Liquid epoxy encapsulating material with low thermal expansion coefficient and preparation method thereof

Abstract

The application provides a liquid epoxy plastic sealing material with low thermal expansion coefficient and a preparation method thereof. The epoxy plastic sealing material comprises, by weight fraction, 4-10% of epoxy resin, 80-90% of modified inorganic silicon filler, 1-10% of curing agent and 0.1-1% of accelerator, wherein the sum of the content of each component is 100%, and the modified inorganic silicon filler is prepared by modifying inorganic silicon with gamma-glycidoxypropyltrimethoxysilane first and then reacting with aminated dibenzocyclooctane. In the application, the inorganic silicon filler is surface modified by aminated dibenzocyclooctane group, the dibenzocyclooctane group undergoes a conformational transition from boat form to chair form in the heating process, thereby actively regulating the thermal expansion coefficient of the system; in addition, the amino group of the aminated dibenzocyclooctane group covalently reacts with the epoxy resin matrix, can be fully dispersed and involved in the whole molecular crosslinking network; due to the synergistic effect of actively regulating the thermal expansion coefficient of the system and reducing the interface defects, the thermal expansion coefficient of the liquid epoxy plastic sealing material in the forming stage is significantly reduced, and the warping problem of the plastic sealing body is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor advanced packaging technology, in particular to a liquid epoxy plastic sealing material with low thermal expansion coefficient and a preparation method thereof. BACKGROUND

[0002] The manufacturing of chips mainly consists of three steps of chip design, wafer manufacturing and packaging testing. The wafer manufacturing dominated by advanced photoetching, i.e. advanced process, is the core field in the industry in recent decades. However, with the rapid development of photoetching technology, the process has been greatly reduced from 130 nm in about 2000 to 2 nm at present, close to the physical limit. Therefore, it is imperative to develop advanced packaging technology to further improve the performance of chips.

[0003] As a key technology in semiconductor manufacturing, advanced packaging realizes significant improvement in chip interconnection density and heterogeneous integration capacity through innovative packaging architecture design, and has become a solution to reduce research and development costs and break through the performance limit of traditional processes. Wafer-level packaging, 2.5D packaging and 3D packaging are typical advanced packaging architectures, which all need to use a representative material of advanced packaging, i.e. liquid epoxy plastic sealing material. At present, the liquid epoxy plastic sealing material mainly consists of low-viscosity liquid epoxy resin, spherical inorganic fillers, curing agent, catalyst, coupling agent and other functional additives. Due to its excellent flowability, it can better fill complex and large-sized packaging structures, and further realize mechanical connection and protection, electrical protection and heat dissipation of the packaging architecture through heating and curing. However, due to the mismatch between the modulus and the thermal expansion coefficient of the liquid epoxy plastic sealing material and the chip, there is inconsistent shrinkage during the heating and curing and cooling stages, resulting in different degrees of warping of the packaging structure. Excessive warping will cause failure of the packaging structure.

[0004] In the prior art, the thermal expansion coefficient is reduced and the warping is improved by increasing the content of fillers or introducing small particle size fillers. However, these methods will cause flowability to decrease on the one hand, and will cause the fillers to be unevenly dispersed in the matrix on the other hand, resulting in problems such as stress concentration and reduced reliability. Therefore, it is urgent to develop a liquid epoxy plastic sealing material with low thermal expansion coefficient to improve the warping problem of the liquid epoxy plastic sealing material packaging structure. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a liquid epoxy plastic sealing material with low thermal expansion coefficient and a preparation method thereof. By introducing amino-dibenzocyclooctane with heating shrinkage function at the interface between the epoxy resin and the inorganic silicon, the problems raised in the above background technology are solved.

[0006] To achieve the above object, the present application is implemented by the following technical solutions:

[0007] According to a first aspect of the present application, there is provided a liquid epoxy encapsulating material with low thermal expansion coefficient, comprising the following components in percentage by weight: 4-10% of epoxy resin, 80-90% of modified inorganic silica filler, 1-10% of curing agent, 0.1-1% of accelerator, wherein the sum of the content of each component is 100%, and the modified inorganic silica filler is prepared by modifying inorganic silica with γ-glycidoxypropyltrimethoxysilane and then reacting with aminated dibenzocyclooctane.

[0008] Preferably, the inorganic silica of the modified inorganic silica filler is selected from silica powder, and the maximum particle size of the silica powder ranges from 25 to 75 μm.

[0009] Preferably, the epoxy resin is selected from at least one of alicyclic epoxy resin, bisphenol F epoxy resin, bisphenol A epoxy resin, polycyclic aromatic epoxy resin, phenolic epoxy resin, and epoxy resin with biphenyl structure.

