JPH0687964A - Method for improving surface of resin and method for forming electroless metal plating and small electronic circuit board produced by the methods - Google Patents

Abstract

PURPOSE:To obtain a resin substrate having a surface excellent in adhesiveness without being affected by its shape and useful as an electronic substrate material, etc., by irradiating a resin substrate with UV laser light comprising a specific main wavelength component under the atmosphere of an amine compound gas and an amide compound gas. CONSTITUTION:A resin substrate such as a polytetrafluoroethylene film is placed in a chamber 3, and the chamber is evacuated with a vacuum pump 5. Ar gas as an inert gas is charged into a container 7 from a bomb 11, while controlling the flow of the gas with a mass flow meter 10, the container 7 having an amine compound (e.g. dimethylaminoethyl acrylate) and/or an amide compound (e.g. acrylamide) 8 therein. Thus, the gas of the amine compound and/or the gas of the amide compound are charged together with the Ar gas into the chamber 3 through a cock 4. The resin substrate in the chamber 3 is subsequently irradiated with laser light 1 through a quartz window 2 in the atmosphere of the gases of the compounds to provide the resin substrate whose surface has good adhesiveness to an adhesive, coating agent, plating, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying a resin surface, a method for forming electroless plating using this method, and a small electronic circuit board manufactured by using the method for forming electroless plating. .

[0002]

2. Description of the Related Art At the present time, it has become possible to design circuits by taking advantage of workability by using an organic substrate or an organic interlayer insulating material as an electronic circuit substrate material. On the other hand, the heat resistance of the substrate material has been required due to the miniaturization and high integration of the electronic circuit substrate. In addition, the demand for high-frequency dielectric properties has become stricter due to the use of higher frequencies and the widespread use of radio, and a substrate with a low dielectric loss is particularly required. As such a substrate, for example, polyimide or a fluorine resin such as polytetrafluoroethylene (PTFE) is used. The former is excellent in dielectric properties, heat resistance, solvent solubility and etching properties, and the latter is excellent in dielectric properties, chemical resistance, moisture resistance and water resistance. As the fluorine-based resin, a resin having a dielectric constant controlled by mixing a filler is often used. However, many of these substrate materials are difficult to adhere to, and the adhesion of plating, resist, coating materials, adhesives, etc. is poor,
The application was limited. Surface modification is often used as a means for improving the adhesion of these base materials. The surface modification is mainly divided into a physical one aiming at an anchor effect and a chemical one modifying a surface chemical structure.

Physical surface modification includes surface roughening using a sandblast, a wire brush or the like. These methods utilize the anchor effect, and although they have some effect on polyimide, they are not sufficient, and they are not effective on fluorine-based resins having strong water and oil repellency such as PTFE.

As chemical surface modification, there are alkali treatment, acid treatment, ultraviolet treatment, corona discharge treatment, plasma treatment and the like, and polyimide can be expected to have a great effect depending on its use. In the case of a fluorine-based resin, industrially, a tetra-etching treatment, which is a kind of alkali treatment, is used. Also, although it is in the research stage,
No. 9 bulletins and magazines (eg, International Journal of Adhesion and Adhesives (INT. J. ADHESION AND ADHESIVES, Vol. 11, No. 4, No. 24)
Plasma treatments under various gas atmospheres, as described in pp. 7-254, October 1991). Furthermore, as another technique, the present inventors proposed to irradiate a KrF excimer laser on the PTFE surface in a glycidyl methacrylate gas atmosphere to improve the peel strength with an epoxy adhesive (1992 Polymer Presented at the annual conference), but was not practically sufficient.

Further, although other methods can improve the surface energy of the fluororesin, they have not yet improved the adhesiveness of the adhesive, coating, plating and the like.

When electroless plating is applied to a substrate having poor adhesion such as PTFE, a surface treatment must be performed to attach plating nuclei. Industrially, for example, a tetra-etching treatment of immersing a substrate in the above alkaline solution is performed. This method increases the polar component of the surface energy by hydrolyzing the surface of the substrate and improves the adhesion of the plating nuclei.

However, since these methods are of the wet type, variations in quality are large, and it is difficult to selectively process only necessary portions. In the case of the full additive method, for example, resist coating, patterning, and electroless plating are performed after nucleation, but since nucleation is performed on the entire surface, the nuclei remaining between the patterns adversely affect the insulating property.

