1. The utility model provides an underfill for electronic packaging device which characterized in that: the underfill is mainly composed of the following raw materials in percentage by mass:

wherein the particle size of the modified silicon dioxide is 0.1-100 μm, and the particle size of the nano silicon dioxide is 50-100 nm.

2. The underfill of claim 1, wherein: the underfill adhesive is prepared from the following raw materials in percentage by mass:

wherein the particle size of the modified silicon dioxide is 0.1-100 μm, and the particle size of the nano silicon dioxide is 50-100 nm.

3. The underfill of claim 1 or 2, wherein: the epoxy resin is at least one selected from high-purity glycidyl amine epoxy resin, high-purity trifunctional aminophenol epoxy resin, double-type glycidyl ether epoxy resin and naphthol epoxy resin.

4. The underfill of claim 1 or 2, wherein: the curing agent is at least one selected from methyl tetrahydrophthalic anhydride, methyl hexahydrophthalic anhydride, phthalic anhydride and tetrahydrophthalic anhydride.

5. The underfill of claim 1, wherein: the underfill also comprises 0.2-0.5% by mass of a pigment selected from carbon black.

6. The underfill of claim 1, wherein: the accelerator is at least one selected from imidazole accelerators and modified amine accelerators.

7. A method of preparing the underfill of any one of claims 1 to 6, comprising the steps of:

preparing a silane coupling agent and styrene monomer modified silicon dioxide;

providing epoxy resin, nano silicon dioxide, a curing agent, a pigment and an accelerator, adding the epoxy resin, the nano silicon dioxide, the curing agent, the pigment and the accelerator into the modified silicon dioxide according to a certain proportion, and mixing to obtain a mixture; and

and rolling the mixture, and performing vacuum defoaming to obtain the underfill.

8. The method of claim 7, wherein: the method for preparing the silane coupling agent and the styrene monomer modified silicon dioxide comprises the following steps:

providing silica and adding to a vessel;

adding water into the container, stirring and heating to 70-90 ℃;

adding a silane coupling agent into the container, and carrying out heat preservation reaction for a period of time T₁Obtaining surface-modified silicon dioxide;

adding styrene monomer and initiator into the surface modified silicon dioxide, and reacting for a period of time T₂Obtaining suspension; and

and filtering the suspension, and drying to obtain the silane coupling agent and the styrene monomer modified silicon dioxide.

9. The method of claim 8, wherein: the molar ratio of the silica to the silane coupling agent ranges from (7-4): (2-1).

10. The method of claim 8, wherein: the molar ratio of the surface-modified silicon dioxide, the styrene monomer and the initiator is (8-4): (2-1): (0.3-0.1).

11. The method of claim 8, wherein: the time T1 is 10-18h, and the time T2 is 4-10 h.

12. An electronic packaging device comprises a substrate, a chip arranged on one surface of the substrate, and a plurality of solder ball nodes arranged between the substrate and the chip and electrically connected with the substrate and the chip, wherein an underfill material is filled between the substrate and the chip, and the electronic packaging device is characterized in that: the underfill material is formed by curing the underfill paste of any one of claims 1 to 6.

Background

The underfill is widely applied to circuit board packaging of portable electronic products such as MP3, USB, mobile phones, Bluetooth and the like, is a key material in the packaging technology of electronic devices, is used for filling between a chip and a substrate, dispersing stress borne by the surface of the chip, relieving internal stress generated by mismatching of thermal expansion coefficients of the chip, a solder and the substrate, reducing stress impact caused by difference of the thermal expansion coefficients between the chip and the substrate, and improving the structural strength and reliability of the electronic devices.

With the continuous development of the electronic information industry and the continuous innovation of the technology, the requirements on the packaging technology of electronic products are higher and higher, and the chip packaging is required to have the advantages of high density, small volume, low power consumption, rapidness, smaller delay, low cost and the like.

Whether the underfill is effective or not is related to the difference of the linear expansion coefficients of the chip and the substrate, the thermal expansion coefficient of the underfill is reduced, and the thermal expansion coefficient of the welding salient points can be adjusted, so that the reliability of chip packaging is improved, and the service life of the chip packaging is prolonged. In addition, the lower the thermal expansion coefficient of the underfill, the better its adhesion to the surface of the chip, and the stronger the weather resistance. However, the thermal expansion coefficient of the existing underfill is high, and the requirement of advanced process packaging below 7nm cannot be met, so that the further development of the high-density system-in-package technology is restricted.

