Electrodes and methods for their use and preparation

Abstract

An electrode, and its use and manufacturing method. The electrode includes a substrate, an intermediate layer, and a catalyst layer, the intermediate layer being selected from a metallic Ta layer, a Ti-Ta alloy layer, or a Ti-Pd alloy layer, and the catalyst layer being selected from a noble metal oxide layer. The electrode can be used as an anode for reverse pulse electroplating.

Description

[Technical Field]

[0001] This application relates to the field of electrochemistry, but is not limited thereto, and in particular, but not exclusively, to electrodes and methods of using and making same. [Background technology]

[0002] Printed circuit boards are a key component of electronic devices and are widely used as connection carriers for integrated electronics and other devices. Electroplating, such as reverse pulse electroplating (RPP) of copper, is a common method for the fabrication of printed circuit boards.

[0003] Copper reverse pulse electroplating, which relies on the redox reaction of iron ions, has a very wide range of applications in the electroplating of printed circuit boards. In this application, the electroplating solution contains a large amount of divalent and trivalent iron ions in addition to the copper sulfate and sulfuric acid required for conventional copper plating. Therefore, oxygen evolution reactions do not occur on the anode surface; only the redox reaction of iron ions occurs. In an environment without anodic polarization, a stable oxide layer cannot form on the surface of titanium, which functions as a valve metal. In particular, in the flash plating mode of this type of pulse electroplating, the sulfuric acid concentration in the plating solution can reach 200 g / L to 250 g / L, which increases the corrosion rate at the interface between the titanium electrode coating and the base metal, resulting in frequent abnormal coating peeling during use. Summary of the Invention

[0004] The following is a summary of the subject matter described in detail herein, which is not intended to limit the scope of protection of the claims.

[0005] Through years of careful research, the inventors of the present application have discovered that the main cause of abnormal coating peeling is interfacial corrosion. To improve the electrode life in reverse pulse electroplating applications, the corrosion resistance of the electrode is improved.

[0006] The present application provides an electrode including a substrate, an intermediate layer, and a catalytic layer, wherein the intermediate layer may be selected from a metal Ta layer, a Ti—Ta alloy layer, or a Ti—Pd alloy layer, and the catalytic layer may be selected from a noble metal oxide layer.

[0007] In some embodiments, the Ta content in the Ti—Ta alloy layer of the intermediate layer may be 10 wt% or more, even 20 wt% or more, or even 40 wt% to 50 wt% of the total mass of the alloy.

[0008] In some embodiments, the Pd content in the Ti—Pd alloy layer of the intermediate layer may be 0.01 wt % to 0.25 wt %, or even 0.12 wt % to 0.25 wt %, of the total mass of the alloy.

[0009] In some embodiments, the Ta loading in the intermediate Ta layer or the intermediate Ti—Ta alloy layer is 1 g / m 2 or 10g / m 2 and further 4 g / m 2 or 5g / m 2 It may be.

[0010] In some embodiments, the loading amount of Ti in the Ti-Pd alloy layer of the intermediate layer is 1 g / m 2 or 10g / m 2 and further 4 g / m 2 or 5g / m 2 It may be.

[0011] In some embodiments, the substrate may be selected from metallic Ti or a Ti-based alloy.

[0012] In some embodiments, the catalyst layer may be selected from a Ru-Ti mixed metal oxide, an Ir-Ti mixed metal oxide, a Ru-Ir-Ti mixed metal oxide, a Ru-Ta mixed metal oxide, an Ir-Ta mixed metal oxide, or a Ru-Ir-Ta mixed metal oxide.

[0013] In some embodiments, the content of Ti or Ta in the catalyst layer may be 10 wt% to 60 wt% of the total mass of the metal elements.

[0014] In some embodiments, the loading of Ru or Ir in the catalyst layer is 2 g / m 2 or 20g / m 2 and may be 5 g / m 2 or 10g / m 2 and may be 6 g / m 2 or 8g / m 2 It may be.

[0015] The present application further provides a method of using the above-mentioned electrode, wherein the electrode can be used as an anode for electroplating, further for pulse electroplating, further for reverse pulse electroplating.

[0016] In some embodiments, the reverse pulse electroplating may be reverse pulse electroplating of copper with iron ions as the redox pair for the anodic reaction.

[0017] In some embodiments, reverse pulse electroplating can be used to fabricate printed circuit boards.

