JP3161407B2 - Activating catalyst solution for electroless plating and electroless plating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an activating catalyst solution for electroless plating and an electroless plating method using the same.

[0002]

2. Description of the Related Art For example, a conductor film for a high-frequency coil, a dielectric filter, a capacitor, a hybrid IC or the like is formed on a substrate such as an alumina substrate, a dielectric ceramic substrate, a polyimide substrate, a glass substrate, a glass epoxy substrate, a ferrite substrate, or the like. In the case where a predetermined pattern is formed thereon, electroless plating may be used. In order to perform electroless plating, it is necessary to activate the substrate surface, and an activation catalyst solution is used for the activation.

[0003] The activating catalyst liquid is applied on a substrate, whereby a photosensitive film is formed on the substrate. When such an activation catalyst liquid is applied onto a substrate and then irradiated with ultraviolet light or laser light, the activation is selectively performed only in the irradiated area, and therefore, only in a specific area. It becomes possible to perform plating. According to such an activation catalyst solution, a conductor film having a fine pattern can be efficiently formed on a substrate by using a photolithography technique.

[0004] As an activating catalyst solution that enables the above, a solution in which palladium acetylacetonate is dissolved in an organic solvent such as chloroform has been used. However, when this method is used, it has been necessary to use a large amount of an organic solvent for cleaning the substrate in a developing step or the like. However, it is not easy to use a large amount of an organic solvent, and therefore, it has been difficult to sufficiently wash and remove unnecessary portions of the photosensitive film formed on the substrate. As described above, when an unnecessary portion of the photosensitive film remains, a plating film is deposited even on a portion other than the pattern portion in a subsequent electroless plating process, so that there is a problem that the pattern lacks sharpness. .

Therefore, as an activating catalyst solution which solves the above problems, there has been proposed an activating catalyst solution described in Japanese Patent Application Laid-Open No. Hei 7-336018 (hereinafter referred to as the prior art).

In this prior art, a mixture of an oxalic acid compound such as iron oxalate, a palladium salt such as palladium chloride, and an alkaline solution is used as an activation catalyst solution. Since the activated catalyst solution is hydrophilic, the organic solvent used in the developing step can be replaced with water.

Hereinafter, a conventional electroless plating method using an activating catalyst solution will be described.

First, the activation catalyst liquid is applied to a substrate by a method such as spin coating, and a photosensitive film made of the activation catalyst liquid is formed on the substrate. Next, the photosensitive film is irradiated (exposed) with light such as laser light, whereby a palladium catalyst is deposited on the substrate. In the exposure, only a specific area is exposed using a photomask or the like,
The palladium catalyst may be selectively deposited. In this case, the unexposed portions of the photosensitive film are removed by washing with water or a liquid containing water as a main component. Thereafter, the substrate on which the palladium catalyst has been deposited is immersed in an electroless plating bath, so that the electroless plating film is deposited on the substrate using the palladium catalyst as an activation catalyst.

As described above, when electroless plating is performed using an activated catalyst solution according to the prior art, since the activated catalyst solution is hydrophilic, it is not necessary to use an organic solvent in the developing step. As a result, an aqueous treatment operation can be performed consistently from the preparation step of the activated catalyst solution to the application step on the substrate and the development step to the electroless plating step. In addition, since washing and washing can be performed in the developing step, a large amount of water can be used safely, and unnecessary photosensitive films can be more efficiently removed.

[0010]

However, the above-mentioned conventional activated catalyst liquid has the following problems.

First, an oxalate and a palladium salt are prepared in order to prepare the activated catalyst solution. The palladium oxalate compound produced at that time has a property that it is difficult to dissolve in an alkaline solution. are doing. For this reason, it is difficult to increase the solubility of the palladium oxalate compound in the alkaline solution. In particular, the prior art (Japanese Unexamined Patent Publication No. 7-3
Iron oxalate listed in 36018) has a great problem in this respect. This causes a problem that, when exposing the photosensitive film to deposit the palladium catalyst on the substrate, the photosensitivity of the activating catalyst solution is low, so that the contrast between the exposed portion and the non-exposed portion is hardly obtained. In order to clarify the contrast, long-time exposure is required, which causes problems such as an increase in the cost required for the exposure and a decrease in the efficiency of deposition of the plating film.