In order to reduce the linear expansion coefficient, the filling amount of the toughening agent and the silicon dioxide is generally increased by the conventional underfill. However, increasing the amount of the toughening agent and silica in the underfill raises the viscosity of the system, and the problem of uneven dispersion occurs when the silica content is too high, which impairs the flow properties of the underfill and does not meet the requirements of low viscosity and high fluidity of the sealing material required for electronic package device mounting. In addition, increasing the loading of the toughening agent also decreases the impact resistance of the underfill, making it more difficult to maintain the adhesion of the underfill to the substrate during transportation of the electronic package device.

Disclosure of Invention

The application provides an underfill for electronic packaging devices, aiming at improving the problem that the expansion coefficient of the existing underfill is higher.

The embodiment of the application is realized by the following steps that the underfill for the electronic packaging device mainly comprises the following raw materials in percentage by mass:

wherein the particle size of the modified silicon dioxide is 0.1-100 μm, and the particle size of the nano silicon dioxide is 50-100 nm.

Optionally, in some embodiments of the present application, the underfill is composed of the following raw materials by mass:

wherein the particle size of the modified silicon dioxide is 0.1-100 μm, and the particle size of the nano silicon dioxide is 50-100 nm.

Optionally, in some embodiments herein, the epoxy resin is selected from at least one of a high purity glycidyl amine epoxy resin, a high purity trifunctional aminophenol epoxy resin, a bis-glycidyl ether type epoxy resin, and a naphthol epoxy resin.

Optionally, in some embodiments herein, the curing agent is selected from at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, phthalic anhydride, and tetrahydrophthalic anhydride.

Optionally, in some embodiments of the present application, the underfill further includes a pigment in an amount of 0.2 to 0.5% by mass.

Optionally, in some embodiments herein, the pigment is selected from carbon black.

Optionally, in some embodiments herein, the accelerator is selected from at least one of imidazole accelerators and modified amine accelerators.

Correspondingly, the embodiment of the application also provides a preparation method of the underfill for the electronic packaging device, which comprises the following steps:

preparing a silane coupling agent and styrene monomer modified silicon dioxide;

providing epoxy resin, nano silicon dioxide, a curing agent, a pigment and an accelerator, adding the epoxy resin, the nano silicon dioxide, the curing agent, the pigment and the accelerator into the modified silicon dioxide according to a certain proportion, and mixing to obtain a mixture; and

and rolling the mixture, and performing vacuum defoaming to obtain the underfill.

Optionally, in some embodiments of the present application, the method for preparing the silane coupling agent and the styrene monomer modified silica comprises:

providing silica and adding to a vessel;

adding water into the container, stirring and heating to 70-90 ℃;

adding a silane coupling agent into the container, and carrying out heat preservation reaction for a period of time T₁Obtaining surface-modified silicon dioxide;

adding styrene monomer and initiator into the surface modified silicon dioxide, and reacting for a period of time T₂Obtaining suspension; and

and filtering the suspension, and drying to obtain the silane coupling agent and the styrene monomer modified silicon dioxide.

Alternatively, in some embodiments herein, the silica to silane coupling agent molar ratio ranges from (7-4): (2-1).

Optionally, in some embodiments of the present application, the surface modified silica, the styrene monomer, and the initiator are present in a molar ratio ranging from (8-4): (2-1): (0.3-0.1).

Optionally, in some embodiments of the present application, the time T1 is 10 to 18h, and the time T2 is 4 to 10 h.

Correspondingly, the embodiment of the application also provides an electronic packaging device, which comprises a substrate, a chip arranged on one surface of the substrate, and a plurality of solder ball nodes arranged at intervals, wherein the solder ball nodes are arranged between the substrate and the chip and are electrically connected with the substrate and the chip, an underfill material is filled between the substrate and the chip, and the underfill material is formed by curing the underfill adhesive.

