阅读说明：本技术 一种流动性能优异的环氧底部填充胶的制备方法 (Preparation method of epoxy underfill with excellent flow property ) 是由 王光霖 王建斌 陈田安 谢海华 于 2021-07-29 设计创作，主要内容包括：本发明公开了一种流动性能优异的环氧底部填充胶,其原料以重量份数计包括如下组分：自合成树脂5～15份、环氧树脂30～60份、稀释剂5～10份、偶联剂1～3份、填料60～70份、固化剂15～35份；其中,所述的自合成树脂由以下重量份数的原料化合而成：含烯基的环氧单体33～36份、含氟单体26～34份、4,4'-二壬基-2,2'-联吡啶1.4～1.8份、α-溴代苯乙酸乙酯1～1.5份、氯化亚铜0.2～0.6份、N,N-二甲基甲酰胺120～160份。本发明的底部填充胶具有优异的流动性能；同时优异流动性能不以牺牲填料的添加量为代价,具有低的CTE,可以保证封装元器件的可靠性,适用于大尺寸芯片的封装。(The invention discloses an epoxy underfill adhesive with excellent flow property, which comprises the following components in parts by weight: 5-15 parts of self-synthetic resin, 30-60 parts of epoxy resin, 5-10 parts of diluent, 1-3 parts of coupling agent, 60-70 parts of filler and 15-35 parts of curing agent; the self-synthesis resin is compounded by the following raw materials in parts by weight: 33-36 parts of alkenyl-containing epoxy monomer, 26-34 parts of fluorine-containing monomer, 1.4-1.8 parts of 4,4 '-dinonyl-2, 2' -bipyridine, 1-1.5 parts of alpha-bromophenylacetic acid ethyl ester, 0.2-0.6 part of cuprous chloride and 120-160 parts of N, N-dimethylformamide. The underfill of the present invention has excellent flow properties; meanwhile, the excellent fluidity is not at the cost of the addition amount of the sacrifice filler, the CTE is low, the reliability of the packaged component can be ensured, and the method is suitable for the packaging of large-size chips.)

1. The epoxy underfill with excellent flow property is characterized by comprising the following components in parts by weight:

5-15 parts of self-synthetic resin, 30-60 parts of epoxy resin, 5-10 parts of diluent, 1-3 parts of coupling agent, 60-70 parts of filler and 15-35 parts of curing agent;

the self-synthesis resin is compounded by the following raw materials in parts by weight: 33-36 parts of alkenyl-containing epoxy monomer, 26-34 parts of fluorine-containing monomer, 1.4-1.8 parts of 4,4 '-dinonyl-2, 2' -bipyridine, 1-1.5 parts of alpha-bromophenylacetic acid ethyl ester, 0.2-0.6 part of cuprous chloride and 120-160 parts of N, N-dimethylformamide.

2. The epoxy underfill of claim 1,

the epoxy monomer containing alkenyl is one or the mixture of more than two of allyl glycidyl ether, glycidyl methacrylate and glycidyl acrylate;

the fluorine-containing monomer is one or the mixture of more than two of methacrylic acid dodecafluoroheptyl ester, perfluoroalkyl ethyl methacrylate and methacrylic acid trifluoroethyl ester.

3. The epoxy underfill of claim 2,

the epoxy monomer containing alkenyl is allyl glycidyl ether, and the fluorine-containing monomer is dodecafluoroheptyl methacrylate;

the structural formula of the self-synthesis resin is as follows:

wherein x is more than or equal to 5 and less than or equal to 50, and y is more than or equal to 5 and less than or equal to 25.

4. The epoxy underfill of claim 3, wherein the synthetic path of the self-synthesizing resin is:

5. the epoxy underfill according to any one of claims 1 to 4, wherein the epoxy resin is one or a mixture of two or more of an alicyclic epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol AD type epoxy resin, a bisphenol S type epoxy resin, a hydrogenated bisphenol A type epoxy resin, a naphthalene type epoxy resin, and an epoxidized phenol resin.

