JP7675436B2 - Acidic Degreaser - Google Patents

Description

The invention of this application relates to an acidic degreaser used in pretreatment for electrolytic copper pattern plating.

In general, when a printed wiring board is manufactured by electrolytic copper pattern plating, a seed layer, which is a thin metal film, is first provided on the surface of an insulating substrate, and then a resist pattern is formed using a dry film photoresist (hereinafter referred to as "dry film resist " or " DFR"), etc. This is electrolytic copper plated to form a metal coating made of copper or a copper alloy, and unnecessary portions where the resist material and the seed layer are laminated are removed from the surface of the insulating substrate to obtain a substrate with a conductor circuit pattern (i.e., a printed wiring board).

Here, as a pretreatment for the copper electroplating pattern, the seed layer and the insulating substrate with the resist pattern are degreased, washed, etc. If the solution used for this degreasing treatment is alkaline, the dry film resist may react with the alkaline components in the solution, causing problems such as corrosion, crushing, and peeling. For this reason, a method using an acidic degreaser is adopted. This method is excellent in that it can effectively remove oils and fats remaining on the surface of the seed layer and the resist material without corroding the dry film resist, and can also remove natural oxide films and rust that have formed on the surface of the seed layer.

As an example of this type of acidic degreaser, Patent Document 1 discloses "an acidic degreaser containing (A) an acid selected from a divalent carboxylic acid or an alkane sulfonic acid, (B) an acid selected from the group consisting of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, (C) an alkylbenzene sulfonate, and (D) a surfactant having an acetylene bond in the molecule."

JP 2001-89882 A

However, when a conventional acidic degreaser such as that described in Patent Document 1 is used for pretreatment of electrolytic copper pattern plating, the acidic degreaser may have an unexpected effect on the resist pattern depending on the components and their concentrations, treatment conditions, etc. As a result, floating or peeling occurs between the resist pattern and the seed layer, and when electrolytic copper plating is performed, problems such as metal components made of copper or copper alloys penetrating under the resist material and precipitating occur. On the other hand, when an acidic degreaser that does not corrode the resist pattern and treatment conditions therefor are used, there is a problem that the degreasing power and wettability to the seed layer surface are insufficient, and a high-quality product cannot be obtained.

Therefore, those skilled in the art have been looking for an acidic degreaser for use in pretreatment of electrolytic copper pattern plating that is highly unlikely to cause lifting or peeling between the resist pattern and the seed layer, and that has excellent degreasing power and wettability to the seed layer surface.

Therefore, the inventors conducted extensive research and came to achieve this goal by adopting the following method.

The acidic degreaser according to the present application is used for pretreatment of copper electroplating patterns, and is characterized by containing 0.1% by mass to 20% by mass of one or more acids selected from the group consisting of sulfuric acid and organic acids, 0.01% by mass to 1% by mass of a polyoxyalkylene alkyl ether type nonionic surfactant, and a chloride ion source at a chloride ion concentration of 0.001% by mass to 1% by mass, and having a liquid temperature of 15°C to 35°C when used.

In the acidic degreasing agent according to the present application, the organic acid is preferably one or more selected from the group consisting of citric acid, formic acid, acetic acid, propionic acid, glycolic acid, malic acid, oxalic acid, succinic acid, maleic acid, methanesulfonic acid, lactic acid, and tartaric acid.

In the acidic degreaser according to the present application, the polyoxyalkylene alkyl ether type nonionic surfactant is preferably one or more types represented by the following general formula (1) or general formula (2).
R ₁ -O-(EO) _m -(AO) _n -H...(1)
R ₁ -O-(AO) _n -(EO) _m -H...(2)
(In general formula (1) and general formula (2), _R1 is a linear or branched alkyl group having 3 to 20 carbon atoms, EO is an oxyethylene group, m is an integer of 2 to 20 indicating the number of repetitions of EO, AO represents PO (oxypropylene group) or BO (oxybutylene group), and n is an integer of 0 to 20 indicating the number of repetitions of AO.)

The acidic degreaser according to the present application preferably has a chloride ion source selected from the group consisting of sodium chloride, hydrochloric acid, copper chloride, ammonium chloride, lithium chloride, potassium chloride, magnesium chloride, calcium chloride, vanadium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, and zinc chloride.

The invention of this application makes it possible to provide an acidic degreaser for use in pretreatment of electrolytic copper pattern plating, which is highly unlikely to cause lifting or peeling between the resist pattern and the seed layer, and has excellent degreasing power and wettability to the seed layer and the surface of the resist material.