Unnecessary portions (unexposed portions) of the photosensitive film are washed away with water when the exposure is completed.
Iron oxalate in the photosensitive film reacts with water for washing to cause hydrolysis, and as a result, a hydroxide containing a palladium catalyst is generated. This hydroxide adheres to the substrate, and remains without being removed by washing with water. For this reason,
The non-exposed portion is activated, and in the subsequent electroless plating step, a plating film is deposited also on portions other than the pattern portion (exposed portion). This lowers the reliability with respect to the mutual insulation between the plated patterns. Then, in order to ensure mutual insulation between the patterns, in order to remove the hydroxide adhered to the substrate, the pattern is immersed in an aqueous solution of sodium hydroxide having a pH of 14 or more to perform re-cleaning, or a space between the patterns is removed. Needs to be widened. However, when re-cleaning is performed, the number of steps is increased, and inconveniences such as the need to be careful in handling an aqueous sodium hydroxide solution arise. Increasing the spacing between patterns sacrifices the demand for finer pattern formation.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned technical problems. A palladium catalyst is deposited by short-time exposure, and the photosensitive film can be more efficiently removed in the washing step. An object of the present invention is to provide an activating catalyst solution for electrolytic plating.

[0014]

In order to achieve the above object, an activated catalyst solution for electroless plating according to the present invention comprises a hydrophilic activated catalyst containing a lactate, a palladium salt and an alkaline solution. The liquid was used. More preferably, as a lactate, copper lactate or zinc lactate is used alone, or copper lactate and zinc lactate are used in combination, palladium chloride is used as a palladium salt, and ammonia water or the like is used as an alkaline solution. .

Here, the palladium lactate compound formed by mixing a lactate and a palladium salt is easily dissolved in an alkaline solution. For this reason, the solubility of the palladium lactate compound in the alkaline solution can be easily increased.
By using the activated catalyst liquid having a high solubility of the palladium lactate compound, when depositing the palladium catalyst on the substrate, the contrast between the exposed portion and the unexposed portion can be clearly provided by short-time exposure. Further, since the lactic acid compound hardly hydrolyzes with water, it is possible to efficiently remove the photosensitive film without generating unnecessary compounds when washing the photosensitive film with water in the developing step.

Although it has been described above that copper lactate and zinc lactate are preferably used in combination as the lactate, in this case, other copper salts may be used in place of copper lactate, or zinc lactate may be used. Instead, other zinc salts may be used.

Next, an electroless plating method using the activated catalyst solution of the present invention will be described.

First, the activation catalyst solution of the present invention is applied on a substrate by a method such as spin coating, and a photosensitive film made of the activation catalyst solution is formed on the substrate. Next, the photosensitive film is irradiated with light such as a laser beam, whereby a palladium catalyst is deposited on the substrate. Thereafter, the substrate on which the palladium catalyst has been deposited is immersed in an electroless plating bath, so that the electroless plating film is deposited on the substrate using the palladium catalyst as an activation catalyst.

In the above-mentioned electroless plating method, when irradiating the photosensitive film with light, for example, the photosensitive film is irradiated with light such as ultraviolet rays through a photomask or scanned with light such as laser light. When only a specific area is exposed, it is preferable to provide a developing step of washing unexposed portions of the photosensitive film with water or a liquid containing water as a main component.

After irradiating the photosensitive film with light to deposit a palladium catalyst on the substrate, the substrate may be subjected to a heat treatment before the substrate is immersed in an electroless plating bath. This heat treatment stabilizes the palladium catalyst deposited on the substrate, makes it less susceptible to the external environment, and makes it easier to deposit the plating when immersed in an electroless plating bath. This heat treatment is desirably performed in a nitrogen gas atmosphere.
Within a temperature range of 0 ° C, more preferably from 140 ° C to 1
It is desirable that the heating is performed within a temperature range of 80 ° C. for several minutes to several hours.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on experimental examples.

