JPH04111491A - Wiring board - Google Patents

Abstract

PURPOSE:To prevent the exfoliation of film medium from the bed substrate in electroless plating by using the mixture of a metal, which has the catalyst action of electroless plating, and an oxide of that metal or an oxide, which has sensitiveness to energy beam, as the film medium. CONSTITUTION:By using the mixture of Ni and NiO as a film.medium, the patterning with a laser beam is possible, and when a resin film 11 where a wiring pattern 12' is made is passed in an electroless plating bath 14, a copper layer 13, 7mum thick is stacked on the surface of the wiring pattern 12'. At this time, it contains Ni, which has the catalyst action of electrolytic plating, as the component constituting the film catalyst 12, so the process of activating the surface to be plated and giving catalyst being the pretreatment can be omitted. Moreover, since it contains NiO as the components constituting the film medium 12, the adhesion between the film medium 12 and the bed film 11 improves, and the wiring pattern 12' never exfoliates from the bed film 11.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention relates to a wiring board, and particularly to a wiring board having a fine wiring pattern suitable for mounting and mounting semiconductor elements, chip components, etc. .

(Prior art) Conventionally, with the aim of downsizing electronic devices, wiring boards with fine wiring patterns suitable for mounting and mounting semiconductor elements and chip components have been used for high-density mounting circuits (equipment). ing. In this type of wiring board, a conductive metal thin film is deposited on a predetermined substrate in advance, and an energy beam such as excimer laser light or argon laser light is irradiated onto the conductive metal thin film to form a conductive metal thin film. A desired wiring pattern is formed by selectively removing. At this time, the energy beam irradiates and evaporates and melts only the metal film without damaging the underlying substrate, which is primarily a resin-based material.

In order to selectively remove the metal film by scattering or the like, the thickness of the metal film needs to be 100 nI11 or less at most.

Therefore, in order to lower the wiring resistance, an electroless plating process is required to deposit metal on the wiring pattern.

Here, as a material that can form a desired pattern by selectively removing a thin film medium with good sensitivity by irradiation with an energy beam, for example, a mixture of metallic tellurium and an organic material deposited on a resin substrate is used. There is a thin film medium consisting of It is well known that this thin film medium selectively forms a pattern using a relatively small power of a semiconductor laser, but when a substrate coated with this thin film medium is used for the above purpose, it is necessary to use an electroless plating solution. The film peels off when immersed in water, making it impossible to deposit metal. In addition, it is possible to selectively form a pattern on a wiring board in which a thin film of metallic nickel is deposited on a resin substrate by evaporation, melting, and scattering when irradiated with an argon laser, YAG laser, etc., but electroless plating is not possible. During the process, stress in the deposited film causes the film to peel off, making it impossible to deposit metal.

(Problem to be Solved by the Invention) Conventionally, for the purpose of use in high-density packaging circuits (devices), an energy beam is irradiated onto a thin film medium that has been deposited in advance to selectively remove the thin film medium. As a result, in a wiring board on which a desired wiring pattern is formed, there is a problem that peeling of the thin film medium occurs in the step of depositing metal by electroless plating after forming the wiring pattern.

The present invention has been made in consideration of the above circumstances, and its purpose is to prevent peeling between the base substrate and the thin film medium during the electroless plating process, and to provide highly reliable wiring with low wiring resistance. Our goal is to provide wiring boards.

[Structure of the Invention] (Means for Solving the Problems) The gist of the present invention is to optimize the material of the thin film medium in order to prevent peeling between the base substrate and the thin film medium during the electroless plating process. .

That is, the present invention irradiates an energy beam onto a thin film medium attached to a predetermined substrate, selectively removes the thin film medium to form a desired wiring pattern, and then electroless plating is performed on the wiring pattern. In wiring boards coated with metal,
A mixture of a metal that has a catalytic action for electroless plating and an oxide of the metal or an oxide that is sensitive to energy beams is used as the thin film medium.

Further, the present invention provides a thin film medium having a composition ratio X of oxide expressed as A+-x Bx (A is metal, B is oxide) of 0.
The range is set to 03≦x≦0.97.

(Function) According to the present invention, since the thin film medium contains a metal that has a catalytic action for electroless plating as a component, it is possible to coat the surface to be plated, which is a pretreatment normally performed in the electroless plating process. The activation and catalyst application steps can be omitted, making it possible to simplify the manufacturing process.

Furthermore, compared to the case where the catalyst metal is adsorbed by immersion in a solution in the catalyst application step, the adhesion strength between the thin film medium and the deposited film increases, and peeling between the thin film medium and the deposited film can be prevented. Furthermore, since the thin film medium contains oxides as components, the adhesion between the thin film medium and the underlying substrate is improved.
Peeling between the base substrate and the thin film medium can be prevented.

