Cleaning composition for residual soldering flux of DBC (Direct Bonding Copper) substrate

Abstract

The invention discloses a cleaning composition for DBC (Direct Bonding Copper) substrate soldering flux residues, which is prepared from the following raw materials in percentage by mass: 3 to 15 percent of organic alkali, 1 to 10 percent of organic acid, 0.1 to 1 percent of rosin-based quaternary ammonium salt surfactant (S), 0.1 to 1 percent of corrosion inhibitor and the balance of ether organic solvent, and the sum of the mass percent is 100 percent. The cleaning composition containing the rosin-based quaternary ammonium salt surfactant has good cleaning, corrosion inhibition, high temperature resistance and the like, and residual soldering flux on the surface of the DBC substrate can be cleaned at a time.

Description

Technical Field

[0001] The invention belongs to the technical field of cleaning agents, and in particular relates to a cleaning agent composition for a DBC board. Background Art

[0002] Package cleaning agents are widely used in various links of chip packaging, including chip-level packaging, component-level packaging, etc. With the development of semiconductor packaging technology, higher requirements are also placed on the performance and quality of package cleaning fluids.

[0003] During the semiconductor device packaging process, flux and solder paste are used as welding auxiliary materials. These welding auxiliary materials will produce residues more or less during the welding process, and will also be contaminated with some pollutants during the process. The flux residues and pollutants on the surface are easy to corrode the device under the action of air oxidation and moisture, causing irreversible damage, affecting the stability of the device or even failure. Therefore, in order to ensure the quality and stability of semiconductor devices, it is necessary to introduce a cleaning process and use a cleaning agent in the packaging process.

[0004] There are many disadvantages of packaging cleaning agents on the market, such as unstable cleaning effect, material compatibility issues, swelling or deformation of non-metallic materials, etc. In advanced packaging technology, the structure of products is becoming more and more complex, with tiny gaps, holes and structures with high aspect ratios. Traditional cleaning agents may not be able to effectively enter these complex structures, resulting in incomplete cleaning and failure to completely clean the products. Packaged products are usually composed of a variety of materials, such as metals such as aluminum, copper, and nickel, as well as non-metallic materials such as ceramics, plastics, and rubber. Some cleaning agents may be corrosive to certain metals. Even for short-term cleaning, if the cleaning agent is not properly selected, the surface of metal parts may be corroded, affecting their performance and service life. For non-metallic materials such as plastics and rubber, some cleaning agents may cause them to swell, deform or become embrittled. For example, some organic solvents may soften and dissolve plastic materials, resulting in damage to the packaging structure. Cleaning agents may not be able to completely remove various residues generated during the packaging process, such as flux, oil stains, dust, etc. If these residues remain on the packaged products, they may affect the electrical performance, reliability and service life of the products. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a cleaning composition for residual flux on DBC substrates, which has good dispersion, anti-oxidation, high temperature resistance and other effects, can effectively remove the flux on the surface of the DBC substrate during the welding process at one time, has good anti-oxidation performance and high temperature resistance, has the advantages of good product cleaning effect, high cleaning yield, long service life, and environmental friendliness. It is a green, environmentally friendly packaging cleaning agent with good cleaning ability.

[0006] To achieve the above purpose, this cleaning agent adopts the following technical solutions:

[0007] A cleaning composition for cleaning solder flux residues on a DBC substrate is prepared from the following raw materials in percentage by mass, based on the sum of percentage by mass being 100%: 3-15% of an organic base, 1-10% of an organic acid, 0.1-1% of a rosin-based quaternary ammonium salt surfactant (S), 0.1%-1% of a corrosion inhibitor, 1%-5% of water, and the balance being an ether organic solvent.

