Underfill adhesive with high Tg and low expansion coefficient and preparation method thereof

Abstract

The invention discloses a high-Tg low-expansion-coefficient underfill adhesive and a preparation method thereof. The high-Tg low-expansion-coefficient underfill adhesive comprises the following raw material components in percentage by weight: 10-15% of alicyclic epoxy resin; 15-18% of organic acid anhydride; 0.5%-1.0% of a curing accelerator; 0.1%-0.3% of a defoaming agent; 1-3% of a silane coupling agent; 1.5%-1.8% of carbon powder; and 60-75% of spherical silicon dioxide. By adopting various raw materials with specific proportions and types, the obtained filling adhesive can be quickly cured at low temperature, and element damage caused by high temperature in the packaging process of a heat-sensitive element becomes possible.

Description

Technical Field

[0001] The invention belongs to the technical field of glue and relates to a bottom filling glue, and in particular to a bottom filling glue with high Tg and low expansion coefficient and a preparation method thereof. Background Art

[0002] As a key material for flip chip packaging, bottom filling material can effectively protect high-density solder balls, disperse the stress borne on the chip surface, and increase the processability of chips and packaged devices. Therefore, the use of bottom filling glue can protect the chip circuit surface and solder balls.

[0003] The Chinese invention patent with application number 201910920443.5 discloses a bottom filling glue, which is composed of the following raw material components in mass percentage: 35-43% bisphenol F epoxy resin, 1-2% imidazole catalyst, 0.3-0.5% silicone defoamer, 55-63% SiO2, and 0.5-0.7% carbon black. The bottom filling glue adopts bisphenol F epoxy resin under the action of imidazole catalyst, and is evenly mixed with silicone defoamer, silica and carbon black, so that the linear expansion coefficient of the prepared bottom filling glue can be effectively controlled, and the capillary fluidity is good, so that it has good cold and heat shock resistance, good adhesion, low total chlorine, low potassium, low sodium and other advantages. The Chinese invention patent with application number 202010927606.5 discloses a thermal conductive filling glue and its preparation method and application. The raw materials of the thermally conductive bottom filling glue are as follows: 10 to 50 parts by weight of epoxy resin, 7 to 10 parts by weight of silicone-modified epoxy resin, 1 to 3 parts by weight of curing agent, 0.1 to 0.5 parts by weight of defoaming agent, 3 to 25 parts by weight of diluent, and 160 to 1200 parts by weight of filler. As the bottom filling glue, the thermally conductive filling glue maintains the original bottom filling glue characteristics, low CTEa1, low viscosity, good capillary fluidity, and has a high thermal conductivity of 2.5W / mK to 4.0W / mK.

[0004] However, the current bottom filling glue has a slightly slow curing speed and there are problems of delamination and cracking when used in narrow-pitch and large-size chips. Summary of the invention

[0005] In order to solve the above technical problems, the object of the present invention is to provide a bottom filling glue with high Tg and low expansion coefficient.

[0006] In order to achieve the above object, the present invention provides a bottom filling adhesive with high Tg and low expansion coefficient, which comprises the following raw material components in percentage by weight:

[0007]

[0008]

[0009] Optimally, the alicyclic epoxy resin is a mixture of one or more selected from 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, hexahydrophthalic acid diglycidyl ether, 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester and CELLOXIDEE HPE3150CE.

[0010] Optimally, the organic acid anhydride is a mixture of one or more selected from phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride and maleic anhydride.

[0011] Optimally, the curing accelerator is an amine accelerator or a phosphorus accelerator, and the phosphorus accelerator is a mixture of one or more selected from methoxymethyltriphenylphosphine chloride, methyltriphenylphosphine bromide, ethyltriphenylphosphine bromide, ethyltriphenylphosphine iodide and triphenylphosphine.

[0012] Optimally, the silane coupling agent is a mixture of one or more selected from β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

[0013] Optimally, the defoaming agent is BESM5300, the carbon powder is MA100, and the spherical silica is SS-N10M.

[0014] Another object of the present invention is to provide a method for preparing the above-mentioned bottom filling glue with high Tg and low expansion coefficient, comprising the following steps:

[0015] (a) weighing alicyclic epoxy resin, organic acid anhydride, silane coupling agent and carbon powder in proportion, putting them into a reaction kettle and stirring to form a uniform solution;

[0016] (b) weighing spherical silica in proportion, adding it to the homogeneous solution and stirring evenly; controlling the temperature at 20-30° C., weighing a curing accelerator in proportion, and then adding it to the reaction kettle and stirring evenly;

[0017] (c) Weigh the defoaming agent in proportion and put it into the reaction kettle for vacuum stirring.

[0018] Optimally, in step (c), the vacuum stirring refers to stirring and mixing for 1 to 2 hours under the conditions of a vacuum degree of -0.098 to -0.095 MPa and a rotation speed of 300 to 600 rpm.

