A copper electroplating bath for filling HDI micro blind vias and its use method

Abstract

The present invention relates to the field of C25D3 / 38, and specifically provides an electroplating copper bath for filling HDI micro blind vias and a use method thereof. The electroplating copper bath comprises 80-120 g / L of copper sulfate pentahydrate, 30-50 g / L of sulfuric acid, 15-30 mg / L of sodium chloride, 1-5 mL / L of sodium propane sulfonate, 12-20 mL / L of polyethylene glycol, 2-4 mL / L of an amine compound, 0.5-3 mL / L of a nitrogen-containing heterocyclic compound, 1-4 mL / L of an additive, and the balance being ultrapure water. The electroplating copper bath for filling HDI micro blind vias solves the problem of depressions, bulges, and cracks that are prone to occur in existing copper baths after via filling, resulting in insufficient uniformity and stability of the copper plating layer. The bath makes the copper plating layer flat and smooth, with fine crystallization, and improves the ductility and tensile strength stability of the copper plating layer. The bath helps to extend the service life of HDI boards and improve production efficiency, thereby having extremely high practical application value.

Description

Technical Field

[0001] The present invention relates to the field of C25D3 / 38, in particular to an electroplating copper bath for filling HDI micro blind vias and a use method thereof. Background Art

[0002] The miniaturization and functional diversification of electronic products have put forward new and stringent requirements for high-density interconnection technology (HDI). HDI boards are specifically designed with multiple micro blind vias. Achieving efficient and uniform filling of micro blind vias in HDI boards is currently a major problem facing electroplating copper baths.

[0003] Currently, the most effective approach is to optimize the additives in the copper electroplating bath to improve the hole filling rate and filling effect. Chinese patent CN105839151A discloses a leveling agent and copper electroplating bath for copper interconnect HDI boards. The leveling agent is prepared using a triazole-oxadiazole compound, a quaternary ammonium compound, and water as raw materials. Combined with an accelerator and other raw materials, the copper electroplating bath can control the surface copper growth rate during blind via copper filling, improving production efficiency. However, the solution fails to effectively address the lack of uniformity and stability of the copper coating, such as pitting, bulging, and cracking, that can occur during the actual via filling process.

[0004] Therefore, a copper electroplating bath for filling HDI micro blind vias is provided to solve the problem of insufficient uniformity and stability of the copper plating layer, such as depressions, bulges, and cracks, which are easily seen after hole filling in the existing copper bath. The mechanical properties of the plating layer are improved, the stability of the copper electroplating bath for electronic circuits and the quality of copper interconnects are enhanced, the cost of HDI copper interconnect production is reduced, and production efficiency is improved. The invention has extremely high practical application value. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a copper electroplating bath for filling HDI micro blind vias, which comprises at least the following raw materials: 80-120 g / L of copper sulfate pentahydrate, 30-50 g / L of sulfuric acid, 15-30 mg / L of sodium chloride, 1-5 mL / L of sodium propane sulfonate, 12-20 mL / L of polyethylene glycol, 2-4 mL / L of an amine compound, 0.5-3 mL / L of a nitrogen-containing heterocyclic compound, 1-4 mL / L of an additive, and the balance being ultrapure water.

[0006] As a preferred technical solution, the nitrogen heterocyclic compound is selected from one or more of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazole, 1,2-ethylenethiourea, Janus green, and diazine black. 2-Mercaptobenzimidazole has a certain effect of smoothing copper deposits and improving their glossiness. However, when added to a copper electroplating bath, the ductility and tensile strength stability of the copper deposit decrease with storage time, and the copper deposit is prone to developing fine wrinkles and small particle protrusions on the surface, which greatly inconveniences HDI board production. Preferably, the nitrogen-containing heterocyclic compound is a combination of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazole and 1,2-ethylenethiourea, which makes the surface of the copper coating flat and smooth, with fine crystals and no obvious pits or protrusions, effectively improving the ductility and tensile strength stability of the copper coating, and helping to extend the service life of the HDI board; during the research process, the applicant found that, especially when the mass ratio of the 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazole and 1,2-ethylenethiourea is (4-6): (1-3): (5-8), the synergistic effect with the sodium propane sulfonate, polyethylene glycol and amine compounds in the system is the best, the degree of copper crystallization is increased, the pore filling rate and the smoothness and flatness of the copper coating surface are effectively improved, and it also has the effect of increasing the working current density.