Further, if this oxide is made sensitive to energy beams, patterning by energy beam irradiation can be performed more effectively. For these reasons, a good plated deposit film can be obtained in the electroless plating process, and the wiring resistance is sufficiently low (for example, sheet resistance of 3 mΩ).
In addition, since the wiring is formed by energy beam irradiation in the present invention, it is also effective for wiring boards that have wiring on the sides, which was difficult to do in the past. . For example, JP-A-62-
In the case of a board on which a solid-state image sensor is mounted, such as that seen in Publication No. 318685, the present invention makes it possible to manufacture a wiring board with continuous wiring formed on the top and side surfaces of the board, achieving electrically reliable wiring connections. This makes it possible to reduce the size and weight of solid-state imaging devices.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

<Example 1> Fig. 1 is a sectional view showing the manufacturing process of a wiring board according to the first example of the present invention, and this example relates to a wiring board for mounting semiconductor elements, chip components, etc. .

First, as shown in FIG. 1(a), a polyetheretherketone (hereinafter abbreviated as PEEK) resin film 11 having a thickness of 50 μm is prepared, which has been wound into a roll and attached in advance. This resin film 11 was placed in a vacuum chamber 21 of a film forming apparatus shown in FIG. 2, and while the resin film 11 was being rewound, reactive sputtering was performed using a mixed gas of argon and oxygen using nickel metal as a target 22. . As a result, a thin film medium 12 having a thickness of 80 nm was formed on the surface of the resin film 11, as shown in FIG. 1(b).

The partial pressure ratio of argon and oxygen in this reactive tank was 10:1, the gas flow rate was 28 sec, and the gas pressure at this time was 5 mTorr. The applied power is 5
At 00 W, the deposition rate of the thin film medium 12 under these sputtering conditions was 20 nm/min. In addition, in Figure 2, 23
24 indicates an exhaust system, and 24 indicates a valve connecting the exhaust system 23 and the vacuum chamber 21.

The thin film medium 12 formed by the above method was confirmed to contain Ni and NiO by X-ray diffraction, and was confirmed to be a system in which Ni and NiO were dispersed into fine particles by observation with a transmission electron microscope.

In addition, wet analysis revealed that N i (50) −N i
It was found to be O(50). Furthermore, the wavelength is 830n
The reflectance of the thin film medium for light of m is 43%, and the absorption coefficient is 4
At 0%, it had sufficient sensitivity for the GaAjJAs semiconductor laser.

Next, on the surface of the thin film medium 12 formed on the surface of the resin film 11, as shown in FIG.
When the laser beam was irradiated while scanning with a power of 51, the irradiated area covered the thin film medium 12 over a width of approximately 1 μm.
The wiring pattern 12 is scattered as shown in FIG. 1(C).
was formed. The line width of this wiring pattern 12° is 20μ
m, the wiring resistance is 100Ω/cm.

Sheet resistance was 200Ω/hole. Here, since the thin film medium 12 contains NiO, which has absorption in the laser wavelength region, the thin film medium 12 can be selectively removed even with relatively low power laser light. Ta.

Next, the resin film 1 with the wiring pattern 12' formed thereon is
1 was passed through an electroless plating bath 41 as shown in FIG. 4, and a 7 μm thick copper layer 13 was deposited on the wiring pattern 12' surface as shown in FIG. 1(d). . At this time, since Ni, which has a catalytic effect for electroless plating, is included as a component constituting the thin film medium 12, the activation and catalytic application of the surface to be plated, which is a pretreatment usually performed in the electroless plating process, is performed. This process could be omitted. In addition, since NiO is included as a component constituting the thin film medium 12, the thin film medium 12 and the base film 11
The wiring pattern 12' was not peeled off from the base film 11. After drying in an infrared oven,
When I measured the resistance, the wiring resistance was 1.3Ω/cll1
One sheet resistance was approximately 3 mΩ/mouth.

In this way, according to this embodiment, Ni is used as the thin film medium 12.
By using a mixture of NiO and NiO, patterning can be performed with a laser beam, and copper can be deposited by electroless plating without causing peeling of the thin film medium 12. Therefore, a highly reliable wiring board with low wiring resistance can be realized. Moreover, since the resin film 11 wound into a roll is used as the substrate material, the film 11 is wound up one after another.

By unwinding, it is possible to manufacture wiring boards in series. Further, there is an advantage that it can be easily realized by simply selecting the material of the thin film medium 12 without requiring any major changes in the conventional process.