6. The epoxy underfill according to any one of claims 1 to 4,

the diluent is one or a mixture of more than two of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, dodecyl glycidyl ether, 4-tert-butylphenyl glycidyl ether and trihydroxymethyl triglycidyl ether;

the silane coupling agent is one or the mixture of more than two of gamma-glycidyl ether propyl trimethoxy silane, gamma-mercapto propyl trimethoxy silane, gamma-aminopropyl triethoxy silane and phenyl amino propyl trimethoxy silane;

the curing agent is liquid aromatic amine or modified amine curing agent.

7. The epoxy underfill according to any one of claims 1 to 4, wherein the filler is spherical silica.

8. The epoxy underfill according to claim 7, wherein the spherical silica has a particle size of 100 to 250 nm, 5 to 10 μm and 10 to 20 μm.

9. The epoxy underfill of claim 7, wherein the surface of the spherical silica is epoxidised.

10. A method of preparing the epoxy underfill according to any one of claims 1 to 9, comprising the steps of:

(1) mixing cuprous chloride, alpha-bromophenylacetic acid ethyl ester and 4,4 '-dinonyl-2, 2' -bipyridine to obtain a mixture; in N₂Adding an epoxy monomer containing alkenyl, a fluorine-containing monomer and N, N-dimethylformamide into the mixture under the atmosphere, reacting for 7.5-8 hours at 83-87 ℃ under stirring, precipitating by using methanol and washing to obtain synthetic resin;

(2) and (2) putting the self-synthesized resin obtained in the step (1), epoxy resin, a diluent, a coupling agent, a filler and a curing agent into a stirring kettle, uniformly stirring, vacuumizing and defoaming to prepare the epoxy underfill with excellent fluidity.

Technical Field

The invention belongs to the field of adhesives, and particularly relates to a preparation method of an epoxy underfill adhesive with excellent flow property.

Background

Due to the rapid development of intelligent wearable equipment, wireless communication, broadband internet products and new energy automobiles, the integration level of electronic devices is higher and higher, and the chip area is continuously enlarged. As the chip area increases, the Coefficient of Thermal Expansion (Coefficient Thermal Expansion) between the chip and the substrate gradually increases. Therefore, it is necessary to fill underfill between the chip and the substrate to reduce the deformation caused by the difference in thermal expansion coefficient between the chip and the substrate when the system generates heat, and even the crack between the chip and the substrate.

The flip chip technology is one of the main technologies of the current chip packaging, the chip faces downwards to be interconnected with a substrate, and a chip electrode and a substrate wiring layer are firmly welded through a welding spot. The flip chip technology has the characteristics of high packaging density, short interconnection distance, and excellent electrical property and reliability. The underfill is used as a material applied to the flip chip technology, and is filled in a gap between a chip and a substrate connected with a solder ball through capillary action, so that the chip, the solder ball salient point and the substrate are tightly and firmly connected together, a welding point is sealed and protected, and stress generated on the welding point due to mismatch of thermal expansion coefficients of the chip and the substrate is reduced. The underfill has a non-negligible effect on improving the reliability of electronic packaging.

During the packaging process of large-size chips, the underfill has been a complicated problem for the filling of large-size chips. The large area of the large chip makes the difference in the coefficient of thermal expansion between the large chip and the substrate large, requiring the underfill to have a lower CTE to balance the difference in the coefficient of thermal expansion between the large chip and the substrate. Therefore, underfill applied to large-sized chips has a high filler content. Meanwhile, the viscosity of the underfill is increased due to the high filler content, the fluidity of the underfill is deteriorated at the process temperature, and the underfill cannot be completely and rapidly filled between the chip and the substrate, so that the problems of bubbles, cracking and the like are caused. How to make the underfill have both low CTE and excellent flow property is a key issue of attention and research of most researchers.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the preparation method of the epoxy underfill with excellent flow property, and the prepared product has excellent flow speed and low CTE and ensures that the chip package has higher reliability.