[0007] The CAS number of the 2-mercaptobenzimidazole is 583-39-1, which was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; the CAS number of the 1-(4-ethoxyphenyl)-5-mercapto-tetrazole is purchased from Hubei Huaying Biotechnology Co., Ltd.; the CAS number of the 1,2-ethylenethiourea is 96-45-7, which was purchased from Hubei Zhonglong Kangsheng Fine Chemical Co., Ltd.

[0008] As a preferred technical solution, the sodium propane sulfonate is selected from the group consisting of sodium alcoholthiopropane sulfonate, sodium dimethylformamidopropane sulfonate, sodium 3-(benzothiazole-2-sulfanyl)propane sulfonate, sodium 3-sulfanyl-1-propanesulfonate, and dimethyl-dithioformamide sulfonic acid, or a combination thereof. Preferably, the sodium propane sulfonate is a combination of sodium alcoholthiopropane sulfonate and sodium 3-sulfanyl-1-propanesulfonate. Preferably, the mass ratio of the sodium alcoholthiopropane sulfonate and sodium 3-sulfanyl-1-propanesulfonate is (3-5):(2-4). The present application significantly improves the HDI micro-blind hole filling effect and the micro-blind hole filling rate by using sodium alcoholthiopropane sulfonate and sodium 3-sulfanyl-1-propanesulfonate in a mass ratio of (3-5):(2-4), thereby solving the problem of the existing electroplating copper bath. During actual blind via filling, the copper thickness of the hole wall gradually decreases from the hole mouth to the inside of the hole, resulting in uneven filling and even serious sealing. This improves the stability of the copper plating bath for electronic circuits and the quality of copper interconnects, thereby improving work efficiency. This may be because, in the presence of amine compounds and additives, sodium thioalkylpropane sulfonate and sodium 3-thio-1-propanesulfonic acid salt are evenly distributed in various parts of the micro blind via, effectively accelerating the deposition at the bottom of the micro blind via, and improving the micro blind via filling uniformity and micro blind via filling rate.

[0009] The sodium thioalcohol propane sulfonate and 3-thio-1-propanesulfonic acid sodium salt were purchased from Jiangsu Mengde New Material Technology Co., Ltd.

[0010] As a preferred technical solution, the amine compound is selected from at least one of polyethyleneimine, polyetheramine, cocoyl diethanolamide, and cocamidopropyl betaine; preferably, the amine compound is a combination of polyethyleneimine and cocoyl diethanolamide; preferably, the mass ratio of the polyethyleneimine and cocoyl diethanolamide is (0.8-1.2): (1.8-2.5); during the exploration process, the applicant found that when the mass ratio of the polyethyleneimine and cocoyl diethanolamide is controlled to be (0.8-1.2): (1.8-2.5), especially when the weight-average molecular weight of polyethyleneimine is 600, the electroplating copper bath is ensured to have higher stability, improve the filling effect, and also have antistatic, anti-rust and anti-corrosion effects.

[0011] The CAS number of the polyethyleneimine is 9002-98-6, the product number is E54370, and it was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.; the CAS number of the coconut diethanolamide is 68603-42-9, and it was purchased from Jiangsu Aikon Biopharmaceutical Research and Development Co., Ltd.

[0012] As a preferred technical solution, the alcohol compound is selected from at least one of polyethylene glycol 2000, polyethylene glycol 3000, polyethylene glycol 4000, and polyethylene glycol 6000; preferably, the alcohol compound is a combination of polyethylene glycol 4000 and polyethylene glycol 6000, and preferably, the mass ratio of polyethylene glycol 4000 and polyethylene glycol 6000 is (6-10): (4-7); in the present application, by adopting polyethylene glycol 4000 and polyethylene glycol 6000 with a mass ratio of (6-10): (4-7), the dispersibility of each substance in the system is improved, and the nitrogen-containing heterocyclic compound, additive and sodium chloride in the system are synergistically inhibited from adsorbing on the HDI board surface and the electrodeposition of high current density at the orifice, thereby avoiding the "flowering" phenomenon on the surface of the copper plating, ensuring the flatness and smoothness of the copper plating surface, and effectively improving the ductility and tensile strength of the copper plating.