[0018] The present application further provides a method for fabricating the above-mentioned electrode, the method including: providing an electrode substrate; forming an intermediate layer on the substrate by a vapor deposition method, for example, a magnetron sputtering method; and forming a catalyst layer on the intermediate layer by a coating heat treatment method.

[0019] Other features and advantages of the present application will be set forth in the description that follows or may be learned by the practice of the present application. Other advantages of the present application may be realized or obtained by the solutions set forth in the description and drawings. Other aspects will be appreciated by reading and understanding the accompanying drawings and detailed description. [Brief explanation of the drawings]

[0020] The accompanying drawings are used to provide understanding of the technical solutions of the present application and constitute a part of this specification, and are used to explain the technical solutions of the present application together with the examples of the present application, but do not limit the technical solutions of the present application.

[0021] [Figure 1] FIG. 1 is a cross-sectional view of the electrode fabricated in Example 1 taken by a scanning electron microscope (SEM).

[0022] [Figure 2] FIG. 2 is a scanning electron microscope (SEM) image of the surface of the electrode prepared in Example 1.

[0023] In the figure, 1. substrate, 2. intermediate layer, and 3. catalyst layer. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present application will be described with reference to the drawings. It should be noted that the embodiments and features in the embodiments of the present application can be arbitrarily combined unless they are inconsistent.

[0025] An embodiment of the present application provides an electrode. For example, the electrode includes a substrate, an intermediate layer, and a catalyst layer stacked in this order from bottom to top. The intermediate layer and the catalyst layer may be symmetrically disposed on both sides of the substrate.

[0026] The substrate may be metallic titanium (Ti) or a Ti-based alloy, such as a Ti-Nb alloy containing a small amount of Nb, a Ti-Ta alloy containing a small amount of Ta, or a Ti-Nb-Ta alloy containing small amounts of Nb and Ta, for example, a Ti-Nb-Ta alloy in which the combined content of Nb and Ta is 5 wt% or less of the total mass of the alloy.

[0027] The intermediate layer may be metallic Ta or a Ti alloy, such as a Ti—Ta alloy or a Ti—Pd alloy, including an ASTM Grade 7 or ASTM Grade 11 Ti alloy. The Ta content in the Ti—Ta alloy may be 10 wt % or more, even 20 wt % or more, even 40 wt % to 50 wt % of the total mass of the alloy, for example, a Ta to Ti mass ratio of 40:60, 50:50, etc. The Pd content in the Ti—Pd alloy may be 0.01 wt % to 0.25 wt %, even 0.12 wt % to 0.25 wt %, for example, 0.15 wt %, 0.18 wt %, 0.20 wt %, etc. of the total mass of the alloy. The alloy content may provide both excellent oxidation resistance and excellent corrosion resistance.

[0028] The intermediate layer can be fabricated by a vapor deposition method, such as magnetron sputtering, chemical vapor deposition, etc. The Ta loading amount in the intermediate metal Ta layer or the intermediate Ti-Ta alloy layer is 1 g / m 2 or 10g / m 2 , for example 4g / m 2 , 5g / m 2 The loading amount of Ti in the Ti-Pd alloy layer of the intermediate layer may be 1 g / m 2 or 10g / m 2 , for example 4g / m 2 or 5g / m 2 , or the loading amount of Pd in ​​the Ti-Pd alloy layer of the intermediate layer is 0.1 g / m 2 or 25g / m 2 , for example 1g / m 2 , 5g / m 2 , 10g / m 2 , 15g / m 2 etc. Magnetron sputtering in particular allows the formation of a dense intermediate layer on the substrate, which further improves corrosion resistance.

[0029] In an example of a magnetron sputtering process, the substrate temperature is controlled to 200°C to 400°C, an inert gas is used as the sputtering gas, the vacuum level is 0.1 Pa to 0.5 Pa, the power of the DC power supply is 100 W to 500 W, the distance between the target and the substrate is 30 mm to 100 mm, and the required loading amount can be obtained by controlling the ratio of the target materials used and adjusting the sputtering time.

[0030] The material of the catalyst layer is Ru-Ti mixed metal oxide, Ir-Ti mixed metal oxide, Ru-Ir-Ti mixed metal oxide, Ru-Ta mixed oxide, Ir-Ta mixed oxide, or Ru-Ir-Ta mixed oxide, and the content of Ti or Ta element in the catalyst layer may be 10 wt% to 60 wt%, for example, 20 wt%, 30 wt%, 40 wt%, 50 wt%, etc., of the total mass of the metal elements. The loading amount of Ru or Ir in the catalyst layer is 2 g / m 2 or 20g / m 2 , plus 5g / m 2 or 10g / m 2 , for example 6 g / m 2 , 8g / m 2 etc.