The specific technical scheme is as follows:

the invention aims to provide an epoxy underfill adhesive with excellent flow property, which comprises the following raw materials in parts by weight:

5-15 parts of self-synthetic resin, 30-60 parts of epoxy resin, 5-10 parts of diluent, 1-3 parts of coupling agent, 60-70 parts of filler and 15-35 parts of curing agent;

the self-synthesis resin is compounded by the following raw materials in parts by weight: 33-36 parts of an alkenyl-containing epoxy monomer, 26-34 parts of a fluorine-containing monomer, 1.4-1.8 parts of 4,4 '-dinonyl-2, 2' -bipyridine, 1-1.5 parts of alpha-bromoethyl phenylacetate, 0.2-0.6 part of cuprous chloride and 120-160 parts of N, N-dimethylformamide.

The invention has the beneficial effects that: the underfill disclosed by the invention has excellent flowing property, high flowing speed and complete filling, and reduces defects formed in the flowing and curing process; meanwhile, the excellent fluidity is not at the cost of the addition amount of the sacrifice filler, the CTE is low, the reliability of the packaged component can be effectively ensured, and the method is suitable for the packaging of large-size chips.

Further, the self-synthesizing resin is prepared by Atom Transfer Radical Polymerization (ATRP), and the obtained polymer has a narrow molecular weight distribution.

The beneficial effect of adopting the further scheme is that: fluoropolymers have a particularly low surface energy and therefore excellent flow properties; meanwhile, the fluorine-containing polymer has excellent surface hydrophobicity and remarkable chemical resistance, so that the reliability of chip packaging is further ensured; on one hand, epoxy groups on a polymer chain can participate in curing and crosslinking, and form a three-dimensional network with epoxy resin, so that the toughness and the impact resistance of the underfill are improved; on the other hand, the epoxy group can make up the defect of poor bonding property of the fluorine-containing polymer and endow the material with excellent bonding property.

Further, the epoxy monomer containing alkenyl is one or a mixture of more than two of allyl glycidyl ether, glycidyl methacrylate and glycidyl acrylate.

The beneficial effect of adopting the further scheme is that: the epoxy monomer containing alkenyl is copolymerized with the fluorine-containing monomer, and the defect of weak bonding force of the fluorine-containing polymer is made up through high bonding strength of the epoxy group.

Further, the fluorine-containing monomer is one or a mixture of more than two of dodecafluoroheptyl methacrylate, perfluoroalkyl ethyl methacrylate and trifluoroethyl methacrylate.

The beneficial effect of adopting the further scheme is that: the fluorine-containing monomer is polymerized to obtain the fluorine-containing polymer, and the fluorine-containing polymer has special low surface energy and can endow the underfill with excellent flowing property; meanwhile, the fluorine-containing polymer has excellent surface hydrophobicity and remarkable chemical resistance, and the reliability in the chip packaging process is ensured.

Still further, the epoxy monomer containing alkenyl is allyl glycidyl ether, and the fluorine-containing monomer is dodecafluoroheptyl methacrylate;

the structural formula of the self-synthesis resin is as follows:

wherein x is more than or equal to 5 and less than or equal to 50, and y is more than or equal to 5 and less than or equal to 25.

The synthetic route of the self-synthetic resin is as follows:

the epoxy resin is one or a mixture of two or more of alicyclic epoxy resin, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AD epoxy resin, bisphenol S epoxy resin, hydrogenated bisphenol A epoxy resin, naphthalene epoxy resin, and epoxidized phenol resin. Wherein the alicyclic epoxy resin is Celloxide 2021P of Daluo Japan, the bisphenol A epoxy resin is EPIKOTE 828EL of Vast of Netherlands, the bisphenol F epoxy resin is YL983U of Mitsubishi Japan, and the naphthalene epoxy resin is HP 4032D of DIC corporation.