[Experimental Example 1] To prepare about 10 ml of the activated catalyst solution according to each of Samples 1 to 5, zinc lactate [Zn (C ₃ H ₅ O ₃ ) ₂ .3H ₂ O] and copper lactate [Cu (C ₃
H ₅ O _{3) 2],} and was dissolved in aqueous ammonia 2 ml (28%) of palladium chloride [PdCl _2] with a composition ratio as shown in Table 1 below, it was diluted with water 8 ml, then this The mixture was filtered with a 0.45 μm Millipore filter.

[0023]

[Table 1]

Next, each of the activated catalyst solutions according to Samples 1 to 5 was applied at a rotation speed of 1000 rpm for 30 seconds.
A photosensitive film was formed by spin coating on an alumina substrate. Then, ultraviolet light from an excimer lamp (wavelength: 172 nm) was applied to the photosensitive film through a quartz / chrome photomask at an illuminance of 10 mmW / cm ² for 3 seconds and 5 seconds.
After irradiation for 10 seconds and 30 seconds, respectively, the photosensitive film was washed with water and removed, and immersed in 1 liter of an electroless plating solution (60 ° C.) containing the following composition for 10 minutes to perform electroless plating.

NiSO ₄ .6H ₂ O 30 g Sodium hypophosphite 10 g Sodium acetate (anhydrous) 10 g Samples 1 to 5 thus obtained were subjected to nickel electroless treatment. The deposition state of the plating film was observed. The results are shown in Table 2 below.

[0026]

[Table 2]

As shown in Table 2, according to the activated catalyst solution containing zinc lactate, copper lactate, palladium chloride and aqueous ammonia, when the irradiation time of ultraviolet rays is 30 seconds, all of the samples 1 to 5 A nickel electroless plating film was deposited. Further, in Samples 2 and 3, deposition of the plating film was possible even when the irradiation time of ultraviolet rays was extremely short, such as 3 seconds. For example, when the activated catalyst solution of Sample 2 is irradiated with ultraviolet rays for 10 seconds, the resolution (line / space) of 0.3 μm on the substrate is 2 (line / space).
The formation of a 5 μm nickel pattern was confirmed.

Incidentally, based on the sample 2 of this experimental example,
The amount of palladium chloride to be mixed is 0.01 g to 0.05 g
The same experiment was performed using the sample changed in the range. As a result, it was found that the nickel electroless plating film was deposited even when the mixing amount of palladium chloride was changed.

[Experimental Example 2] In Experimental Example 1, the composition ratio of zinc lactate, copper lactate, and palladium chloride was variously changed.
In this experimental example 2, instead of copper lactate, copper chloride [CuCl
₂ · 2H ₂ O] was used. Zinc lactate, copper chloride and palladium chloride were dissolved in 2 ml of aqueous ammonia (28%) at a composition ratio as shown in Table 3 below, and then dissolved in 8 ml.
The mixture was then filtered through a 0.45 μm Millipore filter.

[0030]

[Table 3]

Next, each of the activated catalyst solutions according to Samples 6 to 8 was spin-coated by the same method as in Experimental Example 1 to form a photosensitive film. Was irradiated for 10 seconds, 20 seconds, and 30 seconds, and then the photosensitive film was washed and removed, immersed in a similar electroless plating bath for 10 minutes, and subjected to electroless plating.

With respect to the samples 6 to 8 thus obtained, the deposition state of the nickel electroless plating film was observed. The results are shown in Table 4 below.

[0033]

[Table 4]

As shown in Table 4 above, when the irradiation time was set to 30 seconds, plating films were deposited on all of Samples 6 to 8. In Sample 7, precipitation was observed for 20 seconds.

Similar results were obtained when copper sulfate was used instead of copper chloride as the copper salt.