[0019] The bottom filling glue with high Tg and low expansion coefficient of the present invention adopts a variety of raw materials in specific proportions and types, so that the obtained filling glue can be quickly cured at low temperature, which makes it possible to avoid component damage caused by high temperature during the packaging process of heat-sensitive components; in addition, the epoxy resin has a stable cyclohexyl molecular structure, and with stable spherical silica, it can effectively reduce the thermal expansion coefficient, solve the problem of delamination and cracking that may occur in the bottom filling glue under narrow spacing and large-size chips, and provide dimensional stability for the packaging application of chips. It is crucial to meet the application of high-density packaging of electronic components with relatively large heat generation. The preparation method of the bottom filling glue with high Tg and low expansion coefficient has the advantages of cost-effectiveness and simple operation in large-scale production.

[0020] The present invention also preferably uses a phosphorus accelerator to optimize the type and amount of phosphorus-containing compounds, which can further improve the comprehensive performance of the bottom filler. For example, by introducing specific phosphorus compounds, the heat resistance of the bottom filler can be significantly improved while maintaining its good electrical insulation properties. The test results show that the shrinkage rate of the filler at high temperature is significantly lower than that of the traditional filler; and in the long-term high-temperature aging test, its adhesion remains stable without obvious softening. The thermal expansion coefficient of the filler is low, which can effectively reduce the stress caused by temperature changes, thereby improving the reliability of chip packaging.

[0021] In order to further verify the performance of the filler in practical applications, the present invention also conducted actual chip packaging tests. In the test, chips of different sizes and types were used, including BGA, CSP and SIP. The test results show that the chip package using the filler performs well in mechanical strength, thermal cycle test and long-term reliability test, meeting the strict requirements of high-density packaging on material performance.

[0022] In summary, the chip bottom filling glue with high Tg and low expansion coefficient disclosed in the present invention not only has superior performance in theory, but also shows good effects in practical applications. The development of this filling glue provides a new material choice for chip packaging technology, which helps to promote the development of electronic packaging technology towards higher performance, smaller size and higher reliability. DETAILED DESCRIPTION

[0023] The bottom filling glue with high Tg and low expansion coefficient of the present invention comprises the following raw material components in percentage by weight: 10-15% of alicyclic epoxy resin; 15-18% of organic anhydride; 0.5-1.0% of curing accelerator; 0.1-0.3% of defoaming agent; 1-3% of silane coupling agent; 1.5-1.8% of carbon powder; and 60-75% of spherical silica. By adopting a variety of raw materials in specific proportions and types, the obtained filling glue can be quickly cured at low temperature, making it possible to avoid component damage caused by high temperature during the packaging process of heat-sensitive components; in addition, the epoxy resin has a stable cyclohexyl molecular structure, and with the stable spherical silica, it can effectively reduce the thermal expansion coefficient, solve the problem of delamination and cracking that may occur in the bottom filling glue under narrow spacing and large-size chips, and provide dimensional stability for chip packaging applications, which is crucial, while meeting the application of high-density packaging of electronic components with relatively large heat generation.

[0024] The alicyclic epoxy resin is a mixture of one or more selected from 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate (2021P of Daicel Japan), hexahydrophthalic acid diglycidyl ether (Yantai Donghua DE184), 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE85) and CELLOXIDE EHPE3150CE (Daicel Japan). The organic anhydride is a mixture of one or more selected from phthalic anhydride, trimellitic anhydride, pyromellitic dianhydride, tetrahydrophthalic anhydride (THPA), methyltetrahydrophthalic anhydride (MeTHPA) and maleic anhydride. The curing accelerator is an amine accelerator or a phosphorus accelerator, wherein a phosphorus accelerator is preferred. The phosphorus accelerator is a mixture of one or more selected from methoxymethyl triphenylphosphine chloride, methyl triphenylphosphine bromide, ethyl triphenylphosphine bromide, ethyl triphenylphosphine iodide and triphenylphosphine. By introducing specific phosphorus compounds, the heat resistance of the bottom filler can be significantly improved while maintaining its good electrical insulation properties. The test results show that the shrinkage rate of the filler at high temperature is significantly lower than that of the traditional filler; and in the long-term high-temperature aging test, its adhesion remains stable without obvious softening. The filler has a low thermal expansion coefficient and can effectively reduce the stress caused by temperature changes, thereby improving the reliability of chip packaging. The silane coupling agent is a mixture of one or more selected from β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-aminopropyltriethoxysilane. The defoamer is BESM5300, the carbon powder is MA100, and the spherical silica is SS-N10M.