[0008] Furthermore, the general structural formula of the rosin-based quaternary ammonium salt surfactant (S) is as follows:

[0009]

[0010] Furthermore, the preparation method of the rosin-based quaternary ammonium salt surfactant (S) comprises the following steps:

[0011] (1) Synthesis of intermediate Ⅰ

[0012]

[0013] Weigh 30.25g of rosin acid, 9.25g of epichlorohydrin, and 31.94g of tetrabutylammonium bromide and add them to a three-necked flask containing 100mL of anhydrous ethanol. A reflux condenser is installed on the three-necked flask to prevent the solvent from volatilizing. Stir the mixed solution with a magnetic stirrer to allow the reactants to fully contact. At the same time, slowly heat to a reaction temperature of about 100-120°C, react for 2-4 hours, and after the reaction is completed, cool the reaction mixture to room temperature. Then transfer the reaction solution to a separatory funnel, add an appropriate amount of deionized water for washing, wash away unreacted tetrabutylammonium bromide and other water-soluble impurities, remove the solvent ethanol by reduced pressure distillation, and obtain a crude product. Then select a suitable recrystallization solvent (such as ethyl acetate-n-hexane mixed solvent), dissolve the crude product in a hot recrystallization solvent, and then slowly cool to allow the product to crystallize and precipitate, and filter to obtain the purified product intermediate I.

[0014] (2) Synthesis of Intermediate II

[0015]

[0016] Add 4.5 ml of diethanolamine, 0.71 g of sodium bicarbonate as an acid-binding agent to a flask containing 8.1 g of intermediate I, and add 30 ml of anhydrous ethanol as a solvent and heat in an 80°C oil bath for reaction. After 0.5 h, bubbles emerge from the reaction system. After 3 h, the color of the reaction system becomes darker, without turbidity or bubbles, and the reaction is stopped. After cooling slightly, transfer the product to a beaker, wash with distilled water 5 times (5×20 ml) until the water layer is clear, and then remove water and ethanol by reduced pressure distillation. After drying, a brown viscous intermediate II is obtained.

[0017] (3) Synthesis of rosin-based quaternary ammonium salt surfactants

[0018]

[0019] In a three-necked flask filled with 100ml of dimethyl sulfoxide, add 32.24g of tetrabutylammonium bromide, then slowly add 8.38g of intermediate II and 28.6g of 1,9-dibromononane. Under a certain vacuum degree (such as 10-100mmHg), slowly heat the temperature to 190℃-200℃, react for 1-3 hours, and after the reaction is completed, cool the reaction mixture to room temperature. Then transfer the reaction solution to a separatory funnel, add an appropriate amount of dichloromethane for extraction, and remove the solvent by vacuum distillation to obtain the product rosin-based quaternary ammonium salt surfactant.

[0020] Furthermore, the organic acid is selected from one or more of benzoic acid, tartaric acid and the like.

[0021] Furthermore, deionized water has an electrical conductivity less than or equal to 1 us / cm.

[0022] Furthermore, the ether organic solvent is selected from one or more materials such as dipropylene glycol methyl ether, methyl tert-butyl ether, and diethylene glycol dibutyl ether.

[0023] Furthermore, the corrosion inhibitor is selected from one or more of materials such as 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, benzotriazole, and 5-mercaptobenzimidazole.

[0024] Furthermore, the organic base is selected from one or more of diethanolamine, triethanolamine, methylolamine and the like.

[0025] Furthermore, the surfactant is a rosin-based quaternary ammonium salt surfactant.

[0026] Furthermore, the preparation method of the cleaning composition comprises the following steps:

[0027] (1) Add organic acid and water in proportion and shake to dissolve evenly;

[0028] (2) After the organic acid and water are dissolved, add an ether organic solvent, a corrosion inhibitor, and a rosin-based quaternary ammonium salt surfactant in sequence, stir and add an organic base, and when the pH range is 7.3-7.8, stop adding the organic base and continue stirring;

[0029] (3) Stop stirring and let the mixture stand until it reaches room temperature to obtain a transparent, clear and uniform composition.

[0030] The method of using the cleaning composition of the present invention is to directly sample the cleaning composition, heat it to 40-55°C, use it to clean the DBC substrate with residual solder flux under 40kHz ultrasonic conditions for 5min-20min, then rinse it with normal temperature water ultrasonically, and then dry it at 80°C.