Experimental Example 3 In Experimental Example 1, the composition ratio of zinc lactate, copper lactate, and palladium chloride was changed variously.
In this experimental example 3, instead of zinc lactate, zinc chloride [Zn
Cl ₂ ] was used. Zinc chloride, copper lactate and palladium chloride were mixed at a composition ratio of 2 ml as shown in Table 5 below.
Was dissolved in aqueous ammonia (28%), diluted with 8 ml of water, and then the mixture was filtered through a 0.45 μm Millipore filter.

[0037]

[Table 5]

Next, each of the activated catalyst solutions according to Samples 9 to 11 was spin-coated by the same method as in Experimental Example 1 to form a photosensitive film, and then the same ultraviolet light was formed on each photosensitive film. For 10 seconds, 20 seconds, and 30 seconds, the photosensitive film was washed and removed, and immersed in a similar electroless plating bath for 10 minutes to perform electroless plating.

With respect to the samples 9 to 11 thus obtained, the deposition state of the nickel electroless plating film was observed. The results are shown in Table 6 below.

[0040]

[Table 6]

As shown in Table 6, deposition of a plating film was confirmed in Sample 11 when the irradiation time was set to 20 seconds, and in Samples 10 and 11 when the irradiation time was set to 30 seconds. In sample 9,
UV irradiation time is relatively long (specifically 3 minutes)
Immersed in the electroless plating bath, then 2-3
After the separation, deposition of the plating film was confirmed.

This experimental example shows that even when zinc lactate is not used, a nickel electroless plating film can be deposited by adjusting the irradiation time of ultraviolet rays when copper lactate is used as a copper salt. .

Similar results were obtained when zinc sulfate was used instead of zinc chloride as the zinc salt.

[Experiment 4] Experiment 4 is an experiment outside the scope of the present invention.

In Experimental Example 1, the composition ratio of zinc lactate, copper lactate, and palladium chloride was variously changed.
Then, instead of zinc lactate, zinc chloride [ZnCl ₂ ]
Copper chloride [CuCl ₂ .2H ₂ O] was used instead of copper lactate. Zinc chloride, copper chloride and palladium chloride were dissolved in 2 ml of aqueous ammonia (28%) at a composition ratio as shown in Table 7 below, then diluted with 8 ml of water. Was filtered with a Millipore filter.

[0046]

[Table 7]

Next, for each of the activated catalyst solutions according to Samples 12 to 14, the same method as in Experimental Example 1 was used.
After spin-coating to form a photosensitive film, and then irradiating each photosensitive film with the same ultraviolet ray for 10 seconds, 20 seconds, and 30 seconds, the photosensitive film was washed and removed. Electroless plating was performed by immersion for minutes.

With respect to the samples 12 to 14 thus obtained, the deposition state of the nickel electroless plating film was observed.
As a result, no plating film was deposited on any of the samples regardless of the irradiation time.

Experimental Example 5 In Experimental Example 1, the composition ratio of zinc lactate, copper lactate, and palladium chloride was changed variously.
In Experimental Example 5, copper lactate was not added to the activated catalyst solution, and only zinc lactate was used as the lactate. Zinc lactate and palladium chloride were dissolved in 2 ml of aqueous ammonia (28%) at a composition ratio as shown in Table 8 below.
and then dilute the mixture with 0.45 μm
Was filtered with a Millipore filter.

[0050]

[Table 8]

Next, for each of the activated catalyst solutions according to Samples 15 to 19, a method similar to that of Experimental Example 1 was used.
After spin-coating to form a photosensitive film, and then irradiating each photosensitive film with the same ultraviolet rays for 3 seconds, 5 seconds, and 10 seconds, the photosensitive film is washed off and immersed in an electroless plating bath for 10 minutes. Then, electroless plating was performed. However, in this Experimental Example 5, instead of nickel plating, the electroless plating bath was immersed in 1 liter of formalin-based electroless copper plating solution (36 ° C.) containing the following composition for 10 minutes, and electroless plating was performed. Was done.

CuSO ₄ .5H ₂ O... 70 g EDTA .4H ₂ O... 100 g NaOH... 60 g For each of the samples 15 to 19 thus obtained, the copper electroless plating film The precipitation state was observed. The results are shown in Table 9 below.