<Example 2> Next, a second example of the present invention will be described. This embodiment relates to a wiring board for mounting semiconductor elements, chip components, etc. similar to the first embodiment.

A sputtering device similar to that in the first embodiment was prepared, and two targets, a nickel, lead, and boron oxide sintered target and a palladium metal target were installed, and the sputtering device was sputtered in a vacuum chamber of the sputtering device. Sputtering was performed with argon gas while unwinding a PEEK resin film with a thickness of 50 μm that had been wound into a shape and attached in advance.

The argon gas flow rate during sputtering was 28 seconds, and the gas pressure at this time was 5 mTorr. The powers applied to the oxide sintered target and the palladium metal target were 150 W and 500 W, respectively, the film deposition rate under these sputtering conditions was 35 r+m/min, and the thickness of the thin film medium deposited on the film was 5 ounces. Met.

The thin film medium formed by the above method was determined to have P by X-ray diffraction.
d, N i O, P b O, B203, and from transmission electron microscopy observation, N in the Pd metal matrix.
ip, PbO, B20. It was confirmed that the system consisted of dispersed fine particles. In addition, by wet analysis, P d (94)-N i 0(4)-P b 0(1
)-8203(1). Further, the thin film medium had a reflectance of 53% and an absorption rate of 25% for light with a wavelength of 830 nm, and had sufficient sensitivity for the GaAllAs semiconductor laser.

Next, GaA, QAs laser light with a wavelength of 830 tv was applied to the thin film medium surface formed on the film surface.
When irradiated while scanning with a power of mW, the thin film medium was scattered over a width of about 1 μm in the irradiated area, with a line width of 20 μm, a wiring resistance of 50 Ω/cm, and a sheet resistance of 1.
A wiring pattern of 00Ω/hole was formed.

Next, when the film with the wiring pattern formed thereon was passed through an electroless plating machine, a 7 μm thick copper layer was deposited on the surface of the wiring pattern, and after drying in an infrared oven, the resistance was measured. The resistance was 1.3 Ω/cm, and the sheet resistance was about 3 mΩ/mouth.

<Example 3> Next, a third example of the present invention will be described. This embodiment relates to a wiring board for mounting a solid-state image sensor.

A sputtering device similar to that of the first embodiment was prepared, and reactive sputtering was performed using a mixed gas of argon and oxygen on the surface and side surfaces of a transparent glass substrate in the vacuum chamber of the sputtering device equipped with nickel metal as a target. A thin film medium having a thickness of 80 nm was deposited. The sputtering conditions and the thin film medium used at this time were the same as in the first embodiment. wavelength 5
The thin film medium had a reflectance of 35% and an absorption rate of 56% for light at 80 r+m, and had sufficient sensitivity to the argon laser.

Next, as shown in FIG. 5, argon laser light with a wavelength of 580 nm output from the argon laser 53 is irradiated while scanning with a power of 50 mW on the surface of the thin film medium formed on the surface and side surface of the transparent glass substrate 51. As a result, the thin film medium was scattered over a width of approximately 20 μm in the irradiated area, with a line width of 100 μm and a wiring resistance of 20 Ω/cm.
, A wiring pattern 52 with a sheet resistance of 40Ω/hole was formed.

Furthermore, when the transparent glass substrate 51 was passed through an electroless plating bath, a 7 μm thick copper layer was deposited on the surface of the wiring pattern 52, and after drying in an infrared oven, the wiring resistance was measured to be 0.3Ω/ cms sheet resistance approximately 3111Ω/
It was the mouth.

Thereafter, as shown in FIG. 6, a solid-state image sensor 62 is mounted on a transparent glass substrate 51 via a metal bump 61, and a flexible wiring board 64 corresponding to the side surface of the transparent glass substrate 51 is attached to an anisotropic conductive rubber 63. Connected via. When the solid-state image sensor was tested for operation, a good output signal was obtained.

In this way, in this embodiment, not only can the same effects as in the first embodiment described above be obtained, but also a wiring board having wiring on the side surface can be realized, so that it is possible to mount a solid-state image sensor and electrically Highly reliable wiring connections can be achieved, making it possible to contribute to the reduction in size and weight of solid-state imaging devices.

Note that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without departing from the gist of the present invention, as described below.

In the example, a glass substrate and PEEK resin were used as base substrates for forming the required wiring pattern, but other than these, conventional printed wiring boards such as glass epoxy substrates and phenol substrates, silicon wafers, and ceramic substrates may also be used. In addition, polyimide resin, polyetherimide resin, polyphenylene sulfide resin, and polycarbonate resin may be used.