[0031] The catalyst layer can be prepared by a coating heat treatment method. The catalyst layer can be formed by coating a Ru and Ti-containing, Ir and Ti-containing, Ru, Ir, and Ti-containing, Ru and Ta-containing, Ir and Ta-containing, or Ru, Ir, and Ta-containing coating solution on the surface of the intermediate layer, followed by drying and heat treatment. The coating heat treatment process can be performed several times until the desired loading amount is achieved.

[0032] The electrode of the present application is suitable for use as an anode for reverse pulse electroplating, particularly for copper reverse pulse electroplating, to produce printed circuit boards. By providing the intermediate layer described above, a stable, dense, and highly corrosion-resistant oxide layer is formed on the substrate, thereby reducing corrosion at the interface between the substrate and the coating (especially a noble metal oxide coating), and achieving a good balance between oxidation resistance and corrosion resistance.

[0033] The present application has the following beneficial effects:

[0034] In the case of the electrode of the present application, a corrosion-resistant valve metal interlayer (e.g., a metallic Ta layer, a Ti-Ta alloy layer, or a Ti-Pd alloy layer) is first formed on the substrate by a vapor deposition process before the coating of the catalyst layer. The presence of this alloy interlayer improves the corrosion resistance of the electrode in concentrated sulfuric acid solutions and significantly extends the life of titanium-coated anodes in reverse pulse electroplating applications. Example 1 Metallic titanium (Ti) was used as the electrode substrate. Titanium plates meeting the requirements of ASTM-B265 Grade 1 were selected and pressed to obtain a 2 mm thick titanium mesh with a lattice coefficient of 2.0. The titanium mesh was then sandblasted with iron sand and pickled with sulfuric acid.

[0035] A Ta-Ti alloy intermediate layer was formed on a Ti substrate by magnetron sputtering. The mass ratio of Ta to Ti in the alloy was 40:60, and the Ta loading in the alloy layer was 4 g / m. 2 Specifically, a titanium substrate was placed in a single-chamber magnetron sputtering system, the temperature of the titanium substrate was controlled at 300°C, magnetron sputtering was performed, the sputtering gas was commercially available high-purity argon, the vacuum level was 0.3 Pa, the power of the DC power supply was 200 W, the distance between the target and the substrate was 50 mm, both titanium and tantalum targets were used by controlling the ratio of the target materials, and sputtering continued for 10 minutes.

[0036] A catalyst layer of Ir-Ta mixed metal oxide was formed on the intermediate layer, with an Ir loading of 8 g / m 2 Aqueous iridium chloride solution and tantalum pentachloride salt were used to prepare an n-butanol solution with an iridium mass concentration of 3 wt%, with a mass ratio of elemental iridium to elemental tantalum of 2:1. This solution was applied to the surface of the anode with a brush. For each 1 g of iridium applied to one square meter of coating, the anode was dried at 80 °C, heat-treated at 500 °C for 10 minutes, then removed for cooling and coated with 8 g / m 2 Coating was continued until an iridium loading target of 0.01 was reached.

[0037] In this way, the electrodes were fabricated. Example 2 The same metallic titanium (Ti) as in Example 1 was used as the electrode substrate.

[0038] A Ta-Ti alloy intermediate layer was formed on a Ti substrate by magnetron sputtering. The mass ratio of Ta to Ti in the alloy was 50:50, and the Ta loading in the alloy layer was 5 g / m. 2 The steps for forming the intermediate layer were the same as in Example 1 except for the alloy ratio and loading amount.

[0039] A catalyst layer of Ir-Ta mixed metal oxide was formed on the intermediate layer, with an Ir loading of 6 g / m 2 The steps for forming the catalyst layer were the same as those in Example 1 except for the loading amount.

[0040] In this way, the electrodes were fabricated. Example 3 The same metallic titanium (Ti) as in Example 1 was used as the electrode substrate.

[0041] A Ta-Ti alloy intermediate layer was formed on a Ti substrate by chemical vapor deposition. The mass ratio of Ta to Ti in the alloy was 50:50, and the Ta loading in the alloy layer was 5 g / m. 2Specifically, titanium dichloride was selected as the titanium source, tantalum dichloride was selected as the tantalum source, and hydrochloric acid was used as the solvent, and these were introduced into a reaction chamber at 500°C and deposited for 20 minutes until the specified deposition amount was reached.