[0025] The preparation method of the bottom filling glue with high Tg and low expansion coefficient comprises the following steps: (a) weighing alicyclic epoxy resin, organic anhydride, silane coupling agent and carbon powder in proportion, putting them into a reactor and stirring to form a uniform solution; (b) weighing spherical silica in proportion, adding it to the uniform solution and stirring evenly; controlling the temperature at 20-30°C, weighing a curing accelerator in proportion, and then putting it into the reactor and stirring evenly; (c) weighing a defoaming agent in proportion, putting it into the reactor and stirring it in vacuum. The preparation method of the bottom filling glue with high Tg and low expansion coefficient has the advantages of cost-effectiveness and simple operation in large-scale production. In step (c), the vacuum stirring refers to stirring and mixing for 1-2 hours under the conditions of vacuum degree -0.098-0.095MPa and rotation speed 300-600 rpm.

[0026] In order to enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only embodiments of a part of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained under the premise of equivalent changes and modifications made by ordinary technicians in the field should belong to the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a bottom filler with high Tg and low expansion coefficient and a preparation method thereof, which are specifically as follows:

[0029] (a) 15 g of 2021p alicyclic epoxy resin produced by Daicel, 17 g of methyltetrahydrophthalic anhydride (MeTHPA) (commercially available), 1.6 g of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Qufu Chenguang), and 1.7 g of MA100 carbon powder were weighed and put into a reaction kettle and stirred for 1 hour to form a uniform solution;

[0030] (b) Weigh 70.9 g of SS-N10M spherical silica produced by Zhejiang Huafei Electronic Substrate, put it into a reactor and stir it for 2 hours to form a uniform solution; control the temperature at 20-30° C., weigh 0.6 g of curing accelerator triphenylphosphine (Annaiji), put it into the reactor and stir it for 1 hour to form a uniform solution;

[0031] (c) Weigh 0.2 g of BESM5300 defoamer produced by Shierli and put it into a reaction kettle. Stir and mix under vacuum degree of -0.098 to -0.095 MPa (measured by China Leierda Instrument No. YL10207224) and rotation speed of 300 to 600 rpm for 1 hour to form a uniform solution to obtain the product.

[0032] Example 2

[0033] This embodiment provides a bottom filling adhesive with a high Tg and a low expansion coefficient and a preparation method thereof, which is basically the same as that in Embodiment 1, except that 15 g of DE184 alicyclic epoxy resin (Yantai Donghua) is added.

[0034] Example 3

[0035] This embodiment provides a bottom filling adhesive with a high Tg and a low expansion coefficient and a preparation method thereof, which is basically the same as that in Embodiment 1, except that 15 g of 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE85) is added.

[0036] Example 4

[0037] This embodiment provides a bottom filling glue with high Tg and low expansion coefficient and a preparation method thereof, which is basically the same as that in Example 1, except that 0.6 g of curing accelerator methyl triphenylphosphonium bromide (Anagy) is weighed.

[0038] Example 5

[0039] This embodiment provides a bottom filling glue with high Tg and low expansion coefficient and a preparation method thereof, which is basically the same as that in Example 1, except that 17 grams of tetrahydrophthalic anhydride (THPA) (Annegy) is used.

[0040] Example 6

[0041] This embodiment provides a bottom filler with high Tg and low expansion coefficient and a preparation method thereof, which are specifically as follows:

[0042] (a) 10 g of 2021p alicyclic epoxy resin produced by Daicel, 18 g of methyltetrahydrophthalic anhydride (MeTHPA) (commercially available), 3.0 g of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Chenguang, Qufu), and 1.8 g of MA100 carbon powder were weighed and put into a reaction kettle and stirred for 1 hour to form a uniform solution;

[0043] (b) Weigh 65.9 g of SS-N10M spherical silica produced by Zhejiang Huafei Electronic Substrate, put it into a reactor and stir it for 2 hours to form a uniform solution; the temperature is controlled at 20-30° C., weigh 1.0 g of curing accelerator triphenylphosphine (Annaiji), put it into the reactor and stir it for 1 hour to form a uniform solution;

[0044] (c) Weigh 0.3 g of BESM5300 defoamer produced by Shierli and put it into a reactor. Stir and mix under vacuum degree of -0.098 to -0.095 MPa (measured by China Leierda Instrument No. YL10207224) and rotation speed of 300 to 600 rpm for 1 hour to form a uniform solution to obtain the product.