14(a) to 14(g) are metallurgical microscope images taken from above of insulating substrates with seed layers and resist patterns (i.e., copper-clad laminates with resist patterns having electroless copper plating films) in Examples 1 to 7 in which the acidic degreasers of the present application were used. 13A to 13E are metallurgical microscope images of an insulating substrate with a seed layer and a resist pattern, as viewed from above, in Examples 8 to 12, in which the acidic degreaser of the present application was used. 13(a) to 13(d) are metallurgical microscope images of an insulating substrate with a seed layer and a resist pattern, as viewed from above, in Examples 13 to 16, in which the acidic degreaser of the present application was used. 13A to 13C are metallurgical microscope images of an insulating substrate having a seed layer and a resist pattern, as viewed from above, in Examples 17 to 19, in which the acidic degreaser of the present application was used. 13A to 13D are metallurgical microscope images of the insulating substrate with a seed layer and a resist pattern from above in Comparative Examples 1 to 4, in which acidic degreasers with different concentration conditions were used. 13(a) to 13(g) are metallurgical microscope images of an insulating substrate having a seed layer and a resist pattern from above in Comparative Example 5 to Comparative Example 11, in which acidic degreasers having different compositions and/or liquid temperatures during use were used. 13A and 13B are metallurgical microscope images of an insulating substrate with a seed layer and a resist pattern from above in Comparative Example 12 and Comparative Example 13, in which acidic degreasers with different concentration conditions were used. 13A and 13B are metallurgical microscope images of an insulating substrate having a seed layer and a resist pattern from above in Comparative Example 14 and Comparative Example 15, in which acidic degreasers having different concentration conditions were used. 14(a) and 14(b) are cross-sectional observation images of test pieces obtained by electrolytic copper plating on an insulating substrate having a seed layer and a resist pattern in Example 18 using the acidic degreaser of the present application, and in Comparative Example 7 using acidic degreasers having different compositions and liquid temperatures during use.

Below, an embodiment of the acidic degreaser according to the present application will be described with reference to Figures 1 to 9.

The acidic degreaser according to the present application is used for pretreatment of copper electroplating patterns, and contains a predetermined amount of "one or more acids selected from the group consisting of sulfuric acid and organic acids," a "polyoxyalkylene alkyl ether type nonionic surfactant," and a "chloride ion source," and has a liquid temperature of 15°C to 35°C when in use.

A. Components of the Acidic Degreaser Hereinafter, each component of the acidic degreaser of the present application will be described.

A-1. Acid component The acid component is the main component in the acidic degreaser, and is composed of one or more of sulfuric acid and organic acids. This acid component has the function of degreasing and cleaning oil and other contaminants adhering to the seed layer made of copper or copper alloy on the insulating substrate and the surface of the resist material, and also of removing natural oxide films and the like formed on the surface of the seed layer.

Among these acid components, organic acids include citric acid, formic acid, acetic acid, propionic acid, glycolic acid, malic acid, oxalic acid, succinic acid, maleic acid, methanesulfonic acid, lactic acid, and tartaric acid.

The content of the acid component in the acidic degreaser is 0.1% by mass to 20% by mass. If the content of the acid component is less than 0.1% by mass, the effect of degreasing and cleaning dirt such as oil and fat attached to the surface of the seed layer and the resist material on the insulating substrate decreases, and the effect of removing natural oxide films and the like formed on the surface of the seed layer also tends to decrease, which is not preferable. On the other hand, if the content of the acid component exceeds 20% by mass, the acidic degreaser corrodes the resist material, which is not preferable because it tends to cause lifting or peeling between the resist pattern and the seed layer. The content of the acid component is more preferably 1% by mass to 20% by mass, and even more preferably 5% by mass to 15% by mass. If the content of the acid component is 1% by mass to 20% by mass, the effect of degreasing and cleaning dirt such as oil and fat attached to the surface of the seed layer and the resist material tends to be further improved, and if the content of the acid component is 5% by mass to 15% by mass, the effect tends to be most improved and the cost-effectiveness is high. In addition, when the acidic degreasing agent contains two or more types of acid components, the content of the acid components is stated as the total content.

A-2. Polyoxyalkylene alkyl ether type nonionic surfactants Nonionic (also called "nonionic " or " nonionic") surfactants have the advantage of being excellent in emulsifying and solubilizing power and causing little foaming. Among these nonionic surfactants, the representative ones that are most widely used industrially are polyoxyalkylene alkyl ether type nonionic surfactants. Polyoxyalkylene alkyl ether type nonionic surfactants are ether type surfactants obtained mainly by adding alkylene oxide to alcohol, and have the excellent function of effectively reducing the surface tension of an acidic degreaser without adding a separate alcohol compound.

The polyoxyalkylene alkyl ether type nonionic surfactant is preferably one or more of the following general formula (1) or (2):

R ₁ -O-(EO) _m -(AO) _n -H...(1)
R ₁ -O-(AO) _n -(EO) _m -H...(2)
In general formula (1) and general formula (2), _R1 is a linear or branched alkyl group having 3 to 20 carbon atoms, EO is an oxyethylene group, and m is an integer of 2 to 20 indicating the number of repetitions of EO, AO represents PO (oxypropylene group) or BO (oxybutylene group), and n is an integer of 0 to 20 indicating the number of repetitions of AO.