[0010] Preferably, the curing agent is selected from at least one of acid anhydride curing agent, amine curing agent, phenolic curing agent, and thiol curing agent.

[0011] Specifically, the acid anhydride curing agent is selected from at least one of methyl nadic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0012] The amine curing agent is selected from at least one of polyetheramine, m-phenylenediamine, diaminodiphenyl sulfone, and isophorone diamine.

[0013] The phenolic curing agent is selected from at least one of linear phenolic curing agent and phenolic amine curing agent.

[0014] The thiol curing agent is selected from at least one of pentaerythritol tetra(3-mercaptopropionate), trimethylolpropane trimercaptoacetate, and polythiol.

[0015] Preferably, the accelerator is selected from imidazole accelerator or modified amine accelerator.

[0016] Specifically, the imidazole accelerator is selected from at least one of imidazole, 2,4-dimethylimidazole, 2-methylimidazole, and 2-phenylimidazole.

[0017] The modified amine accelerator is selected from at least one of N,N-dimethylcyclohexylamine, triethylenediamine, tris(dimethylaminopropyl)amine, and 2,2-dimethylpropionic acid quaternary amine salt.

[0018] According to a second aspect of the present application, there is provided a preparation method of a liquid epoxy encapsulating material with low thermal expansion coefficient, comprising the following steps:

[0019] Step 1, first mix inorganic silicon with γ-glycidoxypropyltrimethoxysilane, vacuumize to carry out the first reaction, then add aminobenzocyclooctane under vacuum to carry out the second reaction, and obtain modified inorganic silicon filler;

[0020] Step 2, mix epoxy resin with the modified inorganic silicon filler uniformly, then add curing agent and accelerator to obtain a preliminary mixture, and grind the preliminary mixture to obtain the liquid epoxy plastic encapsulating material.

[0021] Preferably, in step 1, the mass ratio of the inorganic silicon to the γ-glycidoxypropyltrimethoxysilane is 100:0.2~100:0.5;

[0022] The mass ratio of the inorganic silicon to the aminobenzocyclooctane is 100:1~100:5.

[0023] Preferably, in step 1, the temperature of the first reaction is 60~120℃, and the time is 1~3h;

[0024] The temperature of the second reaction is 100~150℃, and the time is 1~3h.

[0025] Preferably, the mixing speed of the preliminary mixture is 1500~2500rpm, and the mixing time is 1~10min;

[0026] The grinding speed is 1500~2500rpm, and the grinding time is 1~10min.

[0027] The grinder in the application is selected from any one of a ball mill, a sand mill or a three-roll grinder.

[0028] The application provides a liquid epoxy plastic encapsulating material with low thermal expansion coefficient and a preparation method thereof.

[0029] (1) The liquid epoxy plastic encapsulating material with low thermal expansion coefficient provided by the application has the following beneficial effects: the inorganic silicon filler is modified by aminobenzocyclooctane group, benzocyclooctane will undergo a conformational transition from boat type to chair type during heating, produce a negative thermal expansion effect, and significantly shrink in volume, offsetting the thermal expansion of the epoxy resin during curing, thereby actively regulating the thermal expansion coefficient of the system; in addition, the amino group of the aminobenzocyclooctane group covalently reacts with the epoxy resin matrix, so that the inorganic silicon filler is fully dispersed in the epoxy resin matrix and participates in the entire molecular crosslinking network, eliminating the interface defects of traditional physical filling; due to the synergistic effect of actively regulating the thermal expansion coefficient of the system and reducing the interface defects, the thermal expansion coefficient of the liquid epoxy plastic encapsulating material during the forming stage is significantly reduced, and the warping problem of the plastic encapsulating body is greatly improved. DETAILED DESCRIPTION

[0030] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the present application will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0031] Unless otherwise specified, the various raw materials, equipment and the like used in the present application can be purchased from the market or prepared by the existing method.

[0032] The present application provides a liquid epoxy plastic sealing material with low thermal expansion coefficient, which comprises the following components in percentage by weight: 4-10% of epoxy resin, 80-90% of modified inorganic silicon filler, 1-10% of curing agent, and 0.1-1% of accelerator, wherein the modified inorganic silicon filler is prepared by modifying inorganic silicon with γ-glycidoxypropyltrimethoxysilane first and then reacting with aminobisbenzo cyclooctane.

[0033] The preparation method of the modified inorganic silicon filler is as follows:

[0034] Step 1: mix inorganic silicon with γ-glycidoxypropyltrimethoxysilane, perform the first reaction under vacuum, and modify the surface of the silicon powder with γ-glycidoxypropyltrimethoxysilane, and the reaction process is shown in formula I.