[0008]

Therefore, it is possible to selectively modify the surface of a required portion without being influenced by the shape of the resin base material, and it is excellent in the adhesiveness to the adhesive, the coating agent, the plating and the like. A method of modifying the resin surface is desired. Further, there is a demand for a method of forming electroless plating that does not leave plating nuclei between patterns and does not affect insulation when electroless plating is performed. The present invention aims to solve the above-mentioned conventional problems.

[0009]

As a result of earnest studies, the present inventors were able to solve the above-mentioned conventional problems. That is, the first aspect of the present invention is to place the resin base material in an amine compound gas and / or amide compound gas atmosphere,
In that state, the surface of the resin substrate is irradiated with an ultraviolet laser having a main wavelength component of 360 nm or less,
A method for modifying a resin surface is provided.

In a second aspect of the present invention, only the required portion of the resin surface is surface-modified by the method described above, and plating nuclei are selectively adhered only to the surface-modified portion. The present invention provides a method for forming electroless plating, in which generation and patterning of electrolytic plating are performed simultaneously.

The third aspect of the present invention is the second aspect of the present invention.
A small electronic circuit board manufactured by a manufacturing process including the electroless plating forming process of the method described in 1.

The present invention will be described in more detail below. The resin surface modification method of the present invention comprises irradiating an excimer laser beam on the surface of a resin substrate under an atmosphere of an amine compound gas and / or an amide compound gas to modify the resin surface only on the irradiated portion, and to form an adhesive or coating. It significantly improves the adhesion to materials, plating and the like. Further, by surface-modifying only the necessary part by this method and applying electroless plating, only the surface-modified part is nucleated and the electroless plating pattern is directly formed. Insulation deterioration can be eliminated.

The resin base material that can be used in the present invention is not particularly limited as long as it is an organic polymer compound. In particular, although fluorine-based polymers such as PTFE and polyvinylidene fluoride, liquid crystal polymers, polyolefin-based polymers such as polyethylene, and polyimides have not been able to obtain a sufficient surface-modifying effect by conventional methods, the method of the present invention By applying the above, practical adhesion to an adhesive or plating can be obtained. Note that, for example, polyethylene terephthalate, polyparaphenylsulfone, and the like can be surface-modified with a practical effect even when using a low wavelength component of a low pressure mercury lamp, and there is little merit in using a laser as a light source.

The amine compound or amide compound used in the present invention preferably has a molecular weight of 500 or less. If the molecular weight exceeds 500, it is difficult to gasify. In addition, an amine or amide compound having a photopolymerizable unsaturated group in the molecule is preferable because it effectively grafts on the resin surface. Specifically, acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropylacrylamide, N, N-isopropylacrylamide, acryloylmorpholin, vinylpyrrolidone, vinylpyridine, vinylaniline, Vinyl imidazole,
Vinylpyrazine is preferred.

The ultraviolet laser having a dominant wavelength component of 360 nm or less according to the present invention is specifically F ₂ (157n
m), ArF (193 nm), KrCl (222n)
m), KrF (248 nm), XeCl (308n
m) and XeF (351 nm) excimer lasers are preferred. In particular, ArF and KrF are preferable because they have good light source stability and a large surface modification effect. In addition, the energy per pulse is preferably 1 J / cm ² to 1 mJ / cm ² , and if it exceeds this, the effect of ablation is too strong and damages the resin, or even removes amine compounds attached or covalently bonded to the resin surface. Resulting in. If it is less than this range, the resin surface cannot be modified because the energy is insufficient.

The amide compound gas and / or amine compound gas used in the present invention can be introduced so that the degree of vacuum in the chamber irradiated with the laser beam is within a suitable range from 1 mTorr to normal pressure. That is, the selection may be made according to the respective boiling points of the amide compound gas or the amine compound gas used. However, a high degree of vacuum of less than 1 mTorr is not preferable because the degree of contact between the amide compound gas or the amine compound gas and the resin deteriorates. Also,
This gas is preferably introduced by forcibly introducing into the chamber with an inert gas such as argon gas.
When the amide compound gas and the amine compound gas are mixed and used, the ratio of the two is not particularly limited and can be freely selected.

