitably increasing the formation density of the pattern. It is an object of the present invention to provide a method of manufacturing a flexible double-sided circuit wiring board capable of forming fine circuit wiring patterns on both sides at a high density.

[0008]

Therefore, the flexible double-sided circuit wiring board of the present invention is provided.
According to the manufacturing method of (1), a required circuit wiring pattern is formed on one surface of the flexible insulating base material, and the other surface corresponds to a predetermined position of the circuit wiring pattern. Forming a metal mask having a hole at a portion thereof,
After a surface protection layer is formed on the metal mask, excimer laser light is irradiated from the metal mask side to form a conduction hole reaching the circuit wiring pattern from the hole, and then the metal mask is formed. After removing the conductive hole, a conductive layer is formed on the bottom and the inner wall surface of the conductive hole and the other surface of the flexible insulating base material, and then another conductive layer is formed on the conductive layer including the conductive hole. A step of forming a circuit wiring pattern can be employed.

[0010]

FIG. 1 is a conceptual cross-sectional view of a principal part of a flexible double-sided circuit wiring board according to an embodiment of the present invention.
FIG. 2 shows a sectional perspective view of the same. In both figures, 1 is a flexible insulating base material such as a polyimide film,
Reference numeral 2 denotes a circuit wiring pattern formed on one surface of the flexible insulating base material, which is formed to have a width of 50 μm in this embodiment. A protective film 6 made of a polyimide film or the like is adhered to the surface of the circuit wiring pattern 2 using an adhesive 5 to form a surface protective layer 7.

From the other surface of the flexible insulating base material 1 at the place where the circuit wiring pattern 2 is formed, a diameter equal to or larger than the width of the circuit wiring pattern 2 is obtained. The conductive hole 8 having a bottom is formed so as to reach the circuit wiring pattern 2, and the inner wall surface and the bottom surface of the conductive hole 8 and the other surface of the flexible insulating base material 1 are provided. The above circuit wiring pattern 2
Another circuit wiring pattern 11 is formed so as to be electrically connected to the circuit wiring patterns 2 and 11 on the front and back sides by a conductive portion having a bottom. In this embodiment, the diameter of the conduction hole 8 was 80 μm.

FIGS. 3 (1) to 3 (4) are manufacturing process diagrams of the flexible double-sided circuit wiring board, as shown in FIG. 3 (1).
First, a flexible double-sided copper-clad laminate having an adhesive or a non-adhesive type is prepared, and a required circuit wiring pattern 2 is formed on one surface of the flexible insulating base material 1. Along with
On the other side, a metal mask 4 having a hole 3 equal to or larger than the width of the circuit wiring pattern 2 at a corresponding position where the circuit wiring pattern 2 is located is formed by a normal photofabrication method. Form. And a circuit wiring pattern 2
A protective film 6 such as a polyimide film is adhered to the surface of the substrate with an adhesive 5 to form a surface protective layer 7.

Next, as shown in FIG. 2B, excimer laser light A is irradiated from the side of the metal mask
A conduction hole 8 reaching the circuit wiring pattern 2 from the hole 3 is formed by abrasion.

Therefore, as shown in FIG. 3 (3), the metal mask 4 is first removed by etching, and then the bottom and inner wall surfaces of the conduction hole 8 and the other surface of the flexible insulating base material 1 are provided with a required thickness. Is formed. The conductive layer 9 can be formed by chromium or copper ion beam sputtering or vapor deposition, followed by electrolytic copper plating, or chemical copper plating and electrolytic copper plating. A resist layer 10 corresponding to a required circuit wiring pattern is formed on the surface of the conductive layer 9 including the conduction hole 8 by, for example, applying an electrodeposition resist and then performing exposure and development treatments. Form.

Next, as shown in FIG.
Unnecessary portions of the conductive layer 9 which are not covered and exposed by etching are removed by etching, and the resist layer 10 is peeled off, so that the conductive layer portion formed in the conduction hole 8 and the circuit wiring pattern 2 Another electrically connected circuit wiring pattern 11 can be formed, thereby obtaining a flexible double-sided circuit wiring board having the structure described above.

[0016]

According to <br/> preparation of flexible double-sided circuit wiring board according to the present invention, the flexible insulating base - the circuit wiring pattern formed on both sides of the scan material - electrically connecting the down When a conductive portion is provided, it is not necessary to form a land portion on one of the circuit wiring patterns as in the related art, so that one of the circuit wiring patterns can be formed finely and with a high density. It is possible.

The means for forming the interconnecting portion for the circuit wiring patterns on both sides is a method of further attaching the circuit wiring pattern when forming the through-hole conductive layer as in the conventional technique. Therefore, one of the circuit wiring patterns can be finely formed in an originally thin state.

Also, the other circuit wiring pattern formed on the other surface of the flexible insulating base material is similarly formed of a thinner conductive layer than the conventional one formed by means such as electrolytic copper plating. It can be formed, and the other circuit wiring pattern can be formed finer than before, so that it has a flexible double-sided surface suitable for use in mounting electronic components at high density. A circuit wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is a conceptual cross-sectional configuration view of a principal part of a flexible double-sided circuit wiring board configured according to an embodiment of the present invention.

FIG. 2 is a conceptual cross-sectional perspective configuration diagram of the flexible double-sided circuit wiring board of FIG. 1;

FIGS. 3 (1) to (4) are manufacturing process diagrams of a flexible double-sided circuit wiring board according to one embodiment of the present invention.

FIG. 4 is a conceptual sectional perspective view of a conventional flexible double-sided circuit wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible insulating base material 2 Circuit wiring pattern 3 Hole 4 Metal mask 5 Adhesive 6 Protective film 7 Surface protective layer 8 Conducting hole 9 Conductive layer 10 Resist layer 11 Circuit wiring pattern

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-214497 (JP, A) JP-A-2-146871 (JP, U) Patent 2760093 (JP, B2) Patent 2911273 (JP, B2) Patent 3002307 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 1/11 H05K 3/40

Claims (1)

(57) [Claims] 1. A required circuit wiring pattern is formed on one surface of a flexible insulating base material, and a portion corresponding to a predetermined position of the circuit wiring pattern is formed on the other surface. After forming a metal mask having a hole and forming a surface protective layer on the circuit wiring pattern, excimer laser light is irradiated from the metal mask side to form a circuit wiring pattern through the hole.
After the conductive hole reaching the contact hole is formed, the metal mask is removed, and then a conductive layer is formed on the bottom and inner wall surfaces of the conductive hole and the other surface of the flexible insulating base material. Forming, and then forming another circuit wiring pattern on the conductive layer including the conductive hole.