A tetraphenyl phosphonium salt high-latency catalyst and its application in a chip packaging epoxy plastic encapsulating material

Abstract

The application belongs to the technical field of phosphine salt catalysts and packaging, and discloses a tetraphenyl phosphonium salt high-latency catalyst and application of the catalyst in a chip packaging epoxy plastic packaging material; tetraphenyl phosphonium cations and large steric hindrance aryl organic acid anions are combined through ionic bonds in a molar ratio of 1:0.95-1.05, and the organic acid anions are selected from naphthalene ring dicarboxylic acid monoanions, diphenyl sulfonic acid anions or tert-butyl phenyl phosphoric acid anions; the catalyst has no epoxy ring opening catalytic activity, the ionic bond is quickly dissociated when the temperature reaches 160 DEG C or above, the solubility is greater than or equal to 10 wt% at 170 DEG C, the total halide content is less than 10 ppm, and the thermal decomposition temperature is higher than 220 DEG C. The application adopts an ionic structure design, solves the problems of normal temperature pre-crosslinking of existing small-molecule organic phosphine accelerators, reduction of halogen impurities to reduce device reliability, poor compatibility of microcapsule type accelerators, and complex process, is suitable for existing epoxy plastic packaging material production processes, and can be used in the field of semiconductor packaging.

Description

Technical Field

[0001] This invention belongs to the field of phosphine salt catalysts and encapsulation technology, and in particular to a tetraphenylphosphine salt high latency catalyst and its application in chip encapsulation epoxy molding compound. Background Technology

[0002] The advanced process chip and third-generation semiconductor power device industries are expanding rapidly. Epoxy molding compounds, which account for over 90% of semiconductor packaging materials, determine the performance and lifespan of packaged devices based on their curing efficiency, storage stability, and long-term reliability. Among these, epoxy curing accelerators are the core functional components that regulate the curing behavior of molding compounds, and the industry's demand for accelerators with high latency, high catalytic activity, and low ionic impurities continues to rise.

[0003] Currently, mainstream epoxy curing accelerators on the market are mainly divided into two categories. The first category is small-molecule organophosphorus accelerators, typical products including tetraphenylphosphonium bromide and triphenylphosphine-benzoquinone adducts. Under high temperature conditions, these accelerators dissociate to release nucleophilic phosphine centers, which attack the oxygen atoms of the epoxy groups to initiate ring-opening reactions, achieving cross-linking between epoxy resin and phenolic curing agents. This type of accelerator has a mature preparation process, low cost, and high catalytic activity, and is currently widely used in epoxy molding compounds for packaging mid-to-low-end consumer electronics devices. However, this type of accelerator has a certain solubility in epoxy resin at room temperature, which slowly initiates pre-cross-linking of the system, resulting in a room temperature storage period of less than 7 days for the molding compound. At the same time, the halide ion impurities contained in tetraphenylphosphonium halide are prone to migration under high temperature and high pressure conditions, causing device leakage and failing to meet the long-term reliability requirements of high-end packaging.

[0004] The second type is microencapsulated latent accelerators. Their working principle involves using polymers such as polyurethane and polymethacrylate as wall materials to encapsulate the active accelerator into core-shell microspheres. At room temperature, the wall material isolates the accelerator from contact with the epoxy and curing agent components. During high-temperature encapsulation, the wall material melts and releases the accelerator, initiating curing. This type of accelerator theoretically exhibits excellent latency and has been tested in some industrial-grade molding compounds with high shelf-life requirements. However, the wall material of this type of accelerator has poor compatibility with the epoxy system, leading to interface defects after curing, reducing the mechanical strength and dielectric properties of the molding compound. Furthermore, the microencapsulation process is complex and costly, with poor batch-to-batch particle size stability, easily resulting in uneven curing and insufficient product yield. With the increasing demands for shelf life, curing efficiency, and reliability in high-end packaging scenarios such as 14nm and below process logic chips and silicon carbide power devices, neither of the existing two types of accelerators can simultaneously meet these performance requirements. Therefore, there is an urgent need to develop new high-latency epoxy curing accelerators to meet the application needs of high-end semiconductor packaging. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as the tendency of small molecule phosphine accelerators to induce halogenated impurities in epoxy pre-crosslinking and the poor compatibility and high cost of microencapsulated accelerators, this invention provides a tetraphenylphosphine salt high-latency catalyst and its application in epoxy molding compounds for chip packaging.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A tetraphenylphosphine salt high-latency catalyst is disclosed. The catalyst is a single-component ionic organophosphine compound, composed of a tetraphenylphosphine cation and an organic acid anion containing a sterically hindered aryl structure, which are directionally bonded by ionic bonds. The organic acid anion is selected from any one of dicarboxylic acid monoanions containing a naphthalene ring structure, sulfonic acid anions containing a biphenyl structure, and phosphate anions containing tert-butyl-substituted phenyl groups. The molar ratio of the tetraphenylphosphine cation to the organic acid anion is controlled at 1:0.95-1.05. The catalyst molecule does not contain any free protic acid or free organic base components. The ionic bonds are stable at room temperature and do not have the activity to catalyze the ring-opening reaction of epoxy resins. When the temperature is raised to above 160°C, the ionic bonds rapidly dissociate, releasing the highly catalyzed tetraphenylphosphine component, which can rapidly catalyze the crosslinking reaction between epoxy resins and phenolic curing agents.

[0007] Furthermore, the dicarboxylic acid monoanion containing the naphthalene ring structure is any one of 2,6-naphthalenedicarboxylic acid monoanion, 1,4-naphthalenedicarboxylic acid monoanion, and 1,8-naphthalenedicarboxylic acid monoanion; the sulfonic acid anion containing the biphenyl structure is any one of 4,4'-biphenyl disulfonic acid monoanion, 2-biphenyl sulfonic acid anion, and 4-methyl-2-biphenyl sulfonic acid anion; and the phosphate anion containing tert-butyl-substituted phenyl is any one of 2,6-di-tert-butylphenyl phosphate monoanion, p-tert-butylphenyl phosphate dianion, and 2,4-di-tert-butylphenyl phosphate dianion.

[0008] Furthermore, the average particle size of the tetraphenylphosphine salt high latency catalyst is controlled to be 1-20 μm, the initial thermal decomposition temperature is ≥220℃, the melting point range is controlled to be 160-190℃, the solubility in epoxy resin at 25℃ is ≤0.1wt%, and the solubility in epoxy resin at 170℃ is ≥10wt%, which can achieve rapid dissolution and catalysis under high temperature conditions, and exist stably in particulate form at room temperature without interacting with epoxy groups.

[0009] Furthermore, the catalyst was added at a rate of 0.2 parts by weight to an equimolar mixture of 100 parts by weight of o-cresol epoxy resin and linear phenolic resin. After being sealed and stored at 25°C for 30 days, the gelation time change rate of the system at 175°C was ≤10%. Under the same conditions, the gelation time change rate of the system using ordinary tetraphenylphosphonium bromide as an accelerator was ≥40%. The catalyst can improve the room temperature storage stability of the epoxy system.

[0010] Furthermore, the preparation steps specifically include: S1. Dissolve the organic acid component in an aqueous ethanol solution with a volume fraction of 70-90%, control the mass concentration of the organic acid component to be 5-15%, and stir until completely dissolved to obtain a clear and transparent organic acid solution. S2. Add a 20-30% (w / w) aqueous solution of tetraphenylphosphonium hydroxide to the organic acid solution at a uniform rate, control the temperature of the reaction system at 40-60℃, stir continuously during the addition, and keep the reaction at the temperature for 1-3 hours after the addition is completed, until the pH value of the system stabilizes at 6.5-7.5. S3. After the reaction is complete, the system is rapidly cooled to 0-10℃, allowed to stand to precipitate crystals, and then filtered. The filter cake is washed 2-3 times with deionized water at 0-5℃ and then dried under vacuum to obtain the tetraphenylphosphine salt high latency catalyst.

[0011] Furthermore, the molar ratio of tetraphenylphosphonium hydroxide to organic acid components is controlled at 1:0.98-1.02, the vacuum drying temperature is controlled at 70-90℃, the drying time is controlled at 8-16h, the vacuum degree during the drying process is ≥-0.09MPa, and the moisture content in the prepared catalyst is ≤0.1wt%, which can avoid the adverse effects of residual moisture on the performance of epoxy molding compound after curing.

[0012] Furthermore, the purity of the tetraphenylphosphine salt high-latency catalyst is ≥99.5%, wherein the total content of halide ion impurities is ≤10ppm, the content of sodium ion impurities is ≤5ppm, and the content of potassium ion impurities is ≤5ppm, to avoid the migration of impurity ions under high temperature and high pressure conditions, thereby improving the dielectric properties and long-term reliability of the epoxy molding compound after curing.

[0013] Furthermore, the tetraphenylphosphine salt high-latency catalyst is added to the raw material system of the epoxy molding compound as an epoxy curing accelerator. Based on the total weight of the epoxy molding compound, the addition amount of the tetraphenylphosphine salt high-latency catalyst is controlled at 0.05-1wt%. The catalyst remains stable during the melt mixing process of the epoxy molding compound, does not initiate a pre-crosslinking reaction, improves the production stability and yield of the epoxy molding compound, and rapidly dissociates to exert a catalytic effect during the subsequent encapsulation and curing process, ensuring that the curing reaction is completed.

[0014] Furthermore, the raw material system of the epoxy molding compound also includes epoxy resin, phenolic curing agent, inorganic filler, silane coupling agent, release agent, ion scavenger, and colorant. Based on the total weight of the epoxy molding compound, the content of epoxy resin is controlled at 5-18 wt%, the content of phenolic curing agent is controlled at 3-12 wt%, the content of inorganic filler is controlled at 72-89 wt%, the content of silane coupling agent is controlled at 0.1-0.8 wt%, the content of release agent is controlled at 0.1-0.8 wt%, and the content of ion scavenger is controlled at 0.1-0.8 wt%. The content of the scavenging agent is controlled at 0.1-0.5 wt%, the content of the colorant is controlled at 0.1-0.5 wt%, the epoxy resin is selected from one or more combinations of o-cresol epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, and naphthalene ring type epoxy resin, the phenolic curing agent is selected from one or more combinations of linear phenolic resin, biphenyl type phenolic resin, and aralkyl phenolic resin, and the inorganic filler is selected from one or more combinations of fused silica, crystalline silica, and spherical silica.

[0015] Furthermore, the epoxy molding compound is used for packaging logic chips, IGBT power semiconductor chips, and third-generation semiconductor silicon carbide chips with processes of 14nm and below. The curing temperature of the epoxy molding compound is controlled at 170-190℃, and the curing time is controlled at 60-120s. The packaged part obtained after curing has a high-temperature reverse bias test time of ≥1500h under the conditions of 150℃ and 1500V reverse voltage, which can meet the long-term reliability requirements of high-end chip packaging.

[0016] The present invention has the following beneficial effects: This invention utilizes a structural design that involves the directional ionic bonding of tetraphenylphosphonium cations and sterically hindered aryl organic acid anions. The ionic bonds are stable at room temperature and rapidly dissociate under high-temperature encapsulation conditions, which can efficiently catalyze the crosslinking reaction between epoxy and curing agent. This effectively solves the defects of existing small-molecule organophosphorus accelerators, such as easy pre-crosslinking of epoxy systems at room temperature and insufficient storage stability. At the same time, the preparation process adopts a halogen-free reaction route, which can improve the long-term reliability of epoxy molding compounds.

[0017] This invention employs a single-component ionic compound structure, eliminating the need for additional polymer wall coating. It exhibits excellent compatibility with all components of epoxy molding compounds and participates in the construction of the cross-linking network during curing, without introducing additional interface defects. This effectively solves the defects of existing microencapsulated accelerators, such as poor compatibility with epoxy systems and the tendency to lead to a decline in the mechanical and dielectric properties of molding compounds. Furthermore, the preparation process uses a simple neutralization crystallization route, resulting in high batch stability and controllable production costs. This avoids the problems of high cost and large batch performance fluctuations caused by complex microencapsulation processes.

[0018] The tetraphenylphosphine salt high-latency catalyst of this invention is compatible with the mature production process of existing epoxy molding compounds. It can replace existing accelerators without adjusting the existing mixing, extrusion, and preforming processes. It can not only upgrade the performance of epoxy molding compounds for low- and mid-range consumer electronics packaging, but also meet the stringent requirements of advanced process logic chips, third-generation semiconductor power devices and other high-end packaging scenarios for the storage stability, curing efficiency and long-term reliability of molding compounds. It has broad application value in the field of semiconductor packaging materials. Attached Figure Description

[0019] Figure 1 This invention provides a flowchart for the preparation of a tetraphenylphosphine salt high-latency catalyst; Figure 2 A bar chart showing the change rate of gelation time of different samples stored at 25°C for 30 days, as proposed in this invention. Figure 3 This is a line graph showing the gel time of epoxy molding compound at different temperatures, as proposed in this invention. Figure 4 This is a radar chart showing the overall performance of the epoxy molding compound proposed in this invention. Detailed Implementation

[0020] The following will refer to the appendices in the embodiments of the present invention. Figure 1-4 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 In this embodiment, the tetraphenylphosphine salt high latency catalyst uses 2,6-naphthalenedicarboxylic acid monoanion as the organic acid anion, and the specific preparation steps are as follows: S1. Dissolve 2,6-naphthalenedicarboxylic acid in a 70% (v / v) aqueous ethanol solution, controlling the mass concentration of 2,6-naphthalenedicarboxylic acid to be 5%, and stir until completely dissolved to obtain a clear and transparent organic acid solution. S2. Add a 20% tetraphenylphosphonium hydroxide aqueous solution dropwise to the organic acid solution at a uniform rate, control the temperature of the reaction system at 40°C, stir continuously during the dropwise addition, and keep the reaction at the temperature for 1 hour after the dropwise addition is completed, until the pH value of the system stabilizes at 6.5. S3. After the reaction is complete, the system is rapidly cooled to 0℃, allowed to stand and crystallize, and then filtered. The filter cake is washed twice with deionized water at 0℃ and then placed in a vacuum drying oven. The vacuum degree is controlled at -0.092MPa, the drying temperature is 70℃, and the drying time is 8h to obtain a tetraphenylphosphine salt high latency catalyst.

[0022] The catalyst prepared in this embodiment has an average particle size of 1 μm, a molar ratio of tetraphenylphosphonium cation to 2,6-naphthalenedicarboxylic acid monoanion of 1:0.98, a purity of 99.6% as determined by high performance liquid chromatography, a total halide ion content of 7 ppm as determined by ion chromatography, a sodium ion content of 3 ppm, a potassium ion content of 2 ppm, an initial thermal decomposition temperature of 225℃, and a melting point of 162℃.

[0023] The catalyst prepared in this embodiment is used in an epoxy molding compound for chip packaging. The raw material components of the epoxy molding compound are: 6 parts by weight of o-cresol epoxy resin, 4 parts by weight of linear phenolic resin, 88.65 parts by weight of fused silica, 0.3 parts by weight of γ-glycidyl etheroxypropyltrimethoxysilane, 0.3 parts by weight of oxidized polyethylene wax, 0.3 parts by weight of hydrotalcite, 0.2 parts by weight of carbon black, and 0.05 parts by weight of the catalyst prepared in this embodiment. The epoxy molding compound is used for 14nm process logic chip packaging, with a curing temperature of 170℃ and a curing time of 120s.

[0024] Example 2 The tetraphenylphosphine salt high latency catalyst in this embodiment uses 4,4'-biphenyl disulfonic acid monoanion as the organic acid anion, and the specific preparation steps are as follows: S1. Dissolve 4,4'-biphenyl disulfonic acid in an 80% (v / v) aqueous ethanol solution, controlling the mass concentration of 4,4'-biphenyl disulfonic acid to be 10%, and stir until completely dissolved to obtain a clear and transparent organic acid solution. S2. Add a 25% tetraphenylphosphonium hydroxide aqueous solution at a constant rate to the organic acid solution, control the temperature of the reaction system at 50°C, stir continuously during the addition, and keep the reaction at the temperature for 2 hours after the addition is completed, until the pH value of the system stabilizes at 7.0. S3. After the reaction is complete, the system is rapidly cooled to 5°C, allowed to stand to precipitate crystals, and then filtered. The filter cake is washed twice with deionized water at 2°C and then placed in a vacuum drying oven. The vacuum degree is controlled at -0.095MPa, the drying temperature is 80°C, and the drying time is 12h to obtain a tetraphenylphosphine salt high latency catalyst.

[0025] The catalyst prepared in this embodiment has an average particle size of 10 μm, a molar ratio of tetraphenylphosphonium cation to 4,4'-biphenyl disulfonic acid monoanion of 1:1.00, a purity of 99.7% as determined by high performance liquid chromatography, a total halide ion content of 5 ppm as determined by ion chromatography, a sodium ion content of 2 ppm, a potassium ion content of 2 ppm, an initial thermal decomposition temperature of 232℃, and a melting point of 175℃.

[0026] The catalyst prepared in this embodiment is used in an epoxy molding compound for chip packaging. The raw material components of the epoxy molding compound are: 8 parts by weight of biphenyl-type epoxy resin, 5 parts by weight of biphenyl-type phenolic resin, 85.2 parts by weight of spherical silica, 0.4 parts by weight of γ-aminopropyltriethoxysilane, 0.4 parts by weight of carnauba wax, 0.4 parts by weight of hydrotalcite, 0.3 parts by weight of carbon black, and 0.5 parts by weight of the catalyst prepared in this embodiment. The epoxy molding compound is used for IGBT power semiconductor chip packaging, with a curing temperature of 180°C and a curing time of 90 seconds.

[0027] Example 3 The tetraphenylphosphine salt high-latency catalyst in this embodiment uses 2,6-di-tert-butylphenyl phosphate monoanion as the organic acid anion, and the specific preparation steps are as follows: S1. Dissolve 2,6-di-tert-butylphenylphosphoric acid in a 90% (v / v) aqueous ethanol solution, control the mass concentration of 2,6-di-tert-butylphenylphosphoric acid to be 15%, and stir until completely dissolved to obtain a clear and transparent organic acid solution. S2. Add a 30% tetraphenylphosphonium hydroxide aqueous solution at a constant rate to the organic acid solution, control the temperature of the reaction system at 60℃, and stir continuously during the addition. After the addition is completed, keep the reaction at the temperature for 3 hours until the pH value of the system stabilizes at 7.5. S3. After the reaction is complete, the system is rapidly cooled to 10℃, allowed to stand to precipitate crystals, and then filtered. The filter cake is washed three times with deionized water at 5℃ and then placed in a vacuum drying oven. The vacuum degree is controlled at -0.098MPa, the drying temperature is 90℃, and the drying time is 16h to obtain a tetraphenylphosphine salt high latency catalyst.

[0028] The catalyst prepared in this embodiment has an average particle size of 20 μm, a molar ratio of tetraphenylphosphonium cation to 2,6-di-tert-butylphenyl phosphate monoanion of 1:1.02, a purity of 99.8% as determined by high performance liquid chromatography, a total halide ion content of 3 ppm as determined by ion chromatography, a sodium ion content of 1 ppm, a potassium ion content of 1 ppm, an initial thermal decomposition temperature of 241 °C, and a melting point of 188 °C.

[0029] The catalyst prepared in this embodiment is used in an epoxy molding compound for chip packaging. The raw material components of the epoxy molding compound are: 10 parts by weight of naphthalene ring epoxy resin, 6 parts by weight of arylalkylphenol resin, 81.1 parts by weight of crystalline silica, 0.5 parts by weight of γ-mercaptopropyltrimethoxysilane, 0.5 parts by weight of oxidized polyethylene wax, 0.5 parts by weight of hydrotalcite, 0.4 parts by weight of titanium black, and 1 part by weight of the catalyst prepared in this embodiment. The epoxy molding compound is used for the packaging of third-generation semiconductor silicon carbide chips, with a curing temperature of 190°C and a curing time of 60 seconds.

[0030] Example 4 The tetraphenylphosphine salt high latency catalyst in this embodiment uses 1,8-naphthalenedicarboxylic acid monoanion as the organic acid anion, and the specific preparation steps are as follows: S1. Dissolve 1,8-naphthalenedicarboxylic acid in a 75% (v / v) aqueous ethanol solution, controlling the mass concentration of 1,8-naphthalenedicarboxylic acid to be 8%, and stir until completely dissolved to obtain a clear and transparent organic acid solution. S2. Add a 22% tetraphenylphosphonium hydroxide aqueous solution dropwise to the organic acid solution at a uniform rate, control the temperature of the reaction system at 45℃, stir continuously during the dropwise addition, and keep the reaction at the temperature for 1.5h after the dropwise addition is completed, until the pH value of the system stabilizes at 6.8; S3. After the reaction is complete, the system is rapidly cooled to 3°C, allowed to stand to precipitate crystals, and then filtered. The filter cake is washed twice with deionized water at 1°C and then placed in a vacuum drying oven. The vacuum degree is controlled at -0.093MPa, the drying temperature is 75°C, and the drying time is 10h to obtain a tetraphenylphosphine salt high latency catalyst.

[0031] The catalyst prepared in this embodiment has an average particle size of 5 μm, a molar ratio of tetraphenylphosphonium cation to 1,8-naphthalenedicarboxylic acid monoanion of 1:0.99, a purity of 99.6% as determined by high performance liquid chromatography, a total halide ion content of 6 ppm as determined by ion chromatography, a sodium ion content of 2 ppm, a potassium ion content of 3 ppm, an initial thermal decomposition temperature of 228 °C, and a melting point of 167 °C.

[0032] The catalyst prepared in this embodiment is used in an epoxy molding compound for chip packaging. The raw material components of the epoxy molding compound are: 7 parts by weight of dicyclopentadiene-type epoxy resin, 4.5 parts by weight of linear phenolic resin, 86.7 parts by weight of fused silica, 0.3 parts by weight of γ-glycidyl etheroxypropyltrimethoxysilane, 0.3 parts by weight of carnauba wax, 0.3 parts by weight of hydrotalcite, 0.2 parts by weight of carbon black, and 0.2 parts by weight of the catalyst prepared in this embodiment. The epoxy molding compound is used for 7nm process logic chip packaging, with a curing temperature of 175℃ and a curing time of 100s.

[0033] Comparative Example 1 This comparative example uses tetraphenylphosphonium bromide, a small-molecule organophosphorus accelerator based on existing technology, as a comparison. The tetraphenylphosphonium bromide was purchased from a commercially available conventional industrial-grade product with a purity of 99.0%, a bromide ion content of 120 ppm, an average particle size of 8 μm, and a melting point of 295 °C.

[0034] The epoxy molding compound formulation in this comparative example is identical to that of Example 4, except that the accelerator is replaced with tetraphenylphosphonium bromide. The preparation process and curing conditions are also the same as in Example 4. This comparative example corresponds to the first type of existing small molecule organophosphorus accelerator technology described in the background art.

[0035] Comparative Example 2 This comparative example uses a microencapsulated triphenylphosphine accelerator from the prior art as a comparison. The microencapsulated triphenylphosphine was purchased from a commercially available conventional product, with polyurethane as the wall material, a core material content of 20%, and an average particle size of 15 μm.

[0036] The epoxy molding compound formulation in this comparative example is identical to that of Example 4, except that the accelerator is replaced with microencapsulated triphenylphosphine. The preparation process and curing conditions are also the same as in Example 4. This comparative example corresponds to the second type of microencapsulated accelerator technology described in the background art.

[0037] Experimental data tables and explanations Table 1 Catalyst Synthesis Parameters and Physicochemical Properties Table 1 Explanation: The catalysts prepared in Examples 1-4 in Table 1 all have a purity higher than 99.5%, a total halide ion content lower than Comparative Example 1, and a solubility in epoxy resin at room temperature lower than 0.1 wt%. This addresses the shortcomings of existing small molecule organophosphorus accelerators, such as easy solubility at room temperature leading to pre-crosslinking and halide ion content. The solubility at 170°C is higher than 10 wt%, ensuring rapid dissolution and catalytic effect at high temperatures. The melting point range is within the 160-190°C range, and the thermal decomposition temperature is higher than 220°C, meeting the latency design requirements.

[0038] Table 2. Performance Test Results of Epoxy Molding Compound Table 2 Explanation: The gelation time change rate of Examples 1-4 in Table 2 is less than 10%, which is much lower than 42.1% of Comparative Example 1 and 18.3% of Comparative Example 2, thus addressing the deficiency of insufficient storage stability of the two existing types of accelerators; the flexural strength after curing is all higher than 140 MPa, which is much higher than 112 MPa of Comparative Example 2, thus addressing the deficiency of poor compatibility of microencapsulated accelerators leading to decreased mechanical properties; the dielectric constant at 175℃ is all lower than 3.2, which is lower than the two comparative examples, and the HTRB test pass rate is all higher than 98%, thus addressing the deficiency of insufficient reliability of existing accelerators.

[0039] refer to Figure 2The catalytic activity release rate in this figure is the proportion of the active catalytic component that has dissociated and exerted its effect to the total amount of catalyst added after holding at the corresponding temperature for 30 minutes. The higher the value, the more complete the catalytic activity release. In Example 1 of this invention, the catalyst has an activity release rate of less than 5% within the temperature range corresponding to room temperature storage and melt mixing, and has no catalytic activity. It will not trigger pre-crosslinking of epoxy molding compound, effectively avoiding the defect of small molecule accelerators that are prone to crosslinking at room temperature. After reaching the encapsulation and curing temperature, the activity release rate is close to 100%, which can fully catalyze the curing reaction. It solves the problems of insufficient activity release and easy residue of impurities in the curing stage of microencapsulated accelerators.

[0040] refer to Figure 3 This figure illustrates the temperature-responsive catalytic characteristics of various catalysts. Example 3 exhibits a gel time exceeding 300 seconds at 150°C, demonstrating excellent latency. The gel time decreases rapidly as the temperature rises above 160°C, reaching a gel rate of less than 90 seconds at 170°C, matching the process requirements of "low-temperature storage and high-temperature rapid curing" in semiconductor packaging. Comparative Example 1 shows a gel time of only about 200 seconds at 150°C, indicating excessively high catalytic activity at low temperatures, which can easily lead to storage failure of the molding compound. Comparative Example 2 still shows a gel time exceeding 200 seconds at 170°C, indicating insufficient high-temperature catalytic efficiency, which can easily lead to incomplete encapsulation curing. The ionic bond dissociation activation energy of the catalyst in this invention matches the temperature window of the packaging process, simultaneously meeting the dual requirements of latency and curing efficiency.

[0041] refer to Figure 4 This figure comprehensively compares the overall performance of the catalyst of this invention with two existing types of accelerators. Example 2 scores higher than both comparative examples in all performance dimensions, especially in storage stability and reliability. Comparative Example 1 has the lowest scores in storage stability and reliability, corresponding to its inherent defects of containing halide ions and being prone to pre-crosslinking at room temperature; Comparative Example 2 has the lowest scores in mechanical strength and curing efficiency, corresponding to its defects of poor wall material compatibility and slow high-temperature release rate. The catalyst of this invention overcomes the shortcomings of the two existing technologies, and its overall performance meets the full-dimensional performance requirements of high-end packaging scenarios such as 14nm and below process logic chips and silicon carbide power devices.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A tetraphenylphosphine salt high-latency catalyst, characterized in that, The catalyst is a single-component ionic organophosphorus compound, which is formed by the directional bonding of a tetraphenylphosphonium cation and an organic acid anion containing a sterically hindered aryl structure through ionic bonds. The organic acid anion is selected from any one of dicarboxylic acid monoanions containing a naphthalene ring structure, sulfonic acid anions containing a biphenyl structure, and phosphate anions containing tert-butyl-substituted phenyl groups. The molar ratio of the tetraphenylphosphonium cation to the organic acid anion is controlled to be 1:0.95-1:1.

05.

2. The tetraphenylphosphine salt high latency catalyst according to claim 1, characterized in that, The dicarboxylic acid monoanion containing a naphthalene ring structure is any one of 2,6-naphthalenedicarboxylic acid monoanion, 1,4-naphthalenedicarboxylic acid monoanion, and 1,8-naphthalenedicarboxylic acid monoanion; the sulfonic acid anion containing a biphenyl structure is any one of 4,4'-biphenyl disulfonic acid monoanion, 2-biphenyl sulfonic acid anion, and 4-methyl-2-biphenyl sulfonic acid anion; and the phosphate anion containing a tert-butyl-substituted phenyl group is any one of 2,6-di-tert-butylphenyl phosphate monoanion, p-tert-butylphenyl phosphate dianion, and 2,4-di-tert-butylphenyl phosphate dianion.

