A highly operable and reliable epoxy composition

Abstract

This invention relates to the field of epoxy molding compound technology, specifically to a highly operable and reliable epoxy composition. The epoxy composition comprises multiple components, including epoxy resin, phenolic resin, and modified siloxanes. The modified siloxane is prepared in two steps: first, polymethylvinylsiloxane is prepared, followed by further reaction to obtain the final product. Various preferred types of raw materials are available. The epoxy composition of this invention exhibits significant benefits when used in semiconductor packaging. The introduction of modified siloxanes with specific structures synergistically optimizes the mechanical and processing properties of the material, enhances the uniformity of system dispersion and interfacial bonding strength, improves toughness, reduces flexural modulus, and alleviates brittleness issues. It also enhances interfacial stability, reduces interlayer separation and defects, provides excellent film-forming properties, good flow and encapsulation, improves processing yield and dimensional stability, overcomes the difficulties of traditional epoxy compositions, and expands application prospects and value potential.

Description

Technical Field

[0001] This invention relates to the field of epoxy molding compound technology, and more particularly to an epoxy composition with high operability and high reliability. Background Technology

[0002] As semiconductor packaging evolves towards higher density, larger size, and thinner profiles, QFN (Quad Flat No-Leader) has been widely used in power devices, RF modules, and other fields due to its excellent electrical performance and heat dissipation characteristics. By combining with wafer-level packaging (WLP) technology, QFN can further achieve wafer-level processing, that is, completing the packaging steps at the wafer stage, reducing dicing and assembly steps, and improving integration and production efficiency. However, it also inevitably presents challenges such as process control, thermal stress, and rework. In terms of process control, packaging yield is significantly affected by mold flow uniformity, easily leading to problems such as flow marks, porosity, and warpage.

[0003] Epoxy molding compound (EMC) is prone to surface flow marks (mold flow marks) during injection molding, which manifest as color differences or textures along the resin flow path, severely affecting product appearance, reliability, and causing printing defects. This defect is mainly caused by insufficient mold design and process adaptability, improper process parameter settings, insufficient flowability of the epoxy molding compound, or material characteristics. It can be resolved by increasing the runner cross-sectional area, adjusting the gate position, adding or adjusting the position of mold vents, and optimizing molding process parameters. Excessively high EMC viscosity or unsuitable filler particle size distribution can increase flow resistance. Because the EMC flow front has a high degree of curing, it forms delamination marks with the subsequently less cured fluid. Furthermore, volatile gases and small insoluble molecules in the EMC that are not promptly expelled will form flow marks on the surface of the encapsulated body along the flow path.

[0004] In recent years, the industry has attempted to improve performance through material modification, such as introducing low-viscosity epoxy resins, dispersants, and nanofillers to enhance dispersibility. However, it still faces challenges such as narrow process windows and high costs. Therefore, there is an urgent need for an epoxy molding compound formulation that balances flow properties, surface quality, and cost-effectiveness to meet the high standards required for wafer-level packaging (QFN).

[0005] This invention utilizes modified siloxane as a specific component for preparation, overcoming the shortcomings of existing technologies and providing a highly operable and reliable epoxy composition and its applications. The epoxy molding compound described in patent document CN119614125A, prepared using hydroxyl-terminated silicone oil as a specific component, requires further combination with thermally conductive fillers and adhesion promoters of specific components to improve EMC reliability, encapsulation yield, and extend the mold clearing cycle, thus limiting its application. Furthermore, hydroxyl groups have relatively weak polarity, which is incompatible with the polarity of various EMC resins or additives, causing powder agglomeration during mixing, poor dispersibility, and weak adhesion to metals, ultimately reducing EMC reliability, encapsulation yield, and mold clearing cycle. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to use modified siloxane as a specific component to prepare epoxy compositions, overcome the shortcomings of the prior art, and provide an epoxy composition with high operability and high reliability and its application.

[0007] To achieve the above objectives, the present invention provides a highly operable and reliable epoxy composition, comprising, by weight, the following components: 3-11 parts epoxy resin, 3-10 parts phenolic resin, 70-90 parts inorganic filler, 0.2-1 parts coupling agent, 0.1-3 parts curing accelerator, 0.3-1 parts release agent, 0.3-1 parts stress modifier, 0.2-0.5 parts colorant, 0.2-1 parts ion scavenger, and 1-1.5 parts modified siloxane.