[0031] The significant advantages of the present invention are:

[0032] (1) The structure of the rosin-based quaternary ammonium salt surfactant (S) used in the present invention introduces the tricyclic diterpene group and long carbon chain of rosin. According to the principle of like dissolves like, the rosin-based group in the surfactant can combine with the organic pollutants in the rosin flux on the metal circuit board, and then soften and disperse into the cleaning agent with the help of the hydrophilic group, thereby achieving the effect of decontamination protection. At the same time, the long carbon group in its structure has chelating, dispersing and antibacterial effects, and can cooperate with the materials in the system to achieve a win-win situation, showing excellent cleaning ability. The introduction of the long carbon chain further reduces the critical micelle concentration, improves the wettability of the surfactant, enhances the adhesion, and can effectively remove the flux residue on the surface of the DBC board while having good corrosion resistance and high temperature resistance;

[0033] (2) The organic acid and organic base materials used in the present invention can be used to adjust the pH value of the cleaning solution to ensure that the system can adapt to the needs of a specific cleaning environment. The organic acid material can form a complex with the metal ions through its acidic properties, thereby increasing the solubility of the metal ions in the solution and helping to remove metal dirt attached to the surface of the object. The organic base can act as a catalyst or promoter to accelerate the chemical reaction during the cleaning process and improve the cleaning efficiency.

[0034] (3) The corrosion inhibitor used in the present invention forms a film structure on the surface of the metal material, physically and chemically adsorbs and isolates the metal from the corrosive medium, thereby slowing down the corrosion of the metal. This adsorption helps to form a protective layer during the cleaning process, reducing direct contact with the metal surface and potential corrosion risks.

[0035] (4) The cleaning composition obtained by the present invention can clean the residual solder flux in the packaging process at one time, protect the DBC board from corrosion, and the actual cleaning yield is more than 95%.

[0036] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Comparison diagram of the surface of the silver-plated layer of the DBC substrate before (left) and after (right) cleaning with the cleaning composition obtained in Example 3;

[0038] Figure 2This is a comparison of the oxidation conditions on the surface of the DBC substrate chip before (left) and after (right) cleaning with the cleaning composition obtained in Example 3. DETAILED DESCRIPTION

[0039] A cleaning composition for cleaning solder flux residues on a DBC substrate is prepared from the following raw materials in percentage by mass: 3-15% of an organic base, 1-10% of an organic acid, 0.1-1% of a rosin-based quaternary ammonium salt surfactant (S), 0.1%-1% of a corrosion inhibitor, and the balance being an ether organic solvent, based on the sum of the percentages by mass being 100%.

[0040] The organic base is selected from one or more of diethanolamine, triethanolamine, monoethanolamine and the like.

[0041] The organic acid is selected from one or more of benzoic acid, tartaric acid and the like.

[0042] The corrosion inhibitor is selected from one or more materials such as 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, benzotriazole, 5-mercaptobenzimidazole and the like.

[0043] The water is deionized water with a conductivity less than or equal to 1 us / cm.

[0044] The general structural formula of the rosin-based quaternary ammonium salt surfactant (S) is as follows:

[0045]

[0046] The preparation method of the rosin-based quaternary ammonium salt surfactant (S) comprises the following steps:

[0047] (1) Synthesis of Intermediate I: Weigh 30.25 g of rosin acid, 9.25 g of epichlorohydrin, and 32.24 g of tetrabutylammonium bromide and add them to a three-necked flask containing 100 mL of ethanol. Install a reflux condenser on the three-necked flask to prevent the solvent from volatilizing. Stir the mixed solution with a magnetic stirrer to ensure that the reactants are fully in contact. At the same time, slowly heat to a reaction temperature of about 100-120°C and react for 2-4 hours. After the reaction is completed, cool the reaction mixture to room temperature. Then transfer the reaction solution to a separatory funnel and add an appropriate amount of deionized water to wash away unreacted tetrabutylammonium bromide and other water-soluble impurities. Separate the organic phase and dry the organic phase with anhydrous sodium sulfate to remove the water therein. Remove the solvent ethanol by vacuum distillation to obtain a crude product. Then select a suitable recrystallization solvent (such as ethyl acetate-n-hexane mixed solvent), dissolve the crude product in the hot recrystallization solvent, then slowly cool to allow the product to crystallize and filter to obtain the purified product.