In the above general formula (1) and general formula (2), if the carbon number of R ₁ is less than ₃ , the degreasing power of the acidic degreaser tends to decrease, which is not preferable. On the other hand, if the carbon number of R ₁ exceeds 20, the solubility in water, which is a solvent, tends to decrease, which is not preferable. The carbon number of R ₁ is more preferably 5 to 18, and even more preferably 7 to 16. If the carbon number of R ₁ is 5 to 18, the degreasing power and solubility in water of the acidic degreaser tend to be further improved, and if the carbon number of R 1 is 7 to 16, this tendency is the highest. Furthermore, if this R ₁ is a branched alkyl group, the degreasing power of the acidic degreaser tends to improve, which is more preferable.

In addition, in the above general formulas (1) and (2), if m is less than 2, the solubility in water, which is the solvent, tends to decrease, which is not preferable. On the other hand, if m exceeds 20, the degreasing power of the acidic degreaser tends to decrease, which is not preferable. And, if m is 4 to 15, the solubility in water and the degreasing power of the acidic degreaser tend to improve, which is more preferable.

In the above general formulas (1) and (2), if n exceeds 20, the solubility in water, which is the solvent, tends to decrease, which is undesirable. If n is 0 to 15, the stability of the acidic degreaser in high-temperature environments tends to increase, which is more preferable.

The content of the polyoxyalkylene alkyl ether type nonionic surfactant in the acidic degreaser is 0.01% by mass to 1% by mass. If the content of this polyoxyalkylene alkyl ether type nonionic surfactant is less than 0.01% by mass, the surface tension of the acidic degreaser increases, the wettability of the acidic degreaser to the seed layer and the resist material surface decreases, and the degreasing power of the acidic degreaser tends to decrease, which is not preferable. On the other hand, if the content of this polyoxyalkylene alkyl ether type nonionic surfactant exceeds 1% by mass, it is not preferable because lifting or peeling tends to occur between the resist pattern and the seed layer. And, if the content of this polyoxyalkylene alkyl ether type nonionic surfactant is 0.1% by mass to 0.5% by mass, the surface tension of the acidic degreaser decreases, and the wettability of the acidic degreaser to the seed layer and the resist material surface tends to improve, which is more preferable.

A-3. Chloride ion source The chloride ion source is a compound that ionizes chloride ions ( ^Cl- ) into water when it comes into contact with the water solvent. If the acidic degreaser contains this chloride ion source, it has an excellent effect of suppressing the acidic degreaser from corroding the resist material on the insulating substrate.

Examples of chloride ion sources include sodium chloride, hydrochloric acid, copper chloride, ammonium chloride, lithium chloride, potassium chloride, magnesium chloride, calcium chloride, vanadium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, zinc chloride, etc. The acidic degreaser of the present application contains at least one or more of the group consisting of these compounds.

The content of the chloride ion source in the acidic degreaser is 0.001% by mass to 1% by mass in terms of chloride ion concentration. If the content of the chloride ion source is less than 0.001% by mass in terms of chloride ion concentration, the effect of suppressing the acidic degreaser from corroding the resist material on the insulating substrate is reduced, which is undesirable because lifting or peeling tends to occur between the resist pattern and the seed layer. On the other hand, even if the content of the chloride ion source exceeds 1% by mass in terms of chloride ion concentration, the effect of suppressing the acidic degreaser from corroding the resist material is not improved, and it is undesirable because it is simply a waste of resources.

B. Liquid temperature of the acidic degreaser when used The liquid temperature of the acidic degreaser according to the present application when used is 15°C to 35°C. If the liquid temperature when used is less than 15°C, the degreasing power of the acidic degreaser tends to decrease, which is not preferable. On the other hand, if the liquid temperature when used exceeds 35°C, floating or peeling tends to occur between the resist pattern and the seed layer, which is not preferable. In addition, the liquid temperature when the acidic degreaser is used is preferably 20°C to 35°C, more preferably 25°C to 35°C. If the liquid temperature when the acidic degreaser is used is 20°C to 35°C, the degreasing and cleaning effect of the acidic degreaser tends to be further improved, and if the liquid temperature when the acidic degreaser is used is 25°C to 35°C, the effect is most improved and the time required for the degreasing process can be shortened.

C. Preparation method of acidic degreaser There is no particular limitation on the preparation method of the acidic degreaser of the present application, and it can be prepared by a known method. For example, the acidic degreaser of the present application can be obtained by contacting a predetermined amount of sulfuric acid and/or organic acid, a polyoxyalkylene alkyl ether type nonionic surfactant, and a chloride ion source with water as a solvent at room temperature and stirring the mixture with a stirrer or the like.

The acidic degreaser according to the present application will be specifically described below with reference to examples. However, the invention according to the present application is not limited to these examples.