As described above, the resin substrate is preferably placed under reduced pressure or in an inert gas atmosphere. This is to stabilize radicals generated when the resin and the amide compound gas and / or the amine compound gas are irradiated with a laser, and to promote a covalent bond between the amide or amine compound gas and the resin. Further, under reduced pressure, compounds that are liquid at room temperature are easily gasified, which is preferable.

When electroless plating is formed on a resin substrate and patterning is simultaneously performed by using the method for modifying a resin surface of the present invention, when the surface of the substrate is modified, a space between the laser light source and the resin is used. It is possible to insert a mask into the substrate, modify only necessary portions, and then apply the conventional electroless plating. The plating nuclei adhere only to the modified surface of the substrate, resulting in the plating being patterned and deposited. At this time, it is necessary to select a mask substrate having a high laser beam transmission property, and synthetic quartz or the like is preferable.

The resin base material to which the method of the present invention is applied is preferably a small substrate in which the size of one unit is 1000 cm ² or less. Originally the laser light is 10mm x 50
Although it is about mm square, since the laser light used in the resin surface modification method of the present invention has relatively low energy, it is possible to use by expanding the irradiation area of the laser light with a lens. Is. However, a too large substrate is not effective in view of the irradiation area of the laser.

An example of an apparatus for carrying out the method of the present invention is shown in FIG.
Shown in. The chamber 3 is moved by the vacuum pump 5 from 1 mTorr
Adjusted to normal pressure. In addition, amide or amine compound 8
Is filled in the container 7. Ar gas as an inert gas enters the container 7 while being regulated by the mass flow meter 10 from the Ar cylinder 11. The amide or amine compound enters the chamber 3 together with Ar gas through the opened cock 4 by using a heating means (not shown) if necessary. The resin substrate is irradiated with laser light 1 through a quartz window 2 on a chamber 3 under an amide or amine compound gas atmosphere. Although not shown, when using a mixed gas of an amine compound and an amide compound,
For example, it is possible to arrange the containers 7 in parallel and inject Ar gas into each container to fill the chamber 3 at the same time. When an amide or amine compound having a high boiling point is used, the container 7 to the chamber 3 may be heated.

[0021]

In the method for modifying the resin surface of the present invention, a covalent bond is formed between the resin surface and the amide or amine compound gas by irradiating with a laser beam of a specific wavelength, and the resin surface and adhesive or Good adhesion to plating and the like. Since the method of modifying the resin surface uses laser light, the surface modification can be performed only on a necessary portion regardless of the shape of the resin substrate. Therefore, electroless plating having good adhesion can be formed without performing special pretreatment.

[0022]

EXAMPLES The present invention will be described below with reference to examples. Example 1. In the chamber 3 of the apparatus shown in FIG. 1, as a sample, a PTFE having a thickness of 200 μm and a size of 50 × 50 mm square is used.
The film was put in, and the inside pressure was reduced to 10 mTorr. Next, the cock of the container 7 containing dimethylaminoethyl acrylate was opened, and 100 sccm of Ar gas was flown into the container as a carrier gas. The pressure in the chamber at that time was 10
It was 0 mTorr. Next, use a KrF excimer laser 1 cm
After irradiating the sample surface through the quartz window for 7 minutes under the condition of × 3 cm square shape, 62 mJ / cm ² · pulse, pulse width 10 ns and frequency 10 Hz, close the cock of the container 7,
After leaking the inside of the chamber with nitrogen gas, the sample was taken out. Of the sample surface taken out, only the irradiated part,
It was slightly yellowish and darkened. Two pieces of this sample were prepared, and a strip test piece of 1 cm × 10 cm including an irradiation surface was prepared for a peeling test, and the irradiation surface was bonded with an epoxy adhesive Araldide Standard (manufactured by Ciba Geigy). The curing condition at this time was room temperature for 2 days. The peel test piece thus obtained is referred to as test piece 1.

The sample obtained above was used as a plating nucleating agent activator Neogant (manufactured by Japan Schering Co.).
After immersing in water for 5 minutes at room temperature and rinsing with water, immerse in activator reducer Neogant (manufactured by Japan Schering Co.) for 5 minutes, and stir in electroless copper plating solution Enplate Cu704 (manufactured by Meltex) at 45 ° C. with air stirring. After immersion for 4 hours under this condition, copper plating having a thickness of about 18 μm was formed only on the portion exposed to the laser beam. This sample is also 1 cm x 10 cm
Was cut into strips to obtain copper / PTFE peel test pieces. The test piece thus obtained is referred to as test piece 2.