[0008] Furthermore, the preparation steps of the modified siloxane are as follows:

[0009] (1) Mix octamethylcyclotetrasiloxane, decamethyltetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate, heat to 105-115℃ and stir for 3-5 h, then heat to 145-155℃ and stir for 0.5-1.5 h, and then distill under reduced pressure at 165-175℃ for 2-4 h to obtain polymethylvinylsiloxane;

[0010] (2) Mix polymethylvinylsiloxane, mercapto-polyethylene glycol-carboxyl, benzoin dimethyl ether and tetrahydrofuran, and irradiate under a 365nm wavelength ultraviolet lamp while stirring for 25-35 minutes to obtain modified siloxane.

[0011] Preferably, in step (1), the weight ratio of octamethylcyclotetrasiloxane, decamethyltetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate is 33.4:0.25-0.35:16.6-24.9:0.025-0.035.

[0012] Preferably, in step (2), the weight ratio of polymethylvinylsiloxane, mercapto-polyethylene glycol-carboxyl, benzoin dimethyl ether and tetrahydrofuran is 20:30-50:0.15-0.25:150-250.

[0013] Preferably, the weight-average molecular weight of the thiol-polyethylene glycol-carboxyl group in step (2) is 400.

[0014] Preferably, the epoxy resin is one or more of the following: bisphenol A type epoxy resin, linear phenolic epoxy resin, bisphenol F type epoxy resin, biphenyl aryl alkyl type epoxy resin, triphenol methane type epoxy resin, and naphthalene-based epoxy resin.

[0015] Preferably, the phenolic resin is a biphenyl-type phenolic resin.

[0016] Preferably, the inorganic filler includes one or more of crystalline silicon dioxide, aluminum oxide, boron nitride, silicon nitride, and aluminum nitride.

[0017] Preferably, the coupling agent is one or more of the following: non-functional siloxane coupling agent, mercapto siloxane coupling agent, amino siloxane coupling agent, or epoxy siloxane coupling agent.

[0018] Preferably, the curing accelerator is one or more of imidazole curing accelerators, amine curing accelerators, organophosphorus curing accelerators, and acid anhydride curing accelerators.

[0019] Preferably, the release agent is one or more of brown polyethylene wax, natural palm wax, stearic acid, oxidized polyethylene wax, lignite ester, or polyamide wax.

[0020] Preferably, the colorant is carbon black.

[0021] Preferably, the stress modifier is one or more of rubber toughening agents, elastomer toughening agents, and inorganic nanoparticle toughening agents.

[0022] Preferably, the ion trapping agent is one or more of cation trapping and anion trapping.

[0023] The present invention also provides an application of a highly operable and reliable epoxy composition for semiconductor packaging.

[0024] The beneficial effects of this invention are:

[0025] This invention achieves synergistic optimization of the mechanical and processing properties of epoxy compositions by introducing modified siloxanes with specific structures. These modified siloxanes act as compatibility and bridging agents between the epoxy resin and inorganic fillers, significantly improving the dispersion uniformity and interfacial bonding strength of the system, and enhancing the overall structural density of the material. After addition, the material exhibits excellent toughness and moderate rigidity, effectively reducing the flexural modulus while maintaining high strength, and reasonably alleviating the brittleness problem caused by stress concentration, thus providing better resistance to external impacts. Simultaneously, the introduction of flexible segments enhances the elastic deformation capacity of the composition, enabling it to maintain high structural integrity under complex loading environments and reducing the formation and propagation of microcracks.

[0026] Furthermore, the molecular design of the modified siloxane facilitates its chemical interaction with the epoxy matrix, further enhancing interfacial stability and reducing interlayer separation and defects caused by curing shrinkage or thermal cycling. This system exhibits excellent film-forming efficiency and durable film-forming properties during the film-forming process, ensuring excellent reliability and durability of the products even under harsh environments such as high temperature and high humidity. This material system also possesses superior flow and encapsulation properties, enabling it to fully encapsulate electronic devices, meeting the stringent requirements of microstructure filling, and improving the processing yield and dimensional stability of the products.

