High-voltage-resistant high-reliability epoxy molding compound for semiconductor packaging

Abstract

The invention relates to an epoxy molding compound for semiconductor packaging, in particular to a high-voltage-resistant high-reliability epoxy molding compound for semiconductor packaging. The epoxy molding compound provided by the invention comprises the following main components in parts by weight: 5-15 parts of epoxy resin; 1-10 parts of special epoxy resin; 2.5 to 10 parts of phenolic resin; 0.05 to 0.5 part of a curing accelerator; 60-90 parts of a filler; 0.1 to 1 part of a modifier; 0.1 to 1.5 parts of a release agent; and 0.1-1 part of a coupling agent. According to the invention, the optimal content range of each core component of the epoxy molding compound is defined, and a multi-component synergistic system is formed. The high-proportion filler can further reduce the dielectric loss of the material, and cooperates with the special epoxy resin to improve the compression strength; the coupling agent enhances the interface bonding force between the filler and the resin, and reduces the interface breakdown risk in a high-pressure environment; and the curing accelerator accurately regulates and controls the curing rate, so that internal defects caused by uneven curing are avoided, and the long-term reliability of the device under high voltage is ensured.

Description

Technical Field

[0001] This invention relates to an epoxy molding compound for semiconductor packaging, and more particularly to a high-voltage resistant and high-reliability epoxy molding compound for semiconductor packaging. Background Technology

[0002] Epoxy molding compounds possess numerous superior properties and have been widely used in the packaging field, serving as the mainstream material for semiconductor components and integrated circuit packaging. In recent years, semiconductors have evolved towards higher integration, with larger chips, more complex structures, and higher reliability requirements. This necessitates higher high-voltage resistance performance from the molding compounds used in packaging to ensure device reliability.

[0003] Epoxy molding compounds for semiconductor packaging generally include epoxy resin, curing agent, curing accelerator, filler, flame retardant, release agent, coupling agent, colorant, and mechanical modifier. The most common traditional o-cresphenolic epoxy resins include SQCN700-1.3 and CNE195XL-7, which contain epoxy groups and some hydroxyl groups. Under the action of heat and the phenolic resin curing agent, the epoxy groups of the epoxy resin undergo ring-opening and chemical reaction with the phenolic resin, producing cross-linking and curing, thus becoming a thermosetting plastic. However, because o-cresphenolic epoxy resin has a large number of hydroxyl groups after curing, it has a high dielectric constant, meaning that the material is easily polarized and conductive under an electric field, making it difficult to meet the requirements for high voltage resistance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-pressure resistant and high-reliability epoxy molding compound for semiconductor packaging.

[0005] The technical solution of this invention to solve the technical problem is as follows: This invention provides a high-voltage, high-reliability epoxy molding compound for semiconductor packaging. The main components of the epoxy molding compound and the weight percentages of each component are as follows: 5-15 parts epoxy resin 1-10 parts of special epoxy resin 2.5-10 parts phenolic resin Curing accelerator 0.05~0.5 parts 60-90 parts of filler Modifier 0.1~1 part Release agent 0.1~1.5 parts 0.1 to 1 part of coupling agent; The aforementioned specialty epoxy resins refer to a class of epoxy resins that, based on general-purpose epoxy resins, have undergone chemical modification or structural design to acquire special properties such as high-temperature resistance, low-temperature resistance, corrosion resistance, flame retardancy, high toughness, and low dielectric constant, meeting the stringent requirements of high-end fields such as aerospace, electronics, and new energy. These resins typically incorporate special groups (such as fluorine, silicon, aromatic rings, heterocyclic rings, etc.) into their molecular structure, exhibiting significant performance advantages under specific operating conditions compared to general-purpose bisphenol A epoxy resins.

[0006] The special epoxy resin in this invention is a phenol-aralkyl type epoxy resin, with the following molecular formula: n is 1-20.

[0007] Furthermore, the epoxy resin is selected from any one or more of the following: o-cresol epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenolic glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, alicyclic epoxy resin, and heterocyclic epoxy resin.

[0008] Furthermore, the phenolic resin is selected from any one or more of the following: linear phenolic resin and its derivatives, linear phenolic resin and its derivatives, monohydroxy or dihydroxynaphthol phenolic resin and its derivatives, condensates of p-xylene and phenol or naphthol, and copolymers of dicyclopentadiene and phenol.

