A soldering flux composition for semiconductors and a method for producing the same

Abstract

This invention relates to the field of electronic packaging materials technology, specifically to a semiconductor flux composition and its preparation method. The composition comprises: a film-forming agent, a composite activation system, a high-boiling-point composite solvent, and composite functional additives. The composite activation system is a gradient temperature-responsive halogen-free activation system, composed of a long-chain dibasic organic acid, a hydroxyl-containing polybasic organic acid, and an organic amine activator in a specific ratio. The flux composition of this invention is halogen-free and environmentally friendly, possesses gradient-controllable activation performance, exhibits excellent high-temperature deoxidation ability, and shows extremely low corrosion to metal pads. It is suitable for ultra-fine pitch semiconductor interconnect processes below 30μm, with a solder joint void ratio ≤2% and a surface insulation resistance ≥10 Ω·cm. 14 Ω meets the requirements of high-reliability semiconductor applications such as wafer-level packaging, flip-chip, and 2.5D / 3D advanced packaging. Its fabrication method is simple and controllable, making it suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of electronic packaging materials technology, and in particular to a flux composition for semiconductors and its preparation method. Background Technology

[0002] As semiconductor technology rapidly develops towards high density, high integration, and miniaturization, advanced packaging technologies such as wafer-level packaging (WLP), flip-chip (FC), 2.5D / 3D stacked packaging, and high-bandwidth memory (HBM) have become the industry mainstream. The interconnect bump pitch has been reduced to below 50μm, and even exceeded 30μm, which has placed far more stringent requirements on the core material of the soldering process, flux, than on traditional PCB-grade flux.

[0003] The core function of flux is to remove the oxide layer from the solder pads and solder surfaces, reduce the surface tension of the molten solder, inhibit secondary oxidation during the soldering process, and ensure the mechanical strength and electrical reliability of the interconnect solder joints. Currently, fluxes used in semiconductor packaging mainly suffer from the following problems: The contradiction between environmental protection and activity: Although halogenated fluxes have excellent deoxidation activity, the residual halogen ions can lead to failure risks such as electromigration, corrosion and leakage during long-term use, and have been strictly restricted by international environmental regulations such as RoHS and REACH. Most existing halogen-free fluxes use a single organic acid activation system, which requires a significant increase in the amount of organic acid to improve deoxidation ability. This not only leads to excessive corrosion of the pads and UBM (Under-Bump Metal Layer), but also causes poor storage stability and premature decomposition failure at high temperatures.

[0004] Insufficient adaptability to ultra-fine pitch processes: In 30-50μm ultra-fine pitch interconnect scenarios, the rheological properties of existing fluxes are poor, which can easily lead to defects such as printing collapse, oil seepage, and solder bridging; at the same time, the wettability and spreadability are insufficient, which can easily lead to yield problems such as cold solder joints and insufficient balls, and cannot meet the process requirements of advanced packaging.

[0005] Poor high-temperature reliability and void control: The reflow peak temperature of lead-free solder has reached over 260°C, and the soldering temperature of power device packages even exceeds 300°C. The evaporation rate of existing flux solvent systems does not match the reflow profile. Boiling and splashing are prone to occur during the preheating stage, and a large amount of volatile gas is generated during the reflow process, resulting in a high void rate of solder joints, usually exceeding 5%, which cannot meet the reliability requirements of automotive-grade and military-grade semiconductors.

[0006] Insufficient controllability of residues and long-term insulation: No-clean fluxes leave mostly hygroscopic residues after soldering, resulting in low surface insulation resistance (SIR) and a tendency to fail due to electromigration in high humidity environments (85℃ / 85%RH). Water-washable fluxes require long-term cleaning with high-temperature deionized water, which is not only inefficient but also prone to damaging the wafer's micro-nano structure. Incomplete cleaning can also leave reliability risks.