[0035] Formula I

[0036] Step 2: add aminobisbenzo cyclooctane again and perform the second reaction under vacuum, and then the modified silicon powder reacts with aminobisbenzo cyclooctane to obtain the modified inorganic silicon filler, and the reaction process is shown in formula II.

[0037] Formula II

[0038] The specific preparation method of the liquid epoxy plastic sealing material is as follows:

[0039] Mix the modified inorganic silicon filler with the epoxy resin uniformly, add the curing agent and the accelerator to obtain the primary mixture, and finally grind the primary mixture to obtain the liquid epoxy plastic sealing material after vacuum degassing.

[0040] The present application neutralizes the expansion of the matrix by the negative expansion characteristics of aminobisbenzo cyclooctane in the modified inorganic silicon filler, and combines the excellent compatibility of aminobisbenzo cyclooctane with the resin to eliminate the interface thermal mismatch stress as a whole, inhibit the deformation of the liquid epoxy plastic sealing material, and reduce the warpage value.

[0041] The technical solutions of the present application are further explained below in combination with specific embodiments, so as to facilitate further understanding of the present application by those skilled in the art.

[0042] Example 1

[0043] Preparation of modified inorganic silica filler: 100 parts of silica powder with a maximum particle size of 25 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum extraction and mixing reaction was carried out at 80°C for 2 h, then 1 part of aminobisbenzo cyclooctane was added, vacuum extraction and mixing reaction was carried out at 130°C for 2 h, and thus modified silica powder was obtained;

[0044] Preparation of liquid epoxy encapsulating material: 89% of modified silica powder, 2.25% of bisphenol A epoxy resin and 2.25% of bisphenol F epoxy resin were added into a homogenizer, mixing was carried out at a rotation speed of 2000 rpm for 5 min, then 6.3% of methyl nadic anhydride and 0.2% of 2,4-dimethylimidazole were added, grinding was carried out using a three-roll grinding machine at a rotation speed of 1500 rpm for 1 min, and finally vacuum defoaming was carried out, and thus liquid epoxy encapsulating material was obtained.

[0045] Example 2

[0046] The preparation method of this example is the same as that of Example 1, except that in the preparation of modified inorganic silica filler, 100 parts of silica powder with a maximum particle size of 25 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum extraction and mixing reaction was carried out at 80°C for 2 h, then 2.5 parts of aminobisbenzo cyclooctane was added, vacuum extraction and mixing reaction was carried out at 130°C for 2 h, and thus modified silica powder was obtained.

[0047] Example 3

[0048] The preparation method of this example is the same as that of Example 1, except that in the preparation of modified inorganic silica filler, 100 parts of silica powder with a maximum particle size of 25 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum extraction and mixing reaction was carried out at 80°C for 2 h, then 3.5 parts of aminobisbenzo cyclooctane was added, vacuum extraction and mixing reaction was carried out at 130°C for 2 h, and thus modified silica powder was obtained.

[0049] Example 4

[0050] The preparation method of this example is the same as that of Example 1, except that in the preparation of modified inorganic silica filler, 100 parts of silica powder with a maximum particle size of 25 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum extraction and mixing reaction was carried out at 80°C for 2 h, then 5 parts of aminobisbenzo cyclooctane was added, vacuum extraction and mixing reaction was carried out at 130°C for 2 h, and thus modified silica powder was obtained.

[0051] Example 5

[0052] The preparation method of this example is the same as that of Example 1, except that in the preparation process of the modified inorganic silica filler, 100 parts of silica powder with a maximum particle size of 25 μm and 0.2 parts of γ-glycidoxypropyltrimethoxysilane are added to the reaction kettle, vacuum mixing and reaction is carried out at 80°C for 2h, then 1 part of aminobenzocyclooctane is added, vacuum mixing and reaction is carried out at 130°C for 2h, and the modified silica powder is obtained.

[0053] Example 6

[0054] The preparation method of this example is the same as that of Example 1, except that in the preparation process of the modified inorganic silica filler, 100 parts of silica powder with a maximum particle size of 25 μm and 0.4 parts of γ-glycidoxypropyltrimethoxysilane are added to the reaction kettle, vacuum mixing and reaction is carried out at 80°C for 2h, then 1 part of aminobenzocyclooctane is added, vacuum mixing and reaction is carried out at 130°C for 2h, and the modified silica powder is obtained.

