Palladium catalyst liquid

Abstract

This invention provides a palladium catalyst solution that inhibits copper corrosion, imparts excellent nickel plating deposition properties to the copper surface, and inhibits the diffusion of nickel plating on copper to impart excellent patterning. The palladium catalyst solution of this invention is characterized by containing (A) an organic acid, (B) a chloride, and (C) a palladium salt.

Description

Technical Field

[0001] This invention relates to palladium catalyst liquid. Prior Technology

[0002] In electronic-related fields such as printed wiring boards, semiconductor packages, and electronic components, electroless nickel plating is applied to copper circuits.

[0003] When performing electroless nickel plating on copper circuits, inorganic acids such as hydrochloric acid and sulfuric acid are used as palladium catalyst solutions.

[0004] However, using the aforementioned acid-based palladium catalyst solution can lead to copper corrosion.

[0005] The existing disclosure states that after a substrate containing a copper surface is brought into contact with a composition containing palladium ions, it is then brought into contact with a composition containing organic acids such as organic amino carboxylic acids (see Patent Document 1).

[0006] However, regarding the composition disclosed in Patent Document 1, after the step of contacting the composition containing palladium ions, it is necessary to clean the composition to remove the palladium ions and their deposits, which is a rather complicated process.

[0007] Furthermore, the composition disclosed in Patent Document 1 has the problem of not being able to adequately suppress copper corrosion.

[0008] Furthermore, the composition disclosed in Patent Document 1 has the following problems: insufficient nickel plating precipitation in subsequent steps, and the nickel plating is prone to diffusion, resulting in poor patterning.

[0009] Therefore, efforts are being made to develop a palladium catalyst liquid that can inhibit copper corrosion, impart excellent nickel plating precipitation properties to the copper surface, and inhibit the diffusion of nickel plating on copper to impart excellent patterning properties.

[0010] [Preliminary Technology Documents] [Patent Literature] [Patent Document 1] Japanese Patent No. 5570585 Summary of the Invention

[0011] [Invention Summary] [The problem the invention aims to solve] The present invention was made in view of the above-mentioned problems, and aims to provide a palladium catalyst liquid that can inhibit copper corrosion, impart excellent nickel plating precipitation on the copper surface, and inhibit the diffusion of nickel plating on copper to impart excellent patterning.

[0012] [Methods used to solve problems] In order to achieve the above objectives, the inventors of this case conducted in-depth research and discovered that the above objectives could be achieved by using a palladium catalyst solution containing (A) organic acid, (B) chloride, and (C) palladium salt, thus completing the present invention.

[0013] That is, the present invention relates to the following palladium catalyst liquid. 1. A palladium catalyst liquid, characterized in that it contains (A) an organic acid, (B) a chloride, and (C) a palladium salt. 2. The palladium catalyst solution of item 1, wherein the aforementioned organic acid is selected from at least one of the group consisting of organic sulfonic acids, organic carboxylic acids, and organic isophosphorous acid. 3. The palladium catalyst solution as described in item 1 or 2, wherein the content of the aforementioned organic acid is 10~250g / L. 4. The palladium catalyst solution of item 1 or 2, wherein the aforementioned chloride is selected from at least one of the group consisting of sodium chloride, potassium chloride, ammonium chloride and calcium chloride. 5. The palladium catalyst solution as described in item 1 or 2, wherein the content of the aforementioned chloride is 3~50 g / L. 6. The palladium catalyst solution of item 1 or 2, wherein the aforementioned palladium salt is selected from at least one of the group consisting of palladium sulfate, palladium chloride, palladium oxide, palladium iodide, palladium bromide, palladium nitrate, palladium acetate, tetraamminepalladium chloride, dinitrodiamminepalladium, and dichlorodiethylenediaminepalladium. 7. The palladium catalyst solution as described in item 1 or 2, wherein the content of the aforementioned palladium salt is 1~100 mg / L.

[0014] [Invention Effects] The palladium catalyst solution of the present invention can inhibit copper corrosion, impart excellent nickel plating precipitation on the copper surface, and inhibit the diffusion of nickel plating on copper to impart excellent patterning. Implementation

[0015] [The form in which the invention is implemented] The present invention will now be described in detail.

