An electronic plating additive composition and its application in suppressing lateral nickel electrodeposition at the silver-ferrite interface.

Abstract

This invention discloses an electronic plating additive composition and its application in suppressing lateral nickel electrodeposition at the silver-ferrite interface. The electronic plating additive composition is characterized by comprising a sulfur-containing compound, a surfactant, and a brightener as a nickel lateral deposition inhibitor, in a mass ratio of 1-30:5-50:4-15. Combined with specific electronic plating conditions, this invention can completely suppress lateral nickel deposition at the silver-ferrite interface, resulting in a nickel plating layer with a bright metallic appearance and good adhesion.

Description

Technical Field

[0001] This invention belongs to the field of electronic electroplating technology, specifically relating to an electronic electroplating additive composition and its application in suppressing lateral nickel electrodeposition at the silver-ferrite interface. Background Technology

[0002] Multilayer chip inductors (MLCIs) possess excellent electromagnetic interference immunity, small size, good solderability, and heat resistance, making them indispensable passive electronic components on circuit boards (motherboards) of current electronic terminal equipment. MLCIs consist of three parts: a ferrite substrate, internal electrodes, and terminal electrodes. They are primarily fabricated by alternating printing, lamination, and sintering of mixed metal oxide pastes such as Fe2O3, NiO, CuO, and ZnO with silver conductor paste. To meet surface mount technology requirements, MLCI terminal electrodes typically have a three-layer structure: a bottom layer, an intermediate layer, and an outer layer. The bottom layer is generally a silver layer sintered at both ends of the magnet substrate, connecting to the exposed portion of the internal electrode; the intermediate layer is a nickel layer electroplated on the surface of the silver terminal electrode, used to protect the silver layer, with a thickness of approximately 2-4 μm; the outer layer is a tin layer electroplated on the surface of the nickel layer, used to improve the rapid soldering performance of the terminal electrodes, with a thickness of approximately 5-10 μm.

[0003] In the process of electroplating nickel interlayers, the nickel plating layer tends to grow along the silver end towards the ferrite, a phenomenon known as lateral deposition of nickel at the silver-ferrite interface. This lateral deposition reduces the electrode spacing at the MLCI terminals, decreasing inductance performance and potentially causing short circuits. Aminosulfonate electroplating is a common process for preparing nickel interlayers in MLCI. Adding specific additive combinations to the aminosulfonate electroplating solution can completely suppress lateral nickel electrodeposition at the silver-ferrite interface while maintaining a bright metallic appearance, ensuring excellent performance of the MLCI electroplated product. Therefore, developing additive combinations and methods that can completely suppress lateral nickel electrodeposition at the silver-ferrite interface has significant industrial application value.

[0004] CN 111636077A discloses a pretreatment process to prevent nickel plating creep on ceramic chips, in which the ceramic chip is placed in a weakly alkaline solution, and the corrosiveness of the weakly alkaline solution is used to remove the catalyst that causes creep on the ceramic. CN113046756A discloses a pretreatment solution to improve creep on chip ferrite products, which uses the complexation of hydroxy acid groups with metal ions to remove residual metal ions on the ferrite surface, thereby ensuring that conditions for nickel plating extension are not formed during the electroplating process. CN107759252A discloses a surface treatment method to suppress creep on electronic ceramic components, which uses perchloric acid and a catalyst to form a high-resistivity protective film on the product surface, increasing the surface resistance of the product, thereby suppressing creep during the electroplating of electronic ceramic components. To date, no existing technology has been found that directly adds a combination of additives to the nickel plating solution for electronic electroplating. The additives utilize the adsorption of inhibitors on ferrites and the inhibition of lateral nickel electrodeposition on the ferrite surface at the silver-ferrite interface, the reduction of pinholes in the nickel plating layer by surfactants, and the enhancement of the brightness of the nickel plating layer to achieve the purpose of inhibiting lateral nickel electrodeposition at the silver-ferrite interface while ensuring the quality of the nickel plating layer. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electronic electroplating additive composition.

[0006] Another object of the present invention is to provide the application of the above-described electronic plating additive composition in suppressing the lateral electrodeposition of nickel at the silver-ferrite interface.

[0007] Another object of the present invention is to provide a method for suppressing lateral nickel electrodeposition at the silver-ferrite interface.

[0008] The technical solution of the present invention is as follows:

[0009] An electronic electroplating additive composition comprises a sulfur-containing compound as a nickel lateral deposition inhibitor, a surfactant, and a brightener in a mass ratio of 1-30: 5-50: 4-15, wherein...

[0010] The sulfur-containing compounds are 2-imino-4-thiourea, 3-hydroxyphenylthiourea, propenylthiourea, 1,3-bis(m-nitrophenyl)thiourea, 4,4'-diaminobenzenesulfonylaniline, diaminostilbene disulfonic acid, or lignin sulfonate.