[0055] Example 7

[0056] The preparation method of this example is the same as that of Example 1, except that in the preparation process of the modified inorganic silica filler, 100 parts of silica powder with a maximum particle size of 55 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane are added to the reaction kettle, vacuum mixing and reaction is carried out at 80°C for 2h, then 1 part of aminobenzocyclooctane is added, vacuum mixing and reaction is carried out at 130°C for 2h, and the modified silica powder is obtained.

[0057] Example 8

[0058] The preparation method of this example is the same as that of Example 1, except that in the preparation process of the modified inorganic silica filler, 100 parts of silica powder with a maximum particle size of 75 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane are added to the reaction kettle, vacuum mixing and reaction is carried out at 80°C for 2h, then 1 part of aminobenzocyclooctane is added, vacuum mixing and reaction is carried out at 130°C for 2h, and the modified silica powder is obtained.

[0059] Example 9

[0060] The preparation method of this example is the same as that of Example 1, except that in the preparation process of the liquid epoxy encapsulating material, 87% of the modified silica powder, 4.5% of dicyclopentadiene epoxy resin are added to the homogenizer and mixed at a speed of 2000 rpm for 5 min, then 7.5% of polyether amine and 1% of methyl imidazole are added and ground with a grinder at a speed of 1500 rpm for 1 min, and finally vacuum degassing is carried out, to obtain the liquid epoxy encapsulating material.

[0061] Comparative Example 1

[0062] 89% of a silicon powder with a maximum particle size of 25 μm, 2.25% of a bisphenol A epoxy resin, 2.25% of a bisphenol F epoxy resin, 6.3% of methyl nadic anhydride, and 0.2% of 2,4-dimethylimidazole were added into a homogenizer and mixed at a speed of 2000 rpm for 5 min, then ground using a three-roll grinder at a speed of 1500 rpm for 1 min, and finally vacuum defoamed to obtain a liquid epoxy encapsulating material.

[0063] Comparative Example 2

[0064] The preparation method of this comparative example was the same as that of Example 1, except that in the preparation of the modified inorganic silicon filler: 100 parts of a silicon powder with a maximum particle size of 25 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum mixed and reacted at 80°C for 2 h, and then 0.5 parts of aminobenzocyclooctane was added, vacuum mixed and reacted at 130°C for 2 h to obtain a modified silicon powder.

[0065] Comparative Example 3

[0066] The preparation method of this comparative example was the same as that of Example 1, except that in the preparation of the modified inorganic silicon filler: 100 parts of a silicon powder with a maximum particle size of 25 μm and 0.5 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum mixed and reacted at 80°C for 2 h, and then 8 parts of aminobenzocyclooctane was added, vacuum mixed and reacted at 130°C for 2 h to obtain a modified silicon powder.

[0067] Comparative Example 4

[0068] The preparation method of this comparative example was the same as that of Example 1, except that in the preparation of the modified inorganic silicon filler: 100 parts of a silicon powder with a maximum particle size of 25 μm and 0.1 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum mixed and reacted at 80°C for 2 h, and then 1 part of aminobenzocyclooctane was added, vacuum mixed and reacted at 130°C for 2 h to obtain a modified silicon powder.

[0069] Comparative Example 5

[0070] The preparation method of this comparative example was the same as that of Example 1, except that in the preparation of the modified inorganic silicon filler: 100 parts of a silicon powder with a maximum particle size of 25 μm and 0.6 parts of γ-glycidoxypropyltrimethoxysilane were added into a reaction kettle, vacuum mixed and reacted at 80°C for 2 h, and then 1 part of aminobenzocyclooctane was added, vacuum mixed and reacted at 130°C for 2 h to obtain a modified silicon powder.

[0071] Test Method

[0072] The viscosity at 25℃ was tested by a rotational rheometer;

[0073] The glass transition temperature was tested by a dynamic mechanical analyzer DMA;

[0074] The thermal expansion coefficients CTE1 and CTE2 were tested by a thermal mechanical analyzer TMA;

[0075] The warpage value was tested by a warpage tester, and the measurement process was as follows: first, the liquid epoxy encapsulating material obtained in each example and the comparative example was uniformly scraped on a glass slide with a size of 10 cm x 5 cm x 0.1 cm, the thickness of the material was 0.1 cm, and the curing condition was 150℃ / 1h. After cooling, the height of the glass slide at one end was measured, which was the warpage value.

[0076] The test results of the viscosity, the glass transition temperature, the thermal expansion coefficient 1, the thermal expansion coefficient 2 and the warpage value of the measured liquid epoxy encapsulating material are shown in Table 1.

[0077] Table 1

[0078]

[0079] According to the comparison of the data in Table 1, it can be known from the comparison of Example 1 and Comparative Example 1 that the viscosity is low, CTE1 and CTE2 are large, and the warpage is large when the silicon powder is not modified.