[0048] (2) Synthesis of Intermediate II: Add 4.5 ml of diethanolamine, 0.71 g of acid-binding agent sodium bicarbonate, and 30 ml of anhydrous ethanol as solvent to a flask containing 8.1 g of Intermediate I. Heat the reaction in an 80°C oil bath. After 0.5 h, bubbles emerge from the reaction system. After 3 h, the color of the reaction system becomes darker, and there is no turbidity or bubbles. Stop the reaction. After cooling slightly, transfer the product to a beaker and wash it with distilled water 5 times (5×20 ml) until the water layer is clear. Then remove water and ethanol by vacuum distillation. After drying, a brown viscous intermediate II is obtained.

[0049] (3) Synthesis of rosin-based quaternary ammonium salt surfactants: After adding 32.24 g of tetrabutylammonium bromide to a three-necked flask containing 100 ml of dimethyl sulfoxide, slowly add 8.38 g of intermediate II and 28.6 g of 1,9-dibromononane. Under a certain vacuum degree (such as 10-100 mmHg), slowly heat the temperature to 190°C-200°C and react for 1-3 hours. After the reaction is completed, cool the reaction mixture to room temperature. Then transfer the reaction solution to a separatory funnel, add an appropriate amount of dichloromethane for extraction, and remove the solvent by reduced pressure distillation to obtain the product.

[0050] The preparation method of the cleaning composition is:

[0051] (1) Add organic acid and water in proportion and shake to dissolve evenly;

[0052] (2) After the organic acid and water are dissolved, add an ether organic solvent, a corrosion inhibitor, and a rosin-based quaternary ammonium salt surfactant in sequence, stir and add an organic base, and when the pH range is 7.3-7.8, stop adding the organic base and continue stirring;

[0053] (3) Stop stirring and let the mixture stand until it reaches room temperature to obtain a transparent, clear and uniform composition.

[0054] The method of using the cleaning composition of the present invention is to directly sample the cleaning composition, heat it to 40-55°C, use it to clean the DBC substrate with residual solder flux under 40kHz ultrasonic conditions for 5min-20min, then rinse it with normal temperature water ultrasonically, and then dry it at 80°C.

[0055] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0056] Example:

[0057] A cleaning composition for a DBC substrate, the preparation method of which is as follows:

[0058] (1) adding organic acid and water in the above proportions, and shaking to dissolve evenly;

[0059] (2) After the organic acid and water are dissolved, add an ether organic solvent, a corrosion inhibitor, and a rosin-based quaternary ammonium salt surfactant in sequence, stir and add an organic base, and when the pH range is 7.3-7.8, stop adding the organic base and continue stirring;

[0060] (3) Stop stirring and let the mixture stand until it reaches room temperature to obtain a transparent, clear and uniform composition.

[0061] The preparation method of the rosin-based quaternary ammonium salt surfactant (S) comprises the following steps:

[0062] (1) Synthesis of Intermediate I: Weigh 30.25 g of rosin acid, 9.25 g of epichlorohydrin, and 32.24 g of tetrabutylammonium bromide and add them to a three-necked flask containing 100 mL of ethanol. Install a reflux condenser on the three-necked flask to prevent the solvent from volatilizing. Stir the mixed solution with a magnetic stirrer to ensure that the reactants are fully in contact. At the same time, slowly heat to a reaction temperature of 100°C and react for 3 hours. After the reaction is completed, cool the reaction mixture to room temperature. Then transfer the reaction solution to a separatory funnel and add an appropriate amount of deionized water to wash away unreacted tetrabutylammonium bromide and other water-soluble impurities. Separate the organic phase and dry the organic phase with anhydrous sodium sulfate to remove the water therein. Remove the solvent ethanol by vacuum distillation to obtain a crude product. Then select a suitable recrystallization solvent (such as an ethyl acetate-n-hexane mixed solvent), dissolve the crude product in a hot recrystallization solvent, and then slowly cool to allow the product to crystallize and precipitate. Filter to obtain a purified product.

[0063] (2) Synthesis of Intermediate II: Add 4.5 ml of diethanolamine, 0.71 g of acid-binding agent sodium bicarbonate, and 30 ml of anhydrous ethanol as solvent to a flask containing 8.1 g of Intermediate I. Heat the reaction in an 80°C oil bath. After 0.5 h, bubbles emerge from the reaction system. After 3 h, the color of the reaction system becomes darker, there is no turbidity, and no bubbles are generated. Stop the reaction. After cooling slightly, transfer the product to a beaker and wash it with distilled water 5 times (5×20 ml) until the water layer is clear. Then remove water and ethanol by distillation under reduced pressure. After drying, a brown viscous intermediate II is obtained.

[0064] (3) Synthesis of rosin-based quaternary ammonium salt surfactants: After adding 32.24 g of tetrabutylammonium bromide to a three-necked flask containing 100 ml of dimethyl sulfoxide, slowly add 8.38 g of intermediate II and 28.6 g of 1,9-dibromononane. Under a certain vacuum degree (such as 10-100 mmHg), slowly heat the temperature to 200°C and react for 2 hours. After the reaction is completed, cool the reaction mixture to room temperature. Then transfer the reaction solution to a separatory funnel, add an appropriate amount of dichloromethane for extraction, and remove the solvent by vacuum distillation to obtain a rosin-based quaternary ammonium salt surfactant (S). Its structural characterization data are as follows:

[0065] 1 HNMR (300Mhz, DMSO-d6), δ: 5.75 (m, 2H, H), 5.50 (m, 2H, H), 0.86 (m, 12H, CH3), 1.26 (t, 6H, CH2), 1.29 (m, 4H, CH2), 1. 36 (m, 4H, CH2), 1.27 (m, 6H, CH3), 1.12 (m, 6H, CH3), 2.38 (m, 2H, CH), 2.34 (m, 4H, CH2), 2.55 (m, 8H, CH2), 2.62 (m, 4H, CH2), 3.46 (m, 8H, CH2), 4.33 (m, 4H, CH2), 4.14 (m, 2H, CH), 1.53 (m, 4H, CH2), 2.01 (m, 4H, CH2), 1.44 (m, 4H, CH2), 1.5 6(m, 4H, CH2), 2.19 (m, 4H, CH2), 2.42 (m, 4H, CH2), 1.80 (m, 2H, CH), 1.66 (m, 2H, CH), 4.81 (m, 4H, OH), 5.37 (m, 2H, OH);

[0066] 13 C NMR (125Mhz, DMSO-d6), δ: 21.9, 29.6, 29.3, 26.9, 22.3, 17.0, 14.6, 34.8, 75.2, 78.1, 78.7, 53.3, 69.1 , 60.1, 177.9, 18.7, 37.8, 22.7, 39.2, 23.5, 26.6, 46.8, 45.1, 51.3, 34.5, 122.4, 121.2, 146.0, 135.5;

[0067] HRMS calculated value C 63 H 108 Br2N2O 10 :1213.37, measured value:1210.64.

[0068] Table 1 Components and contents in different cleaning agent compositions

[0069]

[0070]

[0071] The DBC substrates with solder paste attached to the surface but not cleaned were immersed in the cleaning agent compositions prepared in Examples 1-5 and Comparative Examples 1-5, respectively, and ultrasonically cleaned (40Khz) under the set temperature and time ultrasonic conditions, and then rinsed with ultrapure water spray, and then dried. The metallographic microscope was used to observe to confirm the cleaning effect, and the operating conditions and results are shown in Table 2.

