JPH05291727A - Manufacture of wiring board - Google Patents

Abstract

PURPOSE:To manufacture a highly accurate and fine wiring board whose connection reliability is excellent by removing a soot-like smear which has adhered in a hole working operation by means of an excimer laser. CONSTITUTION:A wiring part is worked, by means of a subtraction method, on a copper foil on one side of a two-layer metal-clad film which is constituted of a polyimide film 1 and the copper foil 2. A prescribed wiring pattern 3 is formed. The face of the polyimide film 1 is irradiated with an excimer laser; a non-through hole 4 which reaches the copper foil 2 in the wiring pattern 3 is formed. A low-temperature plasma treatment which uses a mixed gas of oxygen gas and a gas containing fluorine is executed; a soot-like smear 5 which has adhered to the peripheral part of the worked hole is removed. A titanium layer 6 and a copper layer 7 are formed continuously on the face of the polyimide including the inside of the non-through hole 4. A plated resist is formed; a wiring pattern 8 is formed by a copper sulfate plating operation; the plated resist is removed; after that, the copper layer 7 and the titanium layer 6 in parts where the wiring pattern 3 is not formed are removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board which enables high density wiring.

[0002]

2. Description of the Related Art In recent years, the trend toward smaller and thinner electronic devices has been increasing, and there is a strong demand for higher density of wiring boards. In response to this, a high-density multilayer wiring board in which a high-definition flexible wiring board having a fine wiring with a line width of 50 μm or less is multilayered has been proposed.
In such a high-definition flexible wiring board, micro holes with a diameter of about 50 to 200 μm are required as interlayer connection holes.
In place of the conventional punching process, excavation laser excavation has been studied for fine drilling. Unlike other lasers (carbon dioxide gas laser and YAG laser), excimer laser has a wavelength in the ultraviolet region, so it has a high photon energy and a diameter of 30 μm due to the direct cleavage of polymer chemical bonds.
It is also possible to process ultra-fine holes.

[0003]

However, in drilling with an excimer laser, soot-like smear, which is presumed to be a fragment generated due to bond cleavage of a polymer, adheres to the periphery of the hole when scattered from the hole. However, it is a problem in the metallization in the hole in the later process. The present invention provides a method for manufacturing a wiring board which removes soot-like smear attached during drilling with an excimer laser and enables the manufacture of a high-definition wiring board with excellent connection reliability.

[0004]

The present invention is based on A. A step of forming a predetermined hole by an excimer laser at a predetermined position of the insulating resin base material, and B. A step of performing a low temperature plasma treatment using a mixed gas of oxygen gas and a fluorine-containing gas, and C.I. A step of forming a metal layer on the surface of the insulating resin substrate including the inside of the hole;
And a step of forming a predetermined wiring pattern on the surface of the insulating resin base material.

1 (a) to 1 (f) are sectional views for explaining a method of manufacturing a flexible wiring board which is an embodiment of the present invention. A two-layer metal clad film (made by Hitachi Chemical Co., Ltd., product name MCF5000I) composed of a polyimide film 1 and a copper foil 2 is formed into a predetermined wiring pattern 3 by wiring the one-sided copper foil by the subtract method. (Fig. 1
(A)). Next, an excimer laser machine (INDEX 200 type) manufactured by Sumitomo Heavy Industries, Ltd. was used to irradiate an excimer laser from the polyimide film surface to form non-through holes 4 having a diameter of 50 μm and reaching the copper foil 2 of the wiring pattern ( Figure 1
(B)). Table 1 shows the excimer laser processing conditions. Next, Yamato Scientific Co., Ltd. plasma etching equipment (PR-501
A type) and the plasma treatment shown in Table 2 was performed to remove the soot-shaped smear 5 attached to the periphery of the processed hole. As the plasma treatment, low temperature plasma treatment using a mixed gas of oxygen gas and fluorine-containing gas is used, and fluorocarbon gas is preferable as the fluorine-containing gas. The partial pressure ratio of oxygen gas in the mixed gas is preferably 0.3 to 0.9. Next, the sample was taken out from the plasma processing apparatus, and a titanium layer 6 and a titanium layer 6 were formed on the polyimide surface including the inside of the non-through hole 4 under the conditions shown in Table 3 using a sputtering apparatus (MLH-6135) manufactured by Nippon Vacuum Technology Co., Ltd. The copper layer 7 was continuously formed (FIG. 1 (c)). Next, after cooling in a sputtering device, the sample was taken out and a positive type liquid resist (manufactured by Shipley, trade name TF-20) was used.
Spin coating with a spin coater (rotation speed: 700 RPM,
Rotation time: 60 seconds). Furthermore, after prebaking at 85 ° C. for 15 minutes, contact exposure was performed at an exposure amount of 500 mJ / cm 2, and development was performed with a special solution. As a result, a predetermined resist pattern 8 was obtained (FIG. 1 (d)). Next, after dipping in a surfactant solution for 60 seconds, the purely washed sample was subjected to copper sulfate plating shown in Table 4 to form a wiring pattern 9 having a thickness of 15 μm (FIG. 1 (e)). Then, after removing the resist pattern 8 with acetone, an ammonium persulfate solution (concentration: 30 g / l, liquid temperature: 4
The surface of the titanium layer 6 was exposed by performing a quick etching on the surface of the titanium layer 6 by immersing it in (0 ° C.). Further exposed titanium layer 6
A part of ammonia solution (ammonia water: 17 ml, hydrogen peroxide water: 170 ml, EDTA: 7 g, pure water: 300 m
By performing the etching in l), a double-sided flexible wiring board having a fine wiring pattern 9 with a line / space of 20 μm / 20 μm on one side was obtained (FIG. 1 (f)). The present invention is not limited to the production of the flexible wiring board as described above, and after forming the insulating resin layer on the multilayer ceramic substrate, excimer laser processing is performed to form a blind via hole. It is also applicable to the production of a multilayer wiring board in which fine wiring is formed by using a thin metal layer formed by a vacuum film forming method or the like as a base metal layer in the semi-additive method. Further, the metal thin layer forming method in the step of forming the metal layer on the surface of the insulating resin base material including the inside of the hole is also applicable to the manufacturing step in which the electroless plating method is applied in addition to the vacuum film forming method.

[0008]

According to the present invention, soot-shaped smears during excimer laser processing can be reliably removed in a short time, and connection reliability and productivity in minute holes are remarkably improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of the present invention.

[Explanation of symbols]

 1. Polyimide film 2. Copper foil 3. Wiring pattern 4. Non-through hole 5. Soot-like smear 6. Titanium layer 7. Copper layer 8. Resist pattern 9. Fine wiring pattern

Claims (3)

[Claims] 1. A. A step of forming a predetermined hole by an excimer laser at a predetermined position of the insulating resin base material, and B. A step of performing a low temperature plasma treatment using a mixed gas of an oxygen gas and a fluorine-containing gas, and C. A step of forming a metal layer on the surface of the insulating resin substrate including the inside of the hole, and D. And a step of forming a predetermined wiring pattern on the surface of the insulating resin base material. 2. A non-through hole reaching a copper foil by an excimer laser is provided at a predetermined position of a polyimide film with a single-sided copper foil, which is formed by applying a polyimide precursor on a copper foil and heating it for imidization. Wiring board manufacturing method. 3. The partial pressure ratio of oxygen gas in the mixed gas is 0.3 to.
The method for producing a wiring board according to claim 1 or 2, which is 0.9.