Also, a PT of 30 mm × 80 mm square and 1 mm thick
Place the FE substrate in the chamber under the same conditions as above, and
mJ / cm ² · pulse, 10 ns, 10 Hz, irradiation area 2.
A 5 cm x 7.5 cm square KrF excimer laser beam is used for 10 times.
The PTFE surface was illuminated through a 100 μm line and space quartz / chrome mask for 1 minute. The obtained sample is immersed in a plating nucleation treatment agent activator Neogant (manufactured by Japan Schering Co.) at room temperature for 5 minutes, washed with water, and then immersed in an activator reducer Neogant (manufactured by Japan Schering Co.) for 5 minutes. When immersed in an electroless copper plating solution Enplate Cu704 (manufactured by Meltex Co.) at 45 ° C. under air stirring for 4 hours, a Cu plating having a thickness of about 18 μm was formed only on the portion exposed to the laser beam. The pattern width obtained at this time was about 110 μm. The comb-shaped test pattern shown in FIG. 2 was formed by the same process. This comb-shaped test pattern is called a test piece 3.

Example 2. A polyimide film Kapton (manufactured by DuPont) having a thickness of 50 μm and a size of 50 × 50 mm is put in the chamber of the apparatus shown in FIG.
The pressure was reduced to rr. Next, the cock of the container containing dimethylaminoethyl acrylate was opened, and 100 sccm of Ar gas as a carrier gas was flown into the container. The pressure in the chamber at that time was 100 mTorr. Then Kr
F excimer laser with 1cm x 3cm square shape, 40mJ
/ Cm ² · pulse, pulse width 10 ns, frequency 10 Hz
After irradiating the sample surface through the quartz window for 7 minutes, the cock of the container was closed, the inside of the chamber was leaked with nitrogen gas, and then the sample was taken out. Of the sample surface taken out,
Only the irradiated area was darkened. Two pieces of this sample were prepared, and a strip test piece of 1 cm × 10 cm was cut out for the peeling test including the irradiation surface, and the irradiation surface was bonded with an epoxy adhesive Araldide Standard (manufactured by Ciba Geigy). The curing condition at this time was room temperature for 2 days. The peel test piece thus obtained is referred to as test piece 4.

Next, a thickness of 50 μm, a 5.0 × 7.5 cm square, and a polyimide film Kapton (made by DuPont) 30 m
J / cm ² · pulse, pulse width 10 ns, frequency 10 H
z, irradiation area 2.5 cm x 7.5 cm square, using KrF excimer laser light, surface-modified sample under the same chamber conditions as above, at room temperature in activator Neogant (Nippon Schering Co.) After immersing in water for 5 minutes and rinsing with water, immerse in Activator Reducer Neogant (made by Nippon Schering Co., Ltd.) for 5 minutes, and then in electroless copper plating solution Enplate Cu704 (made by Meltex Co., Ltd.) at 45 ° C. under air stirring. When immersed for 4 hours, copper plating having a thickness of about 18 μm was formed only on the portion exposed to the laser beam. This sample was similarly cut into 1 cm × 10 cm strips to obtain copper / Kapton peel test pieces. The test piece thus obtained is referred to as test piece 5.

Also, 30 mm × 80 mm square, thickness 100 μm
Put the Polyimide film Kapton of No.3 into the chamber under the same conditions as above, and apply 30 mJ / cm ² pulse, pulse width 10 ns, frequency 10 Hz, irradiation area 2.5 cm x 7.5 cm.
KrF excimer laser light at the corner is 100μ for 10 minutes
The PTFE surface was illuminated through a quartz / chrome mask of m lines and spaces. The obtained sample is immersed in a plating nucleation treatment agent activator Neogant (manufactured by Japan Schering Co.) at room temperature for 5 minutes, washed with water, and then immersed in an activator reducer Neogant (manufactured by Japan Schering Co.) for 5 minutes. Immersed in electroless copper plating solution Enplate Cu704 (made by Meltex Co.) at 45 ° C under air stirring for 4 hours, only about 18 μm where laser light hits
A thick copper plating was formed. The pattern width obtained at this time was about 115 μm. The comb-shaped test pattern shown in FIG. 2 was formed by the same process. This comb-shaped test pattern is referred to as a test piece 6.