[0011] The surfactant is sodium diethylhexyl sulfonate, sodium dihexyl succinate sulfonate, sodium dodecyl sulfate, or sodium isooctyl sulfate.

[0012] The brightener is o-sulfonylbenzylimide, propoxylated propynyl alcohol, N,N-diethylpropynylamine sulfate, sodium propynyl sulfonate, propoxybutynediol, butynediol, sodium vinyl sulfonate, or sodium diethyl succinate sulfonate.

[0013] In a preferred embodiment of the present invention, the sulfur-containing compound is 2-imino-4-sulfurized biuret, 3-hydroxyphenylthiourea, or diaminostilbene disulfonic acid; the surfactant is sodium diethylhexylsulfonate, sodium dodecyl sulfate, or sodium isooctyl sulfate; and the brightener is o-sulfonylbenzeneimide, sodium propynylsulfonate, or butynediol.

[0014] More preferably, the sulfur-containing compound is diaminostilbene disulfonic acid, the surfactant is sodium diethylhexylsulfonate, and the brightener is butynediol.

[0015] More preferably, the sulfur-containing compound is 3-hydroxyphenylthiourea, the surfactant is sodium isooctyl sulfate, and the brightener is o-sulfonylbenzeneimide.

[0016] More preferably, the sulfur-containing compound is 2-imino-4-sulfurized biuret, the surfactant is sodium dodecyl sulfate, and the brightener is sodium propyne sulfonate.

[0017] In a preferred embodiment of the present invention, the mass ratio of the sulfur-containing compound, surfactant, and brightener is 1-3:5:1.5-3.

[0018] Another technical solution of the present invention is as follows:

[0019] The application of the above-mentioned electronic plating additive composition in suppressing the lateral electrodeposition of nickel at the silver-ferrite interface.

[0020] In a preferred embodiment of the present invention, in the electroplating additive composition, the concentration of the sulfur-containing compound in the aminosulfonate electroplating nickel plating bath is 10-300 mg / L, the concentration of the surfactant in the aminosulfonate electroplating nickel plating bath is 50-500 mg / L, and the concentration of the brightener in the aminosulfonate electroplating nickel plating bath is 40-150 mg / L; the aforementioned aminosulfonate electroplating nickel plating bath comprises 200-400 g / L Ni[SO3NH2]2·4H2O, 10-35 g / L NiCl2·6H2O, and 25-45 g / L H3BO3; the electroplating temperature is 45-60 °C, and the current density is 0.1-5.0 A / dm³. 2 .

[0021] Another technical solution of the present invention is as follows:

[0022] A method for suppressing lateral nickel electrodeposition at the silver-ferrite interface includes: adding the above-mentioned electroplating additive composition to an aminosulfonate electroplating nickel plating bath and performing electroplating.

[0023] In a preferred embodiment of the present invention, in the electroplating additive composition, the concentration of the sulfur-containing compound in the aminosulfonate electroplating nickel plating bath is 10-300 mg / L, the concentration of the surfactant in the aminosulfonate electroplating nickel plating bath is 50-500 mg / L, and the concentration of the brightener in the aminosulfonate electroplating nickel plating bath is 40-150 mg / L; the aminosulfonate electroplating nickel plating bath comprises 200-400 g / L Ni[SO3NH2]2·4H2O, 10-35 g / L NiCl2·6H2O, and 25-45 g / L H3BO3; the electroplating temperature is 45-60°C, and the current density is 0.1-5.0 A / dm³. 2

[0024] The beneficial effects of this invention are:

[0025] 1. This invention, combined with specific electronic plating conditions, can completely suppress the lateral deposition of nickel at the silver-ferrite interface, and the nickel plating layer has a bright metallic appearance and good adhesion.

[0026] 2. The sulfur-containing compound in this invention acts as a nickel lateral deposition inhibitor, selectively adsorbing onto the ferrite surface to form an insulating film and increasing the surface resistivity of the ferrite. When the mass concentration of the sulfur-containing compound is below 10 mg / L, the insulating film is difficult to form, easily leading to nickel lateral deposition at the silver-ferrite interface; when the mass concentration of the sulfur-containing compound is above 300 mg / L, it easily forms a large amount of adsorption on the silver layer surface, making nickel deposition difficult and affecting the quality of the nickel plating layer.

[0027] 3. The surfactant in this invention has a combination of characteristics, including reducing the surface tension of the nickel plating solution, increasing the wetting effect on the silver / nickel layer surface, reducing the adsorption of sulfur-containing compounds on the silver / nickel layer surface, and facilitating the detachment of hydrogen bubbles from the workpiece. When the surfactant concentration is below 50 mg / L, it is difficult to sufficiently reduce the surface tension of the plating solution, resulting in low wettability and easy pinholes in the nickel plating layer. When the surfactant concentration is above 150 mg / L, it hinders the adsorption of nickel transverse inhibitors on the ferrite surface, reduces the number of active deposits on the nickel substrate surface, and leads to increased nickel layer particle size and reduced gloss.

