Silver colloid diffusion preventing agent as well as preparation method and application thereof

Abstract

The invention discloses a silver colloid diffusion preventing agent as well as a preparation method and application thereof. Wherein the elargol diffusion preventing agent comprises the following components in mass concentration: 100 to 500 mg / l of alkyl alkoxy silane, 50 to 250 mg / l of a first emulsifier, 50 to 250 mg / l of a second emulsifier, 5 to 10 mg / l of a cationic surfactant, a pH buffer solution and the balance of water; the cationic surfactant is polyhydroxy short-chain fluorine-containing quaternary ammonium salt, the first emulsifier is hydrophilic polyether silicone oil, and the second emulsifier is long-carbon-chain fatty acid polyoxyethylene. The elargol diffusion preventing agent prepared by the preparation method provided by the invention can effectively prevent diffusion of elargol, also has relatively high stability, and can be compatible and applicable to elargol diffusion preventing application of substrate boards made of different materials.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and in particular to a silver glue diffusion preventing agent, a preparation method and an application thereof. Background Art

[0002] Conductive silver glue is mainly made of resin, silver powder and additives. Because it combines adhesion, excellent conductivity and chemical stability, it is widely used in the field of semiconductor packaging.

[0003] When conductive silver glue is applied to the surface of a solid substrate such as a lead frame or a carrier, the organic components in the conductive silver glue can easily migrate along the surface of the substrate due to the high surface roughness of the substrate or contamination of the surface by other additives, protective agents or other organic matter. This can cause the glue to seep out and cause silver glue diffusion problems. When the diffusion phenomenon is severe, it not only affects the reliability of the bonding area, but is also likely to cause short circuits in the subsequent wire bonding process.

[0004] Not only is the diffusion problem of conductive silver paste prone to occur during traditional lead frame packaging (such as QFN / DFN), but with the development of packaging technology, substrate packaging (such as FCCSP, FCBGA, etc.) faces more severe challenges. For example, silver paste can easily penetrate the microporous structure on the substrate, resulting in abnormal impedance of adjacent conductive holes.

[0005] Silver paste diffusion inhibitors are key materials developed to address these issues. For example, Chinese patent CN114773989A proposes a diffusion inhibitor containing a benzyl group. This silver paste diffusion inhibitor effectively prevents the diffusion of conductive silver paste while also exhibiting corrosion resistance, improving the corrosion resistance of the silver-plated layer. For example, Chinese patent CN115895437A proposes a silver paste diffusion inhibitor composed of 300-350 mg / L Silquest A-187, 200-250 mg / L polyether-modified silica, 50-100 mg / L tetramethylammonium bromide, and 10-20 mg / L carbonyl heterocyclic compound. The resulting hydrophobic film prevents the leakage of conductive silver paste. Chinese patent CN118772785A discloses a method for preparing a hyperbranched polymer, a key component of a silver paste diffusion inhibitor, which inhibits the leakage of conductive silver paste. For example, Liu Yue et al. (Liu Yue, Ding Yunhu, Tao Ming, et al. Preparation and properties of silane-type anti-silver glue diffusion agent [J]. Materials Protection, 2018, 51(04): 80-83) proposed to use silane coupling agent KH-550 as the main film-forming agent to develop an anti-silver glue diffusion agent, which greatly improved the contact angle of the silver-plated layer, thereby preventing the diffusion of silver glue.

[0006] However, existing anti-silver glue diffusion agents still have some problems. For example, their components are complex and their stability is poor. They are easy to fail during high-temperature curing and are not compatible with high-precision dispensing processes. In addition, existing anti-silver glue diffusion agents are generally only suitable for substrate surfaces of a single material and are not compatible with substrate surfaces of heterogeneous materials with large differences in surface energy, such as ceramic substrates, BT resin substrates, etc. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a preparation method of an anti-silver glue diffusion agent. The preparation method is used to prepare an anti-silver glue diffusion agent, which can effectively prevent the diffusion of silver glue, while also having high stability and being compatible with anti-silver glue diffusion applications on substrates of different materials.

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

[0009] A silver glue diffusion preventing agent, characterized in that it comprises, by mass concentration, 100-500 mg / l alkyl alkoxy silane, 50-250 mg / l first emulsifier, 50-250 mg / l second emulsifier, 5-10 mg / l cationic surfactant, pH buffer solution and the balance solvent water;

[0010] The cationic surfactant is a polyhydroxy short-chain fluorine-containing quaternary ammonium salt, and its structure is shown in the chemical formula (I):

[0011] The general chemical formula (I) is

[0012] Among them, R F C6F 13 、C8F 17 ;

[0013] The first emulsifier is hydrophilic polyether silicone oil, and the second emulsifier is long carbon chain fatty acid polyoxyethylene.