[0013] The polyethylene glycol 4000 and polyethylene glycol 6000 were purchased from Hai'an Petrochemical Plant in Jiangsu Province.

[0014] As a preferred technical solution, the additive is a polyether compound containing hydroxyl groups in its structure; preferably, the polyether compound containing hydroxyl groups in its structure is selected from at least one of polyethylene glycol trimethyl nonyl ether, butanol polyoxyethylene polyoxypropylene ether, octadecyl alcohol polyoxyethylene ether, polyethylene glycol allyl methyl ether, and propylene glycol polyether; preferably, the polyether compound containing hydroxyl groups in its structure is a combination of polyethylene glycol allyl methyl ether and propylene glycol polyether; preferably, the mass ratio of polyethylene glycol allyl methyl ether and propylene glycol polyether is (1-2): (2-3); during the exploration process, the present application found that when polyethylene glycol allyl methyl ether and propylene glycol polyether are used in a mass ratio of (1-2): (2-3), the dispersion stability of the system is improved, which helps to reduce the dissociation degree of copper sulfate in the system and improve the quality of the coating. At the same time, the synergistic effect between the nitrogen-containing heterocyclic compound and sodium propane sulfonate and sodium chloride is improved, thereby avoiding the formation of pitting and wrinkles on the surface of the copper coating, making the copper coating bright, smooth and flat.

[0015] The CAS number of the propylene glycol polyether is 25322-69-4, the product number is P815571, and it was purchased from Shanghai McLean Biochemical Technology Co., Ltd.; the CAS number of the polyethylene glycol allyl methyl ether is 27252-80-8, and it was purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0016] The preparation method of the electroplating copper bath for filling HDI micro blind vias is as follows: according to the formula, copper sulfate pentahydrate, sulfuric acid, sodium chloride, sodium propane sulfonate, polyethylene glycol, amine compounds, nitrogen-containing heterocyclic compounds, and additives are added to ultrapure water and stirred for 15-30 minutes.

[0017] The second aspect of the present invention provides a method for using a copper electroplating bath for filling HDI micro blind vias, wherein the process conditions during use are: cathode current density: 0.5-4A / dm 2 , Adaptable temperature: 10-35℃, cathode swing: 12-15 times / min, stirring method: air stirring.

[0018] Beneficial effects:

[0019] 1. The present invention provides a copper electroplating bath for filling HDI micro blind vias, which solves the problem of depression, bulges, and cracks that are prone to occur in existing copper baths after via filling, and the problem of insufficient uniformity and stability of the copper plating layer. It improves the mechanical properties of the plating layer, enhances the stability of the copper electroplating bath for electronic circuits and the quality of copper interconnects, reduces the cost of HDI copper interconnect production, and improves production efficiency, with extremely high practical application value.

[0020] 2. By using a combination of nitrogen-containing heterocyclic compounds such as 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazole and 1,2-ethylenethiourea, the surface of the copper coating is made flat and smooth, with fine crystals and no obvious pits or protrusions, which effectively improves the ductility and tensile strength stability of the copper coating and helps to extend the service life of the HDI board.

[0021] 3. When the mass ratio of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazole and 1,2-ethylenethiourea is (4-6):(1-3):(5-8), the synergistic effect with sodium propane sulfonate, polyethylene glycol and amine compounds in the system is the best, the fineness of copper crystallization is increased, the pore filling rate and the smoothness and flatness of the copper plating surface are effectively improved, and it also has the effect of increasing the working current density.

[0022] 4. By using sodium thiosulfanylpropane sulfonate and sodium 3-thio-1-propanesulfonic acid salt in a mass ratio of (3-5): (2-4), the HDI micro blind hole filling effect is significantly improved, the micro blind hole filling rate is increased, and the problem of the existing electroplating copper bath gradually decreasing the copper thickness of the hole wall from the hole mouth to the inside of the hole during actual blind hole filling, resulting in uneven hole filling and even severe sealing, is solved. The stability of the electronic circuit electroplating copper bath and the quality of copper interconnects are improved, thereby improving work efficiency.