<Copper-clad laminate with resist pattern having electroless copper plating film (seed layer)>
The copper-clad laminate was immersed in an electroless copper plating solution (Melplate CU-390 manufactured by Meltex Inc.) at room temperature for 20 minutes, then washed with water and dried to provide a 0.3 μm electroless copper plating film as a seed layer on the surface. Next, a dry film resist (LDF725 manufactured by Nikko Materials Co., Ltd., thickness 25 μm) was laminated on the copper-clad laminate having the electroless copper plating film, and exposure was performed by irradiating h-line light (wavelength 405 nm, light intensity 80 mJ/cm ² ) from a mercury lamp using a direct exposure device (Fdi-3M manufactured by Oak Manufacturing Co., Ltd.) through a photomask. A developer solution (aqueous sodium carbonate solution with a concentration of 0.75% by mass) at a liquid temperature of 30°C was sprayed at 0.10 MPa for 27 seconds onto the copper-clad laminate with resist material having this exposed electroless copper plating film to develop the resist material, thereby obtaining a "copper-clad laminate with resist pattern having electroless copper plating film (seed layer)" with a line/space (L/S) of 5 μm/5 μm.

<Acidic degreasing agent>
An acidic degreaser was prepared having a composition of 10 mass% sulfuric acid as an acid component, 0.25 mass% polyoxyethylene trimethylnonyl ether (Tergitol TMN-10 manufactured by Dow Chemical Co.) as a polyoxyalkylene alkyl ether type nonionic surfactant, 0.01 mass% sodium chloride as a chloride ion source in terms of chloride ion concentration, and the remainder water. The surface tension of this acidic degreaser was measured by the Wilhelmy surface tension measurement method. Table 1 shows the composition of the acidic degreaser and its surface tension.

<Evaluation of Acidic Degreasers>
The above-mentioned "copper-clad laminate with a resist pattern having an electroless copper plating film (seed layer)" was degreased by immersing it in an acidic degreaser at a liquid temperature of 30° C. for 10 minutes, then washed with water and dried, and the floating and twisting of the dry film resist pattern was observed from above using a metallurgical microscope. FIG. 1(a) shows the image observed under the metallurgical microscope, and Table 1 shows the evaluation results. In Table 1 and Tables 2 to 6 described later, when the dry film resist pattern treated with the acidic degreaser was in a good condition without floating or twisting, the "DFR condition" was recorded as "◯", and when the dry film resist was floating or twisted, the "DFR condition" was recorded as "×".

Next, a copper Hull Cell plate was prepared, a fingerprint was applied to it, and then it was immersed in an acidic degreaser at a liquid temperature of 30°C for 3 minutes. After rinsing and drying, the remaining fingerprints were visually observed. The evaluation results are shown in Table 1 as "Degreasing power (%)".

Furthermore, a copper-clad laminate similar to the above was separately prepared and subjected to a heat treatment at 120°C for 2 hours to form an oxide film on the surface of the copper foil in the copper-clad laminate, after which it was immersed in an acidic degreaser at a liquid temperature of 30°C for 1 minute and the remaining state of the oxide film was visually observed. The evaluation results are shown in Table 1. In Table 1 and Tables 2 to 6 described below, when the oxide film was completely removed from the copper foil surface, the "oxide film removal performance" was marked with "Good", and when the oxide film remained on the copper foil surface, the "oxide film removal performance" was marked with "Poor".

In Example 2, the test was conducted in the same manner as in Example 1, except that the concentration of sulfuric acid was set to "0.1% by mass." Therefore, the test and evaluation method of Example 2 will not be described. The composition of the acidic degreaser in Example 2, the evaluation results, and the metallurgical microscope images are shown in Table 1 and Figure 1 (b).

In Example 3, the test was conducted in the same manner as in Example 1, except that the concentration of sulfuric acid in the acidic degreaser was changed to "20 mass %." Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser in Example 3, the evaluation results, and the metallurgical microscope observation image are shown in Table 1 and Figure 1 (c).

In Example 4, the test was conducted in the same manner as in Example 1, except that the concentration of polyoxyethylene trimethyl nonyl ether, a polyoxyalkylene alkyl ether-type nonionic surfactant in the acidic degreaser, was changed to "0.01% by mass." Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser in Example 4, the evaluation results, and the metallurgical microscope observation image are shown in Table 1 and Figure 1 (d).

In Example 5, the test was conducted in the same manner as in Example 1, except that the concentration of polyoxyethylene trimethyl nonyl ether, a polyoxyalkylene alkyl ether-type nonionic surfactant in the acidic degreaser, was changed to "1 mass %." Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser in Example 5, the evaluation results, and the metallurgical microscope observation image are shown in Table 1 and Figure 1 (e).

In Example 6, the test was carried out in the same manner as in Example 1, except that the polyoxyalkylene alkyl ether type nonionic surfactant in the acidic degreaser was changed to "polyoxyethylene polyoxypropylene-2-ethylhexyl ether (Ecosurf EH-9 manufactured by The Dow Chemical Company) " . Therefore, the description of the test and evaluation methods will be omitted. The composition of the acidic degreaser of Example 6, the evaluation results, and the metallurgical microscope images are shown in Table 1 and FIG. 1(f).