[0027] By optimizing the material formulation and rationally introducing specific modifiers, this invention overcomes the problem of traditional epoxy compositions being unable to balance strength and modulus, giving the material a wider range of application adaptability. It not only ensures the long-term stability and safety of the product in practical applications, but also improves the process friendliness of the production process, significantly expanding the application prospects and value space of the material. Detailed Implementation

[0028] 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.

[0029] The sources and types of raw materials used in the specific embodiments of the present invention are as follows:

[0030] Biphenyl-type epoxy resin: Mitsubishi Chemical Corporation, YX-4000H;

[0031] MAR type epoxy resin: Nippon Kayaku Co., Ltd., NC3000;

[0032] MAR type phenolic resin: Meiwa Kasei Corporation, MEHC-7851SS;

[0033] Fused silica: Lianrui, DQ1150, Cut 75µm;

[0034] Accelerator: Hebei Liuhe Chemical Co., Ltd., DBU;

[0035] Carbon black: Mitsubishi Chemical Corporation, MA-600;

[0036] Oxidized polyethylene wax: Clariant GmbH, Germany, Licowax E PED;

[0037] Montanic acid polyol ester wax: Clariant GmbH, Germany, LICOWAX E PWD;

[0038] Coupling agent: Chenguang, CG-O187;

[0039] Ion scavenger: Toa Synthetic Co., Ltd., IXE-700;

[0040] Example 1:

[0041] The raw materials for Example 1 are shown in Table 1:

[0042] Table 1 Raw material ratio for Example 1

[0043] raw material Dosage / g raw material Dosage / g Biphenyl type epoxy resin 25 Oxidized polyethylene wax 2 MAR type epoxy resin 33 Mondanate polyol ester wax 1 MAR type phenolic resin 45 carbon black 2 Molten silica 880 Coupling agent 4 Accelerator 2 Stress modifier 3 Ion scavengers 3 Modified siloxane 1

[0044] Weigh and mix the raw materials according to the amounts in Table 2, then mix them at 110°C for 4 minutes on a rubber mixing mill, and after natural cooling, pulverize to obtain a high-strength, low-modulus epoxy composition.

[0045] The preparation steps of the modified siloxane are as follows:

[0046] (1) Mix 33.4g of octamethylcyclotetrasiloxane, 0.25g of decamethyltetrasiloxane, 16.6g of tetramethyltetravinylcyclotetrasiloxane and 0.025g of tetramethylammonium hydroxide pentahydrate, heat to 110℃ and stir for 4h, then heat to 150℃ and stir for 1h to decompose the catalyst, and then distill under reduced pressure at 170℃ for 3h to remove unreacted cyclic compounds and oligomers to obtain polymethylvinylsiloxane;

[0047] (2) Mix 20g of polymethyl vinyl siloxane, 40g of mercapto-polyethylene glycol-carboxyl (weight average molecular weight of 400), 0.2g of benzoin dimethyl ether and 200g of tetrahydrofuran, and irradiate under a 365nm wavelength ultraviolet lamp while stirring for 30min to obtain modified siloxane.

[0048] Example 2:

[0049] The raw materials for Example 2 are shown in Table 2:

[0050] Table 2 Raw material ratio for Example 2

[0051] raw material Dosage / g raw material Dosage / g Biphenyl type epoxy resin 25 Oxidized polyethylene wax 2 MAR type epoxy resin 33 Mondanate polyol ester wax 1 MAR type phenolic resin 45 carbon black 2 Molten silica 880 Coupling agent 4 Accelerator 2 Stress modifier 3 Ion scavengers 3 Modified siloxane 1.5

[0052] The preparation steps of the modified siloxane are as follows:

[0053] (1) Mix 33.4g of octamethylcyclotetrasiloxane, 0.35g of decamethyltetrasiloxane, 24.9g of tetramethyltetravinylcyclotetrasiloxane and 0.035g of tetramethylammonium hydroxide pentahydrate, heat to 115℃ and stir for 5h, then heat to 155℃ and stir for 1.5h to decompose the catalyst, and then distill under reduced pressure at 175℃ for 4h to remove unreacted cyclic compounds and oligomers to obtain polymethylvinylsiloxane;

[0054] (2) Mix 20g of polymethyl vinyl siloxane, 50g of mercapto-polyethylene glycol-carboxyl (weight average molecular weight of 400), 0.25g of benzoin dimethyl ether and 250g of tetrahydrofuran, and irradiate under a 365nm wavelength ultraviolet lamp while stirring for 35min to obtain modified siloxane.