[0023] 5. When polyethylene glycol allyl methyl ether and propylene glycol polyether are used in a mass ratio of (1-2): (2-3), the dispersion stability of the system is improved, which helps to reduce the dissociation degree of copper sulfate in the system and improve the quality of the coating. At the same time, the synergistic effect between the nitrogen-containing heterocyclic compound and sodium propane sulfonate and sodium chloride is enhanced, thereby avoiding the generation of pitting and wrinkles on the surface of the copper coating and making the copper coating bright, smooth and flat. DETAILED DESCRIPTION

[0024] Example 1

[0025] Example 1 of the present invention provides a copper electroplating bath for filling HDI micro blind vias, comprising the following raw materials: 100 g / L copper sulfate pentahydrate, 40 g / L sulfuric acid, 20 mg / L sodium chloride, 3 mL / L sodium propane sulfonate, 15 mL / L polyethylene glycol, 3 mL / L amine compound, 2 mL / L nitrogen-containing heterocyclic compound, 2 mL / L additives, and the balance being ultrapure water.

[0026] The nitrogen-containing heterocyclic compound is a combination of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazolyl and 1,2-ethylenethiourea, and the mass ratio of the 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazolyl and 1,2-ethylenethiourea is 5:2:6.

[0027] The CAS number of the 2-mercaptobenzimidazole is 583-39-1, which was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; the CAS number of the 1-(4-ethoxyphenyl)-5-mercapto-tetrazole is purchased from Hubei Huaying Biotechnology Co., Ltd.; the CAS number of the 1,2-ethylenethiourea is 96-45-7, which was purchased from Hubei Zhonglong Kangsheng Fine Chemical Co., Ltd.

[0028] The sodium propane sulfonate is a combination of sodium thioalcoholpropane sulfonate and sodium 3-thio-1-propanesulfonate, and the mass ratio of the sodium thioalcoholpropane sulfonate to the sodium 3-thio-1-propanesulfonate is 4:3.

[0029] The sodium thioalcohol propane sulfonate and 3-thio-1-propanesulfonic acid sodium salt were purchased from Jiangsu Mengde New Material Technology Co., Ltd.

[0030] The amine compound is a combination of polyethyleneimine and coconut diethanolamide; the mass ratio of the polyethyleneimine to coconut diethanolamide is 1:2.

[0031] The CAS number of the polyethyleneimine is 9002-98-6, the product number is E54370, and it was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.; the CAS number of the coconut diethanolamide is 68603-42-9, and it was purchased from Jiangsu Aikon Biopharmaceutical Research and Development Co., Ltd.

[0032] The alcohol compound is a combination of polyethylene glycol 4000 and polyethylene glycol 6000, and the mass ratio of the polyethylene glycol 4000 to the polyethylene glycol 6000 is 8:5.

[0033] The polyethylene glycol 4000 and polyethylene glycol 6000 were purchased from Hai'an Petrochemical Plant in Jiangsu Province.

[0034] The additive is a polyether compound containing hydroxyl groups in its structure; the polyether compound containing hydroxyl groups in its structure is a combination of polyethylene glycol allyl methyl ether and propylene glycol polyether; the mass ratio of the polyethylene glycol allyl methyl ether to the propylene glycol polyether is 1.5:2.5.

[0035] The CAS number of the propylene glycol polyether is 25322-69-4, the product number is P815571, and it was purchased from Shanghai McLean Biochemical Technology Co., Ltd.; the CAS number of the polyethylene glycol allyl methyl ether is 27252-80-8, and it was purchased from Shanghai McLean Biochemical Technology Co., Ltd.

[0036] The preparation method of the electroplating copper bath for filling HDI micro blind vias is as follows: according to the formula, copper sulfate pentahydrate, sulfuric acid, sodium chloride, sodium propane sulfonate, polyethylene glycol, amine compounds, nitrogen-containing heterocyclic compounds, and additives are added to ultrapure water and stirred for 20 minutes.

[0037] The second aspect of the embodiment 1 of the present invention provides a method for using a copper electroplating bath for filling HDI micro blind vias, wherein the process conditions during use are: cathode current density: 1.5A / dm 2 , Adaptable temperature: 25℃, cathode swing: 14 times / min, stirring method: air stirring.

[0038] Example 2

[0039] Example 2 of the present invention provides a copper electroplating bath for filling HDI micro blind vias, comprising the following raw materials: 120 g / L copper sulfate pentahydrate, 50 g / L sulfuric acid, 25 mg / L sodium chloride, 4 mL / L sodium propane sulfonate, 20 mL / L polyethylene glycol, 4 mL / L amine compound, 3 mL / L nitrogen-containing heterocyclic compound, 3 mL / L additives, and the balance being ultrapure water.

[0040] The nitrogen-containing heterocyclic compound is a combination of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazolyl and 1,2-ethylenethiourea, and the mass ratio of the 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazolyl and 1,2-ethylenethiourea is 6:3:8.

[0041] The CAS number of the 2-mercaptobenzimidazole is 583-39-1, which was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; the CAS number of the 1-(4-ethoxyphenyl)-5-mercapto-tetrazole is purchased from Hubei Huaying Biotechnology Co., Ltd.; the CAS number of the 1,2-ethylenethiourea is 96-45-7, which was purchased from Hubei Zhonglong Kangsheng Fine Chemical Co., Ltd.

[0042] The sodium propane sulfonate is a combination of sodium thioalcoholpropane sulfonate and sodium 3-thio-1-propanesulfonate, and the mass ratio of the sodium thioalcoholpropane sulfonate to the sodium 3-thio-1-propanesulfonate is 5:4.

[0043] The sodium thioalcohol propane sulfonate and 3-thio-1-propanesulfonic acid sodium salt were purchased from Jiangsu Mengde New Material Technology Co., Ltd.

[0044] The amine compound is a combination of polyethyleneimine and coconut diethanolamide; the mass ratio of the polyethyleneimine to coconut diethanolamide is 1.2:2.5.

[0045] The CAS number of the polyethyleneimine is 9002-98-6, the product number is E54370, and it was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.; the CAS number of the coconut diethanolamide is 68603-42-9, and it was purchased from Jiangsu Aikon Biopharmaceutical Research and Development Co., Ltd.

[0046] The alcohol compound is a combination of polyethylene glycol 4000 and polyethylene glycol 6000, and the mass ratio of the polyethylene glycol 4000 to the polyethylene glycol 6000 is 10:7.

[0047] The polyethylene glycol 4000 and polyethylene glycol 6000 were purchased from Hai'an Petrochemical Plant in Jiangsu Province.

[0048] The additive is a polyether compound containing hydroxyl groups in its structure; the polyether compound containing hydroxyl groups in its structure is a combination of polyethylene glycol allyl methyl ether and propylene glycol polyether; the mass ratio of the polyethylene glycol allyl methyl ether to the propylene glycol polyether is 2:3.

[0049] The CAS number of the propylene glycol polyether is 25322-69-4, the product number is P815571, and it was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; the CAS number of the polyethylene glycol allyl methyl ether is 27252-80-8, and it was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0050] The preparation method of the electroplating copper bath for filling HDI micro blind vias is as follows: according to the formula, copper sulfate pentahydrate, sulfuric acid, sodium chloride, sodium propane sulfonate, polyethylene glycol, amine compounds, nitrogen-containing heterocyclic compounds, and additives are added to ultrapure water and stirred for 20 minutes.

[0051] The second aspect of the embodiment 2 of the present invention provides a method for using a copper electroplating bath for filling HDI micro blind vias, wherein the process conditions during use are: cathode current density: 1.5A / dm 2 , Adaptable temperature: 25℃, cathode swing: 14 times / min, stirring method: air stirring.