The beneficial effect of adopting the further scheme is that: different types of epoxy resin are selected for matching, so that the properties of the bottom filling adhesive, such as the Tg point, the bonding strength, the tensile strength, the modulus and the like, reach a balance point, and the bottom filling adhesive has excellent comprehensive properties.

Further, the diluent is one or a mixture of more than two of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, dodecyl glycidyl ether, 4-tert-butylphenyl glycidyl ether and trihydroxymethyl triglycidyl ether.

The beneficial effect of adopting the further scheme is that: the viscosity of the system is adjusted by the diluent so as to meet the requirement of the sizing process of the underfill and adjust the surface smoothness and flatness of the cured product.

Further, the silane coupling agent is one or the mixture of more than two of gamma-glycidyl ether propyl trimethoxy silane, gamma-mercapto propyl trimethoxy silane, gamma-aminopropyl triethoxy silane and phenyl amino propyl trimethoxy silane.

The beneficial effect of adopting the further scheme is that: the silane coupling agent is beneficial to improving the wettability of the underfill to the base material and improving the fluidity; improving the compatibility between the resin and the filler; the wettability of the underfill to the substrate is improved, and the bonding strength is enhanced.

Further, the curing agent is liquid aromatic amine or modified amine curing agent. Among them, the liquid aromatic amine-based curing agent is preferably one or a mixture of two or more of 3-3 '-diethyl-4, 4' -diaminodiphenylmethane, 3, 5-diethyltoluene-2, 4-diamine, and 3, 5-diethyltoluene-2, 6-diamine. Wherein the modified amine curing agent is one or a mixture of more than two of polyether amine, 591 curing agent, 793 curing agent and 590 curing agent.

The beneficial effect of adopting the further scheme is that: the underfill is ensured to have excellent flowing property, and the requirement of the underfill on the packaging of large-size chips is met; the requirements of curing temperature and curing speed required by a large-size chip packaging process are met.

The filler is spherical silica, preferably spherical silica compositions with different particle sizes, and more preferably compositions with particle sizes of 100-250 nanometers, 5-10 micrometers and 10-20 micrometers. The surface of the spherical silica is preferably subjected to epoxidation treatment, and the spherical silica is preferably epoxidized spherical silica of Jiangsonirui. Further, the mass ratio of the spherical silicon dioxide with the particle size of 100-250 nanometers, 5-10 micrometers and 10-20 micrometers is preferably 1: (3-6): (8-16).

The beneficial effect of adopting the further scheme is that: compared with non-spherical silica powder, the spherical silica powder has better fluidity under the condition of the same filler content; the combination of the silica micro powder with different particle sizes can maximize the addition of the filler under the condition of the same viscosity, so that the underfill has lower CTE, and the reliability of large-size chip packaging is ensured.

The second object of the present invention is to provide a method for preparing the epoxy underfill having excellent flow properties, which comprises the following steps:

(1) mixing cuprous chloride, alpha-bromophenylacetic acid ethyl ester and 4,4 '-dinonyl-2, 2' -bipyridine to obtain a mixture; in N₂Adding an alkenyl-containing epoxy monomer, a fluorine-containing monomer and N, N-dimethylformamide to the mixture under an atmosphere at 8Reacting for 7.5-8 hours at 3-87 ℃ under stirring, precipitating and washing by using methanol, and obtaining synthetic resin;

(2) and (2) putting the self-synthesized resin obtained in the step (1), epoxy resin, a diluent, a coupling agent, a filler and a curing agent into a stirring kettle, uniformly stirring, vacuumizing and defoaming to prepare the epoxy underfill with excellent fluidity.

Detailed Description

The principles and features of this invention are described below in conjunction with examples, which are set forth to illustrate, but are not to be construed to limit the scope of the invention.