In Example 7, the test was carried out in the same manner as in Example 1, except that the polyoxyalkylene alkyl ether type nonionic surfactant in the acidic degreaser was changed to "polyoxyethylene tridecyl ether (Noigen TDS-80 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)". Therefore, the description of the test and evaluation methods will be omitted. The composition and evaluation results of the acidic degreaser of Example 7, as well as the metallurgical microscope observation image, are shown in Table 1 and FIG. 1(g).

In Example 8, the test was conducted in the same manner as in Example 1, except that the content of sodium chloride, which is the chloride ion source in the acidic degreaser, was changed to "0.001 mass%" in terms of chloride ion concentration. Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser in Example 8, the evaluation results, and the metallurgical microscope observation image are shown in Table 1 and Figure 2 (a).

In Example 9, the test was conducted in the same manner as in Example 1, except that the content of sodium chloride, which is the chloride ion source in the acidic degreaser, was changed to "0.1 mass%" in terms of chloride ion concentration. Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser in Example 9, the evaluation results, and the metallurgical microscope observation image are shown in Table 1 and Figure 2 (b).

In Example 10, the test was conducted in the same manner as in Example 1, except that the content of sodium chloride, which is the chloride ion source in the acidic degreaser, was changed to "1 mass %" in terms of chloride ion concentration. Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser in Example 10, the evaluation results, and the metallurgical microscope observation image are shown in Table 1 and Figure 2 (c).

In Example 11, the test was conducted in the same manner as in Example 1, except that the liquid temperature of the acidic degreaser during use was changed to "15°C." Therefore, the description of the test and evaluation method will be omitted. The composition of the acidic degreaser in Example 11, the evaluation results, and the metallurgical microscope observation images are shown in Table 1 and Figure 2 (d).

In Example 12, the test was conducted in the same manner as in Example 1, except that the temperature of the acidic degreaser during use was changed to "35°C." Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser in Example 12, the evaluation results, and the metallurgical microscope observation image are shown in Table 1 and Figure 2 (e).

Here, the composition and evaluation results of the acidic degreasers in Examples 1 to 12, which are "forms of acidic degreasers containing only sulfuric acid as an acid," are shown in Table 1.

In Example 13, the test was conducted in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "0.1% by mass glycolic acid," an organic acid. Therefore, the test and evaluation methods are not described here. The composition and evaluation results of the acidic degreaser in Example 13, as well as the metallurgical microscope image, are shown in Table 2 and Figure 3(a).

In Example 14, the test was conducted in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "20% by mass glycolic acid," an organic acid. Therefore, the test and evaluation methods are not described here. The composition of the acidic degreaser in Example 14, the evaluation results, and the metallurgical microscope images are shown in Table 2 and Figure 3 (b).

In Example 15, the test was conducted in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "5% by mass citric acid," an organic acid. Therefore, the test and evaluation methods are not described here. The composition of the acidic degreaser in Example 15, the evaluation results, and the metallurgical microscope images are shown in Table 2 and Figure 3 (c).

In Example 16, the test was conducted in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "5% by mass methanesulfonic acid," an organic acid. Therefore, the test and evaluation methods are not described here. The composition of the acidic degreaser in Example 16, the evaluation results, and the metallurgical microscope images are shown in Table 2 and Figure 3 (d).

Here, the composition and evaluation results of the acidic degreasers in Examples 13 to 16, which are "forms of acidic degreasers containing only organic acids as acids," are shown in Table 2.

In Example 17, the test was conducted in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "0.05% by mass sulfuric acid" and the organic acid "0.05% by mass glycolic acid." Therefore, the test and evaluation methods are not described here. The composition and evaluation results of the acidic degreaser in Example 17, as well as the metallurgical microscope image, are shown in Table 3 and Figure 4(a).

In Example 18, the acid component in the acidic degreaser was changed to "10% by weight sulfuric acid" and "0.1% by weight glycolic acid," an organic acid, and the resist pattern width was changed to "line/space (L/S) 6 μm/6 μm." Except for this, the test and evaluation methods are omitted. The composition of the acidic degreaser in Example 18, the evaluation results, and the metallurgical microscope images are shown in Table 3 and Figure 4 (b).

Next, in Example 18, the "copper-clad laminate with resist pattern having electroless copper plating film (seed layer)" obtained by the above-mentioned method (i.e., performed using the acidic degreaser of Example 18) after degreasing and cleaning was immersed in an electric copper plating solution (Lucent Copper PVF manufactured by Meltex Co., Ltd.) and a test piece was prepared in which an electric copper plating film was provided on the surface of the electroless copper plating film at a current density of 2 A / dm ² at room temperature for 45 minutes, and the cross-section of this test piece was observed by an electron microscope. The cross-sectional observation image is shown in Figure 9 (a). In Figure 9 (a) and Figure 9 (b) described later, 1 corresponds to the "dry film resist pattern", 2 corresponds to the "electric copper plating film", 3 corresponds to the "seed layer (electroless copper plating film)", 4 corresponds to the "seed layer surface", 5 corresponds to the "copper-clad laminate (copper foil on an insulating substrate)", and 6 corresponds to the "copper component that has entered and precipitated under the dry film resist pattern".