[0055] Comparative Example 1:

[0056] The difference from Example 1 is that no modified siloxane is added.

[0057] Comparative Example 2:

[0058] The difference from Example 1 is that the mercapto-polyethylene glycol-carboxyl group in step (2) is replaced with an equimolar amount of mercaptopropionic acid.

[0059] Comparative Example 3:

[0060] The difference from Comparative Example 1 is that the phenolic resin used is phenol-aralkyl epoxy resin (Meiwa Kasei Corporation, MEHC-7800S).

[0061] Comparative Example 4:

[0062] The difference from Comparative Example 2 is that the modified siloxane was replaced with hydroxyl-terminated modified silicone oil (Shin-Etsu Chemical Industry Co., Ltd., KF-6001).

[0063] Performance testing:

[0064] Spiral Flow Length (SF): The spiral flow length is measured using a spiral die. The length of the spiral flow is measured in cm under the following conditions: molding machine temperature of 175°C, injection clamping pressure of 6.9 MPa, and curing time of 120 s.

[0065] Gelation Time (GT): Pour epoxy molding compound powder onto the center of a 175±2℃ heating plate and immediately spread the powder evenly with a depressor, controlling the spreading area to be within 5cm². 2Timing begins from the start of powder melting. Using a depressor, the melt is stirred at a frequency of 1 time per second. The endpoint is determined when the melt changes from a fluid to a gel state, and the time taken is recorded. This process is repeated three times (the difference between the three measurements should not exceed 2 seconds), and the gelation time is taken as the average of the three measurements.

[0066] Flash length: Measured on a molding machine using a flash metal mold, with a mold temperature of 175±2℃ and a transmitted pressure of 70kg±2kg / cm. 2 Take 20±2g of sample powder, pour it into the molding chamber of the plastic sealer, and after molding for 120 seconds, open the mold and move the mold to the operating table. FLASH mold to measure the length of overflow from different grooves, expressed in mm.

[0067] Pudding mold: This method is used to simulate the force exerted when epoxy molding compound peels off a Cu metal surface. A molding press is used to create a sample strip (black rubber base diameter = 3.5mm, base area = 9.621mm²). 2 The molding conditions are as follows: metal mold temperature 175±2℃, injection pressure 70±2kg / cm². 2 The curing time is 120 seconds. After molding, the metal part of the sample is placed on the die pusher platform for direct testing, and the data is recorded.

[0068] Flexural strength and modulus: A molding die was used to press a specimen (80mm long, 10mm wide, and 4mm high) under the following conditions: metal mold temperature 175±2℃, injection pressure 70±2kg / cm². 2 The curing time was 120 seconds. The flexural modulus of the molded specimen was measured using a universal tensile testing machine via a three-point bending test.

[0069] Hot hardness: The specimens were pressed using a molding machine under the following conditions: metal mold temperature 175±2℃, injection pressure 70±2kg / cm². 2 The curing time is 120 seconds. After the mold is opened, the mold is quickly moved to the operating table, the fixture is opened and the stopwatch is started. After 10 seconds, the hardness data of the three samples is quickly tested with a rubber hardness tester.

[0070] Reliability testing: First, the required components were packaged using a molding machine. Then, the packaged frame was placed in a constant temperature and humidity chamber at 85°C and 85% humidity for 168 hours. After the frame was removed, the delamination was analyzed using an ultrasonic scanning microscope. The results are shown in Table 3.