[0007] Therefore, developing a halogen-free, environmentally friendly, highly active, low-corrosion, semiconductor flux composition that is compatible with ultra-fine pitch interconnects, has low voids, and high long-term reliability is a technical problem that urgently needs to be solved in the current advanced packaging field and has important industrial application value. Summary of the Invention

[0008] In view of this, the purpose of this invention is to provide a flux composition for semiconductors and its preparation method, so as to solve the problems of existing semiconductor fluxes, such as the contradiction between environmental protection and activity, poor adaptability to ultra-fine pitch, high void ratio, and insufficient long-term reliability. This composition is adaptable to advanced packaging processes with ultra-fine pitch below 30μm, and has both excellent deoxidation activity and extremely low metal corrosion, low solder joint void ratio, excellent long-term insulation reliability, and simple and controllable preparation process, which is suitable for industrial production.

[0009] To achieve the above objectives, the present invention provides a flux composition for semiconductors and a method for preparing the same.

[0010] A flux composition for semiconductors comprises the following raw materials in parts by weight: 5-25 parts film-forming agent, 2-12 parts composite activation system, 60-90 parts high-boiling-point composite solvent, and 0.1-5 parts composite functional additive; The composite activation system is a gradient temperature-responsive halogen-free activation system, which is composed of long-chain dibasic organic acids, hydroxyl-containing polybasic organic acids, and organic amine activators in a mass ratio of 3-6:1-3:1-2.

[0011] Preferably, the long-chain dicarboxylic organic acid is one or more selected from azelaic acid, sebacic acid, dodecanoic acid, and tetradecanoic acid; The hydroxyl-containing polybasic organic acid is one or more of citric acid, malic acid, tartaric acid, and dimethylolpropionic acid; The organic amine activator is one or more of triethanolamine, dimethylethanolamine, 2-methylimidazole, 2-ethyl-4-methylimidazole, and benzimidazole.

[0012] The composite activation system of this invention employs a gradient temperature response design, with different components having different decomposition / activation temperatures: The activation temperature range of long-chain dibasic organic acids is 220-260℃, which is highly matched with the melting temperature range of lead-free solder. As the main activator, it rapidly releases its activity in the reflow peak temperature range to remove the dense oxide layer on the surface of the pads and solder. The activation temperature range of hydroxyl-containing polybasic organic acids is 180-220℃. As a pre-activator, it gently removes the weak oxide layer on the surface in the later stage of the preheating stage, while improving the initial wettability of the solder. Organic amine activators form acid-base complexes with organic acids, which can inhibit the corrosiveness of organic acids and improve storage stability at room temperature. At high temperatures, the complexes dissociate and release their activity simultaneously. They can also neutralize residual acidic substances after welding, further reducing the risk of corrosion.

[0013] The three components work together to achieve the effects of "low-temperature stability, gradient release, high-temperature efficiency, and low corrosion after welding", perfectly resolving the core contradiction between the activity and corrosiveness of halogen-free flux.

[0014] Preferably, the film-forming agent is a mixture of modified hydrogenated rosin resin and water-soluble film-forming resin in a mass ratio of 4-8:1. The modified hydrogenated rosin resin is one or more of hydrogenated rosin methyl ester, polymerized rosin, maleic acid modified rosin, and phenolic modified rosin, and its softening point is 120-160℃. The water-soluble film-forming resin is one or more of water-soluble acrylic resin, polyethylene glycol, and polyvinylpyrrolidone.

[0015] High softening point modified hydrogenated rosin resin has excellent thermal stability. It does not decompose or carbonize at a high reflow temperature of 260℃, which can effectively inhibit the secondary oxidation of solder. At the same time, it can regulate the rheological properties of the composition and prevent collapse and bridging during ultra-fine pitch printing / coating. The addition of water-soluble film-forming resins enables bidirectional adaptation to controllable residues: In no-wash scenarios, it works synergistically with rosin resin to form a dense, non-hygroscopic insulating protective film, improving surface insulation resistance; In water washing scenarios, it can significantly improve the water solubility of residues, and can be completely cleaned with room temperature deionized water without the need for high-temperature cleaning, thus avoiding damage to the wafer structure.

[0016] Preferably, the high-boiling-point composite solvent is prepared by compounding a main solvent and a co-solvent at a mass ratio of 5-10:1, wherein the main solvent has a normal-pressure boiling point of 200-280℃ and the co-solvent has a normal-pressure boiling point of 180-220℃.