[0014] The alkyl alkoxysilane in the anti-silver glue diffusion agent of the present invention forms a silicon film with a three-dimensional silicon-oxygen network structure on the substrate surface through a hydrolysis-condensation reaction, forming a basic hydrophobic film layer and a physical barrier, thereby improving the ability to prevent silver glue diffusion to a certain extent. However, when a single alkyl alkoxysilane is hydrolyzed to form a film on the substrate surface, due to the uneven hydrolysis and condensation rate, it is easy to cause micropore defects in the film layer. This makes the conductive silver glue have insufficient adhesion to the substrate surface with a large difference in polarity, resulting in its limited ability to prevent silver glue diffusion. It is even more incompatible with forming a film on substrate surfaces of different materials to achieve the purpose of preventing silver glue diffusion. Therefore, a small amount of polyhydroxy short-chain fluorine-containing quaternary ammonium salt is added to the anti-silver glue diffusion agent system of the present invention to improve and adjust it.

[0015] The fluorocarbon chains in the polyhydroxy short-chain fluorine-containing quaternary ammonium salt synergistically act with the long carbon chain alkyl groups in the alkyl alkoxy groups to form a dense monomolecular layer on the surface of the silicon film through self-assembly, and form a dense and uniform composite hydrophobic film layer on the substrate board surface, fundamentally ensuring the anti-diffusion performance of the anti-silver glue diffusion agent of the present invention; further, the charge effect of the quaternary ammonium groups in the polyhydroxy short-chain fluorine-containing quaternary ammonium salt not only gives the anti-silver glue diffusion agent system an antibacterial and anti-corrosion function, but also, in a weakly acidic environment, the protonation degree of the quaternary ammonium groups is increased, and they are preferentially adsorbed on the charged substrate board surface or droplet surface through electrostatic action, thereby enhancing the compactness of the above-mentioned film layer or interacting with the conductive silver glue system through charge action, which is further beneficial to the anti-diffusion performance of the present invention; in addition, the polyhydroxy structure in the polyhydroxy short-chain fluorine-containing quaternary ammonium salt can coordinate with the oxide on the metal surface to form a passivation layer, thereby playing a metal protection role.

[0016] Furthermore, the structure of the alkylalkoxysilane is shown in the chemical formula (II):

[0017] The general chemical formula (II) is R1-Si(OR')3,

[0018] wherein R1 is an alkyl group having 12 to 18 carbon atoms; and R' is an alkyl group having 1 to 4 carbon atoms.

[0019] Furthermore, the alkylalkoxysilane includes at least one of dodecyltrimethoxysilane, hexadecyltriethoxysilane, and octadecyltrimethoxysilane.

[0020] Furthermore, the hydrophilic polyether silicone oil includes one or more of Dow Corning water-based silicone oil, JP-204 polyether-modified silicone oil, and DM-204 polyether-modified silicone oil.

[0021] Furthermore, the structure of the long carbon chain fatty acid polyoxyethylene is shown in the chemical formula (III):

[0022] The general chemical formula (III) is R2COO-(CH2CH2O) n -H,

[0023] Wherein, R2 is an alkyl group having 12 to 18 carbon atoms; n is an integer from 2 to 20.

[0024] Furthermore, the long carbon chain fatty acid polyoxyethylene includes one or more of polyoxyethylene laurate, polyoxyethylene oleate, and polyoxyethylene stearate.

[0025] Furthermore, the mass concentration ratio of the alkylalkoxysilane, the first emulsifier and the second emulsifier is (1-2):1:1.

[0026] The hydrophilic polyether silicone oil and the long-chain fatty acid polyoxyethylene together constitute the composite emulsification system of the present invention. Combined with the preparation method of the anti-silver colloid diffusion agent provided by the present invention, the anti-silver colloid diffusion agent system of the present invention forms a stable nanoscale microemulsion state, further ensuring the stability of its anti-silver colloid diffusion performance.

[0027] Furthermore, the mass concentration ratio of the alkylalkoxysilane to the cationic surfactant is (10-50):1.

[0028] Furthermore, the pH buffer is an organic acid buffer, which is used to adjust the pH of the silver colloid diffusion preventing agent to 6-6.5.