Example 1

The preparation method of the epoxy underfill with excellent flow property comprises the following steps:

(1) 0.4g of cuprous chloride, 1.5g of ethyl alpha-bromophenylacetate and 1.4g of 4,4 '-dinonyl-2, 2' -bipyridine were sequentially added to a hermetically dried Schlenk tube, followed by N for three times₂Circulating to remove air in the pipe; then at N₂Allyl glycidyl ether (35.3mL), dodecafluoroheptyl methacrylate (18.8mL), and N, N-dimethylformamide (138.0mL) were added to the tube under an atmosphere; reacting for 8 hours under the condition of magnetic stirring at 85 ℃, and removing the residual catalyst, unreacted monomers and ligand by methanol precipitation and washing for three times to obtain the self-synthesis resin.

(2) At normal temperature, by weight, sequentially putting 10 parts of the self-synthetic resin obtained in the step (1), EPIKOTE 828EL 45 parts of bisphenol A epoxy resin, HP 4032D 15 parts of naphthalene epoxy resin, 5 parts of dodecyl glycidyl ether, 3 parts of gamma-aminopropyltriethoxysilane, 65 parts of Jiangsuo epoxidized spherical silica (5 parts of 150-nanometer spherical silica, 15 parts of 10-micrometer spherical silica and 45 parts of 20-micrometer spherical silica) and 30 parts of 3-3 '-diethyl-4, 4' -diamine diphenylmethane into a stirring kettle, uniformly stirring, vacuumizing and defoaming to obtain the epoxy underfill with excellent flow property.

Example 2

The preparation method of the epoxy underfill with excellent flow property comprises the following steps:

(1) the same as in example 1.

(2) At normal temperature, by weight, sequentially putting 10 parts of the self-synthetic resin obtained in the step (1), 10 parts of alicyclic epoxy resin Celloxide 2021P 45 parts, 15 parts of naphthalene type epoxy resin HP 4032D, 5 parts of dodecyl glycidyl ether, 3 parts of gamma-aminopropyl triethoxysilane, 65 parts of Jiangsuerui epoxidized spherical silica (5 parts of 150-nanometer spherical silica, 15 parts of 10-micrometer spherical silica and 45 parts of 20-micrometer spherical silica) and 30 parts of 3-3 '-diethyl-4, 4' -diamine diphenylmethane into a stirring kettle, uniformly stirring, and vacuumizing and defoaming to obtain the epoxy underfill with excellent flow property.

Example 3

The preparation method of the epoxy underfill with excellent flow property comprises the following steps:

(1) the same as in example 1.

(2) At normal temperature, by weight, sequentially putting 10 parts of the self-synthetic resin obtained in the step (1), 30 parts of bisphenol A epoxy resin EPIKOTE 828EL, 20 parts of bisphenol F epoxy resin YL983U 20, 10 parts of naphthalene epoxy resin HP 4032D, 5 parts of dodecyl glycidyl ether, 3 parts of gamma-glycidyl ether propyl trimethoxy silane, 70 parts of Jiangsuo Union epoxy spherical silica (5 parts of 150-nanometer spherical silica, 20 parts of 10-micrometer spherical silica and 45 parts of 20-micrometer spherical silica) and 30 parts of 3, 5-diethyltoluene-2, 4-diamine into a stirring kettle, uniformly stirring, vacuumizing and defoaming to obtain the epoxy underfill with excellent flow property.

Example 4

The preparation method of the epoxy underfill with excellent flow property comprises the following steps:

(1) the same as in example 1.

(2) At normal temperature, by weight, 5 parts of the self-synthetic resin obtained in the step (1), 20 parts of alicyclic epoxy resin Celloxide 2021P, 25 parts of bisphenol F epoxy resin YL983U 25, 10 parts of naphthalene epoxy resin HP 4032D, 5 parts of butyl glycidyl ether, 3 parts of gamma-glycidyl ether propyl trimethoxy silane, 70 parts of Jiangsuo Union epoxy spherical silica (150 nanometer spherical silica 5 parts, 10 micrometer spherical silica 20 parts and 20 micrometer spherical silica 45 parts), and 30 parts of 3, 5-diethyltoluene-2, 4-diamine are sequentially put into a stirring kettle, uniformly stirred, vacuumized and defoamed to prepare the epoxy underfill adhesive with excellent flow property.