In Example 19, the test was conducted in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "10% by weight sulfuric acid" and "10% by weight glycolic acid", an organic acid. Therefore, the test and evaluation methods are not described here. The composition and evaluation results of the acidic degreaser in Example 19, as well as the metallurgical microscope image, are shown in Table 3 and Figure 4 (c).

Here, the composition and evaluation results of the acidic degreaser in Examples 17 to 19, which are "in the form of an acidic degreaser containing sulfuric acid and an organic acid as acids," are shown in Table 3.

Comparative Example

[Comparative Example 1]
In Comparative Example 1, the test was performed in the same manner as in Example 1, except that the concentration of sulfuric acid, which is the acid component in the acidic degreaser, was changed to "0.01 mass %." Therefore, the description of the test and evaluation methods will be omitted. The composition and evaluation results of the acidic degreaser of Comparative Example 1, as well as the metallurgical microscope observation image, are shown in Table 4 and FIG. 5(a). As can be seen from these test results, the acidic degreaser of Comparative Example 1, which has a low content of sulfuric acid, which is the acid component, had a low degreasing power and insufficient oxide film removal performance.

[Comparative Example 2]
In Comparative Example 2, the test was conducted in the same manner as in Example 1, except that the concentration of sulfuric acid, which is an acid component in the acidic degreaser, was changed to "60 mass %". Therefore, the description of the test and evaluation method will be omitted. The composition of the acidic degreaser of Comparative Example 2, the evaluation results, and the metallurgical microscope observation images are shown in Table 4 and FIG. 5 (b). As can be understood from these test results, in Comparative Example 2, which has a high content of sulfuric acid, which is an acid component, the surface tension of the acidic degreaser was high, and floating and twisting occurred on the dry film resist pattern.

[Comparative Example 3]
In Comparative Example 3, the test was performed in the same manner as in Example 1, except that the concentration of polyoxyethylene trimethyl nonyl ether, which is a polyoxyalkylene alkyl ether type nonionic surfactant in the acidic degreaser, was changed to "0.001 mass%". Therefore, the description of the test and evaluation method will be omitted. The composition and evaluation results of the acidic degreaser of Comparative Example 3 and the metallurgical microscope observation image are shown in Table 4 and FIG. 5 (c). As can be understood from these test results, Comparative Example 3, which has a low content of polyoxyalkylene alkyl ether type nonionic surfactant, had a high surface tension and a low degreasing power.

[Comparative Example 4]
In Comparative Example 4, the test was performed in the same manner as in Example 1, except that the concentration of polyoxyethylene trimethyl nonyl ether, which is a polyoxyalkylene alkyl ether type nonionic surfactant in the acidic degreaser, was changed to "5 mass%". Therefore, the description of the test and evaluation method will be omitted. The composition of the acidic degreaser of Comparative Example 4, the evaluation results, and the metallurgical microscope observation image are shown in Table 4 and FIG. 5 (d). As can be understood from these test results, in Comparative Example 4, which has a high content of polyoxyalkylene alkyl ether type nonionic surfactant, floating and twisting occurred in the dry film resist pattern after treatment with the acidic degreaser.

[Comparative Example 5]
In Comparative Example 5, the test was carried out in the same manner as in Example 1, except that the nonionic surfactant in the acidic degreaser was changed to "EO (ethylene oxide)-PO (propylene oxide) copolymer (Pluronic (registered trademark) L-44 manufactured by ADEKA Corporation)" which is not a polyoxyalkylene alkyl ether type. Therefore, the description of the test and evaluation methods is omitted. The composition and evaluation results of the acidic degreaser of Comparative Example 5, as well as the metallurgical microscope observation image, are shown in Table 4 and FIG. 6(a). As can be seen from these test results, in Comparative Example 5, which uses a different type of nonionic surfactant, the acidic degreaser had a high surface tension and a low degreasing power.

[Comparative Example 6]
In Comparative Example 6, the test was conducted in the same manner as in Example 1, except that the nonionic surfactant in the acidic degreaser was changed to the same "EO-PO copolymer" as in Comparative Example 5, and the liquid temperature of the acidic degreaser during use was changed to "40°C". Therefore, the description of the test and evaluation method will be omitted. The composition of the acidic degreaser of Comparative Example 6, the evaluation results, and the metallurgical microscope observation images are shown in Table 4 and FIG. 6(b). As can be understood from these test results, in Comparative Example 6, which uses a different type of nonionic surfactant and has a high liquid temperature during use, the surface tension of the acidic degreaser is high, the degreasing power is low, and the dry film resist pattern after treatment with the acidic degreaser has lifting, twisting, and the like.