[0029] The present invention uses acetic acid and sodium acetate buffer to adjust the silver colloid diffusion preventing agent of the present invention to be in a weakly acidic environment. On the one hand, it is beneficial to control the hydrolysis and condensation rate of the alkyl alkoxysilane, so as to avoid the micropore defects in the film layer formed by the alkyl alkoxysilane caused by excessively rapid cross-linking, and also prevent the film layer from being discontinuous due to excessively slow cross-linking. On the other hand, in the weakly acidic environment, it can prevent the quaternary ammonium groups in the polyhydroxy short-chain fluorine-containing quaternary ammonium salt from agglomerating, thereby further ensuring the uniformity and stability of the composite film formed by the polyhydroxy short-chain fluorine-containing quaternary ammonium salt and the alkyl alkoxysilane.

[0030] The present invention also provides a method for preparing a silver glue diffusion preventing agent, which is characterized by comprising the following steps:

[0031] S1 material mixing

[0032] The alkylalkoxysilane, the first emulsifier, the second emulsifier and the cationic surfactant are mixed in predetermined amounts and stirred to obtain a milky white mixture;

[0033] S2 Primary Hydration Treatment

[0034] Pure water was added to the milky mixture in two stages, specifically comprising:

[0035] 1. In the first stage, add 5-10% of the total amount of pure water and stir at a high speed of 2000-3000 rpm until a transparent foam layer is formed in the mixture;

[0036] 2. In the second stage, 5-10% of the total amount of pure water is added, and shear stirring is carried out at a speed of 800-1200 rpm until a translucent milky first pre-dispersion is formed;

[0037] S3 system composite

[0038] Pour the translucent milky pre-dispersion into the remaining amount of pure water and stir evenly to obtain a second dispersion;

[0039] S4 post-processing

[0040] The pH of the second dispersion is adjusted to 6-6.5 by using the pH buffer solution to obtain the silver colloid diffusion preventing agent.

[0041] The application of the anti-silver glue diffusion agent of the present invention comprises the following steps:

[0042] Dissolve a certain amount of anti-silver glue diffusion agent in water and stir evenly to form an anti-silver glue diffusion liquid, wherein the anti-silver glue diffusion agent accounts for 3-5% of the total volume of the liquid;

[0043] The substrate surface is sequentially pickled and washed with water;

[0044] The surface of the substrate is immersed in the anti-silver glue diffusion liquid for 30-60 seconds, and the working temperature of the anti-silver glue diffusion liquid is 25-30°C.

[0045] The beneficial technical effects of the present invention are:

[0046] 1. The silver colloid diffusion prevention agent provided by the present invention comprises an alkyl alkoxysilane, a hydrophilic polyether silicone oil, a long carbon chain fatty acid polyoxyethylene, and a polyhydroxy short chain fluorine-containing quaternary ammonium salt, and the pH buffer is used to adjust the diffusion agent system to a weak acidity. The components of the present invention work synergistically to form a nanometer-scale, uniform, and dense hydrophobic film on the substrate surface, which has good silver colloid diffusion prevention performance and can be applied to substrate surfaces of different materials. In addition, quaternary ammonium groups are introduced into the hydrophobic film, which not only increases the density of the hydrophobic film, but also enhances the interaction between the hydrophobic film and the conductive silver colloid through the charge effect, further enhancing the silver colloid diffusion prevention ability.

[0047] 2. The hydrophilic polyether silicone oil and long carbon chain fatty acid polyoxyethylene of the present invention form a composite emulsion system, which is compounded with the preparation method of the anti-silver glue diffusion agent provided by the present invention, so that the anti-silver glue diffusion agent system of the present invention is a stable nano-scale microemulsion dispersion system, which provides a strong guarantee for forming a nano-scale, uniform and dense hydrophobic film on the surface of substrates of different materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 (a) is a photo of the conductive silver glue layer on the gold surface after the dispensing step in Example 1 is completed;

[0049] Figure 1 (b) shows the conductive silver glue layer after the dispensing step on the gold surface in Example 1 was completed and left at room temperature for 5 minutes;

[0050] Figure 1 (c) is a photo of the conductive silver glue layer after dispensing and curing on the gold surface in Example 1;

[0051] Figure 2 (a) is a photo of the conductive silver glue layer on the gold surface just after the glue dispensing step in Comparative Example 1;

[0052] Figure 2 (b) shows the conductive silver glue layer after the dispensing step on the gold surface in Comparative Example 1 was completed and left at room temperature for 5 minutes;

[0053] Figure 2 (c) is a photo of the conductive silver glue layer after dispensing and curing on the gold surface in Comparative Example 1;