[0028] 4. The brightener in this invention can increase the overpotential of nickel ion cathode reduction, resulting in a fine and bright coating. When the concentration of the brightener is below 40 mg / L, the nickel coating has low brightness; when the concentration of the brightener is above 150 mg / L, the nickel coating becomes more brittle, with reduced adhesion and poorer solderability. Attached Figure Description

[0029] Figure 1 Metallurgical micrograph of the silver-ferrite interface obtained after electroplating nickel without the addition of the electroplating additive composition of the present invention.

[0030] Figure 2 Metallographic micrograph of the silver-ferrite interface obtained after electroplating nickel with the electroplating additive composition of Example 1 of the present invention.

[0031] Figure 3 Metallographic micrograph of the silver-ferrite interface obtained after electroplating nickel with the electroplating additive composition of Example 2 of the present invention.

[0032] Figure 4 Metallographic micrograph of the silver-ferrite interface obtained after electroplating nickel with the electroplating additive composition of Example 3 of the present invention.

[0033] In the figure, 1-silver layer, 2-ferrite, 3-nickel lateral electrodeposition. Detailed Implementation

[0034] The technical solution of the present invention will be further explained and described below with reference to specific embodiments and accompanying drawings.

[0035] Examples 1 to 3

[0036] In Examples 1 to 3, the electroplating process for suppressing lateral nickel electrodeposition at the silver-ferrite interface is as follows (taking a multilayer ferrite inductor with dimensions of 4.5 mm × 1.5 mm × 1.5 mm as an example):

[0037] Degreasing (50-70℃, 5-15 min, 50 g / L Na2CO3, 50 g / L Na3PO4, 20 g / L NaOH, 5 mL / L mixed surfactant) → Deionized water washing → Phosphoric acid pickling (30-50℃, 15-60 s, 45% H3PO4 by volume) → Deionized water washing → Electroplating nickel (4-30 min).

[0038] The preparation of the nickel sulfamate plating base solution used in the above-mentioned electronic nickel plating includes: accurately weighing 200-400 g of Ni(SO3NH2)2·4H2O, 10-35 g of NiCl2·6H2O and 25-45 g of H3BO3, adding them to deionized water, heating and dissolving, and adjusting the volume to 1000 mL; the preparation of the concentrated solution of the electronic plating additive composition used in this embodiment includes: accurately weighing 10-300 g of sulfur-containing compound (as a nickel lateral deposition inhibitor), 50-500 g of surfactant, and 40-150 g of brightener, adding them to deionized water, heating and dissolving, and adjusting the volume to 1000 mL; during the above-mentioned electronic plating, 1 mL of the concentrated solution of the electronic plating additive composition is added to the above-mentioned nickel sulfamate plating base solution.

[0039] (3) Electrode preparation: One side of the terminal electrode of the multilayer ferrite inductor (4.5 mm × 1.5 mm × 1.5 mm) is welded to a copper wire, and then the welded side is encapsulated with resin to obtain the inductor electrode. After encapsulation, the conductivity of the electrode is tested with a multimeter. This electrode is used for electronic nickel plating.

[0040] Taking a 1000 mL electroplating solution and a multilayer ferrite inductor electrode (4.5 mm × 1.5 mm × 1.5 mm) as an example, the multilayer ferrite inductor electrode is the cathode, and the nickel plate is the anode. Using the above-mentioned electroplating additive composition, combined with a nickel sulfamate electroplating solution, a temperature of 45-60 ℃, and an electroplating current density of 0.1-5.0 A / dm³,... 2 Electroplating of nickel under specific conditions. The specific composition of the electroplating solution, implementation conditions, and the effect of inhibiting lateral nickel deposition are shown in Table 1 below.