[0042] A catalyst layer of Ir-Ta mixed metal oxide was formed on the intermediate layer, with an Ir loading of 8 g / m 2 The steps for forming the catalyst layer were the same as those in Example 1 except for the loading amount.

[0043] In this way, the electrodes were fabricated. Comparative Example 1 The same metallic titanium (Ti) as in Example 1 was used as the electrode substrate.

[0044] A catalyst layer of Ir-Ta mixed metal oxide was formed on a Ti substrate, with an Ir loading of 12 g / m 2 The steps for forming the catalyst layer were the same as those in Example 1 except for the loading amount.

[0045] In this way, the electrodes were fabricated. Comparative Example 2 The same metallic titanium (Ti) as in Example 1 was used as the electrode substrate.

[0046] An intermediate ceramic oxide layer was formed on the Ti substrate. A solution of titanium trichloride and tantalum pentachloride in n-butanol, each containing 2% titanium and tantalum by mass, was applied to each layer at a concentration of 1 g / m² of metal element. 2 The titanium mesh was then dried at 80°C, heat treated at 500°C for 1 hour, removed for cooling, and finally coated with 3 g / m2 of metallic elements. 2 Coating was continued until the coating temperature reached 100°C.

[0047] A catalyst layer of Ir-Ta mixed metal oxide was formed on the intermediate layer, with an Ir loading of 12 g / m 2The steps for forming the catalyst layer were the same as those in Example 1 except for the loading amount.

[0048] In this way, the electrodes were fabricated. Electrode microstructure The electrode prepared in Example 1 was examined by scanning electron microscopy.

[0049] The cross-sectional view of the electrode is shown in Figure 1. As can be seen from Figure 1, the intermediate layer can cover the surface of the titanium base material without cracks, and can largely prevent the corrosion of the titanium base material in subsequent applications.

[0050] The surface view of the electrode is shown in Figure 2. As can be seen from Figure 2, the intermediate layer does not affect the surface of the iridium-tantalum catalyst layer, and the surface of the catalyst layer still shows the normal pattern formed by the precipitated iridium elements. Electrode life test A pulse power supply was used, and the electrodes of the example and comparative examples were used as anodes. The strip anodes were connected to titanium plate cathodes of the same size by polypropylene bolts. The electrode spacing was 3 cm. The test electrode (anode) was connected to the positive electrode, and the titanium cathode was connected to the negative electrode. The electrolyte was a mixed solution of copper sulfate (Cu 35 g / L) and sulfuric acid (H2SO4 230 g / L), to which ferrous sulfate (iron ion concentration 17 g / L) was added. The current was 800 A / m 2 A forward current of 2400 A / m was applied for 19 ms, and then 2 A reverse current with a current density of 0.01 was applied for 1 ms, and these steps were repeated for pulse plating while maintaining the temperature of the plating solution at 40°C.

[0051] The lifespan of the electrodes of the examples and comparative examples was tested by an adhesion performance test. Specifically, 3M tape was attached to the surface of the anode that had been subjected to repeated pulse electroplating, and then the tape was peeled off to observe whether the coating was peeled off and the titanium base material was exposed. If the titanium base material was clearly exposed, it indicated that the interface between the coating and the titanium base material had peeled off, and the coating had not functioned.

[0052] The test results are shown in Table 1.

[0053] [Table 1]

[0054] As can be seen from Table 1, the life of the electrodes (having the Ta-Ti alloy intermediate layer) in Examples 1 to 3 of the present application is longer than the life of the electrode (excluding the intermediate layer) in Comparative Example 1. In particular, the life of the electrode in Example 2 is 2970 kAh / m 2 This is approximately 3.2 times longer than the electrode life in Comparative Example 1. The main reason is that after the Ta-Ti alloy intermediate layer is applied, the surface of the alloy is oxidized, forming a dense, highly corrosion-resistant Ti-Ta oxide layer at the interface between the Ti substrate and the Ir-Ta catalyst layer, which significantly reduces the wear rate of the Ir in the catalyst layer, improving the corrosion resistance of the electrode and extending its life.