3. The tetraphenylphosphine salt high latency catalyst according to claim 1 or 2, characterized in that, The average particle size of the tetraphenylphosphine salt high latency catalyst is controlled to be 1-20 μm, the initial thermal decomposition temperature is ≥220℃, the melting point range is controlled to be 160-190℃, the solubility in epoxy resin at 25℃ is ≤0.1wt%, and the solubility in epoxy resin at 170℃ is ≥10wt%.

4. The tetraphenylphosphine salt high latency catalyst according to any one of claims 1-3, characterized in that, The catalyst was added in an amount of 0.2 parts by weight to an equimolar mixture of 100 parts by weight of o-cresol epoxy resin and linear phenolic resin.

5. The tetraphenylphosphine salt high latency catalyst according to any one of claims 1-4, characterized in that, The tetraphenylphosphine salt high-latency catalyst was prepared via a neutralization reaction route, and the specific preparation steps included: S1. Dissolve the organic acid component in an aqueous ethanol solution with a volume fraction of 70-90%, control the mass concentration of the organic acid component to be 5-15%, and stir until completely dissolved to obtain a clear and transparent organic acid solution. S2. Add a 20-30% (w / w) aqueous solution of tetraphenylphosphonium hydroxide to the organic acid solution at a uniform rate, control the temperature of the reaction system at 40-60℃, stir continuously during the addition, and keep the reaction at the temperature for 1-3 hours after the addition is completed, until the pH value of the system stabilizes at 6.5-7.

5. S3. After the reaction is complete, the system is rapidly cooled to 0-10℃, allowed to stand to precipitate crystals, and then filtered. The filter cake is washed 2-3 times with deionized water at 0-5℃ and then dried under vacuum to obtain the tetraphenylphosphine salt high latency catalyst.

6. The tetraphenylphosphine salt high latency catalyst according to claim 5, characterized in that, The molar ratio of tetraphenylphosphonium hydroxide to organic acid components is controlled at 1:0.98-1:1.02, the vacuum drying temperature is controlled at 70-90℃, and the drying time is controlled at 8-16h.

7. The tetraphenylphosphine salt high-latency catalyst according to any one of claims 1-6, characterized in that, The tetraphenylphosphine salt high latency catalyst has a purity of ≥99.5%, wherein the total content of halide ion impurities is ≤10ppm, the content of sodium ion impurities is ≤5ppm, and the content of potassium ion impurities is ≤5ppm.

8. The application of a tetraphenylphosphine salt high-latency catalyst according to any one of claims 1-7 in a chip encapsulation epoxy molding compound, characterized in that, The tetraphenylphosphine salt high latency catalyst is added to the raw material system of epoxy molding compound as an epoxy curing accelerator. The total weight of the epoxy molding compound is used as a basis, and the amount of the tetraphenylphosphine salt high latency catalyst added is controlled to be 0.05-1wt.

9. The application according to claim 8, characterized in that, The raw material system of the epoxy molding compound includes epoxy resin, phenolic curing agent, inorganic filler, silane coupling agent, release agent, ion scavenger, and colorant. Based on the total weight of the epoxy molding compound, the content of epoxy resin is controlled at 5-18 wt%, the content of phenolic curing agent is controlled at 3-12 wt%, the content of inorganic filler is controlled at 72-89 wt%, the content of silane coupling agent is controlled at 0.1-0.8 wt%, the content of release agent is controlled at 0.1-0.8 wt%, the content of ion scavenger is controlled at 0.1-0.5 wt%, and the content of colorant is controlled at 0.1-0.5 wt%. The epoxy resin is selected from one or more combinations of o-cresol epoxy resin, biphenyl-type epoxy resin, dicyclopentadiene-type epoxy resin, and naphthalene-type epoxy resin. The phenolic curing agent is selected from one or more combinations of linear phenolic resin, biphenyl-type phenolic resin, and aralkyl phenolic resin. The inorganic filler is selected from one or more combinations of fused silica, crystalline silica, and spherical silica.

10. The application according to claim 8 or 9, characterized in that, The epoxy molding compound is used for packaging logic chips, IGBT power semiconductor chips, and third-generation semiconductor silicon carbide chips with processes of 14nm and below. The curing temperature of the epoxy molding compound is controlled at 170-190℃, and the curing time is controlled at 60-120s.

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