Example 5

The preparation method of the epoxy underfill with excellent flow property comprises the following steps:

(1) the same as in example 1.

(2) At normal temperature, by weight, sequentially putting 10 parts of the self-synthetic resin obtained in the step (1), 10 parts of alicyclic epoxy resin Celloxide 2021P 25 parts, 30 parts of bisphenol F epoxy resin YL983U 30 parts, 5 parts of 4-tert-butylphenyl glycidyl ether, 3 parts of phenylaminopropyl trimethoxy silane, 70 parts of Jiangsuerui epoxidized spherical silica (5 parts of 150-nanometer spherical silica, 20 parts of 10-micrometer spherical silica and 45 parts of 20-micrometer spherical silica) and 30 parts of 3, 5-diethyltoluene-2, 4-diamine into a stirring kettle, uniformly stirring, vacuumizing and defoaming to obtain the epoxy underfill with excellent flow property.

Comparative example 1

Preparing a common underfill:

at normal temperature, by weight, 30 parts of bisphenol A epoxy resin EPIKOTE 828EL, 25 parts of bisphenol F epoxy resin YL983U 25 parts, 15 parts of naphthalene epoxy resin HP 4032D, 5 parts of dodecyl glycidyl ether, 3 parts of gamma-aminopropyl triethoxysilane, 70 parts of Jiangsuo epoxidized spherical silica (5 parts of 150 nm spherical silica, 20 parts of 10 micron spherical silica and 45 parts of 20 micron spherical silica) and 30 parts of 3, 5-diethyltoluene-2, 4-diamine are sequentially put into a stirring kettle, uniformly stirred and vacuumized and defoamed to prepare a sample.

The comparative example is different from example 3 in that 10 parts of the self-synthesized resin was replaced with 10 parts of bisphenol F type epoxy resin YL983U 5 parts and naphthalene type epoxy resin HP 4032D 5 parts.

Testing

The properties of the underfill of the above examples 1 to 5 of the present invention and comparative examples were tested by the following tests. Wherein the flow performance is characterized by the size of the void ratio value and the flow speed; the curing properties are characterized by the curing speed of the DSC curve; the reliability of the packaged components is characterized by the value of the Coefficient of Thermal Expansion (CTE).

Test 1 voidage test

Assembling a 24mm multiplied by 24mm test piece, filling the gap of the test piece with the underfill, completely curing the underfill at 165 ℃, then slicing the test piece, observing the slice by using a scanning electron microscope, and calculating the void ratio.

Test 2 flow Performance test

The PCB and the silicon chip are connected through solder balls, the diameter of each solder ball is 0.4mm, the center distance of each solder ball is 0.8mm, the height of each solder ball is 0.15mm, and the flowing speed of a BGA (ball grid array) packaged chip at 65 ℃ is simulated.

Test 3 Cure Performance test

Obtained by DSC curing constant temperature curve, the heating rate is 50 ℃/min, and the constant temperature is 165 ℃ for curing.

Test 4 coefficient of thermal expansion test (CTE)

Obtained by TMA testing, the rate of temperature rise was 10 ℃/min, in μm/m ℃. Tested according to ASTM D696.

The results of tests 1-4 are shown in Table 1.

TABLE 1 comparison of test Performance of samples prepared in examples 1-5 with that of comparative example 1

As can be seen from the data in Table 1, the underfill of the present invention has excellent flow properties, exhibiting a fast flow rate during the filling of large-sized chips; meanwhile, the underfill has high filler content and low CTE, and solves the problem of contradiction between the flow speed and the high filler content; compared with the traditional underfill, the underfill has obvious advantages, and the packaged component has higher reliability.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.