[0071] Table 3 Performance Test Results

[0072]

[0073] Data Analysis:

[0074] As can be seen from the data in Examples 1-2 in Table 3, the two groups of materials exhibited certain differences in mechanical and processing properties after using different amounts of modified siloxane. With the increase of modified siloxane dosage, the flexural modulus of the material increased, while the helical flow length decreased slightly, indicating that the crosslinking density may increase with the increase of modifier content, thereby improving the rigidity and deformation resistance of the material. Simultaneously, film-forming properties decreased, suggesting that while a higher degree of crosslinking contributes to mechanical properties, it also limits the fluidity of the system, resulting in a reduction in the number of film-forming cycles during molding. Therefore, by adjusting the amount of modified siloxane added, the balance between mechanical properties and processing adaptability of the material can be optimized, achieving controllable performance output. Furthermore, in the reliability test, no porosity or delamination was detected, indicating that the structural system can achieve good structural density and interface stability. Based on the comprehensive apparent performance data, it is speculated that the appropriate dosage of modified siloxane makes the epoxy resin matrix structure more stable and effectively improves film-forming properties, achieving synergistic optimization of mechanical and processing properties.

[0075] As can be seen from the data in Table 3 for Example 1, Example 2, after the addition of modified siloxane, exhibits superior flexural modulus and deformation capacity compared to Comparative Example 1, while maintaining certain strength and film-forming properties. The reduction in spiral flow length indicates improved system fluidity, which helps enhance the dimensional accuracy and interfacial bonding strength of the molded product. The gelation time and thermosetting properties, such as heat hardness, remain largely consistent, indicating that the main structure of the system has not undergone fundamental changes. Compared to the system without modified siloxane, the modulus of the material decreased after the addition, presumably due to the effective relief of stress concentration and reduction of brittleness caused by the introduction of flexible segments, while simultaneously enhancing toughness and impact resistance, thus improving overall balance. Modified siloxane may form a tight bond at the matrix-filler interface, improving compatibility and thereby increasing the number of film formations and reliability, effectively reducing the risk of porosity and delamination. In summary, the addition of modified siloxane not only optimizes the balance of mechanical and process properties of the material but also improves the overall quality and long-term reliability of the molded product.

[0076] As can be seen from the data in Table 3 for Example 2 and Comparative Example 2, the modified siloxane prepared in Example 2 using mercapto-polyethylene glycol-carboxyl groups exhibits better overall film-forming properties and reliability than that of Comparative Example 2 using mercaptopropionic acid. The gelation time and spiral flow length of the two groups are similar, indicating that the basic curing and processing processes are similar. However, Example 2 shows superior film-forming performance and reliability indicators such as delamination. It is speculated that the introduction of polyethylene glycol segments provides better flexibility, allowing the material to more effectively encapsulate the carrier and fill fine gaps during molding. Furthermore, its carboxyl structure facilitates interaction with epoxy groups or filler surfaces, enhancing interfacial bonding. This results in a more uniform and robust distribution of the modified siloxane within the matrix network, reducing the risk of failure due to phase separation or interfacial defects. Data trends show that this structure significantly enhances the integrity of the layered structure of the material without affecting other basic physical properties, thereby improving the stability and durability of the product.

[0077] As can be seen from the data in Table 3 for Example 2 and Comparative Example 3, after selecting different types of phenolic resins, Example 2 exhibits better film-forming properties and toughness overall. Comparative Example 3 shows certain differences in flexural modulus and film-forming cycles, indicating that the material system is sensitive to the type of resin. It is speculated that the unique molecular structure of MAR-type phenolic resin can more effectively form an interpenetrating network structure with epoxy resin, improving crosslinking efficiency and achieving a balance between high strength and high toughness in the matrix. At the same time, this structure helps maintain good fluidity and dispersibility of the system, allowing the filler to be uniformly mixed within the matrix matrix and reducing the formation of microcracks caused by spatial stress concentration. The above structural design not only optimizes the conventional mechanical properties of Example 2 but also demonstrates superior performance in film-forming efficiency and reliability tests, proving that a reasonable matching of the resin structure in the formulation plays a crucial role in overall performance.