[0072] Table 2 Cleaning effect of different cleaning agent compositions on DBC substrates

[0073] Cleaning agent model Temperature / ℃ Time / s Cleaning volume / pcs Cleaning yield Cleaning capacity Example 1 45 300 500 94-96％ generally Example 2 45 300 500 87-90％ better Example 3 45 300 500 ＞99％ Excellent Example 4 45 300 500 70-75％ generally Example 5 45 300 500 87-89％ better Comparative Example 1 45 300 500 ＜70％ generally Comparative Example 2 45 300 500 80-85％ better Comparative Example 3 45 300 500 ＜50％ Poor Comparative Example 4 45 300 500 83-84％ better Comparative Example 5 45 300 500 69-73％ generally

[0074] It can be seen from Tables 1-2 that within the set temperature and time, the cleaning agent composition of the present invention can effectively remove the residual solder paste on the surface of the DBC substrate without causing subsequent oxidation, and has a good cleaning effect and a high cleaning yield.

[0075] Compared with Example 3, Comparative Example 1 does not contain an organic base, and Comparative Example 2 does not contain an organic acid. Under the same ultrasonic conditions, more oxidation residues are found on the surface of the DBC substrate chip, which indicates that the non-neutral conditions significantly reduce the cleaning effect of the solution, resulting in a decrease in the cleaning yield.

[0076] Compared with Example 3, Comparative Example 3 does not contain a rosin-based quaternary ammonium salt surfactant (S). Under the same ultrasonic conditions, the cleaning performance and corrosion inhibition performance of the liquid are greatly reduced, resulting in a very poor cleaning yield.

[0077] Compared with Example 3, Comparative Example 4 does not contain 2-mercaptobenzimidazole. Under the same ultrasonic conditions, due to the reduced corrosion inhibition effect of the solution, its corrosion inhibition effect on the copper layer of the DBC substrate is reduced, the residual oxidation area is increased, and the cleaning yield is reduced.

[0078] Compared with Example 3, Comparative Example 5 uses glycolic acid as the organic acid. Under the same cleaning conditions, glycolic acid is prone to oxidation and corrosion, resulting in a decrease in the cleaning yield.

[0079] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A cleaning composition for DBC substrate flux residue, characterized in that: The composition is made of the following raw materials in percentage by mass: 3-15% organic base, 1-10% organic acid, 0.1-1% rosin-based quaternary ammonium salt surfactant, 0.1%-1% corrosion inhibitor, 1%-5% water, and the balance is ether organic solvent.

2. The cleaning composition according to claim 1, characterized in that The organic base is selected from one or more of diethanolamine, triethanolamine and monoethanolamine.

3. The cleaning composition according to claim 1, characterized in that The organic acid is selected from one or more of benzoic acid and tartaric acid.

4. The cleaning composition according to claim 1, characterized in that The general structural formula of the rosin-based quaternary ammonium salt surfactant is as follows: 。 5. The cleaning composition according to claim 1, characterized in that The corrosion inhibitor is selected from one or more of 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, benzotriazole, and 5-mercaptobenzimidazole.

6. The cleaning composition according to claim 1, characterized in that The water is deionized water with a conductivity less than or equal to 1 us / cm.

7. The cleaning composition according to claim 1, characterized in that The ether organic solvent is selected from one or more of dipropylene glycol methyl ether, methyl tert-butyl ether and diethylene glycol dibutyl ether.

8. The cleaning composition according to claim 1, characterized in that The preparation method of the cleaning composition comprises the following steps: (1) Add water and organic acid in proportion, and stir at 600 rpm under normal pressure until the particles are completely dissolved; (2) After the organic acid and water are dissolved, add the ether organic solvent, corrosion inhibitor, and rosin-based quaternary ammonium salt surfactant in sequence, stir and add the organic base to adjust the pH range to 7.3-7.8; (3) Stop stirring and let the mixture stand to obtain a transparent, clear and uniform composition.

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