[0017] Preferably, the main solvent is one or more selected from diethylene glycol hexyl ether, diethylene glycol dibutyl ether, propylene glycol diphenyl ether, dodecyl alcohol ester, and diethylene glycol monobutyl ether acetate; The co-solvent is one or more of diethylene glycol butyl ether, propylene glycol methyl ether acetate, polyethylene glycol 200, and isopentyl glycol.

[0018] The high-boiling-point composite solvent of this invention employs a dual-system compounding design. The main solvent has a boiling point higher than the melting temperature of lead-free solder and gradually evaporates during the reflow peak temperature range, avoiding premature evaporation that could lead to activity failure. The co-solvent has a boiling point matched to the preheating temperature and can slowly evaporate during the preheating stage, controlling the viscosity and solid content of the composition and preventing preheating boiling and splashing. It also prevents porosity caused by excessive solvent evaporation during the reflow stage, significantly reducing the void ratio of solder joints. Furthermore, this composite solvent system exhibits excellent solubility for each component, ensuring the storage stability of the composition without stratification or precipitation.

[0019] Preferably, the composite functional additive includes at least two of the following: metal corrosion inhibitors, nonionic surfactants, thixotropic agents, and antioxidants.

[0020] Preferably, by weight, the composite functional additive comprises: 0.05-1 part of metal corrosion inhibitor, 0.05-1 part of nonionic surfactant, 0.3-1 part of thixotropic agent, and 0.1-0.5 part of antioxidant; The metal corrosion inhibitor is a combination of two or more of the following: methylbenzotriazole, mercaptobenzothiazole, and imidazoline quaternary ammonium salt corrosion inhibitors. The nonionic surfactant is a compound of a fluorinated nonionic surfactant and a polyoxyethylene ether nonionic surfactant in a mass ratio of 1:2-5.

[0021] Among them, the metal corrosion inhibitor can form a monomolecular adsorption protective film on the surface of the metal pad, blocking the excessive corrosion of the metal substrate by the active ingredients. It has excellent protective effect, especially on UBM layer, aluminum pad, and nickel-palladium-gold pad, while not affecting the removal of oxide layer by the active ingredients. Compound nonionic surfactants can reduce the surface tension of molten solder to below 25mN / m, significantly improving wettability and spreading properties, and reducing solder joint defects. At the same time, the nonionic system has no ionic residues and does not affect the insulation reliability. The thixotropic agent is one or more of hydrogenated castor oil, fumed silica, and polyamide wax, which can precisely control the thixotropic properties of the composition and is suitable for various coating processes such as stencil printing, dip printing, needle transfer, and spraying. The antioxidant is a hindered phenolic antioxidant, which can inhibit the oxidative deterioration of the composition during high-temperature welding and storage, and improve batch stability and shelf life.

[0022] Preferably, the composition is a halogen-free system, with a single halogen element content ≤900ppm and a total halogen content ≤1500ppm, conforming to IPC J-STD-004B and RoHS environmental standards; under lead-free reflow soldering conditions at 260℃, the solder joint void rate is ≤2%; the static corrosion rate on copper pads is ≤0.1μm / h; and the surface insulation resistance is ≥10 Ω·cm. 14 Ω, can pass the reliability test of 1000h high humidity aging at 85℃ / 85%RH.

[0023] The present invention also provides a method for preparing the above-mentioned flux composition for semiconductors, comprising the following steps: Step S1. Weigh the high-boiling-point composite solvent according to the ratio and add it to the reaction vessel. Heat the mixture to 40-60℃ and control the stirring speed at 80-150 rpm. Step S2. Add the film-forming agent to the reactor, maintain the temperature and speed, and stir for 30-60 minutes until the film-forming agent is completely dissolved to obtain a homogeneous resin base liquid; Step S3. Cool down to 30-45℃, add the composite activation system and composite functional additives to the resin base liquid, maintain the stirring speed for 40-90 minutes until all components are completely dissolved to obtain a mixture; Step S4. The mixture is filtered through a 0.22μm precision filter to remove insoluble impurities, thereby obtaining the flux composition for semiconductors.

[0024] Preferably, steps S1-S3 are carried out under a nitrogen protective atmosphere, and the moisture content of the preparation system is controlled below 500 ppm to avoid the influence of moisture on the performance of the composition and ensure storage stability.

[0025] The beneficial effects of this invention are: This invention provides a flux composition for semiconductors and a method for preparing the same. Compared with the prior art, this invention has the following significant advantages: 1. Halogen-free and environmentally friendly with excellent compliance: This invention adopts a completely halogen-free formula system with a single halogen element content of ≤900ppm and a total halogen content of ≤1500ppm, which fully complies with international environmental and industry standards such as RoHS, REACH, and IPC J-STD-004B. There is no risk of ion residue, which is suitable for the environmental protection requirements of high-end semiconductor packaging.

[0026] 2. Gradient activation, resolving the core contradiction between activity and corrosion: The gradient temperature-responsive composite activation system pioneered in this invention achieves low corrosion and high storage stability at room temperature, and rapid and efficient release of activity at high reflow temperature. It can completely remove the oxide layer of various pads such as copper, nickel-palladium-gold, and UBM layers. At the same time, the static corrosion rate of the metal substrate is ≤0.1μm / h, which is far lower than the industry average. This fundamentally solves the problem of "high activity leads to high corrosion, and low corrosion leads to insufficient activity" in halogen-free fluxes.

[0027] 3. Adaptable to advanced packaging processes with ultra-fine pitch: This invention, through the synergistic regulation of film-forming agents and thixotropic agents, possesses excellent rheological properties and can adapt to ultra-fine bump pitches below 30μm. There is no collapse, no oil seepage, and no bridging during coating processes such as stencil printing and dip printing. Combined with the superior wetting properties of compound surfactants, the solder joint failure rate is reduced to below 0.1%, significantly improving the process yield of advanced packaging.

[0028] 4. Low void ratio and high soldering reliability: The high-boiling-point composite solvent system of this invention has a evaporation rate that perfectly matches the reflow temperature curve of lead-free solder. There is no preheating boiling or excessive volatilization at high temperature, which can effectively reduce the formation of pores in the solder joint. The void ratio of the solder joint is ≤2%, which is far lower than the requirement of ≤5% for automotive-grade semiconductors, ensuring the mechanical strength and electrical stability of the interconnect solder joint.

[0029] 5. Controllable residue and excellent long-term insulation reliability: The film-forming system of this invention achieves bidirectional compatibility with both no-wash and washable applications. In no-wash scenarios, a non-hygroscopic, dense insulating film is formed after welding, with a surface insulation resistance ≥10 Ω·cm. 14 Ω can pass the 1000h high humidity aging test at 85℃ / 85%RH without electromigration or leakage failure; in water washing scenarios, it can be 100% cleaned with room temperature deionized water without residue, avoiding damage to the wafer micro-nano structure caused by high temperature cleaning.

[0030] 6. Simple preparation process and strong industrial adaptability: The preparation method of this invention is carried out at low temperature and low pressure throughout the process, with no high temperature reaction and no pollutant emission. The process steps are simple and controllable, with excellent batch stability. It can be directly adapted to existing flux industrial production lines without the need for additional equipment, and has extremely high industrial application value. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0032] The raw materials used in the embodiments and comparative examples of this invention are all commercially available industrial-grade electronic packaging raw materials that meet semiconductor-grade purity requirements.

[0033] Example 1: A flux composition for semiconductors, by weight, has the following formulation: Film-forming agent: 15 parts (12 parts maleic acid-modified hydrogenated rosin, softening point 140℃; 3 parts water-soluble acrylic resin); Composite activation system: 6 parts (3.5 parts sebacic acid, 1.5 parts citric acid, 1 part 2-ethyl-4-methylimidazolium, mass ratio 3.5:1.5:1); High-boiling-point composite solvent: 76 parts (68 parts diethylene glycol hexyl ether, 8 parts diethylene glycol butyl ether, mass ratio 8.5:1); Composite functional additive: 3 parts (0.5 parts methylbenzotriazole, 0.3 parts imidazoline quaternary ammonium salt, 0.2 parts fluorinated nonionic surfactant, 0.5 parts polyoxyethylene lauryl ether, 1 part fumed silica, 0.5 parts hindered phenolic antioxidant).