The thin film medium may consist of at least two types of phases that do not dissolve in solid solution with each other, one of which is a metal that has a catalytic effect for electroless plating, and one of which is an oxide of the metal or an oxide that is sensitive to energy beams. good. Here, as a metal,
Fe.

Co, Ni, Ru, Rh, Pd, Os, Ir.

At least one selected from Pt, Cu, Ag, and Au can be used. In addition to the oxides of the above metals, examples of oxides include chromium oxide, manganese oxide, niobium oxide, and tantalum oxide.

At least one selected from vanadium oxide, lead oxide, boron oxide, tin oxide, bismuth oxide, indium oxide, and tellurium oxide can be used. In particular, in order to selectively remove the thin film medium by irradiation with an energy beam of relatively low power, oxides such as nickel oxide, cobalt oxide, manganese oxide, chromium oxide, etc., which absorb in the wavelength region of semiconductor lasers, etc. It is desirable to select boron oxide, lead oxide, bismuth oxide, indium oxide, tellurium oxide, osmium oxide, etc., which have a relatively low melting point (preferably 500° C. or lower).

When using laser light as the energy beam, A+-
In the notation x Bx (A is metal, B is oxide), x <
In the case of 0.03, since the reflectance of the laser beam is high, there is little absorption of the laser beam, and the thin film medium cannot be selectively removed. In addition, when 0.97<x, a good plating film is not deposited because the catalytic metal serving as plating nuclei is poorly dispersed. Therefore, the composition ratio X of the oxide is 0.0
It is desirable that the range is 3≦x≦0.97.

Means for depositing the thin film medium include vacuum evaporation, electron beam evaporation, ion beam evaporation, sputtering, ion beam sputtering, ion blating, plasma polymerization, spin cord, etc., and may be used as appropriate depending on the composition and underlying substrate. You can choose. Energy beams for selectively removing the thin film medium include semiconductor lasers, argon lasers, YAG lasers, excimer lasers, and the like, and can be appropriately selected depending on the dimensions of the underlying substrate and wiring pattern. Materials for the wiring formed on the wiring board include Cu, Ni, Au, Ag, and metals formed by electroless plating. In addition to electroless plating, the method of depositing metal on the surface of a wiring pattern formed by energy beam irradiation to lower the resistance of the wiring pattern can be achieved by appropriately devising the attachment of leads to the wiring pattern. , it is also possible to use electroplating methods.

[Effects of the Invention] As described in detail above, according to the present invention, by optimizing the material of the thin film medium, it is possible to prevent separation between the underlying substrate and the thin film medium during the electroless plating process. Therefore, a desired pattern is formed by depositing the thin film medium of the present invention on a predetermined substrate, selectively removing the thin film medium by irradiating it with an energy beam, and then depositing metal by electroless plating. In the process, it is possible to obtain an electroless plating film with good adhesion without peeling between the base substrate and the thin film medium, and it is possible to realize a highly reliable wiring board with sufficiently low wiring resistance.

[Brief explanation of the drawing]

1 to 4 are for explaining the first embodiment of the present invention. FIG. 1 is a cross-sectional view showing the manufacturing process of a wiring board, and FIG. 2 is a state in which a thin film medium is formed by a sputtering device. 3 is a schematic diagram showing a state in which a thin film medium is irradiated and scanned with a semiconductor laser. FIG. 4 is a schematic diagram showing a state in which electroless plating is applied to a thin film medium. This is for explaining the third embodiment of the present invention, in which FIG. 5 is a schematic diagram showing a state in which a thin film medium on a transparent glass substrate is irradiated and scanned with an argon laser, and FIG. FIG. 3 is a cross-sectional view showing a state in which elements are mounted and a flexible wiring board is attached. 11... Resin film, 12... Thin film medium, 12', 52... Wiring pattern, 13... Copper layer by electroless plating, 21... Vacuum chamber, 22... Target, 31. 53... Semiconductor laser, 41... Plating bath, 51... Glass transparent substrate, 61... Metal bump, 62... Solid-state image sensor, 63... Anisotropic conductive rubber, 64...・Flexible wiring board.

Claims (2)

[Claims] (1) An energy beam is irradiated onto a thin film medium attached to a predetermined substrate, the thin film medium is selectively removed to form a desired wiring pattern, and metal is deposited on this wiring pattern by electroless plating. In the deposited wiring board, the thin film medium is made of a mixture of a metal that has a catalytic action for electroless plating and an oxide of the metal or an oxide that is sensitive to energy beams. wiring board. (2) The thin film medium is formed by setting the composition ratio x of the oxide in the range of 0.03≦x≦0.97, where it is expressed as A_1_−_xB_x (A is a metal, B is an oxide). The wiring board according to claim 1, characterized in that: