Sn58Bi low-temperature soldering tin ball surface treatment agent and preparation method thereof

Abstract

The application provides a Sn58Bi low-temperature soldering tin ball surface treatment agent and a preparation method thereof, and relates to the technical field of metal surface treatment.The Sn58Bi low-temperature soldering tin ball surface treatment agent is composed of tin ball activators (diethylenetriamine pentaacetic acid and ethylenediamine tetraacetic acid), a film forming agent, a surfactant, a dispersing agent, an antioxidant, a defoaming agent, a stabilizer, a preservative, deionized water and the like.The surface treatment agent can effectively improve the soldering reliability of the Sn58Bi soldering tin ball, prolong the service life of the soldering tin ball, has good oxidation resistance and corrosion resistance under the premise of not affecting the soldering performance, and is suitable for various complex working environments.Meanwhile, the preparation process of the Sn58Bi low-temperature soldering tin ball surface treatment agent is simple, convenient to use, has good physical stability after film forming, can avoid oxidation and the invasion of pollutants during long-term storage of the soldering tin ball, and improves the quality of the soldering tin ball.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, and in particular to a Sn58Bi low-temperature solder ball surface treatment agent and its preparation method. Background Technology

[0002] As the performance requirements for chips become increasingly demanding, the size and cost of traditional monolithic chips are increasing, and yield risks are also gradually rising. Against this backdrop, the integrated circuit industry has begun to break down traditional complex chips into a set of modular chips with individual functions. These modular chips are then electrically and mechanically connected to the underlying base chip using solder balls through packaging processes. This approach can effectively improve chip reliability while reducing costs.

[0003] In traditional packaging processes, Sn37Pb solder balls are commonly used due to their advantages such as low cost, low melting point, and good wettability, making them widely used in electronic packaging. However, because phosphorus (Pb) is toxic, it has caused serious adverse effects on human health and environmental safety. Therefore, countries around the world have proposed relevant laws to prohibit the use of Pb in electronic products. Consequently, current processes primarily use lead-free solder balls such as SnAg-based, SnZn-based, and SnBi-based solder balls for chip fabrication.

[0004] SnAg-based solder balls contain Ag, resulting in higher costs. While their derivative, SnAgCu-based solder balls, reduce costs, their melting point is still higher than SnPb solder balls. SnZn-based solder balls have melting points similar to SnPb-based solder balls and are low-cost, but they suffer from poor wettability and oxidation resistance. Sn58Bi solder balls, with a melting point of 139℃, meet the requirements for low-temperature soldering, reducing the risk of component failure due to excessively high soldering temperatures. Furthermore, Sn58Bi solder balls have a lower Sn content than other types of solder balls, reducing the risk of tin whisker formation. They also offer advantages such as good wettability, high tensile strength, lower cost, environmental friendliness, low toxicity, and compatibility with existing equipment, making them promising for future applications.

[0005] However, Sn58Bi solder balls exhibit problems such as surface oxidation, decreased fluidity, increased soldering temperature, and longer soldering time after prolonged storage, severely impacting soldering reliability and reducing product yield. To address the long-term storage issue, researchers often employ surface treatment techniques to form a thin film on the solder ball surface to prevent oxidation and contaminant intrusion, thereby improving solder ball quality. Currently, research on solder ball surface treatment agents largely focuses on high-temperature solder balls using SAC305, with a lack of research on low-temperature SnBi-based solder balls.

[0006] For example, some research has proposed a rosin-based surface treatment agent for SAC305 solder balls, which involves coating the solder ball surface with a rosin-based agent, thus solving the problem of solder ball surface oxidation to some extent. Although this surface treatment agent is simple to prepare and the coating process is easy to operate, the principle it uses is physical coating of rosin-based agents, resulting in poor film stability and some environmental pollution.

[0007] Therefore, providing a surface treatment agent for Sn58Bi low-temperature solder balls to improve soldering reliability and stability, reduce soldering time and temperature, and enhance environmental protection and safety is an important development direction. Summary of the Invention

[0008] To overcome the above problems, the present invention provides a surface treatment agent for Sn58Bi low-temperature solder balls. The preparation process of the present invention is simple and convenient to use. It can quickly form a protective film on the surface of Sn58Bi low-temperature solder balls and effectively improve the oxidation resistance and corrosion resistance of Sn58Bi low-temperature solder balls, and extend the long-term storage and service life of Sn58Bi low-temperature solder balls.

[0009] The Sn58Bi low-temperature solder ball surface treatment agent of the present invention comprises the following raw materials:

[0010] Solder ball activator 1-5 wt%, film-forming agent 1-5 wt%, surfactant 0.1-1 wt%, dispersant 0.01-0.5 wt%, antioxidant 0.01-0.5 wt%, defoamer 0.01-0.5 wt%, stabilizer 0-0.5 wt%, preservative 0.01-0.5 wt%, balance deionized water;

[0011] The tin ball activator is composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a weight ratio of 2:1.

[0012] Furthermore, the film-forming agent is one or more of chromate, nitrite, molybdate, tungstate, polyphosphate, zinc salt, phosphonic acid, thiol benzothiazole, benzotriazole, and benzotetrazole.

[0013] Preferably, the film-forming agent is benzotetrazole.

[0014] Further, the surfactant is one or more of the following: sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium secondary alkyl sulfonate, sodium fatty acid methyl ester ethoxylate sulfonate, sodium fatty acid methyl ester sulfonate, sodium dioctyl succinate sulfonate, sodium dodecylbenzene sulfonate, benzene chloride ammonium chloride, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ether, octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, and fatty amine polyoxyethylene ether.

[0015] Preferably, the surfactant is an alkylphenol polyoxyethylene ether.

[0016] Furthermore, the dispersant is one or more of the following: glyceryl monostearate, polyacrylic acid, glycerol, polyethylene glycol 400, polyethylene glycol 8000, and fatty acid methyl ester ethoxylate.

[0017] Preferably, the dispersant is polyethylene glycol 8000.

[0018] Furthermore, the antioxidant is one or more of the following: tea polyphenols, phytic acid, isoflavones, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, and ascorbic acid.

[0019] Preferably, the antioxidant is butylated hydroxyanisole.

[0020] Furthermore, the defoamer is one or more of fatty amines, fatty acid glycerides, polyoxypropylene glycerol polyether, dimethyl silicone oil, polyoxypropylene polyoxyethylene glycerol ether, and glycerol polyoxyethylene polyoxypropylene ether.

[0021] Preferably, the defoamer is glycerol polyoxyethylene polyoxypropylene ether.

[0022] Furthermore, the stabilizer is one or more of the following: quinoxaloline formaldehyde dinitrate, dichlorophenol, isothiazolinone, hydrogen sulfide alkyl formaldehyde, polyoxyethylene rosin amine, chlorhexidine, triazabenzene, and hexadecyl pyridine bromide.

[0023] Preferably, the stabilizer is triazabenzene.

[0024] Furthermore, the preservative is one or more of methylparaben, methylisothiazolinone, methylchloroisothiazolinone, phenoxyethanol, benzyl alcohol, and benzoic acid.

[0025] Preferably, the preservative is methylisothiazolinone.

[0026] The present invention also provides a method for preparing the Sn58Bi low-temperature solder ball surface treatment agent, comprising the following steps:

[0027] S1. Mix the solder ball activator, film-forming agent and appropriate amount of deionized water in proportion, heat and stir until completely dissolved, mix evenly and let stand to room temperature to obtain mixture A.

[0028] S2. Add antioxidant, dispersant, stabilizer and preservative to the mixture A, and stir until completely dissolved to obtain mixture B;

[0029] S3. Add surfactant, defoamer and remaining deionized water to the mixture B, mix well to obtain mixture C;

[0030] S4. Add a buffer to the solution C and adjust the pH to 9 to obtain the Sn58Bi low-temperature solder ball surface treatment agent.

[0031] Furthermore, the heating temperature is 50℃-60℃.

[0032] Furthermore, the buffer is one or more of potassium hydroxide, sodium hydroxide, ammonium bicarbonate, ammonia, sodium bicarbonate, glacial acetic acid, hydrochloric acid, phosphoric acid, and nitric acid.

[0033] Preferably, the buffer is sodium hydroxide and nitric acid.

[0034] Furthermore, the amount of buffer added is 0-5 wt% of solution C.

[0035] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0036] The surface treatment agent of this invention can effectively improve the welding reliability of Sn58Bi solder balls and extend the service life of solder balls. Without affecting the welding performance, it also has good oxidation resistance and corrosion resistance, making it suitable for various complex working environments.

[0037] The Sn58Bi low-temperature solder ball surface treatment agent of this invention has a simple preparation process and is easy to use. After film formation, it has good physical stability and can prevent oxidation and contaminant intrusion during long-term storage of solder balls, thereby improving the quality of solder balls. Attached Figure Description

[0038] The present invention will be further described below with reference to the accompanying drawings.

[0039] Figure 1 This is a test result of the void rate detection of Sn58Bi solder ball joints in Test Example 3 of this invention. Detailed Implementation

[0040] The technical solution provided by the present invention will be further described below with reference to the embodiments.

[0041] Example 1

[0042] A surface treatment agent for Sn58Bi low-temperature solder balls, composed of the following raw materials:

[0043] The composition consists of: 4 wt% solder ball activator, 2 wt% benzotetrazole, 1 wt% alkylphenol polyoxyethylene ether, 0.5 wt% polyethylene glycol 8000, 0.5 wt% butylated hydroxyanisole, 0.3 wt% glycerol polyoxyethylene polyoxypropylene ether, 0.2 wt% triazabenzene, 0.1 wt% methylisothiazolinone, with the balance being deionized water.

[0044] The tin ball activator is composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a weight ratio of 2:1.

[0045] The preparation steps of the Sn58Bi low-temperature solder ball surface treatment agent are as follows:

[0046] S1. Mix 4 wt% of solder ball activator, 2 wt% of benzotetrazole and deionized water in a certain proportion, heat to 60°C, stir until completely dissolved, mix evenly and let stand to room temperature to obtain mixture A.

[0047] S2. Add 0.5wt% butylated hydroxyanisole, 0.5wt% polyethylene glycol 8000, 0.2wt% triazabenzene, and 0.1wt% methylisothiazolinone to mixture A, and stir until completely dissolved to obtain mixture B;

[0048] S3. Add 1 wt% alkylphenol polyoxyethylene ether, 0.3 wt% glycerol polyoxyethylene polyoxypropylene ether and the remaining deionized water to mixture B, mix well to obtain mixture C;

[0049] S4. Adjust the pH of the solution C to 9 to obtain the Sn58Bi low-temperature solder ball surface treatment agent.

[0050] Comparative Example 1

[0051] Same as Example 1, except that the activator for the solder balls is ethylenediaminetetraacetic acid.

[0052] Comparative Example 2

[0053] Same as Example 1, except that the tin ball activator is composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a weight ratio of 10:1.

[0054] Comparative Example 3

[0055] Same as Example 1, except that the tin ball activator is composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a weight ratio of 4:1.

[0056] Comparative Example 4

[0057] Same as Example 1, except that the tin ball activator is composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a weight ratio of 4:3.

[0058] Comparative Example 5

[0059] Same as Example 1, except that the tin ball activator is composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a weight ratio of 1:1.

[0060] Test Example 1

[0061] The newly opened Sn58Bi low-temperature solder balls were randomly divided into six groups of the same quality.

[0062] Six groups of Sn58Bi low-temperature solder balls were immersed in the surface treatment agents prepared in Example 1 and Comparative Examples 1-5 for 10 minutes, and then the six groups of Sn58Bi solder balls were cleaned and dried to complete the surface treatment of the samples.

[0063] After high-temperature testing and collision testing of six groups of Sn58Bi solder ball samples, the surface color difference was detected by a colorimeter. The color difference is represented by ΔE, and the results are shown in Table 1.

[0064] The ball-shaking instrument was an LH-ZD20 type ball-shaking machine. The ball-shaking test (collision test) method was as follows: After the solder balls were washed and dried, a sample of 10g / bottle was taken, and the original brightness of the solder balls was measured using a colorimeter. Then, the balls were placed in the ball-shaking machine for a shaking test for 20 minutes at an oscillation frequency of 1400 times / minute. After the test, the brightness of the solder balls was measured again using a colorimeter. The color difference formula (ΔE=(ΔL)) was used. 2 +Δa 2 +Δb 2 ) 1 / 2 The color difference change ΔE of the tin balls was calculated.

[0065] High-temperature testing was conducted using a 101-00S electric heating drying oven. The testing method was as follows: After the solder balls were washed and dried, a 10g sample was taken, and the original brightness of the solder balls was measured using a colorimeter. The sample was then placed in a stainless steel tray and placed in the oven at 80℃ for 48 hours. After the test, the brightness of the solder balls was measured again using a colorimeter. The color difference formula (ΔE=(ΔL)) was applied. 2 +Δa 2 +Δb 2 ) 1 / 2 The color difference change ΔE of the tin balls was calculated.

[0066] Table 1. Surface color difference (ΔE) test results after different proportions of solder ball activators.

[0067] Testing items Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 crash test 0.6181 3.0646 1.6553 0.7685 1.1969 2.0650 High temperature test 0.3742 2.5372 1.1686 0.7126 0.7240 1.4773

[0068] This invention indirectly characterizes the film-forming stability and reliability of the treatment agent by detecting color difference on the surface of solder balls after collision and high-temperature tests. A smaller color difference indicates a better treatment effect, while a larger color difference indicates a worse treatment effect.

[0069] As shown in Table 1, in this invention, the solder ball activator composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a specific ratio can significantly improve the stability and reliability of the surface treatment agent, and has a significant impact on reducing the influence of storage, transportation and high temperature on the reliability of Sn58Bi solder balls.

[0070] Comparative Example 6

[0071] Same as Example 1, except that the pH of the Sn58Bi low-temperature solder ball surface treatment agent is 3.

[0072] Comparative Example 7

[0073] Same as Example 1, except that the pH of the Sn58Bi low-temperature solder ball surface treatment agent is 5.

[0074] Comparative Example 8

[0075] Same as Example 1, except that the pH of the Sn58Bi low-temperature solder ball surface treatment agent is 7.

[0076] Comparative Example 9

[0077] Same as Example 1, except that the pH of the Sn58Bi low-temperature solder ball surface treatment agent is 11.

[0078] Comparative Example 10

[0079] Same as Example 1, except that the pH of the Sn58Bi low-temperature solder ball surface treatment agent is 13.

[0080] Test Example 2

[0081] The Sn58Bi solder ball samples prepared in Examples 6-10 were subjected to high-temperature and impact tests, using the same methods as in Example 1. The test results are shown in Table 2.

[0082] Table 2. Surface color difference test results after different pH surface treatment agents.

[0083] Testing items Example 2 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 crash test 0.4270 2.9391 1.8170 1.2131 0.7116 2.6613 High temperature test 0.2338 1.7672 1.3366 0.7654 0.4238 1.4205

[0084] As shown in Table 2, in this invention, the pH value of the SnBi low-temperature solder ball treatment agent has a significant impact on its performance and treatment effect.

[0085] Test Example 3

[0086] Sn58Bi solder balls were immersed in the Sn58Bi low-temperature solder ball surface treatment agent of Example 1 for 10 minutes, and then the Sn58Bi solder balls were soldered onto the substrate. The solder joint void rate was then tested, and the results are as follows. Figure 1 As shown.

[0087] Depend on Figure 1 It can be seen that the void rate of Sn58Bi solder balls after being treated with the Sn58Bi low-temperature solder ball surface treatment agent of the present invention is 2%, which is less than 20%, and meets the standard for solder joint void rate.

[0088] Example 2

[0089] Same as Example 1, except that: the Sn58Bi low-temperature solder ball surface treatment agent is composed of the following raw materials:

[0090] The composition consists of 1 wt% tin ball activator, 1 wt% benzotetrazole, 0.1 wt% alkylphenol polyoxyethylene ether, 0.01 wt% polyethylene glycol 8000, 0.01 wt% butylated hydroxyanisole, 0.01 wt% glycerol polyoxyethylene polyoxypropylene ether, 0.01 wt% methylisothiazolinone, and the balance being deionized water.

[0091] Example 3

[0092] Same as Example 1, except that: the Sn58Bi low-temperature solder ball surface treatment agent is composed of the following raw materials:

[0093] The composition is as follows: 5 wt% tin ball activator, 5 wt% benzotetrazole, 1 wt% alkylphenol polyoxyethylene ether, 0.5 wt% polyethylene glycol 8000, 0.5 wt% butylated hydroxyanisole, 0.5 wt% glycerol polyoxyethylene polyoxypropylene ether, 0.5 wt% triazabenzene, 0.5 wt% methylisothiazolinone, and the balance is deionized water.

[0094] Example 4

[0095] Same as Example 1, except that the film-forming agent is sodium polyphosphate.

[0096] Example 5

[0097] Same as Example 1, except that the surfactant is sodium fatty acid methyl ester sulfonate.

[0098] Example 6

[0099] Same as Example 1, except that the dispersant is polyacrylic acid.

[0100] Example 7

[0101] Same as Example 1, except that the antioxidant is ascorbic acid.

[0102] Example 8

[0103] Same as Example 1, except that the defoamer is polyoxypropylene polyoxyethylene glycerol ether.

[0104] Example 9

[0105] Same as Example 1, except that the preservative is benzoic acid.

[0106] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A Sn58Bi low-temperature solder ball surface treatment agent, characterized in that, Including the following raw materials: Solder ball activator 1~5wt%, film-forming agent 1~5wt%, surfactant 0.1~1wt%, dispersant 0.01~0.5wt%, antioxidant 0.01~0.5wt%, defoamer 0.01~0.5wt%, stabilizer 0~0.5wt%, preservative 0.01~0.5wt%, balance deionized water; The tin ball activator is composed of diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid in a weight ratio of 2:1, and the film-forming agent is benzotetrazazole. The pH of the Sn58Bi low-temperature solder ball surface treatment agent is 9.

2. The Sn58Bi low-temperature solder ball surface treatment agent according to claim 1, characterized in that, The surfactant is one or more of the following: sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, sodium secondary alkyl sulfonate, sodium fatty acid methyl ester ethoxylate sulfonate, sodium fatty acid methyl ester sulfonate, sodium dioctyl succinate sulfonate, sodium dodecylbenzene sulfonate, chlorinated benzene hydrocarbon amine, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, fatty acid polyoxyethylene ether, and fatty amine polyoxyethylene ether.

3. The Sn58Bi low-temperature solder ball surface treatment agent according to claim 1, characterized in that, The dispersant is one or more of the following: glyceryl monostearate, polyacrylic acid, glycerol, polyethylene glycol 400, polyethylene glycol 8000, and fatty acid methyl ester ethoxylate.

4. The Sn58Bi low-temperature solder ball surface treatment agent according to claim 1, characterized in that, The antioxidant is one or more of the following: tea polyphenols, phytic acid, isoflavones, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, and ascorbic acid.

5. The Sn58Bi low-temperature solder ball surface treatment agent according to claim 1, characterized in that, The defoamer is one or more of fatty amines, fatty acid glycerides, polyoxypropylene glycerol polyether, dimethyl silicone oil, polyoxypropylene polyoxyethylene glycerol ether, and glycerol polyoxyethylene polyoxypropylene ether.

6. The Sn58Bi low-temperature solder ball surface treatment agent according to claim 1, characterized in that, The stabilizer is one or more of the following: quinoxaloformaldehyde dinitrate, dichlorophenol, isothiazolinone, polyoxyethylene rosin amine, chlorhexidine, triazabenzene, and hexadecyl pyridine bromide.

7. The Sn58Bi low-temperature solder ball surface treatment agent according to claim 1, characterized in that, The preservative is one or more of methylparaben, methylisothiazolinone, methylchloroisothiazolinone, phenoxyethanol, benzyl alcohol, and benzoic acid.

8. The method for preparing the Sn58Bi low-temperature solder ball surface treatment agent according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Mix the solder ball activator, film-forming agent and appropriate amount of deionized water in proportion, heat and stir until completely dissolved, mix evenly and let stand to room temperature to obtain mixture A. S2. Add antioxidant, dispersant, stabilizer and preservative to the mixture A, and stir until completely dissolved to obtain mixture B; S3. Add surfactant, defoamer and remaining deionized water to the mixture B, mix well to obtain mixture C; S4. Add a buffer to the mixture C and adjust the pH to 9 to obtain Sn58Bi low-temperature solder ball surface treatment agent.

Images