[0034] A method for preparing a flux composition for semiconductors includes the following steps: S1. Weigh the high-boiling-point composite solvent according to the ratio and add it to the sealed reaction vessel. Probe nitrogen gas throughout the process, heat to 50°C, control the stirring speed at 100 rpm, and control the moisture content of the system to below 300 ppm. S2. Add film-forming agent to the reactor, maintain temperature and speed, stir for 45 minutes until film-forming agent is completely dissolved, and obtain a uniform and transparent resin base liquid; S3. Cool down to 40℃, add the composite activation system and composite functional additives to the resin base liquid, maintain the stirring speed for 60 minutes until all components are completely dissolved to obtain a homogeneous mixture; S4. Filter the mixture twice through a 0.22μm precision filter to remove trace amounts of insoluble impurities, and obtain the semiconductor flux composition, denoted as S1.

[0035] Example 2: A flux composition for semiconductors, by weight, has the following formulation: Film-forming agent: 10 parts (8 parts polymeric rosin, softening point 130℃; 2 parts polyethylene glycol 400); Composite activation system: 4 parts (2.4 parts azelaic acid, 1 part malic acid, 0.6 parts triethanolamine, mass ratio 4:1.67:1); High-boiling-point composite solvent: 84.5 parts (77 parts propylene glycol diphenyl ether, 7.5 parts propylene glycol methyl ether acetate, mass ratio 10.3:1); Composite functional additive: 1.5 parts (0.2 parts mercaptobenzothiazole, 0.2 parts methylbenzotriazole, 0.2 parts fluorinated nonionic surfactant, 0.4 parts polyoxyethylene octylphenol ether, 0.3 parts hydrogenated castor oil, 0.2 parts antioxidant).

[0036] The preparation method is the same as in Example 1, and the resulting flux composition is denoted as S2.

[0037] Example 3: A flux composition for semiconductors, by weight, has the following formulation: Film-forming agent: 20 parts (17 parts phenolic modified rosin, softening point 150℃; 3 parts polyvinylpyrrolidone); Composite activation system: 8 parts (4.8 parts dodecanoic acid, 2 parts tartaric acid, 1.2 parts dimethylethanolamine, mass ratio 4:1.67:1); High-boiling-point composite solvent: 69 parts (62 parts diethylene glycol dibutyl ether, 7 parts isopentyl glycol, mass ratio 8.9:1); Composite functional additive: 3 parts (0.6 parts methylbenzotriazole, 0.4 parts imidazoline quaternary ammonium salt, 0.3 parts fluorinated nonionic surfactant, 0.7 parts polyoxyethylene stearate, 0.8 parts polyamide wax, 0.2 parts antioxidant).

[0038] The preparation method is the same as in Example 1, and the resulting flux composition is designated as S3.

[0039] Example 4: A flux composition for semiconductors, by weight, has the following formulation: Film-forming agent: 5 parts (4 parts hydrogenated rosin methyl ester, softening point 125℃; 1 part water-soluble acrylic resin); Composite activation system: 2 parts (1.2 parts tetradecanoic acid, 0.5 parts dimethylolpropionic acid, 0.3 parts 2-methylimidazole, mass ratio 4:1.67:1); High-boiling-point composite solvent: 90 parts (82 parts dodecyl alcohol ester, 2008 parts polyethylene glycol, mass ratio 10.25:1); Composite functional additive: 3 parts (0.1 parts methylbenzotriazole, 0.1 parts fluorinated nonionic surfactant, 0.3 parts polyoxyethylene lauryl ether, 0.1 parts antioxidant).

[0040] The preparation method is the same as in Example 1, and the resulting flux composition is designated as S4.