[0053]

[Table 9]

As shown in Table 9, when the irradiation time was 10 seconds, the copper electroless plating films were deposited on all of the samples 15 to 19. In samples 18 and 19, deposition of the plating film was possible even when the irradiation time of the ultraviolet rays was extremely short, such as 3 seconds. From this experimental example, it was confirmed that when only zinc lactate was used as the lactate, the electroless plating film was successfully deposited by the electroless plating in the copper plating bath. And for example, sample 19
When UV irradiation was performed for 5 seconds using the activated catalyst solution of No. 1, a Cu pattern having a thickness of 0.3 μm and a resolution (line / space) of 25 μm was confirmed to be deposited on the substrate.

Experimental Example 6 In Experimental Example 1, the composition ratio of zinc lactate, copper lactate, and palladium chloride was changed variously.
In this Experimental Example 5, zinc lactate was not added to the activated catalyst solution,
As lactate, only copper lactate was used. Copper lactate and palladium chloride were dissolved in 2 ml of aqueous ammonia (28%) at a composition ratio as shown in Table 10 below.
and then dilute the mixture with 0.45 μm
Was filtered with a Millipore filter.

[0056]

[Table 10]

Next, for each of the activated catalyst solutions according to Samples 20 to 24, a method similar to that of Experimental Example 1 was used.
After spin-coating to form a photosensitive film, and then irradiating each photosensitive film with the same ultraviolet rays for 30 seconds, 60 seconds, and 180 seconds, the photosensitive film is washed and removed, and placed in a nickel electroless plating bath for 10 minutes. It was immersed for electroless plating. The electroless plating bath used in Experimental Example 6 had the same composition as that used in Experimental Example 1.

With respect to the samples 20 to 24 thus obtained, the deposition state of the nickel electroless plating film was observed.
The results are shown in Table 11 below.

[0059]

[Table 11]

As shown in Table 11 above, the irradiation time was 60
Seconds, the irradiation time for the sample 24 is 18
When the time was set to 0 seconds, the deposition of the plating film was confirmed in all the samples.

From this experimental example, it can be seen that even when only copper lactate is used as the lactate, the nickel electroless plating film can be deposited by adjusting the irradiation time of the ultraviolet light.

[Experiment 7] Unlike Experiments 1 to 6, Experiment 7 is an experiment in which the difference in solubility between palladium lactate and palladium oxalate in an alkaline solution was examined. More specifically, each of lactic acid [C ₃ H ₆ O ₃ ] and oxalic acid [C ₂ H ₂ O ₄ ], 2 ml of ammonia water (28%), 0.1 g of palladium chloride, and water were
The palladium lactate and the palladium oxalate were dissolved in an alkaline solution by dissolving them in the composition ratios shown in Tables 12 and 13 below.

[0063]

[Table 12]

[0064]

[Table 13]

From the results shown in Tables 12 and 13, it was found that 0.1 g of lactic acid and 0.1 g of palladium chloride were completely dissolved in 2 ml of aqueous ammonia (28%). On the other hand, it was found that at least 2 ml of aqueous ammonia (28%) and 6 ml of water were required to completely dissolve 0.1 g of oxalic acid and palladium chloride, respectively. From the above results, it was found that the solubility of the palladium salt in the same amount of the alkaline solution was larger in the lactate salt than in the oxalate salt.

[Other Experimental Examples] The composition of the activating catalyst described above is only an example. For example, the content of zinc lactate can be changed in the range of 0.01 to 0.50 g in 10 ml of the activated catalyst solution, and the content of copper lactate is 0.0
It can be changed in the range of 03 to 0.50 g. Further, the content of palladium chloride is 0.01 to 0.30 g
Ammonia water (28%)
Can be changed in the range of 0.5 to 5 ml. In addition, other hydrophilic palladium salts such as palladium sulfate, nitrate, acetate and the like can be used in place of palladium chloride.