The application has the following beneficial effects:

the low-expansion-coefficient underfill adhesive for the electronic packaging device comprises silane coupling agent and styrene monomer modified silicon dioxide, wherein the surface of the modified silicon dioxide is a polystyrene layer, so that hydrogen bonds on the surface of the silicon dioxide can be eliminated, and the surface of the modified silicon dioxide does not have hydrogen bonds. Thus, the modified silica particles have less interaction force between them, have greater dispersibility, and are more easily dispersed in the underfill. Therefore, the filling amount of the modified silicon dioxide in the low-expansion-coefficient underfill of the electronic packaging device can be 75-80% by mass, the phenomenon of uneven dispersion does not exist, the thermal expansion coefficient of the underfill can be effectively reduced, and the packaging requirement of an advanced process below 7nm is met. In addition, the synergistic effect of the components of the low coefficient of expansion underfill further enables the underfill of the present application to have a lower coefficient of thermal expansion.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a flowchart of a method for preparing an underfill for an electronic package device according to an embodiment of the present disclosure;

fig. 2 is a schematic structural diagram of an electronic package device provided in an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Furthermore, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are given by way of illustration and explanation only, and are not intended to limit the scope of the invention. In the description of this application, the term "including" means "including but not limited to". Various embodiments of the invention may exist in a range of forms; it is to be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention; accordingly, the described range descriptions should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, it is contemplated that the description of a range from 1 to 6 has specifically disclosed sub-ranges such as, for example, from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within a range such as, for example, 1, 2, 3, 4, 5, and 6, as applicable regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any number (fractional or integer) recited within the indicated range.

The embodiment of the application provides an underfill adhesive for an electronic packaging device, which mainly comprises the following raw materials in percentage by mass:

the epoxy resin may be selected from, but not limited to, at least one of a high-purity glycidyl amine epoxy resin, a high-purity trifunctional aminophenol epoxy resin, a double-type glycidyl ether epoxy resin, and a naphthol epoxy resin. In at least one preferred embodiment, the high purity glycidyl amine epoxy resin is selected from SE-300P of SHIN-A, KoreA, the high purity trifunctional aminophenol epoxy resin is selected from Complex high New EPM-304H, the bis type glycidyl ether type epoxy resin is selected from EXA-4850, and the naphthol epoxy resin is selected from HP-4032D, respectively, of DIC, Japan. The epoxy resin has low thermal expansion coefficient and good compatibility with silicon dioxide.

The modified silicon dioxide is silane coupling agent and styrene monomer modified silicon dioxide. The surface of the modified silica is a polystyrene layer, in other words, the polystyrene layer coats the silica particles. Therefore, hydrogen bonds on the surface of the silicon dioxide can be eliminated, so that the surface of the modified silicon dioxide has no hydrogen bonds, the acting force among the modified silicon dioxide particles is smaller, the dispersibility is stronger, and the modified silicon dioxide particles are easier to disperse in the underfill. Therefore, the filling amount of the modified silicon dioxide in the low-expansion-coefficient underfill of the electronic packaging device can be 75-80% by mass, the phenomenon of uneven dispersion does not exist, and the thermal expansion coefficient of the underfill can be effectively reduced.

The particle size range of the modified silicon dioxide is 0.1-100 mu m. The modified silicon dioxide with different particle sizes can be selected according to the size of the gap between the chip and the packaging substrate and/or the size of the gap between the solder ball nodes, and the particle size of the modified silicon dioxide is preferably 0.1-5 μm when the gap is in the range of 100 μm as an example; when the gap between the chip and the packaging substrate is in the range of 50-100 μm, the particle size of the modified silicon dioxide is preferably 0.1-2 μm; when the gap between the chip and the packaging substrate is in the range of 15-50 μm, the particle size of the modified silicon dioxide is preferably 0.1-0.5 μm; when the gap between the chip and the package substrate is in the range of 6 to 15 μm, the particle size of the modified silica is preferably 0.1 to 0.3 μm.

The silane coupling agent may be selected from, but is not limited to, at least one of gamma-methacryloxypropyltrimethoxysilane, vinyltris 2-methoxyethoxysilane, 3-aminopropyltrimethoxysilane and diphenyldimethoxysilane.

The nano silicon dioxide is preferably silicon dioxide with the particle size of 50-100 nm. The nano-silica can be filled in gaps among the modified silica, so that the content of the silica in the underfill is increased, and the thermal expansion coefficient of the underfill is further reduced.

The curing agent may be selected from, but not limited to, at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, phthalic anhydride, and tetrahydrophthalic anhydride.