[0080] According to Examples 1-4 and Comparative Examples 2-3, the mass ratio of the silicon powder to the aminobisbenzosuberane should be within 100:1~100:5. If the amount of the aminobisbenzosuberane is too high, there will be unreacted aminobisbenzosuberane left. If the amount is too low, it is difficult to graft enough aminobisbenzosuberane on the surface of the silicon powder. The optimal mass ratio of the silicon powder to the aminobisbenzosuberane is 100:3.5.

[0081] According to Examples 1, 5-6 and Comparative Examples 4-5, the mass ratio of the silicon powder to the γ-glycidoxypropyltrimethoxysilane should be within 100:0.2~100:0.5. If the amount of the γ-glycidoxypropyltrimethoxysilane is too high, there will be unreacted γ-glycidoxypropyltrimethoxysilane left. If the amount is too low, it is difficult to form sufficient surface modification of the silicon powder to graft enough aminobisbenzosuberane. The optimal mass ratio of the silicon powder to the γ-glycidoxypropyltrimethoxysilane is 100:0.5.

[0082] According to the comparison of the data of Example 1 and Examples 7-8, the maximum particle size of the silicon powder is best at 25μm. As the particle size of the silicon powder decreases, the surface area becomes larger, more epoxy resin can be adsorbed, and the interaction with the epoxy resin is stronger.

[0083] While embodiments of the application have been shown and described, it is to be understood that the application is not limited to the details of the embodiments described, since numerous changes, modifications, substitutions and variations can be made thereto without departing from the spirit and scope of the application as defined by the appended claims and their equivalents.

Claims

1. A liquid epoxy underfill material with low coefficient of thermal expansion, characterized in that: The liquid epoxy encapsulating material comprises the following components by weight fraction: 4-10% of epoxy resin, 80-90% of modified inorganic silica filler, 1-10% of curing agent, and 0.1-1% of accelerator, wherein the sum of the content of each component is 100%, the modified inorganic silica filler is prepared by modifying inorganic silica with γ-glycidoxypropyltrimethoxysilane and then reacting with aminated dibenzocyclooctane; The inorganic silica of the modified inorganic silica filler is selected from silica powder, and the maximum particle size of the silica powder ranges from 25 to 75 μm; The mass ratio of the inorganic silica to the γ-glycidoxypropyltrimethoxysilane ranges from 100:0.2 to 100:0.5; The mass ratio of the inorganic silica to the aminated dibenzocyclooctane ranges from 100:1 to 100:

5.

2. The liquid epoxy molding compound with a low coefficient of thermal expansion according to claim 1, characterized in that: The epoxy resin is selected from at least one of alicyclic epoxy resin, bisphenol F epoxy resin, bisphenol A epoxy resin, polycyclic aromatic epoxy resin, phenolic epoxy resin, and biphenyl structure epoxy resin.

3. The liquid epoxy molding compound with a low coefficient of thermal expansion according to claim 1, characterized in that: The curing agent is selected from at least one of acid anhydride curing agent, amine curing agent, phenolic curing agent, and thiol curing agent.

4. The liquid epoxy molding compound with a low coefficient of thermal expansion according to claim 1, characterized in that: The accelerator is selected from imidazole accelerator or modified amine accelerator.

5. A method of producing a liquid epoxy sealing material having a low coefficient of thermal expansion according to any one of claims 1 to 4, characterized by: The method comprises the following steps: Step 1: First, mix inorganic silica with γ-glycidoxypropyltrimethoxysilane, perform the first reaction under vacuum, then add aminated dibenzocyclooctane to perform the second reaction under vacuum to obtain the modified inorganic silica filler; Step 2: Mix epoxy resin with the modified inorganic silica filler uniformly, then add a curing agent and an accelerator to obtain a preliminary mixture, grind the preliminary mixture, and vacuum degas to obtain the liquid epoxy encapsulating material.

6. The method for preparing a liquid epoxy molding compound with a low coefficient of thermal expansion according to claim 5, characterized in that: In step 1, the temperature of the first reaction ranges from 60 to 120 °C, and the time ranges from 1 to 3 h; The temperature of the second reaction ranges from 100 to 150 °C, and the time ranges from 1 to 3 h.

7. The method for preparing a liquid epoxy molding compound with a low coefficient of thermal expansion according to claim 5, characterized in that: The mixing speed of the preliminary mixture ranges from 1500 to 2500 rpm, and the mixing time ranges from 1 to 10 min; The grinding speed ranges from 1500 to 2500 rpm, and the grinding time ranges from 1 to 10 min.

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