[0054] Figure 3 (a) is a photo of the conductive silver glue layer on the gold surface just after the glue dispensing step in Comparative Example 2;

[0055] Figure 3 (b) shows the conductive silver glue layer after the dispensing step on the gold surface in Comparative Example 2 was completed and left at room temperature for 5 minutes;

[0056] Figure 3 (c) is a photo of the conductive silver glue layer after dispensing and curing on the gold surface in comparative example 2;

[0057] Figure 4 (a) is a photo of the conductive silver glue layer on the gold surface just after the glue dispensing step in Comparative Example 3;

[0058] Figure 4 (b) shows the conductive silver glue layer after the dispensing step on the gold surface in Comparative Example 3 was completed and left at room temperature for 5 minutes;

[0059] Figure 4 (c) is a photo of the conductive silver glue layer after dispensing and curing on the gold surface in comparative example 3;

[0060] Figure 5 (a) is the appearance diagram of Example 1;

[0061] Figure 5 (b) is the appearance diagram of Comparative Example 3;

[0062] Figure 5 (c) is the appearance diagram of Comparative Example 7. DETAILED DESCRIPTION

[0063] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0064] Unless otherwise specified, the materials and reagents used in the present invention can be obtained from commercial sources.

[0065] The present invention provides a silver glue diffusion preventing agent, which comprises, per liter of aqueous solution, 100 to 500 mg / l of alkyl alkoxysilane, 50 to 250 mg / l of a first emulsifier, 50 to 250 mg / l of a second emulsifier, 5 to 10 mg / l of a cationic surfactant, a pH buffer solution, and the balance of solvent water;

[0066] The mass concentration ratio of the alkyl alkoxy silane, the first emulsifier and the second emulsifier is (1-2):1:1, and the mass concentration ratio of the alkyl alkoxy silane and the cationic surfactant is (10-50):1.

[0067] In the present invention:

[0068] Cationic surfactants are polyhydroxy short-chain fluorine-containing quaternary ammonium salts, and their structure is shown in the chemical formula (I):

[0069] The general chemical formula (I) is

[0070] Among them, R F C6F 13 or C8F 17 ; It was prepared by the method described in Ayari, Abdelhamid et al. "PerfluoroalkylEpoxides: Synthesis and Conversion into Ionic Surfactants." Mediterranean Journal of Chemistry 2 (2012): 374-381.

[0071] The structure of alkylalkoxysilane is shown in the chemical formula (II):

[0072] The general chemical formula (II) is R1-Si(OR')3,

[0073] Wherein R1 is an alkyl group having 12 to 18 carbon atoms; R' is an alkyl group having 1 to 4 carbon atoms; preferably, the alkyl alkoxysilane is at least one of dodecyltrimethoxysilane, hexadecyltriethoxysilane, and octadecyltrimethoxysilane.

[0074] The first emulsifier is a hydrophilic polyether silicone oil, preferably Dow Corning water-based silicone oil (DC-193, Dow Corning).

[0075] The second emulsifier is a long carbon chain fatty acid polyoxyethylene, and its structure is shown in the chemical formula (III):

[0076] The general chemical formula (III) is R2COO-(CH2CH2O)nH,

[0077] Wherein, R2 is an alkyl group having 12 to 18 carbon atoms; n is an integer between 2 and 20; preferably, the long-chain fatty acid polyoxyethylene includes one or more of polyoxyethylene laurate, polyoxyethylene oleate, and polyoxyethylene stearate.

[0078] The pH buffer is an organic acid buffer, preferably an acetic acid and sodium acetate buffer, which is used to adjust the pH of the silver colloid diffusion preventing agent to 6-6.5.

[0079] The components and amounts used in the preparation of the silver glue diffusion preventing agent provided by Examples 1-8 are shown in Table 1; the components and amounts used in the preparation of the silver glue diffusion preventing agent provided by Comparative Examples 1-9 are shown in Table 2.

[0080] Table 1. Components and dosages of the anti-silver glue diffusion agents in Examples 1-8

[0081]

[0082]

[0083] Table 2. Components and dosages of the silver glue diffusion-proof agents in Comparative Examples 1-9

[0084]

[0085] The preparation method of the anti-silver glue diffusion agent of Example 1-8 comprises the following steps:

[0086] S1 material mixing

[0087] The alkylalkoxysilane, the first emulsifier, the second emulsifier and the cationic surfactant in the embodiment are mixed in predetermined amounts and stirred to obtain a milky white mixture;

[0088] S2 Primary Hydration Treatment

[0089] Pure water was added to the milky mixture in two stages, specifically comprising:

[0090] 1. In the first stage, add 10% of the total amount of pure water and stir at 3000 rpm until a transparent foam layer is formed in the mixture;

[0091] 2. In the second stage, 10% of the total amount of pure water is added and shear stirring is continued at 1200 rpm until a translucent milky first pre-dispersion is formed;

[0092] S3 system composite

[0093] Pour the first pre-dispersion into the remaining amount of pure water at a uniform speed and stir evenly to obtain a second dispersion;

[0094] S4 post-processing

[0095] The pH of the second dispersion is adjusted to 6 by using the pH buffer solution, thereby preparing the anti-silver colloid diffusion agent in the form of a transparent blue light microemulsion.

[0096] Example 9

[0097] The components and amounts used in the preparation of the silver paste diffusion preventing agent of Example 9 are the same as those of Example 1, but the preparation method thereof is different from that of the example. The specific preparation method comprises the following steps:

[0098] S1 material mixing

[0099] The alkylalkoxysilane, the first emulsifier, the second emulsifier and the cationic surfactant are mixed in predetermined amounts and stirred to obtain a milky white mixture;

[0100] S2 Primary Hydration Treatment

[0101] Pure water was added to the milky mixture in two stages, specifically comprising:

[0102] 1. In the first stage, add 5% of the total amount of pure water and stir at a high speed of 2000 rpm until a transparent foam layer is formed in the mixture;

[0103] 2. In the second stage, 5% of the total amount of pure water is added and shear stirring is continued at 800 rpm until a translucent milky first pre-dispersion is formed;

[0104] S3 system composite

[0105] Pour the translucent milky pre-dispersion into the remaining amount of pure water and stir evenly to obtain a second dispersion;

[0106] S4 post-processing

[0107] The pH of the second dispersion was adjusted to 6.5 using the pH buffer solution (acetic acid / sodium acetate), thereby obtaining the transparent blue-light microemulsion-like anti-silver colloid diffusion agent of Example 9.

[0108] Preparation of Anti-Silver Glue Diffusion Agents of Comparative Examples 1-9

[0109] The preparation methods of the silver paste diffusion preventing agents of Comparative Examples 1-9 differ from the preparation method of Example 1 only in that in the S1 material mixing step, the components and their amounts are different, and the rest are the same and will not be repeated here.

[0110] Comparative Example 10

[0111] The components and amounts used in the preparation of the silver paste diffusion preventing agent in Comparative Example 10 are the same as those in Example 1, but the preparation method thereof is different from that in Example 1. The specific preparation method comprises the following steps:

[0112] S1 material mixing

[0113] The alkylalkoxysilane, the first emulsifier, the second emulsifier and the cationic surfactant in Comparative Example 10 are mixed in predetermined amounts and stirred to obtain a first mixture;

[0114] S2 Primary Hydration Treatment

[0115] 20% of the total amount of pure water was added to the first mixture, and the mixture was sheared and stirred at 3000 rpm to form a first pre-dispersion of the comparative example;

[0116] S3 system composite

[0117] The first pre-dispersion of the comparative example was poured into the remaining amount of pure water at a uniform speed and stirred evenly to obtain the second dispersion of the comparative example;

[0118] S4 post-processing

[0119] The pH buffer solution was used to adjust the pH of the second dispersion of the comparative example to 6, thereby preparing the silver colloid diffusion preventing agent of the comparative example.

[0120] The application method of the anti-silver glue diffusion agent of Examples 1-9 and Comparative Examples 1-10 comprises the following steps:

[0121] Dilution of anti-silver glue diffusion agent:

[0122] A certain amount of anti-silver glue diffusion agent is dissolved in water and stirred evenly to form an anti-silver glue diffusion liquid, wherein the volume percentage of the anti-silver glue diffusion agent is 3-5% of the total volume. The volume percentage of the anti-silver glue diffusion agent in the anti-silver glue diffusion liquids of Examples 1-9 and Comparative Examples 1-10 is 5%;

[0123] Substrate surface pretreatment:

[0124] Use 5% dilute sulfuric acid aqueous solution to clean the substrate surface. Pickling can remove surface oxides. At room temperature, the pickling time is 10 seconds. After the pickling is completed, the substrate surface is washed with deionized water for 10 seconds.

[0125] The acid-washed and water-washed substrate is immersed in a silver glue diffusion-proof liquid for 60 seconds. The silver glue diffusion-proof liquid can be used at a temperature of 25-30° C. In the present invention, the silver glue diffusion-proof liquid is used at a temperature of 25° C.

[0126] The test items involved in the present invention include:

[0127] 1. Preparation of substrate surface

[0128] The substrate surface of the present invention includes three materials: copper surface, gold surface and prepreg, and the size of the substrate surface is 4cm×2.5cm.

[0129] 2. Appearance of anti-silver glue diffusion agent

[0130] Visually inspect the color and transparency of the anti-silver glue diffusion agent.

[0131] 3. Anti-silver glue diffusion agent stability test

[0132] The anti-silver glue diffusing agent was placed in a centrifuge tube and then placed in a high-speed centrifuge. The tube was centrifuged at a speed of 3000 r / min for 30 minutes. The stratification of the anti-silver glue diffusing agent was then recorded. If stratification occurred, it was recorded as unstable. If no stratification occurred, it was recorded as stable.

[0133] 4. Anti-silver glue diffusion performance

[0134] The conductive silver glue was dispensed onto the substrate surface treated with silver-proof adhesive using a syringe. The dots of conductive silver glue were uniform in size, approximately 1 mm in diameter. After standing at room temperature for 5 minutes, the conductive silver glue-coated area on the substrate surface was observed for any diffusion. The substrate was then heated in a 175°C oven for 30 minutes to cure. The conductive silver glue-coated area on the substrate surface was then observed again for any diffusion. F indicates no silver glue diffusion prevention capability. The conductive silver glue used for dispensing was Henkel Loctite Ablestone S3860C.

[0135] The performance test results of the anti-silver glue diffusion agent of Examples 1-9 and Comparative Examples 1-10 are shown in Table 3.

[0136] Table 3. Performance test results of anti-silver glue diffusion agent of Examples 1-9 and Comparative Example 10

[0137]

[0138]

[0139] Figure 1 (a) shows the conductive silver glue layer on the gold surface just after the dispensing step in Example 1; Figure 1 (b) shows the conductive silver glue layer after the dispensing step on the gold surface in Example 1 was completed and left at room temperature for 5 minutes; Figure 1 (c) shows the conductive silver glue layer after dispensing and curing on the gold surface in Example 1; Figure 5(a) is the appearance diagram of Example 1. Combined with the contents of Table 3, it can be seen that the anti-silver glue diffusion agents of Examples 1-9 of the present invention have a transparent microemulsion appearance with a bluish luster. They not only have good anti-silver glue diffusion performance on gold surfaces, copper surfaces and prepregs before curing, but also have good anti-silver glue diffusion performance after high-temperature curing. At the same time, the anti-silver glue diffusion agents of Examples 1-9 all have high stability and can stably and compatibly meet the requirements of anti-silver glue diffusion on substrates of different materials.

[0140] Figure 2 (a) is the conductive silver glue layer on the gold surface just after the glue dispensing step in Comparative Example 1; Figure 2 (b) The conductive silver glue layer after the dispensing step on the gold surface in Comparative Example 1 was left at room temperature for 5 minutes; Figure 2 (c) is the conductive silver glue layer after dispensing and curing on the gold surface in Comparative Example 1. Compared with Example 1, the stability and anti-diffusion performance of Comparative Example 1 on the copper surface are acceptable, but its anti-diffusion performance on the gold surface and prepreg is poor. Figure 2 (a)-(c) also clearly show that before high-temperature curing, the conductive silver glue layer on the gold surface of Comparative Example 1 showed slight diffusion. After high-temperature curing, the conductive silver glue layer on the gold surface of Comparative Example 1 showed serious diffusion. The reason for this is that the film-forming and diffusion-proof ability of a single alkylalkoxysilane on the substrate board is limited, and it cannot be compatible with the anti-silver glue diffusion requirements of various substrate boards with different surface energies. The polyhydroxy short-chain fluorine-containing quaternary ammonium salt added to the anti-silver glue diffusion agent of the present invention, its fluorocarbon chain and alkylalkoxysilane cooperate to construct a dense composite film layer on the substrate board surface through self-assembly and intermolecular forces. Furthermore, the quaternary ammonium group in the polyhydroxy short-chain fluorine-containing quaternary ammonium salt further enhances the density of the film layer through electrostatic action, and the polyhydroxy structure can also form a passivation layer on the metal surface, playing a metal protection role, so that the anti-silver glue diffusion agent of the present invention has excellent anti-silver glue diffusion ability.

[0141] Figure 3 (a) Figure 4 (a) The conductive silver glue layer 1 of Comparative Example 2 and Comparative Example 3 is just completed on the gold surface after the glue dispensing step; Figure 3 (b) Figure 4 (b) The conductive silver glue layer after the dispensing step was completed on the gold surface of Comparative Examples 2 and 3, and then left at room temperature for 5 minutes; Figure 3 (c) Figure 4 (c) Conductive silver glue layers after dispensing and curing on the gold surface in Comparative Examples 2 and 3, respectively; Figure 5(b) is the appearance of comparative example 3. Compared with Example 1, comparative examples 2-3 have poor stability and their appearance is all white emulsion. Comparative examples 2-3 have poor anti-silver glue diffusion ability on gold surface, copper surface and semi-cured sheet. The reason is that: the long carbon chain fatty acid polyoxyethylene and hydrophilic polyether silicone oil of the present invention form a composite emulsification system, and the long carbon chain hydrophobic end of the long carbon chain fatty acid polyoxyethylene ester is firmly embedded in the oil phase of the anti-silver glue diffusion agent system of the present invention through intermolecular force, and is interwoven and entangled with the long carbon chain alkyl in alkyl alkoxy silane on the molecular scale through intermolecular van der Waals force to form a dynamic network structure, which not only enhances the stability of the anti-silver glue diffusion agent system of the present invention, but also further strengthens the interaction between alkyl alkoxy silane and polyhydroxy short chain fluorine-containing The fluorocarbon chains in the quaternary ammonium salt synergistically construct a dense composite membrane layer, and the hydrophilic end of the long carbon chain fatty acid polyoxyethylene ester extends into the aqueous phase of the anti-silver glue diffusion agent system of the present invention, thereby reducing the interfacial tension between the oil phase and the aqueous phase in the anti-silver glue diffusion agent system of the present invention, and forming a stable interface layer of oil core-emulsifier-aqueous phase. At the same time, in a weakly acidic environment, the hydration of the polyether chain segment of the hydrophilic polyether silicone oil is enhanced, and the siloxane chain segment of the polyether forms a chemical bond with the silicon-oxygen three-dimensional network membrane formed by the alkyl alkoxysilane, further improving the interfacial bonding strength between the components in the anti-silver glue diffusion agent system of the present invention. Combined with the preparation method of the present invention, it is effectively ensured that the anti-silver glue diffusion agent system of the present invention forms a stable nano-scale microemulsion dispersion state. In Comparative Examples 2-4, however, the ratio of the first emulsifier, the second emulsifier, and the alkylalkoxysilane is outside the ratio specified in the present invention, or the first emulsifier or the second emulsifier is missing, which weakens the emulsification and dispersion ability of the composite emulsification system and causes the dispersed droplets in the system to be too large, thereby forming an unstable white emulsion. Alternatively, as shown in Comparative Example 10, the S2 primary hydration treatment step in its preparation method does not adopt the two-stage step-by-step hydration step adopted in the present invention, thereby directly affecting the stability of the anti-silver glue diffusion agents of Comparative Examples 2-4 and 10, resulting in poor anti-silver glue diffusion performance on various substrate surfaces.

[0142] Compared with Example 1, Comparative Example 5 has too little alkyl alkoxy content. Although its stability can be guaranteed, the amount of composite film formed with polyhydroxy short-chain fluorine-containing quaternary ammonium salt is insufficient, which directly affects its anti-silver glue diffusion performance on each substrate board surface; Compared with Example 1, Comparative Example 6 has too much alkyl alkoxy content, which directly affects the effective ratio of the composite emulsification system of the present invention, resulting in its poor stability and poor anti-silver glue diffusion performance on each substrate board surface.

[0143] Figure 5(c) is the appearance diagram of Comparative Example 7. The pH buffer of the present invention is used to adjust the anti-silver colloid diffusion agent system of the present invention to a weak acid system. This acidic environment, on the one hand, strengthens the above-mentioned emulsification and dispersion effect, the controlled hydrolysis of alkylalkoxysilane and the directional adsorption of quaternary ammonium salt, and effectively helps to construct a thermodynamically stable and kinetically controllable nano-scale microemulsion anti-silver colloid diffusion system. On the other hand, it also has good process compatibility, avoiding the corrosion of different substrates by strong acids or strong bases, while ensuring the subsequent coating, welding and other processes. In Comparative Examples 7-8, the anti-silver colloid diffusion agent system is either too acidic or too alkaline, which is not conducive to the formation of a stable nano-scale microemulsion as shown in the examples, and easily causes precipitation in the solution, resulting in its lack of practical use.