[0041] Figure 1 The image shows a metallographic micrograph of the silver-ferrite interface after electroplating nickel without the addition of electroplating additives. During electroplating nickel onto the silver layer, the nickel plating extends from the silver layer towards the ferrite, resulting in lateral nickel deposition. The lateral deposition distance is 250 μm, the plating particles are coarse, the plating is dark, and the silver-nickel adhesion is poor. Figure 2 The image shows a metallographic micrograph of the silver-ferrite interface obtained after electroplating nickel with the electroplating additive composition of Example 1 of the present invention. Because the sulfur-containing compound adheres to the ferrite surface to form an insulating film, the lateral deposition of nickel at the silver-ferrite interface is completely suppressed when electroplating nickel on the silver layer. Due to the presence of surfactants and brighteners, the coating particles are fine, the coating is bright, and the silver-nickel layer has good adhesion. Figure 3 The image shows a metallographic micrograph of the silver-ferrite interface obtained after electroplating nickel with the electroplating additive composition of Example 2 of the present invention. Because the sulfur-containing compound adheres to the ferrite surface to form an insulating film, the lateral deposition of nickel at the silver-ferrite interface is completely suppressed when electroplating nickel on the silver layer. Due to the presence of surfactants and brighteners, the coating particles are fine, the coating is bright, and the silver-nickel layer has good adhesion. Figure 4 The image shows a metallographic micrograph of the silver-ferrite interface obtained after electroplating nickel with the electroplating additive composition of Example 3 of the present invention. Because the sulfur-containing compound adheres to the ferrite surface to form an insulating film, the lateral deposition of nickel at the silver-ferrite interface is completely suppressed when electroplating nickel on the silver layer. Due to the presence of surfactants and brighteners, the coating particles are fine, the coating is bright, and the silver-nickel layer has good adhesion.

[0042] Table 1. Composition of Electroplating Solution, Implementation Conditions, and Inhibition Effect on Lateral Deposition.

[0043] Example 1 2 3 Nickel aminosulfonate (g / L) 200 300 400 Nickel chloride (g / L) 10 20 35 Boric acid (g / L) 25 35 45 Sulfur-containing compounds (mg / L) Diaminostilbene disulfonic acid 10 3-Hydroxyphenylthiourea 150 2-Imine-4-sulfurized biuret 300 Surfactant (mg / L) Sodium diethylhexylsulfonate 50 Sodium isooctyl sulfate 250 Sodium dodecyl sulfate 500 Brightening agent (mg / L) Butynediol 40 o-Sylenylbenzeneimide 80 Sodium propyne sulfonate 150 <![CDATA[Current density (A / dm 2 ).]]> 0.5 2.5 5 Electroplating time (min) 30 6 4 Temperature (°C) 45 50 55 Electroplating Single ferrite inductor DC plating 3 ferrite inductors DC plating 6 ferrite inductors DC plating Lateral nickel deposition (μm) 0 0 0

[0044] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. An electroplating additive composition characterized in that: consisting of a sulfur-containing compound as a nickel transverse deposition inhibitor, a surfactant, and a brightener in a mass ratio of 1-30: 5-50: 4-15, wherein, the sulfur-containing compound is diaminodiphenylstyrene disulfonic acid, the surfactant is sodium diethylhexyl sulfonate, and the brightener is butynediol; or the sulfur-containing compound is 3-hydroxyphenyl thiourea, the surfactant is sodium isooctyl sulfate, and the brightener is o-sulfobenzamide; or the sulfur-containing compound is 2-imino-4-thio-bisurea, the surfactant is sodium dodecyl sulfate, and the brightener is propargyl sulfonate.

2. Use of the electroplating additive composition of claim 1 for inhibiting silver-ferrite interface nickel lateral electrodeposition, characterized in that: In the electronic plating additive composition, the concentration of the sulfur-containing compound in the aminosulfonate electronic plating nickel plating solution is 10-300 mg / L, the concentration of the surfactant in the aminosulfonate electronic plating nickel plating solution is 50-500 mg / L, and the concentration of the brightener in the aminosulfonate electronic plating nickel plating solution is 40-150 mg / L.

3. Use according to claim 2, characterized in that: The amino sulfonate electronic electroplating nickel plating solution comprises 200-400 g / L Ni[SO3NH2]2·4H2O, 10-35 g / L NiCl2·6H2O and 25-45 g / L H3BO3; the temperature of electronic electroplating is 45-60 ℃, and the current density is 0.1-5.0 A / dm 2 .

4. A method of inhibiting lateral electrodeposition of nickel at silver- ferrite interfaces, characterized by: comprising: adding the electronic plating additive composition of claim 1 to an aminosulfonate electronic plating nickel plating solution to perform electronic plating; In the electronic plating additive composition, the concentration of the sulfur-containing compound in the aminosulfonate electronic plating nickel plating solution is 10-300 mg / L, the concentration of the surfactant in the aminosulfonate electronic plating nickel plating solution is 50-500 mg / L, and the concentration of the brightener in the aminosulfonate electronic plating nickel plating solution is 40-150 mg / L.

5. The method of claim 4, wherein: The amino sulfonate electronic electroplating nickel plating solution comprises 200-400 g / L Ni[SO3NH2]2·4H2O, 10-35 g / L NiCl2·6H2O and 25-45 g / L H3BO3; the temperature of the electronic electroplating is 45-60 ℃, and the current density is 0.1-5.0 A / dm 2 .

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