[0016] 1. Palladium catalyst solution The palladium catalyst solution of the present invention is characterized by containing (A) an organic acid, (B) a chloride, and (C) a palladium salt. These are hereinafter referred to as "(A) component," "(B) component," and "(C) component," respectively. By containing the aforementioned (A) and (C) components, the palladium catalyst solution of the present invention can inhibit corrosion on the copper surface while imparting excellent nickel plating deposition properties to the copper surface. Furthermore, by containing the aforementioned (B) component, the palladium catalyst solution of the present invention can inhibit corrosion on the copper surface while suppressing the diffusion of nickel plating on the copper, thereby imparting excellent patterning properties. While the exact effect of containing (C) component is unclear, it is believed that the palladium catalyst solution of the present invention, by containing the aforementioned (C) component, enhances the selective deposition of palladium on the copper surface, thereby inhibiting localized corrosion of the copper surface. That is, the palladium catalyst solution of the present invention, by containing the above-mentioned components (A) to (C), can inhibit copper corrosion, impart excellent nickel plating precipitation on the copper surface, and inhibit the diffusion of nickel plating on copper to impart excellent patterning.

[0017] (A)Ingredients (A) is an organic acid. The palladium catalyst solution of the present invention, by containing the above-mentioned (A) component, can inhibit the corrosion of the copper surface while imparting excellent nickel plating precipitation properties to the copper surface.

[0018] There are no particular limitations on organic acids; examples include organic sulfonic acids, organic carboxylic acids, and organic isophosphorous acids. Among these, organic sulfonic acids are particularly suitable from the perspective of better inhibiting corrosion on copper surfaces and further improving the precipitation of nickel plating on copper surfaces.

[0019] Examples of organic sulfonic acids include: aliphatic sulfonic acids with 1 to 5 carbon atoms, such as methanesulfonic acid, ethylsulfonic acid, propylsulfonic acid, and pentylsulfonic acid; and aromatic sulfonic acids, such as toluenesulfonic acid, pyridinesulfonic acid, and phenolsulfonic acid. Among these, methanesulfonic acid is particularly suitable from the perspective of better inhibiting corrosion on copper surfaces and further improving the precipitation of nickel plating on copper surfaces.

[0020] Examples of organic carboxylic acids include: aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, maleic acid, and fumaric acid; and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid. Among these, succinic acid is particularly suitable from the perspective of better inhibiting corrosion of copper surfaces and further improving the precipitation of nickel plating on copper surfaces.

[0021] Examples of organic isophosphorous acids include: methyl diisophosphorous acid, aminotris(methylene isophosphorous acid), 1-hydroxyethylidene-1,1-diisophosphorous acid (HEDP), nitrogen-trimethylene isophosphorous acid (NTMP), and ethylenediaminetetra(methylene isophosphorous acid). Among these, 1-hydroxyethylidene-1,1-diisophosphorous acid (HEDP) is the most suitable due to its superior ability to inhibit corrosion on copper surfaces and enhance the deposition of nickel plating on copper surfaces.

[0022] The above-mentioned organic acids can be used alone or in combination with two or more.

[0023] The concentration of organic acid in the palladium catalyst solution is not particularly limited, but is preferably 10-250 g / L, more preferably 50-200 g / L, and even more preferably 80-150 g / L. Furthermore, the above-mentioned organic acid concentration, for example, when using 70% methanesulfonic acid, refers to the amount of methanesulfonic acid in that 70% methanesulfonic acid solution. For example, when using 70% methanesulfonic acid at a concentration of 150 g / L, the methanesulfonic acid concentration is 105 g / L.

[0024] (B) Ingredients (B) Component is chloride. By containing the above-mentioned component (B), the palladium catalyst solution of the present invention can inhibit the corrosion of the copper surface and inhibit the diffusion of nickel plating on the copper, thereby imparting a more superior patterning property.

[0025] There are no particular limitations on the chloride, and examples include sodium chloride, potassium chloride, ammonium chloride, and calcium chloride. Among these, sodium chloride is particularly suitable from the perspective of inhibiting the corrosion of the copper surface while simultaneously inhibiting the diffusion of nickel plating on the copper, thus imparting a superior pattern. Furthermore, from the perspective of further inhibiting copper corrosion, chlorides other than hydrochloric acid are preferable, and the palladium catalyst solution of the present invention preferably does not contain hydrochloric acid.