[0009] Furthermore, the curing accelerator is selected from any one or more of imidazole compounds, tertiary amine compounds, and organophosphorus compounds; The imidazole compound is selected from any one or more of 2-methylimidazolium, 2,4-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, and 2-(heptadecanyl)imidazolium; The tertiary amine compound is selected from any one or more of triethylamine benzyl dimethylamine, α-methyl benzyl dimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol and 1,8-diazabicyclo(5,4,0)undecene-7; The organophosphorus compound is selected from any one or more of triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tris(p-methylphenyl)phosphine, and tris(nonylphenyl)phosphine.

[0010] Furthermore, the filler is selected from any one or more of alumina micro powder, titanium dioxide micro powder, silicon nitride micro powder, aluminum nitride micro powder, and silica micro powder; The silicon dioxide is crystalline silicon dioxide, molten silicon dioxide, or a mixture thereof, or the silicon dioxide is silicon dioxide modified with a silane coupling agent.

[0011] Furthermore, the coupling agent is any one or more of γ-mercaptopropyltrimethoxysilane, γ-epoxypropylpropyl ethertrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0012] Furthermore, the release agent is selected from any one or more of carnauba wax, synthetic wax, and mineral wax.

[0013] Furthermore, the modifier is selected from liquid silicone oil, silicone rubber, or mixtures thereof.

[0014] Furthermore, the epoxy molding compound also contains one or more of flame retardants and colorants; The flame retardant is present in 0-10 parts of the epoxy molding compound; The colorant content in the epoxy molding compound is 0-3 parts.

[0015] The flame retardant is selected from any one or more of halogen flame retardants, phosphorus flame retardants, nitrogen flame retardants, phosphorus-halogen flame retardants, and phosphorus-nitrogen flame retardants, or a hydroxide flame retardant; The colorant is selected from any one or more of titanium dioxide, zinc oxide, zinc barium white, and carbon black.

[0016] In a preferred embodiment of the present invention, the main components of the epoxy molding compound and the weight parts of each component are as follows: 6-9 parts epoxy resin; 4-6 parts special epoxy resin; 4-6 parts phenolic resin; 0.2-0.3 parts curing accelerator; 70-80 parts filler; 0.8-1 part release agent; 0.3 parts coupling agent; 7-8 parts flame retardant; 0.3 parts colorant; and 1 part modifier.

[0017] This invention also provides a method for preparing the above-mentioned epoxy molding compound: epoxy resin, special epoxy resin, phenolic resin, curing accelerator, filler, adhesive modifier, release agent, and coupling agent are mixed evenly (if other components are included, these components are mixed evenly with the above components simultaneously), and then melt-mixed evenly on an open mixing mill at a temperature of 70~100℃. The evenly mixed material is removed from the open mixing mill, naturally cooled, and pulverized to obtain the powdered material of the epoxy molding compound for improving high voltage resistance in semiconductor devices; further pre-formed into cakes to obtain its molding material.

[0018] The mechanism of action of this invention is as follows: Phenol-arylalkyl epoxy resin is produced by the Friedl-Crafts alkylation reaction of phenol and aryl compounds under a catalyst, followed by epoxidation, resulting in a narrow molecular weight distribution. Compared to o-cresylaldehyde epoxy resin, it has fewer hydroxyl groups after curing, giving the material low water absorption, resistance to damp heat, and excellent electrical insulation properties. It also possesses high heat resistance, low moisture absorption, flame retardancy, and a low dielectric constant. Generally, materials with a lower dielectric constant usually have higher withstand voltage. This is because a low dielectric constant means that the material is less prone to polarization and conductivity under an electric field, thereby increasing the material's insulation performance and voltage withstand capability.

[0019] The present invention has the following technical effects: 1. The epoxy molding compound of this invention is an epoxy molding compound that can improve the high-voltage resistance of semiconductor devices. This composition also possesses necessary flowability, moldability, and flame retardancy. This invention clarifies the optimal content range of each core component of the epoxy molding compound (60-90 parts filler, 0.05-0.5 parts curing accelerator, 0.1-1 parts coupling agent, etc.), and can add 0-10 parts flame retardant and 0-3 parts colorant as needed to form a multi-component synergistic system. A high proportion of filler can further reduce the dielectric loss of the material and synergistically improve the voltage resistance with special epoxy resin; the coupling agent enhances the interfacial bonding force between the filler and the resin, reducing the risk of interfacial breakdown under high-voltage conditions; the curing accelerator precisely controls the curing rate, avoiding internal defects caused by uneven curing, and ensuring the long-term reliability of the device under high voltage.