Example 3. As a sample in the chamber,
GTL-800 with a thickness of 0.635 mm and 50 mm x 75 mm square
0 board (Gore-Tex Japan high-frequency board (fluorine board)) with no copper attached, put 10mTorr
The pressure was reduced to. Next, open the cock of the container containing dimethylaminoethyl acrylate and use A as the carrier gas.
100 sccm of r gas was flown into the container, and the pressure in the chamber was set to 100 mTorr. Next, a KrF excimer laser was irradiated on the sample surface through a quartz window for 7 minutes under the conditions of 62 mJ / cm ² · pulse, pulse width 10 ns and frequency 10 Hz, and the entire surface was surface-modified. Then, the obtained sample was attached to the center of a copper-clad laminate epoxy resin substrate FR-4 of 5.5 cm × 8.0 cm square and 2 mm thick using an adhesive. Next, the same surface treatment as above was applied to the surface of the GTL-8000 opposite to the sticking side through a quartz / chrome mask, and then the protruding copper portion was masked with a tape. When electroless plating was performed by the above process, a copper-plated circuit pattern having a thickness of 18 μm was formed without etching. Subsequently, the above surface modification was performed on the entire surface of the copper-plated circuit pattern.

Another GTL-8000 sheet was punched to form a bayer hole having a diameter of 0.5 mm at a predetermined position, and one surface of the sheet was subjected to the same surface modification as above, and further aligned to form the sheet. Adhered on the copper pattern. Next, perform surface modification through a mask as above,
An electroless copper plating pattern was formed to obtain a two-layer board.
The substrate thus obtained is 150 ° C./1 hour to 30 ° C./1
I did a heat shock test for 100 cycles,
There were no defects such as peeling between conductors or layers, poor buyer hole connection, and substrate cracking.

Example 4. As a sample in the chamber,
Put a BT resin substrate (without copper) and put 10mTorr inside
The pressure was reduced to. Next, open the cock of the container containing dimethylaminoethyl acrylate and use A as the carrier gas.
100 sccm of r gas was flown into the container. The pressure in the chamber at that time was 100 mTorr. Next, use KrF excimer laser with 62 mJ / cm ² · pulse and pulse width 1
K through the mask for 7 minutes at 0 ns and frequency of 10 Hz
Irradiation with an rF laser was performed to modify the surface of the area where plating was required. Next, it was immersed in an activator Neogant at room temperature for 5 minutes to attach plating nuclei to the modified portion. A photosensitive permanent resist dry film photech was attached to the treated surface of this sample, and patterning was performed so that the surface-treated portion was exposed. This sample is immersed in a plating nucleus activator, reducer neogant for 5 minutes at room temperature to activate the plating nucleus,
After washing with water, it was immersed in an enplate Cu704D at 45 ° C. for 5 hours with air stirring to obtain a copper plating pattern of about 18 μm. As a test pattern, a comb-shaped electrode pattern having a space of 2 mm shown in FIG. 2 was manufactured by the same process. This is designated as test piece 7.

Evaluation Results The peel strength results of the test piece 1 (PTFE), the test piece 4 (polyimide film) and the comparative test piece using the same adhesive as in Example 1 are shown below. In addition, the comparative test piece,
Untreated PTFE (Comparative Specimen 1), Tetra Etch Treatment (Comparative Specimen 2), Untreated Kapton Film (Comparative Specimen 3), 650W Low Pressure Mercury Lamp 30 Seconds Irradiated Kapton Film (Comparative Specimen 4), and tested simultaneously did. The crosshead speed (peeling speed) was set to 10 cm / min. The results are shown in Table 1.

[0032]

[Table 1]

The results of peeling test between the test piece 2 (PTFE), the test piece 5 (polyimide film) and the comparative test piece and the electroless copper plating are shown below. The comparative test pieces were untreated PTFE (comparative test piece 5), tetraetch treatment (comparative test piece 6), untreated Kapton film (comparative test piece 7), 650 W low-pressure mercury lamp for 30 seconds irradiation Kapton film (comparative test piece). 8) and tested simultaneously. However, since the plating nuclei do not adhere to the comparative test piece 7 as it is, a general pretreatment is performed using a securigant 9
02 (Nippon Schering's degreaser) at room temperature for 5 minutes, hot water rinse, Neutragant (Nippon Schering's surface roughening agent) at room temperature for 5 minutes, hot water rinse, Pre-dip Neogant (Nippon Schering) It was used after being subjected to a process of immersion in a neutralizing agent) at room temperature for 1 minute and washing with hot water. The peel test conditions were the same as above. The obtained results are shown in Table 2.