[0026] The above-mentioned chlorides can be used alone or in combination with two or more.

[0027] There is no particular limitation on the chloride concentration in the palladium catalyst solution, but it is preferably 3~50 g / L, more preferably 5~30 g / L, and even more preferably 7~20 g / L.

[0028] (C) Components (C) is a palladium salt. The palladium catalyst solution of the present invention, by containing the above-mentioned (C) component, can inhibit the corrosion of the copper surface while imparting excellent nickel plating precipitation properties to the copper surface.

[0029] There are no particular limitations on palladium salts, but examples include: palladium sulfate, palladium chloride, palladium oxide, palladium iodide, palladium bromide, palladium nitrate, palladium acetate, tetraammine palladium chloride, dinitrodiammine palladium, and dichlorodiethylenediamine palladium. Among these, palladium sulfate is particularly suitable from the perspective of better inhibiting corrosion on copper surfaces and further improving the precipitation of nickel plating on copper surfaces.

[0030] The palladium salts mentioned above can be used alone or in combination with two or more.

[0031] There is no particular limitation on the concentration of palladium salt in the palladium catalyst solution, but it is preferably 1~100 mg / L, more preferably 20~80 mg / L, even more preferably 30~70 mg / L, and especially preferably 40~60 mg / L.

[0032] Other ingredients In addition to components (A), (B), and (C) mentioned above, the palladium catalyst solution of this invention may also contain other components. Examples of such other components include stabilizers.

[0033] solvent The palladium catalyst solution of the present invention preferably comprises the above-mentioned components (A), (B), and (C), as well as other components as required, in the solvent at the above-mentioned amounts. Water is preferably chosen as such a solvent because it has a low environmental impact and excellent safety profile.

[0034] The solvent content in the palladium catalyst solution is not particularly limited and can be the remainder after adding the above-mentioned components (A), (B) and (C), as well as other components as required.

[0035] The pH of the palladium catalyst solution of the present invention is not particularly limited, but is preferably below 5, more preferably below 3, even more preferably below 1, and most preferably below 0.5. If the upper limit of the pH is within the above range, it can impart excellent nickel plating precipitation on the copper surface and can suppress the diffusion of nickel plating on the copper to impart even better patterning.

[0036] 2. Method for manufacturing palladium catalyst liquid There is no particular limitation on the method for manufacturing the palladium catalyst liquid of the present invention. It can be manufactured by a manufacturing method having the following steps: adding the above-mentioned components (A), (B) and (C), as well as other components as required, to the solvent.

[0037] In the above steps, components (A), (B), and (C), as well as other components as needed, are added to the solvent in sequence to prepare the palladium catalyst solution. There is no particular limitation on the order in which the components are added.

[0038] In the above steps, there are no special restrictions on the conditions for preparing the palladium catalyst solution. It can be stirred and mixed in a mixing tank at a temperature of 10~40℃ for about 1~10 minutes.

[0039] 3. Methods for imparting palladium catalysts There is no particular limitation on the method of applying palladium catalyst to a copper surface using the palladium catalyst solution of the present invention. For example, a method of applying palladium catalyst with the following steps can be cited: immersing a copper plate in the palladium catalyst solution.

[0040] The temperature of the palladium catalyst solution in the above steps is not particularly limited, but it is preferably 20~40℃, and more preferably 25~35℃. By setting the lower limit of the palladium catalyst solution to the above range, the nickel plating deposition on the copper surface can be further improved, and the diffusion of nickel plating can be suppressed, resulting in better patterning. By setting the upper limit of the palladium catalyst solution to the above range, copper corrosion can be further suppressed.

[0041] The immersion time in the above steps is not particularly limited, but should preferably be 0.5 to 5 minutes, and more preferably 1 to 3 minutes. By limiting the immersion time to the above range, the nickel plating precipitation on the copper surface can be further improved, and the diffusion of nickel plating can be suppressed, resulting in better patterning. By limiting the immersion time to the above range, copper corrosion can be further suppressed.

[0042] [Example] The present invention will be specifically illustrated by the following examples and comparative examples. However, the present invention is not limited to the examples.

[0043] Furthermore, the raw materials used in the embodiments and comparative examples are as follows.