[0078] As can be seen from the data in Table 3 for Example 2 and Comparative Example 4, Example 2 exhibits significant advantages in key performance aspects such as flexural strength, film-forming properties, and reliability. Comparative Example 4, using hydroxyl-terminated silicone oil, only provides limited interfacial reinforcement, suggesting it mainly exists through physical blending with weak interaction with the epoxy matrix. In contrast, Example 2, using polyethylene glycol carboxyl-modified siloxane, likely forms more chemical crosslinking points, enhancing intermolecular bonding strength and improving the integrity and load-bearing capacity of the matrix structure. Furthermore, this group of samples performed excellently in multiple reliability tests, with no abnormalities found in porosity or delamination, indicating sufficient interfacial bonding and a dense structure. Therefore, it can be inferred that this modified siloxane with its specific structure can not only effectively improve the overall mechanical properties of the material but also significantly improve its heat resistance and processing performance, resulting in a final product with both high reliability and high-efficiency processing characteristics.

[0079] 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.

Claims

1. An epoxy composition, characterized in that, By weight, it comprises the following components: 3-11 parts epoxy resin, 3-10 parts phenolic resin, 70-90 parts inorganic filler, 0.2-1 part coupling agent, 0.1-3 parts curing accelerator, 0.3-1 part release agent, 0.3-1 part stress modifier, 0.2-0.5 parts colorant, 0.2-1 part ion scavenger, and 1-1.5 parts modified siloxane; The preparation steps of the modified siloxane are as follows: (1) Mix octamethylcyclotetrasiloxane, decamethyltetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate, heat to 105-115℃ and stir for 3-5 h, then heat to 145-155℃ and stir for 0.5-1.5 h, and then distill under reduced pressure at 165-175℃ for 2-4 h to obtain polymethylvinylsiloxane; (2) Mix polymethylvinylsiloxane, mercapto-polyethylene glycol-carboxyl, benzoin dimethyl ether and tetrahydrofuran, and irradiate under a 365nm wavelength ultraviolet lamp while stirring for 25-35 minutes to obtain modified siloxane; The weight ratio of octamethylcyclotetrasiloxane, decamethyltetrasiloxane, tetramethyltetravinylcyclotetrasiloxane and tetramethylammonium hydroxide pentahydrate in step (1) is 33.4:0.25-0.35:16.6-24.9:0.025-0.035; The weight ratio of polymethylvinylsiloxane, mercapto-polyethylene glycol-carboxyl, benzoin dimethyl ether and tetrahydrofuran in step (2) is 20:30-50:0.15-0.25:150-250; The weight-average molecular weight of the thiol-polyethylene glycol-carboxyl group mentioned in step (2) is 400.

2. The epoxy composition according to claim 1, characterized in that, The epoxy resin is one or more of the following: bisphenol A type epoxy resin, linear phenolic epoxy resin, bisphenol F type epoxy resin, biphenyl aryl alkyl type epoxy resin, triphenol methane type epoxy resin, and naphthalene-based epoxy resin.

3. The epoxy composition according to claim 1, characterized in that, The phenolic resin is a biphenyl-type phenolic resin.

4. The epoxy composition according to claim 1, characterized in that, The inorganic filler includes one or more of crystalline silicon dioxide, aluminum oxide, boron nitride, silicon nitride, and aluminum nitride.

5. The epoxy composition according to claim 1, characterized in that, The coupling agent is one or more of the following: non-functional siloxane coupling agent, mercapto-type siloxane coupling agent, amino-type siloxane coupling agent, or epoxy-type siloxane coupling agent.

6. The epoxy composition according to claim 1, characterized in that, The curing accelerator is one or more of imidazole curing accelerators, amine curing accelerators, organophosphorus curing accelerators, and acid anhydride curing accelerators.

7. The epoxy composition according to claim 1, characterized in that, The release agent is one or more of polyethylene wax, natural palm wax, stearic acid, oxidized polyethylene wax, lignite ester, or polyamide wax.

8. The epoxy composition according to claim 1, characterized in that, The colorant is carbon black.

9. The epoxy composition according to claim 1, characterized in that, The stress modifier is one or more of the following: rubber toughening agent, elastomer toughening agent, and inorganic nanoparticle toughening agent.

10. The epoxy composition according to claim 1, characterized in that, The ion scavenger is one or more of a cation scavenger and anion scavenger.

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