[0144] In Comparative Example 9, after replacing the polyhydroxy short-chain fluorine-containing quaternary ammonium salt with the common cationic surfactant dodecyltrimethylammonium chloride, the prepared emulsion for preventing silver colloid diffusion has a transparent bluish appearance and can maintain good stability, but its anti-silver colloid diffusion performance is not significantly improved, and it cannot take into account the anti-silver colloid diffusion requirements of various different substrates.

[0145] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A silver glue diffusion preventing agent, characterized in that: The invention comprises, by mass concentration, 100 to 500 mg / l of alkyl alkoxysilane, 50 to 250 mg / l of a first emulsifier, 50 to 250 mg / l of a second emulsifier, 5 to 10 mg / l of a cationic surfactant, a pH buffer solution, and the balance of water; The cationic surfactant is a polyhydroxy short-chain fluorine-containing quaternary ammonium salt, and its structure is shown in the chemical formula (I): The general chemical formula (I) is Among them, R F C6F 13 、C8F 17 ; The first emulsifier is hydrophilic polyether silicone oil, and the second emulsifier is long carbon chain fatty acid polyoxyethylene.

2. The anti-silver glue diffusion agent according to claim 1, characterized in that: The structure of the alkylalkoxysilane is shown in the chemical formula (II): The general chemical formula (II) is R1-Si(OR')3, wherein R1 is an alkyl group having 12 to 18 carbon atoms; and R' is an alkyl group having 1 to 4 carbon atoms.

3. The anti-silver paste diffusion agent according to claim 2, characterized in that: The alkylalkoxysilane includes at least one of dodecyltrimethoxysilane, hexadecyltriethoxysilane, and octadecyltrimethoxysilane.

4. The anti-silver glue diffusion agent according to claim 1, characterized in that: The hydrophilic polyether silicone oil includes one or more of Dow Corning water-based silicone oil, JP-204 polyether-modified silicone oil, and DM-204 polyether-modified silicone oil.

5. The anti-silver paste diffusion agent according to claim 1, characterized in that: The structure of the long carbon chain fatty acid polyoxyethylene is shown in the chemical formula (III): The general chemical formula (III) is R2COO-(CH2CH2O) n -H, Wherein, R2 is an alkyl group having 12 to 18 carbon atoms; n is an integer from 2 to 20.

6. The anti-silver paste diffusion agent according to claim 5, characterized in that: The long carbon chain fatty acid polyoxyethylene includes one or more of polyoxyethylene laurate, polyoxyethylene oleate, and polyoxyethylene stearate.

7. The anti-silver paste diffusion agent according to claim 1, characterized in that: The mass concentration ratio of the alkylalkoxysilane, the first emulsifier and the second emulsifier is (1-2):1:1; The mass concentration ratio of the alkylalkoxysilane to the cationic surfactant is (10-50):

1.

8. The anti-silver paste diffusion agent according to claim 1, characterized in that: The pH buffer is an organic acid buffer, which is used to adjust the pH of the silver colloid diffusion preventing agent to 6-6.

5.

9. A method for preparing a silver paste diffusion preventing agent according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1 material mixing The alkylalkoxysilane, the first emulsifier, the second emulsifier and the cationic surfactant are mixed in predetermined amounts and stirred to obtain a milky white mixture; S2 Primary Hydration Treatment Pure water was added to the milky mixture in two stages, specifically comprising:

1. In the first stage, add 5-10% of the total amount of pure water and stir at a high speed of 2000-3000 rpm until a transparent foam layer is formed in the mixture; 2. In the second stage, 5-10% of the total amount of pure water is added, and shear stirring is carried out at a speed of 800-1200 rpm until a translucent milky first pre-dispersion is formed; S3 system composite Pour the translucent milky pre-dispersion into the remaining amount of pure water and stir evenly to obtain a second dispersion; S4 post-processing The pH of the second dispersion is adjusted to 6-6.5 by using the pH buffer solution to obtain the silver colloid diffusion preventing agent.

10. A use of a silver paste diffusion preventing agent according to any one of claims 1 to 8, characterized in that: The steps include: Dissolve a certain amount of anti-silver glue diffusion agent in water and stir evenly to form an anti-silver glue diffusion liquid, wherein the anti-silver glue diffusion agent accounts for 3-5% of the total volume of the liquid; The substrate surface is sequentially pickled and washed with water; The surface of the substrate is immersed in the anti-silver glue diffusion liquid for 30-60 seconds, and the working temperature of the anti-silver glue diffusion liquid is 25-30°C.

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