[0044] (A) Organic acids: 70% methanesulfonic acid (B) Chloride: Sodium chloride • (C) Palladium salt: Palladium sulfate

[0045] (Examples and Comparative Examples) The above-mentioned raw materials were added to water as a solvent at the mixing amounts shown in Table 1, and stirred in a mixing tank to produce palladium catalyst solutions for the examples and comparative examples.

[0046] The following tests were conducted on the obtained palladium catalyst solution to evaluate its properties.

[0047] (Electrolytic nickel plating solution) We are preparing to manufacture a product called ICP Nicoron FPF as an electroless nickel plating solution by Okuno Pharmaceutical Industries, Ltd.

[0048] (Platinum precipitation) A BGA (Ball Grid Array) resin substrate with overresistor-type micro copper pads (φ60~130μm, 30 pads) on a resin substrate was used as the electroless plating target material. The electroless plating target material was subjected to acid degreasing and soft etching. Next, a palladium catalyst solution from the examples and comparative examples was used for catalyst application. Then, electroless nickel plating was performed using the aforementioned prepared electroless nickel plating solution at 84°C for 20 minutes, and the results were evaluated according to the following evaluation criteria. Furthermore, a zero evaluation indicates that the material can be used without problems in practical applications. 〇: No unprecipitated material at all △: A small amount of unprecipitated material was confirmed. ×: Most non-precipitates occurred.

[0049] (Patterned) A BGA resin substrate with fine wiring (L / S = 50 / 50 μm) on a resin substrate was prepared as the material for electroless plating. The electroless plating material was subjected to acid degreasing and soft etching. Next, a palladium catalyst solution from the examples and comparative examples was used for catalyst application. Then, electroless nickel plating with a wiring pattern of L / S = 50 / 50 μm was performed at 84°C for 20 minutes using the aforementioned prepared electroless nickel plating solution. The L / S = 50 / 50 μm wiring pattern after nickel plating was observed under a microscope (1000x) to check whether the electroless nickel plating had diffused beyond the wiring pattern, and was evaluated according to the following evaluation criteria. Furthermore, a zero evaluation indicates that it can be used without problems in practical applications. 〇: No plating diffusion at all △: Confirmed slight plating diffusion ×: Most plating diffusion occurs.

[0050] (Local corrosion of copper) A BGA resin substrate with an overresistor-type copper pad on a resin substrate was prepared as the material for electroless plating. The electroless plating material was subjected to acid degreasing and soft etching. Next, a palladium catalyst solution from the examples and comparative examples was used for catalyst application. Then, electroless nickel plating was performed using the aforementioned prepared electroless nickel plating solution at 84°C for 20 minutes. The Cu-Ni interface cross-section of the nickel-plated film was observed using a FIB apparatus (10000x magnification) to check for localized corrosion into the Cu layer, and the following evaluation criteria were followed. Furthermore, a zero evaluation indicates that the material can be used without problems in practical applications. 〇: No localized corrosion whatsoever △: Some localized corrosion confirmed ×: Numerous localized corrosions occurred.

[0051] The results are shown in Table 1.

[0052] [Table 1]

Claims

1. A palladium catalyst solution for electroless nickel plating on copper surfaces, comprising (A) an organic acid, (B) a chloride, and (C) a palladium salt; wherein the organic acid comprises 80-250 g / L; and the chloride is selected from at least one of the group consisting of sodium chloride, potassium chloride, ammonium chloride, and calcium chloride.

2. The palladium catalyst solution of claim 1, wherein the aforementioned organic acid is selected from at least one of the group consisting of organic sulfonic acids, organic carboxylic acids, and organic isophosphorous acid.

3. The palladium catalyst solution as requested in item 1 or 2, wherein the content of the aforementioned chloride is 3~50 g / L.

4. The palladium catalyst solution of claim 1 or 2, wherein the aforementioned palladium salt is selected from at least one of the group consisting of palladium sulfate, palladium chloride, palladium oxide, palladium iodide, palladium bromide, palladium nitrate, palladium acetate, tetraamminepalladium chloride, dinitrodiamminepalladium, and dichlorodiethylenediaminepalladium.

5. The palladium catalyst solution as claimed in claim 1 or 2, wherein the content of the aforementioned palladium salt is 1~100 mg / L.