[0045] Example 7

[0046] This embodiment provides a bottom filler with high Tg and low expansion coefficient and a preparation method thereof, which are specifically as follows:

[0047] (a) Weigh 15 g of 2021p alicyclic epoxy resin produced by Daicel, 15 g of methyltetrahydrophthalic anhydride (MeTHPA) (commercially available), 1.0 g of β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (Qufu Chenguang), and 1.5 g of MA100 carbon powder, put them into a reaction kettle and stir for 1 hour to form a uniform solution;

[0048] (b) Weigh 66.9 g of SS-N10M spherical silica produced by Zhejiang Huafei Electronic Substrate, put it into a reactor and stir it for 2 hours to form a uniform solution; control the temperature at 20-30° C., weigh 0.5 g of curing accelerator triphenylphosphine (Annaiji), put it into the reactor and stir it for 1 hour to form a uniform solution;

[0049] (c) Weigh 0.1 g of BESM5300 defoamer produced by Shierli and put it into a reactor. Stir and mix under vacuum degree of -0.098 to -0.095 MPa (measured by China Leierda Instrument No. YL10207224) and rotation speed of 300 to 600 rpm for 1 hour to form a uniform solution to obtain the product.

[0050] Comparative Example 1

[0051] This example provides a bottom filling glue and a preparation method thereof, which is basically the same as that in Example 1, except that 10 grams of 2021p alicyclic epoxy resin produced by Daicel is weighed, and the proportion of the alicyclic epoxy resin is less than 10%.

[0052] Comparative Example 2

[0053] This example provides a bottom filling glue and a preparation method thereof, which is basically the same as that in Example 1, except that 20 grams of 2021p alicyclic epoxy resin produced by Daicel is weighed, and the proportion of the alicyclic epoxy resin is more than 15%.

[0054] Comparative Example 3

[0055] This example provides an underfill glue and a preparation method thereof, which is basically the same as that in Example 1, except that 0.6 g of 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) is used as a curing accelerator.

[0056] The performance of the bottom filling glue products in Examples 1-7 and Comparative Examples 1-3 was tested, and the results are listed in Table 1.

[0057] Table 1 Performance of bottom filling glue in Examples 1-7 and Comparative Examples 1-3

[0058]

[0059] Among them, the test standard for HD hardness is GB / T 531-1999, the test standard for linear expansion coefficient α1 is ISO11359-2-1999, the test standard for Tg (℃) is ISO 11359-2-1999, the test standard for capillary flow is GB / T25278-2010, and the test standard for Al / Al shear strength (MPa) is GB / T7124-08.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. At the same time, the above description should be understandable and implementable for those with ordinary knowledge in the relevant technical field. Therefore, other equivalent changes or modifications that do not deviate from the concepts disclosed in the present invention should be included in the scope of protection of the present invention.

Claims

1. A bottom filler with high Tg and low expansion coefficient, characterized in that: It includes the following raw material components in weight percentage: Alicyclic epoxy resin 10~15%; Organic anhydride 15~18%; Curing accelerator 0.5~1.0%; Defoaming agent 0.1~0.3%; Silane coupling agent 1~3%; Toner 1.5~1.8%; Spherical silica 60~75%.

2. The high Tg and low expansion coefficient bottom filler according to claim 1, characterized in that: The alicyclic epoxy resin is a mixture of one or more selected from 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate, hexahydrophthalic acid diglycidyl ether, 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester and CELLOXIDE EHPE3150CE.

3. The high Tg and low expansion coefficient bottom filler according to claim 1, characterized in that: The organic acid anhydride is a mixture of one or more selected from phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride and maleic anhydride.

4. The high Tg and low expansion coefficient bottom filler according to claim 1, characterized in that: The curing accelerator is an amine accelerator or a phosphorus accelerator, and the phosphorus accelerator is a mixture of one or more selected from methoxymethyltriphenylphosphine chloride, methyltriphenylphosphine bromide, ethyltriphenylphosphine bromide, ethyltriphenylphosphine iodide and triphenylphosphine.

5. The high Tg and low expansion coefficient bottom filler according to claim 1, characterized in that: The silane coupling agent is a mixture of one or more selected from β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-aminopropyltriethoxysilane.

6. The high Tg and low expansion coefficient bottom filler according to claim 1, characterized in that: The defoaming agent is BESM5300, the carbon powder is MA100, and the spherical silicon dioxide is SS-N10M.

7. The method for preparing the bottom filling adhesive with high Tg and low expansion coefficient according to any one of claims 1 to 6, characterized in that: The following steps are involved: (a) weighing alicyclic epoxy resin, organic acid anhydride, silane coupling agent and carbon powder in proportion, putting them into a reaction kettle and stirring to form a uniform solution; (b) weighing spherical silica in proportion, adding it to the homogeneous solution and stirring it evenly; controlling the temperature at 20-30° C., weighing a curing accelerator in proportion, and then adding it to the reaction kettle and stirring it evenly; (c) Weigh the defoaming agent in proportion and put it into the reaction kettle for vacuum stirring.

8. The method for preparing the bottom filling adhesive with high Tg and low expansion coefficient according to claim 7, characterized in that: In step (c), the vacuum stirring refers to stirring and mixing for 1 to 2 hours under the conditions of a vacuum degree of -0.098 to -0.095 MPa and a rotation speed of 300 to 600 rpm.

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