[0052] Example 3

[0053] Example 3 of the present invention provides a copper electroplating bath for filling HDI micro blind vias, comprising the following raw materials: 90 g / L copper sulfate pentahydrate, 30 g / L sulfuric acid, 15 mg / L sodium chloride, 2 mL / L sodium propane sulfonate, 12 mL / L polyethylene glycol, 2 mL / L amine compound, 1 mL / L nitrogen-containing heterocyclic compound, 1 mL / L additive, and the balance being ultrapure water.

[0054] The nitrogen-containing heterocyclic compound is a combination of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazolyl and 1,2-ethylenethiourea, and the mass ratio of the 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazolyl and 1,2-ethylenethiourea is 4:1:5.

[0055] The CAS number of the 2-mercaptobenzimidazole is 583-39-1, which was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; the CAS number of the 1-(4-ethoxyphenyl)-5-mercapto-tetrazole is purchased from Hubei Huaying Biotechnology Co., Ltd.; the CAS number of the 1,2-ethylenethiourea is 96-45-7, which was purchased from Hubei Zhonglong Kangsheng Fine Chemical Co., Ltd.

[0056] The sodium propane sulfonate is a combination of sodium thioalcoholpropane sulfonate and sodium 3-thio-1-propanesulfonate, and the mass ratio of the sodium thioalcoholpropane sulfonate to the sodium 3-thio-1-propanesulfonate is 3:2.

[0057] The sodium thioalcohol propane sulfonate and 3-thio-1-propanesulfonic acid sodium salt were purchased from Jiangsu Mengde New Material Technology Co., Ltd.

[0058] The amine compound is a combination of polyethyleneimine and coconut diethanolamide; the mass ratio of the polyethyleneimine to coconut diethanolamide is 0.8:1.8.

[0059] The CAS number of the polyethyleneimine is 9002-98-6, the product number is E54370, and it was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.; the CAS number of the coconut diethanolamide is 68603-42-9, and it was purchased from Jiangsu Aikon Biopharmaceutical Research and Development Co., Ltd.

[0060] The alcohol compound is a combination of polyethylene glycol 4000 and polyethylene glycol 6000, and the mass ratio of the polyethylene glycol 4000 to the polyethylene glycol 6000 is 6:4.

[0061] The polyethylene glycol 4000 and polyethylene glycol 6000 were purchased from Hai'an Petrochemical Plant in Jiangsu Province.

[0062] The additive is a polyether compound containing hydroxyl groups in its structure; the polyether compound containing hydroxyl groups in its structure is a combination of polyethylene glycol allyl methyl ether and propylene glycol polyether; the mass ratio of the polyethylene glycol allyl methyl ether to the propylene glycol polyether is 1:2.

[0063] The CAS number of the propylene glycol polyether is 25322-69-4, the product number is P815571, and it was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; the CAS number of the polyethylene glycol allyl methyl ether is 27252-80-8, and it was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0064] The preparation method of the electroplating copper bath for filling HDI micro blind vias is as follows: according to the formula, copper sulfate pentahydrate, sulfuric acid, sodium chloride, sodium propane sulfonate, polyethylene glycol, amine compounds, nitrogen-containing heterocyclic compounds, and additives are added to ultrapure water and stirred for 20 minutes.

[0065] The second aspect of the embodiment 3 of the present invention provides a method for using a copper electroplating bath for filling HDI micro blind vias, wherein the process conditions during use are: cathode current density: 1.5A / dm 2 , Adaptable temperature: 25℃, cathode swing: 14 times / min, stirring method: air stirring.

[0066] Comparative Example 1

[0067] Comparative Example 1 of the present invention provides a copper electroplating bath for filling HDI micro blind vias, and its specific implementation is the same as that of Example 1, except that the nitrogen-containing heterocyclic compound is 2-mercaptobenzimidazole.

[0068] Comparative Example 2

[0069] Comparative Example 2 of the present invention provides a copper electroplating bath for filling HDI micro blind vias, and its specific implementation is the same as that of Example 1, except that the mass ratio of the sodium thioalkoxypropane sulfonate and the sodium salt of 3-thio-1-propanesulfonic acid is 1:5.

[0070] Comparative Example 3

[0071] Comparative Example 3 of the present invention provides a copper electroplating bath for filling HDI micro blind vias, and its specific implementation is the same as that of Example 1, except that the alcohol compound is polyethylene glycol 4000.