[0034]

[Table 2]

From the results shown in Tables 1 and 2, the effectiveness of the method of the present invention is clearly shown.

Next, the insulation properties between the copper plating patterns of the test piece 3, the test piece 6, the test piece 7 and the comparative test piece were evaluated. The comb-shaped electrode of each test piece was placed in an environment of 50 ° C. and 90% relative humidity, DC 45 V was applied to both ends, and the current value after 24 hours was measured. The comparative test piece was a sample in which electroless copper plating was formed on the entire surface of a tetra-etched 1 mm thick PTFE substrate to a thickness of 18 μm and the same pattern as test piece 3 was formed by etching using an etching resist and ferric chloride. (Comparative test piece 9), 50 μm with the same method
A sample (comparative test piece 10) having a pattern formed on a thick Kapton film and a BT resin substrate (without copper attachment) were pre-treated by dipping in Securligant 902 (a degreasing detergent manufactured by Nippon Schering Co., Ltd.) at room temperature for 5 minutes, washing with water, and neutral. Immerse in Gantt (a surface roughening agent made by Nippon Schering Co., Ltd.) at room temperature for 5 minutes, and then wash with hot water. Predip Neo Gantt (neutralization treatment agent made by Nippon Schering Co., Ltd.) at room temperature for 1 minute and then wash with hot water, and then activator. Immerse in Neogant at room temperature for 5 minutes to attach the plating nuclei to the modified part, attach a photosensitive permanent resist dry film / fotech to the treated surface of this sample, perform the same patterning as sample piece 7, and reducer neogant After activating the plating nuclei for 5 minutes at room temperature, rinse with water and soak in Enplate Cu704D for 5 hours at 45 ° C. with air stirring, Those obtained copper plating pattern of μm was (comparative test piece 11). The results obtained are shown in Table 3.

[0037]

[Table 3]

As described above, the test piece 3, the comparative test piece 9,
There is almost no difference between the test piece 6 and the comparative test piece 10, and it can be seen that the copper wiring manufactured by the method of the present invention has almost the same performance as the conventional one. Further, when applied to the full-additive method, it is found that the test piece 7 of the test piece 7 and the comparative test piece 11 is superior in the inter-wiring insulation characteristic. It is considered that this is because the test piece 7 has no plating nucleus between the wirings.

[0039]

EFFECTS OF THE INVENTION According to the present invention, the surface of a resin can be selectively modified on a required portion without being influenced by the shape of the resin substrate, and the surface of the resin is excellent in adhesion to an adhesive or plating. A method is provided. Further according to the present invention,
Provided is a method for forming electroless plating in which plating nuclei do not remain between patterns and the insulating property is not affected. When the method of the present invention is applied to a plating patterning process, electroless plating can be directly deposited on a substrate in a pattern, and by applying it to an electronic circuit board fabrication, a multilayer board can be fabricated without an etching process.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a surface modification device used in the present invention.

FIG. 2 is a schematic view of a comb-shaped test pattern.

[Explanation of symbols]

 1 Laser Light 2 Quartz Window 3 Chamber 4 Cock 5 Vacuum Pump 6 Vacuum Gauge 7 Vessel 8 Amide or Amine Compound 9 Flow Meter 10 Mass Flow Meter 11 Ar Cylinder

Claims (3)

[Claims] 1. A resin substrate containing a main wavelength component of 360 in an amine compound gas and / or amide compound gas atmosphere.
A method for modifying a resin surface, which comprises irradiating an ultraviolet laser having a wavelength of nm or less. 2. The method according to claim 1, wherein only a necessary portion of the resin surface is surface-modified, and plating nuclei are selectively attached only to the surface-modified portion to generate electroless plating. A method for forming electroless plating, in which patterning is performed simultaneously. 3. Manufactured by a manufacturing process including the electroless plating forming process of the method according to claim 2,
Small electronic circuit board.