In order to more uniformly apply the activated catalyst liquid on the substrate, for example, a hydrophilic binder such as polyvinyl alcohol, a surfactant, or the like may be added to the activated catalyst liquid.

Further, the wavelength of the light applied to the photosensitive film can be changed in the range of 100 to 400 nm. Furthermore, in the above embodiment, electroless plating of nickel and copper was performed, but silver, palladium, gold, platinum, etc.
The present invention can be applied to the case of performing electroless plating of other metals. The substrate on which the electroless plating is performed is not limited to the above-described alumina substrate, and other substrates such as a dielectric or magnetic ceramic substrate, a polyimide substrate, a glass substrate, a plastic substrate such as a glass / epoxy substrate, and a semiconductor substrate. It does not matter.

The electroless plating method according to the present invention can be carried out by omitting the developing step by washing with water described above. For example, the selective exposure of only the specific region of the photosensitive film is not performed, and not only when the entire region is exposed, but also when the selective exposure of only the specific region is performed, the resolution of the plating film to be deposited is so high. If it is not necessary, the developing step may be omitted. In the case where the developing step is performed, washing can be performed using a liquid containing water as a main component instead of water. Furthermore, it does not prevent the use of other liquids.

Further, in the electroless plating method of the present invention, after irradiating the photosensitive film with light to deposit a palladium catalyst on the substrate, and before immersing the substrate in the electroless plating bath,
The substrate may be subjected to a heat treatment. The heat treatment stabilizes the palladium catalyst deposited on the substrate, making it less susceptible to the effects of the external environment, and makes plating easier when the substrate is immersed in an electroless plating bath in a later step. It becomes possible to deposit. This heat treatment is desirably performed in a nitrogen gas atmosphere. The heat treatment is performed at a temperature in the range of 100 ° C. to 300 ° C. More preferably, heat treatment is performed at a temperature in the range of 140 ° C. to 180 ° C. for several minutes to several hours. In the heat treatment, the higher the treatment temperature, the more stable the palladium catalyst is, and the easier it is to deposit the plating. However, the higher the temperature, the lower the resolution of the deposited plating. Therefore, in applications requiring fine patterning, it is desirable to perform the heat treatment at a temperature of about 140 ° C. to 180 ° C.

By using the technique of stabilizing the palladium catalyst by the heat treatment, it is possible to pattern the two main surfaces of the transparent substrate at once by electroless plating, which has been difficult in the past. .
In other words, in the method in which the heat treatment is not performed, when the palladium catalyst is deposited on one main surface and then irradiated with light again from the other main surface, the palladium catalyst on the one main surface is inactivated and a desired plating pattern is formed. I couldn't get it.

Hereinafter, the patterning method will be described.
First, an activation catalyst solution is applied to one main surface of a substrate and exposed to light to deposit a palladium catalyst on the substrate, as in the above-described embodiment. Here, after the unnecessary photosensitive film is removed by washing with water, the substrate is subjected to the above-mentioned predetermined heat treatment. This stabilizes the palladium catalyst deposited on the substrate on the one main surface side. Then
The activation catalyst liquid is applied to the other main surface of the substrate in the same manner, and irradiated with light to deposit a palladium catalyst on the substrate. Thereafter, the unnecessary photosensitive film is removed by washing with water, and the above-mentioned heat treatment is performed again. Then, the substrate having the palladium catalyst deposited on both main surfaces is immersed in an electroless plating bath. Thereby, both principal surfaces of the transparent substrate can be patterned at once by electroless plating.

[0073]

As is clear from the above description, the following excellent effects can be obtained by using the activated catalyst liquid of the present invention.

First, since the activated catalyst liquid of the present invention is hydrophilic, the advantages of the above-mentioned hydrophilicity can be enjoyed. That is, since the developing process can be performed using water, efficient cleaning using a large amount of water can be performed safely and inexpensively. This makes it possible to more completely remove unnecessary photosensitive films,
It is possible to increase the resolution of the pattern of the plating film.