[0041] Example 5: A flux composition for semiconductors, by weight, has the following formulation: Film-forming agent: 25 parts (maleic acid-modified hydrogenated rosin 22 parts, softening point 160℃; polyethylene glycol 400 3 parts); Composite activation system: 12 parts (sebacic acid 6 parts, citric acid 3 parts, 2-ethyl-4-methylimidazolium 3 parts, mass ratio 2:1:1); High-boiling-point composite solvent: 60 parts (diethylene glycol hexyl ether 54 parts, diethylene glycol butyl ether 6 parts, mass ratio 9:1); Composite functional additive: 3 parts (methylbenzotriazole 0.8 parts, imidazoline quaternary ammonium salt 0.7 parts, fluorinated nonionic surfactant 0.3 parts, polyoxyethylene lauryl ether 0.7 parts, fumed silica 0.3 parts, antioxidant 0.2 parts).

[0042] The preparation method is the same as in Example 1, and the resulting flux composition is designated as S5.

[0043] Comparative Example 1: A commercially available brand of halogen-free flux for semiconductor packaging is designated as D1.

[0044] Comparative Example 2: A flux composition with a formulation essentially the same as in Example 1, differing only in that the composite activation system uses only sebacic acid as a single organic acid, in an amount of 6 parts, without the addition of citric acid and 2-ethyl-4-methylimidazole. The preparation method is the same as in Example 1, and the resulting flux composition is designated as D2.

[0045] Comparative Example 3: A flux composition with a formulation essentially the same as in Example 1, except that no metal corrosion inhibitor is added, while the amounts of the remaining components remain unchanged. The preparation method is the same as in Example 1, and the resulting flux composition is designated as D3.

[0046] Comparative Example 4: A flux composition with a formulation essentially the same as in Example 1, differing only in that: the high-boiling-point composite solvent uses only diethylene glycol butyl ether as a single solvent, in an amount of 76 parts, without compounding the main solvent and co-solvent. The preparation method is the same as in Example 1, and the resulting flux composition is designated D4.

[0047] Performance testing: The flux compositions of Examples 1-5 and Comparative Examples 1-4 were subjected to performance tests according to IPC J-STD-004B and GB / T9491-2021 standards. The test items and results are shown in Table 1 below: Table 1 Performance test results of Examples 1-3 Table 2 Performance test results of Examples 4-5 and Comparative Example 1 Table 3 Performance test results of Comparative Examples 2-4 Data Analysis: The test results show that: The flux compositions of Examples 1-5 of this invention are all halogen-free systems with halogen content far below the standard limit and wetting time far shorter than that of the comparative examples, indicating that they have excellent deoxidation activity and wetting performance. The corrosion rate of the copper pads in the embodiments is ≤0.1μm / h, which is much lower than that of the commercially available comparative example 1. However, the corrosion rate of comparative example 2 (single activation system) is increased, and the corrosion rate of comparative example 3 (without corrosion inhibitor) is significantly increased. This shows that the gradient activation system and composite corrosion inhibitor of the present invention synergistically achieve a balance between high activity and low corrosion. The void rate of the solder joints in the embodiments was ≤2%, which was much lower than that in Comparative Example 1 and Comparative Example 4 (single solvent), indicating that the composite solvent system of the present invention can effectively reduce the void rate of solder joints and improve welding reliability. The surface insulation resistance of all embodiments is ≥10 Ω. 14 Ω, still maintains 10 after 1000 hours of high humidity aging. 13 The insulation resistance is above Ω, while the insulation resistance of Comparative Examples 1 and 3 decreased significantly after aging, indicating a risk of electromigration. This shows that the composition of the present invention has excellent long-term insulation reliability. The example showed a bridging rate of 0 in the 30μm ultra-fine pitch test, which was far better than the comparative example, indicating that it can be perfectly adapted to the ultra-fine pitch interconnect process of advanced packaging. The composition in the examples can be completely cleaned with room temperature deionized water without residue, making it suitable for water-washable packaging scenarios.

[0048] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0049] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A flux composition for semiconductors, characterized in that, By weight, it includes the following components: 5-25 parts film-forming agent, 2-12 parts composite activation system, 60-90 parts high-boiling-point composite solvent, and 0.1-5 parts composite functional additive; The composite activation system is a gradient temperature-responsive halogen-free activation system, which is composed of long-chain dibasic organic acids, hydroxyl-containing polybasic organic acids, and organic amine activators in a mass ratio of 3-6:1-3:1-2.