[0055] Furthermore, as can be seen from Table 1, the lifespan of the electrodes (having a Ta-Ti alloy intermediate layer) in Examples 1 to 3 of the present application is longer than that of the electrode (having a ceramic oxide intermediate layer) in Comparative Example 2. In particular, the lifespan of the electrode in Example 2 is approximately 3.9 times that of the electrode in Comparative Example 2. The main reason for this is that ceramic oxide is loose and porous and cannot effectively protect the titanium substrate from corrosion, whereas in the electrodes in the examples of the present application, a dense and highly corrosion-resistant Ti-Ta oxide layer is formed at the interface between the Ti substrate and the Ir-Ta catalyst layer.

[0056] In Examples 1 to 3, the electrodes with intermediate layers fabricated by magnetron sputtering (Examples 1 and 2) have a longer lifespan than the electrode with an intermediate layer fabricated by chemical vapor deposition (Example 3), primarily because the metal layer formed by physical vapor deposition is denser and helps protect the substrate from corrosion.

[0057] In Examples 1 and 2, both of which had intermediate layers fabricated by magnetron sputtering, the loading in Example 2 was higher than that in Example 1, and the lifetime of Example 2 was longer than that of Example 1, mainly due to the higher Ta loading in Example 2, which improved corrosion resistance. However, if the Ta content was too high, the coating adhesion would be reduced, and if the Ta content was too low, the corrosion resistance would be reduced. Therefore, advantageous results were achieved when the Ta content in the intermediate layer was 40 wt% to 50 wt% of the total mass of the alloy.

[0058] Although the embodiments disclosed in the present application are as described above, the described contents are merely embodiments adopted for the convenience of understanding the present application and are not used to limit the present application. Those skilled in the art to which the present application pertains may make modifications and changes to the embodiments and details without departing from the spirit and scope disclosed by the present application, but the scope of patent protection of the present application shall be as defined by the scope of the appended claims.

Claims

1. An electrode comprising a substrate, an intermediate layer, and a catalyst layer, the intermediate layer is selected from a metallic Ta layer, a Ti—Ta alloy layer, or a Ti—Pd alloy layer; The catalyst layer is selected from a noble metal oxide layer. electrode.

2. The Ta content in the Ti-Ta alloy layer of the intermediate layer is 10 wt % or more, preferably 20 wt % or more, more preferably 40 wt % to 50 wt % of the total mass of the alloy, and the Pd content in the Ti-Pd alloy layer of the intermediate layer is 0.01 wt % to 0.25 wt %, preferably 0.12 wt % to 0.25 wt % of the total mass of the alloy.

10. The electrode of claim 1.

3. The Ta loading amount in the intermediate metal Ta layer or the intermediate Ti—Ta alloy layer is 1 g / m ２ to 10 g / m ２ , preferably 4 g / m ２ or 5 g / m ２ and the loading amount of Ti in the Ti—Pd alloy layer of the intermediate layer is 1 g / m ２ to 10 g / m ２ , preferably 4 g / m ２ or 5 g / m ２ That is, 3. The electrode according to claim 1 or claim 2.

4. The substrate is selected from metallic Ti or a Ti-based alloy; 4. The electrode according to claim 1.

5. the catalyst layer is selected from Ru—Ti mixed metal oxide, Ir—Ti mixed metal oxide, Ru—Ir—Ti mixed metal oxide, Ru—Ta mixed metal oxide, Ir—Ta mixed metal oxide, or Ru—Ir—Ta mixed metal oxide; 5. The electrode according to claim 1.

6. the content of Ti or Ta in the catalyst layer is 10 wt % to 60 wt % of the total mass of metal elements; 6. An electrode according to any one of claims 1 to 5.

7. The loading amount of Ru or Ir in the catalyst layer is 2 g / m ２ to 20 g / m ２ , preferably 5 g / m ２ to 10 g / m ２ , more preferably 6 g / m ２ or 8 g / m ２ That is, 7. An electrode according to any one of claims 1 to 6.

8. The electrode is used as an anode for electroplating, preferably for pulse electroplating, more preferably for reverse pulse electroplating. Use of an electrode according to any one of claims 1 to 7.

9. The reverse pulse electroplating is a reverse pulse electroplating of copper having iron ions as a redox pair in the anodic reaction.

9. The use according to claim 8.

10. The reverse pulse electroplating is used to fabricate printed circuit boards.

10. The use according to claim 8 or claim 9.

11. A method for producing an electrode according to any one of claims 1 to 7, comprising the steps of: Providing an electrode substrate; forming an intermediate layer on the substrate by vapor deposition, preferably magnetron sputtering; forming a catalyst layer on the intermediate layer by a coating heat treatment method; A method for providing the above.

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