[0072] Comparative Example 4

[0073] Comparative Example 4 of the present invention provides a copper electroplating bath for filling HDI micro blind vias, and its specific implementation is the same as that of Example 1, except that the raw materials for preparing the copper electroplating bath do not contain additives.

[0074] Performance testing methods

[0075] 1. Hole filling rate: The copper electroplating baths prepared in the examples and comparative examples were used according to the corresponding methods to perform copper electroplating on HDI micro blind via boards made of FR-4, with a blind via diameter of 80 μm and a dielectric layer thickness of 50 μm. The hole filling rate was calculated using the following formula. The results are shown in Table 1.

[0076] Filling rate = (the thickness from the bottom of the blind hole to the most concave part of the copper plating layer on the hole surface / the thickness from the bottom of the blind hole to the surface of the copper layer on the board) × 100%.

[0077] 2. Coating Performance: Referring to IPC-TM-650 (Printed Circuit Association Test Methods Manual), the copper electroplating baths prepared in the Examples and Comparative Examples were used in accordance with the corresponding methods to perform copper filling electroplating on HDI micro blind via boards made of FR-4, with blind vias of 80 μm in diameter and a dielectric layer of 50 μm in thickness. The ductility and tensile strength of the copper coatings were measured using a microcomputer-controlled electronic universal testing machine. The results are shown in Table 1.

[0078] 3. Surface morphology: The copper electroplating baths prepared in the examples and comparative examples were used according to the corresponding methods to perform copper filling electroplating on HDI micro blind via boards made of FR-4, with a blind via diameter of 80 μm and a dielectric layer thickness of 50 μm. The surface morphology of the copper plating layer was observed under a microscope, and the results are shown in Table 1.

[0079] Table 1 shows the performance test results of the copper coatings obtained by using the copper electroplating baths provided in Examples 1-3 and Comparative Examples 1-4.

[0080]

Claims

1. A copper electroplating bath for filling HDI micro blind vias, characterized in that: The invention comprises at least the following raw materials: 80-120 g / L of copper sulfate pentahydrate, 30-50 g / L of sulfuric acid, 15-30 mg / L of sodium chloride, 1-5 mL / L of sodium propane sulfonate, 12-20 mL / L of polyethylene glycol, 2-4 mL / L of amine compounds, 0.5-3 mL / L of nitrogen-containing heterocyclic compounds, 1-4 mL / L of additives, and the balance is ultrapure water; the nitrogen-containing heterocyclic compound is a combination of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazole and 1,2-ethylenethiourea; the mass ratio of 2-mercaptobenzimidazole, 1-(4-ethoxyphenyl)-5-mercapto-tetrazole and 1,2-ethylenethiourea is (4-6):(1-3): (5-8); the sodium propane sulfonate is a combination of sodium alcoholthiopropane sulfonate and sodium 3-thio-1-propanesulfonic acid salt, and the mass ratio of the sodium alcoholthiopropane sulfonate and sodium 3-thio-1-propanesulfonic acid salt is (3-5): (2-4); the polyethylene glycol is a combination of polyethylene glycol 4000 and polyethylene glycol 6000, and the mass ratio of the polyethylene glycol 4000 and polyethylene glycol 6000 is (6-10): (4-7); the additive is a polyether compound containing hydroxyl groups in its structure; the polyether compound containing hydroxyl groups in its structure is a combination of polyethylene glycol allyl methyl ether and propylene glycol polyether, and the mass ratio of the polyethylene glycol allyl methyl ether and propylene glycol polyether is (1-2): (2-3).

2. The electroplating copper bath for filling HDI micro blind vias according to claim 1, characterized in that: The amine compound is selected from at least one of polyethyleneimine, polyetheramine, coconut diethanolamide, and cocamidopropyl betaine.

3. A method for using the electroplating copper bath for filling HDI micro blind vias according to any one of claims 1-2, characterized in that: The process conditions during use are: cathode current density: 0.5-4A / dm 2 , Adaptable temperature: 10-35℃, cathode swing: 12-15 times / min, stirring method: air stirring.

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