2. The flux composition for semiconductors according to claim 1, characterized in that, The long-chain dicarboxylic organic acid is one or more of azelaic acid, sebacic acid, dodecanoic acid, and tetradecanoic acid; The hydroxyl-containing polybasic organic acid is one or more of citric acid, malic acid, tartaric acid, and dimethylolpropionic acid; The organic amine activator is one or more of triethanolamine, dimethylethanolamine, 2-methylimidazole, 2-ethyl-4-methylimidazole, and benzimidazole.

3. The flux composition for semiconductors according to claim 1, characterized in that, The film-forming agent is a mixture of modified hydrogenated rosin resin and water-soluble film-forming resin in a mass ratio of 4-8:

1. The modified hydrogenated rosin resin is one or more of hydrogenated rosin methyl ester, polymerized rosin, maleic acid modified rosin, and phenolic modified rosin, and its softening point is 120-160℃. The water-soluble film-forming resin is one or more of water-soluble acrylic resin, polyethylene glycol, and polyvinylpyrrolidone.

4. The flux composition for semiconductors according to claim 1, characterized in that, The high-boiling-point composite solvent is prepared by compounding a main solvent and a co-solvent in a mass ratio of 5-10:1; The main solvent has a normal boiling point of 200-280℃, and the co-solvent has a normal boiling point of 180-220℃.

5. The flux composition for semiconductors according to claim 4, characterized in that, The main solvent is one or more of diethylene glycol hexyl ether, diethylene glycol dibutyl ether, propylene glycol diphenyl ether, dodecyl alcohol ester, and diethylene glycol monobutyl ether acetate; The co-solvent is one or more of diethylene glycol butyl ether, propylene glycol methyl ether acetate, polyethylene glycol 200, and isopentyl glycol.

6. The flux composition for semiconductors according to claim 1, characterized in that, The composite functional additive includes at least two of the following: metal corrosion inhibitors, nonionic surfactants, thixotropic agents, and antioxidants.

7. The flux composition for semiconductors according to claim 6, characterized in that, By weight, the composite functional additive comprises: 0.05-1 part of metal corrosion inhibitor, 0.05-1 part of nonionic surfactant, 0.3-1 part of thixotropic agent, and 0.1-0.5 part of antioxidant; The metal corrosion inhibitor is a combination of two or more of the following: methylbenzotriazole, mercaptobenzothiazole, and imidazoline quaternary ammonium salt corrosion inhibitors. The nonionic surfactant is a compound of a fluorinated nonionic surfactant and a polyoxyethylene ether nonionic surfactant in a mass ratio of 1:2-5.

8. The flux composition for semiconductors according to claim 1, characterized in that, The composition is a halogen-free system, with a single halogen element content ≤900ppm and a total halogen content ≤1500ppm; under lead-free reflow soldering conditions at 260℃, the solder joint void rate is ≤2%; the static corrosion rate on copper pads is ≤0.1μm / h; and the surface insulation resistance is ≥10 Ω·cm. 14 Ω.

9. A method for preparing a semiconductor flux composition according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1. Weigh the high-boiling-point composite solvent according to the ratio and add it to the reaction vessel. Heat the mixture to 40-60℃ and control the stirring speed at 80-150 rpm. Step S2. Add the film-forming agent to the reactor, maintain the temperature and speed, and stir for 30-60 minutes until the film-forming agent is completely dissolved to obtain a homogeneous resin base liquid; Step S3. Cool down to 30-45℃, add the composite activation system and composite functional additives to the resin base liquid, maintain the stirring speed for 40-90 minutes until all components are completely dissolved to obtain a mixture; Step S4. The mixture is filtered through a 0.22μm precision filter to remove insoluble impurities, thereby obtaining the flux composition for semiconductors.

10. The preparation method according to claim 9, characterized in that, Steps S1 through S3 were carried out under a nitrogen protective atmosphere, and the moisture content of the preparation system was controlled below 500 ppm.

Images