[Comparative Example 7]
In Comparative Example 7, the test was performed in the same manner as in Example 1, except that the concentration of sulfuric acid, which is an acid component in the acidic degreaser, was changed to "5% by mass," the nonionic surfactant was changed to the same "EO-PO copolymer" as in Comparative Example 5, the liquid temperature during use of the acidic degreaser was changed to "40°C," and the width of the resist pattern was changed to "line/space (L/S) of 6 μm/6 μm." Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser of Comparative Example 7, the evaluation results, and the metallurgical microscope observation image are shown in Table 4 and FIG. 6 (c). As can be understood from these test results, Comparative Example 7, which has a different type of nonionic surfactant, does not contain a chloride ion source, and has a high liquid temperature during use, caused floating, twisting, and the like in the dry film resist pattern after treatment with the acidic degreaser.

Next, in Comparative Example 7, for the "copper-clad laminate with resist pattern having electroless copper plating film (seed layer)" obtained by the above-mentioned method (i.e., performed using the acidic degreaser of Comparative Example 7) after degreasing and cleaning, a test piece was obtained in which an electrolytic copper plating film was provided on the surface of the electroless copper plating film by the same method as in Example 18, and the cross-section of the test piece was observed by electron microscope. The cross-sectional observation image is shown in Figure 9 (b).

[Comparative Example 8]
In Comparative Example 8, the test was performed in the same manner as in Example 1, except that "polyethylene glycol having a molecular weight of 3400 (PEG4000S manufactured by Sanyo Chemical Industries, Ltd.)" was used instead of the polyoxyalkylene alkyl ether type nonionic surfactant in the acidic degreaser. Therefore, the description of the test and evaluation method will be omitted. The composition and evaluation results of the acidic degreaser of Comparative Example 8, as well as the metallurgical microscope observation image, are shown in Table 4 and FIG. 6(d). As can be seen from these test results, in Comparative Example 8, which uses a different type of surfactant, the acidic degreaser had a high surface tension and a low degreasing power.

[Comparative Example 9]
In Comparative Example 9, the test was carried out in the same manner as in Example 1, except that sodium chloride, which is a chloride ion source in the acidic degreaser, was not contained. Therefore, the description of the test and evaluation methods will be omitted. The composition of the acidic degreaser of Comparative Example 9, the evaluation results, and the metallurgical microscope observation images are shown in Table 4 and FIG. 6(e). As can be understood from these test results, in Comparative Example 9, which does not contain a chloride ion source, lifting, twisting, etc. occurred in the dry film resist pattern after treatment with the acidic degreaser.

[Comparative Example 10]
In Comparative Example 10, the test was carried out in the same manner as in Example 1, except that the liquid temperature of the acidic degreaser during use was changed to "10°C". Therefore, the description of the test and evaluation methods will be omitted. The composition of the acidic degreaser of Comparative Example 10, the evaluation results, and the metallurgical microscope observation images are shown in Table 4 and FIG. 6(f). As can be seen from these test results, Comparative Example 10, in which the liquid temperature during use was low, had a low degreasing power.

[Comparative Example 11]
In Comparative Example 11, the test was performed in the same manner as in Example 1, except that the liquid temperature of the acidic degreaser during use was changed to "40°C". Therefore, the description of the test and evaluation methods will be omitted. The composition of the acidic degreaser of Comparative Example 11, the evaluation results, and the metallurgical microscope observation images are shown in Table 4 and FIG. 6(g). As can be seen from these test results, in Comparative Example 11, in which the liquid temperature during use was high, floating, twisting, etc. occurred in the dry film resist pattern after treatment with the acidic degreaser.

Here, the compositions and evaluation results of the acidic degreasers in Comparative Examples 1 to 11, which are "acidic degreasers containing only sulfuric acid as an acid," are shown in Table 4.

[Comparative Example 12]
In Comparative Example 12, the test was conducted in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "0.01% by mass glycolic acid", which is an organic acid. Therefore, the description of the test and evaluation methods will be omitted. The composition and evaluation results of the acidic degreaser of Comparative Example 12, as well as the metallurgical microscope observation image, are shown in Table 5 and FIG. 7(a). As can be seen from these test results, in Comparative Example 12, which has a low content of organic acid, the degreasing power of the acidic degreaser was low, and the oxide film removal performance was also insufficient.

[Comparative Example 13]
In Comparative Example 13, the test was performed in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "30% by mass glycolic acid", which is an organic acid. Therefore, the description of the test and evaluation methods will be omitted. The composition of the acidic degreaser of Comparative Example 13, the evaluation results, and the metallurgical microscope observation images are shown in Table 5 and FIG. 7(b). As can be understood from these test results, in Comparative Example 13, which has a high content of organic acid, floating and twisting occurred in the dry film resist pattern after treatment with the acidic degreaser.

Here, the compositions and evaluation results of the acidic degreasers in Comparative Examples 12 and 13, which are "acidic degreasers containing only organic acids as acids," are shown in Table 5.

[Comparative Example 14]
In Comparative Example 14, the test was performed in the same manner as in Example 1, except that the acid components in the acidic degreaser were changed to "0.01% by mass sulfuric acid" and "0.01% by mass glycolic acid" which is an organic acid. Therefore, the description of the test and evaluation methods will be omitted. The composition and evaluation results of the acidic degreaser of Comparative Example 14, as well as the metallurgical microscope observation image, are shown in Table 6 and FIG. 8(a). As can be understood from these test results, Comparative Example 14, which has a low total content of the acidic components sulfuric acid and organic acid, had a low degreasing power of the acidic degreaser and insufficient oxide film removal performance.