[0020] 2. This invention replaces the existing single o-cresphenolic epoxy resin system by adding a phenol-aralkyl type special epoxy resin to the formulation and compounding it with conventional epoxy resin as the resin matrix. The phenol-aralkyl type epoxy resin is synthesized by Friedl-Crafts alkylation reaction and then epoxidized. It has a narrow molecular weight distribution and a significantly reduced number of hydroxyl groups after curing (only 1 / 3 to 1 / 2 of that of traditional o-cresphenolic epoxy resin), which reduces the dielectric constant of the material to 3.5 to 3.8. It is not easily polarized and conducts electricity under an electric field, which greatly improves its high voltage resistance. At the same time, its low hygroscopicity (water absorption rate ≤0.2%) can enhance its resistance to damp heat. After being compounded with conventional epoxy resin, it can also ensure the flowability and moldability of the molding compound, avoiding the performance shortcomings of a single resin system. Detailed Implementation

[0021] The present invention is further illustrated below with reference to embodiments, but these are merely examples and not intended to limit the invention. The sources of the purchase of each component involved in the present invention are explained below: A (Epoxy Resin): o-cresol epoxy resin (Shengquan); B (Specialty Epoxy Resins): Phenolic-Aryl Alkyl Type Epoxy Resin (DIC); C1 (Phenolic Resin 1): Linear phenolic resin (Shanghai Hengfeng); C2 (Phenolic Resin 2): Phenolic Alkyl Phenolic Resin (Shanghai Hengfeng); D1 (Cure Accelerator 1): 2-Methylimidazole; D2 (Cure Accelerator 2): α-Methylbenzyldimethylamine; E (filler): Silica micro powder (d50 is 15um) (Lianrui); F1 (Coupling Agent 1): Coupling agent (γ-mercaptopropyltrimethoxysilane); F2 (Coupling Agent 2): Coupling agent (N-phenyl-3-aminopropyltrimethoxysilane); Release agent: Carnauba wax (carnauba wax); Flame retardant: aluminum hydroxide; Modifier: Liquid silicone oil; Colorant: Carbon black.

[0022] Examples 1-8 The composition of the compositions in Examples 1-8 is shown in Table 1, and the evaluation results are shown in Table 1.

[0023] The preparation methods of the compositions in Examples 1-8 are as follows: After weighing and mixing each component according to the formula, the mixture is melted and mixed evenly on an open rubber mixing mill preheated at 80℃ and 100℃. The evenly mixed material is removed from the open rubber mixing mill, cooled naturally, and pulverized into powder. It is then preformed into cakes to obtain epoxy molding compound. The results are evaluated using the following methods and are shown in Table 1.

[0024] The evaluation methods for the compositions in Examples 1-8 are as follows: High Temperature Reverse Bias (HTRB) Test: Sample preparation – using a high-pressure TO-220 molding press, mold temperature 175℃, injection pressure 60 kg / cm². 2 TO-220 products are encapsulated under a curing time of 120 seconds.

[0025] High Temperature Reverse Bias (HTRB) Test – The HTRB high temperature reverse bias aging test system (manufactured by Ruilai Electronic Machinery Equipment Co., Ltd., HR-1680 HTRB SYSTEM) was used. The test temperature was 125℃, the reverse bias voltage was 800V, the test time was 1000H, and the bias application method was continuous application of reverse voltage. For each example (or comparative example), 5 samples were tested in the high temperature reverse bias (HTRB) test, and the average of the 5 test results was taken as the high temperature reverse bias (HTRB) test result of that example (or comparative example).

[0026] Weldability: Using a low-pressure transfer molding machine (manufactured by Shanghai Rishen Machinery Equipment Co., Ltd., SY-250T), the obtained epoxy resin composition was molded into SOP8L under the conditions of mold temperature 175℃, injection pressure 9.8MPa, and curing time 120s, followed by post-curing at 175℃ for 8 hours. Ten samples were selected and stored at 85℃ and 60% relative humidity for 96 hours, followed by three cycles of 260℃ infrared reflow soldering. Afterwards, the presence of peeling or cracks inside the encapsulated samples was tested using an ultrasonic scanning device, and the number of defective samples was counted. When the number of defective samples is n, it is represented as "n / 10". The evaluation results are shown in Table 1.

[0027] Table 1: Composition and Evaluation Results of the Examples (by weight parts) .

[0028] Comparative Examples 1-8 The compositions of Comparative Examples 1-8 are shown in Table 2. The preparation method and evaluation method are the same as in Example 1. The evaluation results are shown in Table 2.