The lactate used as the composition of the activated catalyst solution of the present invention is very easily dissolved in an alkaline solution, so that a high-concentration activated catalyst solution can be easily obtained. Thus, the deposition rate of the palladium catalyst as the activation catalyst on the substrate can be increased. This makes it possible to deposit the palladium catalyst on the substrate in a shorter exposure time. For example, when irradiation is performed at an illuminance of 10 mmW / cm ² using an excimer lamp having a wavelength of 172 nm, the palladium catalyst is deposited in an extremely short exposure time of 3 seconds in the optimal embodiment, and plating in the electroless plating process Deposition of the film has been confirmed. By shortening the deposition time of the palladium catalyst, the cost required for exposure can be suppressed, and the efficiency of depositing the plating film can be increased.

Next, since the activated catalyst solution of the present invention hardly hydrolyzes with water, it does not generate unnecessary compounds such as hydroxides in the developing step, so that the photosensitive film can be efficiently removed. The exposed part can be removed. As a result, in the subsequent electroless plating step, the plating film is less likely to be deposited on portions other than the pattern portion, and the sharpness of the formed pattern can be improved.

Furthermore, the plating film formed by the electroless plating performed using the activating catalyst solution of the present invention has a high adhesion strength to the substrate because there is no unnecessary inclusion such as iron hydroxide. I have. For this reason, sufficient adhesion strength can be provided even without etching the substrate in advance. In addition, a plating film can be deposited with sufficient adhesion strength even on a substrate on which etching is difficult.

In addition, since there are no unnecessary inclusions,
The effect that the electrical conductivity of the deposited plating film can be improved can also be obtained. Therefore, this plating film can be applied without problem to pattern formation of a high-frequency circuit that requires a higher electric conductivity.

After exposing the activated catalyst liquid to deposit the palladium catalyst on the substrate, the substrate is subjected to a heat treatment, whereby the palladium catalyst can be stabilized. Thereby, it is possible to make the deposited palladium catalyst less affected by the external environment. As a result, for example, it is possible to realize patterning at once by electroless plating on both front and back main surfaces of a transparent substrate. Further, since the heat treatment makes it easier to deposit the plating when immersed in the electroless plating bath, the exposure time required to achieve the same level of plating deposition can be shortened.

Claims (10)

(57) [Claims] 1. An activated catalyst solution for hydrophilic electroless plating, comprising a lactate, a palladium salt and an alkaline solution. 2. An activated catalyst solution for hydrophilic electroless plating, wherein at least one of copper lactate and zinc lactate is used as the lactate according to claim 1. 3. The activation catalyst liquid for hydrophilic electroless plating according to claim 2, wherein at least one of a zinc salt and a copper salt is mixed. Activated catalyst solution for 4. The activation catalyst solution for electroless plating according to claim 1, wherein palladium chloride is used as the palladium salt. 5. The activating catalyst solution for electroless plating according to claim 1, wherein ammonia water is used for the alkaline solution. 6. A step of applying the activation catalyst liquid according to claim 1 on a substrate to form a photosensitive film made of the activation catalyst liquid on the substrate; Irradiating the substrate with light to deposit a palladium catalyst on the substrate; and immersing the substrate on which the palladium catalyst has been deposited in an electroless plating bath, and performing electroless plating using the palladium catalyst as an activation catalyst. And an electroless plating method comprising: 7. In the step of irradiating the photosensitive film with light, the light is applied only to a specific region of the photosensitive film,
7. The electroless plating method according to claim 6, further comprising a step of rinsing a region of the photosensitive film not irradiated with the light with water or a liquid containing water as a main component. 8. The method according to claim 6, further comprising a step of subjecting the substrate to a heat treatment between the step of depositing the palladium catalyst on the substrate and the step of immersing the substrate in an electroless plating bath. The electroless plating method according to claim 7. 9. The electroless plating method according to claim 8, wherein the heat treatment is performed at a temperature in a range from 140 ° C. to 180 ° C. 10. The electroless plating method according to claim 8, wherein the heat treatment is performed in a nitrogen gas atmosphere.