[Comparative Example 15]
In Comparative Example 15, the test was performed in the same manner as in Example 1, except that the acid component in the acidic degreaser was changed to "15% by mass sulfuric acid" and "15% by mass glycolic acid" which is an organic acid. Therefore, the description of the test and evaluation method is omitted. The composition of the acidic degreaser of Comparative Example 15, the evaluation results, and the metallurgical microscope observation image are shown in Table 6 and FIG. 8 (b). As can be understood from these test results, in Comparative Example 15, which has a high total content of the acid components sulfuric acid and organic acid, the dry film resist pattern after treatment with the acidic degreaser had lifting, twisting, and the like.

Here, the composition and evaluation results of the acidic degreasers in Comparative Examples 14 and 15, which are "acidic degreasers containing sulfuric acid and an organic acid as acids," are shown in Table 6.

Comparison of Examples and Comparative Examples
According to the test results shown in Tables 1 to 3 and FIGS. 1 to 4, in Examples 1 to 19 in which the acidic degreaser contains 0.1% by mass to 20% by mass of one or more acids selected from the group consisting of sulfuric acid and organic acids, 0.01% by mass to 1% by mass of a polyoxyalkylene alkyl ether type nonionic surfactant, and a chloride ion source in a chloride ion concentration of 0.001% by mass to 1% by mass, and the liquid temperature during use is 15° C. to 35° C., the acidic degreaser has a low surface tension of 33.6 mN/m or less, does not float or wrinkle on the dry film resist pattern treated with the acidic degreaser, has a high degreasing power of 70% or more, and has good oxide film removal performance.

On the other hand, according to the test results shown in Tables 4 to 6 and Figures 5 to 8, in the acidic degreaser, one or more of the acids selected from the group consisting of sulfuric acid and organic acids, the polyoxyalkylene alkyl ether type nonionic surfactant, the content of the chloride ion source, or the liquid temperature during use are outside the preferred numerical range of the invention of the present application, or the composition of the acidic degreaser itself is different, Comparative Examples 1 to 15 resulted in problems with one or more of the surface tension of the acidic degreaser, the state of the dry film resist after treatment with the acidic degreaser, the degreasing power, and the oxide film removal performance.

In addition, according to the cross-sectional observation images shown in (a) and (b) of FIG. 9, when the acidic degreaser of the present application (specifically, the acidic degreaser of Example 18) is used to perform degreasing and washing, which is a pretreatment for electrolytic copper pattern plating, it was confirmed that an electrolytic copper plating film of the desired shape can be obtained without floating or peeling between the resist pattern and the seed layer (electroless copper plating film). On the other hand, when the same treatment is performed using an acidic degreaser (the acidic degreaser of Comparative Example 7) that is a different type of nonionic surfactant, does not contain a chloride ion source, and has a high liquid temperature during use, floating and peeling occurs between the resist pattern and the seed layer, and when electrolytic copper plating is performed, the copper component penetrates under the resist pattern and precipitates, which is a problem.

The acidic degreaser of the present application is highly unlikely to cause lifting or peeling between the resist pattern and the seed layer, and has excellent degreasing power and wettability to the seed layer and the surface of the resist material, so it can be suitably used in pretreatment of electrolytic copper pattern plating. In particular, it can be suitably used when manufacturing printed wiring boards using an insulating substrate having a seed layer made of copper or a copper alloy.

1 Dry film resist pattern 2 Electrolytic copper plating film 3 Seed layer (electroless copper plating film)
4 Seed layer surface 5 Copper clad laminate (copper foil on insulating substrate)
6 Copper components precipitated under the dry film resist pattern

Claims (3)

An acidic degreaser for use in pretreatment of an insulating substrate having a seed layer and a resist pattern for electrolytic copper pattern plating, comprising:
The composition comprises 0.1% by mass to 20% by mass of one or more acids selected from the group consisting of sulfuric acid and organic acids, 0.01% by mass to 1% by mass of a polyoxyalkylene alkyl ether type nonionic surfactant, and 0.001% by mass to 1% by mass of a chloride ion source in terms of a chloride ion concentration;
An acidic degreaser having a liquid temperature of 15°C to 35°C during use. The acidic degreaser according to claim 1, wherein the organic acid is one or more selected from the group consisting of citric acid, formic acid, acetic acid, propionic acid, glycolic acid, malic acid, oxalic acid, succinic acid, maleic acid, methanesulfonic acid, lactic acid, and tartaric acid. 3. The acidic degreaser according to claim 1, wherein the chloride ion source is at least one selected from the group consisting of sodium chloride, hydrochloric acid, copper chloride, ammonium chloride, lithium chloride, potassium chloride, magnesium chloride, calcium chloride, vanadium chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, and zinc chloride.