[0029] Table 2. Comparative Example Compositions and Evaluation Results (parts by weight) .

[0030] As can be seen from the results of the above embodiments and comparative examples: Examples 1-8 of this invention contain both conventional and specialty epoxy resins, and their high-pressure stability and solderability both meet the standards, with no defective samples. Comparative Examples 1-8 contain only conventional epoxy resin and no specialty epoxy resin; their high-pressure resistance does not meet the standards, and their solderability is also reduced. It is evident that the high-pressure resistant epoxy molding compound of this invention shows significant improvement while ensuring solderability after moisture absorption.

[0031] This invention, through the introduction of special epoxy resin and the improvement of optimized component ratio, enables the molding compound to achieve zero failure in HTRB testing and zero solderability defects under 800V high voltage. In contrast, comparative examples 1-8 do not contain special epoxy resin and cannot simultaneously meet these two key indicators, proving that technical solutions outside the scope of protection of this invention cannot achieve the technical effects of high pressure resistance and high reliability.

[0032] The above are merely embodiments of the present invention and do not limit the scope of the patent. Any equivalent modifications made based on the content of this specification, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A high-voltage, high-reliability epoxy molding compound for semiconductor packaging, characterized in that, The main components of the epoxy molding compound and the weight percentages of each component are as follows: 5-15 parts epoxy resin 1-10 parts of special epoxy resin 2.5-10 parts phenolic resin Curing accelerator 0.05~0.5 parts 60-90 parts of filler Modifier 0.1~1 part Release agent 0.1~1.5 parts 0.1 to 1 part of coupling agent; The special epoxy resin is a phenol-aralkyl type epoxy resin, with the following molecular formula: n is 1-20.

2. The epoxy molding compound according to claim 1, characterized in that, The epoxy resin is selected from any one or more of the following: o-cresol epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, polyphenolic glycidyl ether epoxy resin, aliphatic glycidyl ether epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, alicyclic epoxy resin, and heterocyclic epoxy resin.

3. The epoxy molding compound according to claim 1, characterized in that, The phenolic resin is selected from any one or more of the following: linear phenolic resin and its derivatives, linear phenolic resin and its derivatives, monohydroxy or dihydroxynaphthol phenolic resin and its derivatives, condensates of p-xylene and phenol or naphthol, and copolymers of dicyclopentadiene and phenol.

4. The epoxy molding compound according to claim 1, characterized in that, The curing accelerator is selected from any one or more of imidazole compounds, tertiary amine compounds, and organophosphorus compounds.

5. The epoxy molding compound according to claim 4, characterized in that, The imidazole compound is selected from any one or more of 2-methylimidazolium, 2,4-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, and 2-(heptadecanyl)imidazolium; The tertiary amine compound is selected from any one or more of triethylamine benzyl dimethylamine, α-methyl benzyl dimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol and 1,8-diazabicyclo(5,4,0)undecene-7; The organophosphorus compound is selected from any one or more of triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tris(p-methylphenyl)phosphine, and tris(nonylphenyl)phosphine.

6. The epoxy molding compound according to claim 1, characterized in that, The filler is selected from any one or more of alumina micro powder, titanium dioxide micro powder, silicon nitride micro powder, aluminum nitride micro powder and silica micro powder; the silica is crystalline silica, molten silica or a mixture thereof, or the silica is silica modified with a silane coupling agent.

7. The epoxy molding compound according to claim 1, characterized in that, The coupling agent is any one or more of γ-mercaptopropyltrimethoxysilane, γ-epoxypropylpropyl ethertrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

8. The epoxy molding compound according to claim 1, characterized in that, The release agent is selected from any one or more of carnauba wax, synthetic wax, and mineral wax.

9. The epoxy molding compound according to claim 1, characterized in that, The modifier is selected from liquid silicone oil, silicone rubber, or mixtures thereof.

10. The epoxy molding compound according to claim 1, characterized in that, The epoxy molding compound also contains one or more of the following: flame retardants and colorants; The flame retardant is present in 0-10 parts of the epoxy molding compound; The colorant content in the epoxy molding compound is 0-3 parts; The flame retardant is selected from any one or more of halogen flame retardants, phosphorus flame retardants, nitrogen flame retardants, phosphorus-halogen flame retardants, and phosphorus-nitrogen flame retardants, or a hydroxide flame retardant. The colorant is selected from any one or more of titanium dioxide, zinc oxide, zinc barium white, and carbon black.

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