The low expansion coefficient underfill also includes a pigment. The pigment is a pigment known in the art for use in underfill, such as carbon black and the like, and is not limited herein. In the low-expansion-coefficient underfill adhesive, the mass percentage of the pigment is 0.2-0.5%.

The accelerator may be selected from, but not limited to, at least one of imidazole accelerators and modified amine accelerators. In at least one preferred embodiment, the imidazole-based accelerator is selected from 2-ethyl-4-methylimidazole and the modified amine-based accelerator is selected from fuji 7000 and 7001. The accelerator of the kind has low self-viscosity and strong latency.

The underfill contains silane coupling agent and styrene monomer modified silicon dioxide, and under the synergistic effect of the components in a specific proportion, the underfill has a low thermal expansion coefficient and can meet the requirement of advanced process packaging below 7 nm.

Referring to fig. 1, an embodiment of the present application further provides a method for preparing an underfill for an electronic package device, including the following steps:

step S1: preparing a silane coupling agent and styrene monomer modified silicon dioxide;

step S2: providing epoxy resin, nano-silica, a curing agent, a pigment and an accelerator, adding the epoxy resin, the nano-silica, the curing agent, the pigment and the accelerator into the silane coupling agent and the styrene monomer modified silica according to a certain ratio, and mixing to obtain a mixture; and

step S3: and rolling the mixture, and performing vacuum defoaming to obtain the low-expansion-coefficient underfill for the electronic packaging device.

In at least one embodiment, the step S1 specifically includes:

step S11: providing silica and adding to a vessel;

step S12: adding deionized water into the container, stirring and heating to 70-90 ℃;

step S13: adding a silane coupling agent into the container, and carrying out heat preservation reaction for a period of time T₁Obtaining surface-modified silicon dioxide;

step S14: adding styrene monomer and initiator into the surface modified silicon dioxide, and reacting for a period of time T₂Obtaining suspension; and

step S15: and filtering the suspension, and drying to obtain the silane coupling agent and the styrene monomer modified silicon dioxide.

In step S11, the container may be a container that is conventionally used for chemical reactions, such as a four-neck flask.

The molar ratio of the silica in the step S11 to the silane coupling agent in the step S13 is in the range of (7-4): (2-1).

In the step S13, the time T1 is 10-18 h.

In the step S14, the molar ratio of the surface-modified silica to the styrene monomer to the initiator is in the range of (8-4): (2-1): (0.3-0.1).

In at least one embodiment, the styrene monomer is added slowly, at a rate of 2 drops per second.

The time T2 is 4-10 h.

The initiator may be selected from, but is not limited to, at least one of ammonium persulfate, benzoyl peroxide, dibenzoyl peroxide, and dicumyl peroxide.

In the step S15, the drying is preferably performed at a low temperature of 35 to 60 ℃.

In the step S2, the proportions and types of the epoxy resin, the nano-silica, the curing agent, the pigment and the accelerator are as described above, and are not described herein again.

In at least one embodiment, the mixing is performed by using a centrifugal mixer, wherein the mixing time is 90-300s, the rotation speed of the mixing shaft of the centrifugal mixer is 600-.

In step S3, in at least one embodiment, the mixture is rolled using a three-roll mill.

In at least one embodiment, the centrifugal stirrer is used for vacuum defoaming, the vacuum defoaming time is 30-60s, the rotation speed of the stirring shaft of the centrifugal stirrer is 600-.

Referring to fig. 2, an electronic package device 100 using underfill is further provided, which includes a substrate 10, a chip 20 disposed on a surface of the substrate 10, and a plurality of solder ball nodes 30 disposed between the substrate 10 and the chip 20 and electrically connected to the substrate 10 and the chip 20. An underfill material 40 is filled between the substrate 10 and the chip 20, and the underfill material 40 is formed after the underfill is cured.

The present application will be described in detail with reference to specific examples, which are intended to be part of the present application and are not intended to limit the present application.

Example 1

The underfill adhesive for the electronic packaging device in the embodiment is composed of the following raw materials by mass:

wherein the modified silica is prepared by the following method:

weighing a certain weight of silicon dioxide, adding the silicon dioxide into a four-neck flask, adding deionized water, stirring, heating to 80 ℃, adding gamma-methacryloxypropyl trimethoxysilane, and carrying out heat preservation reaction for 12 hours to obtain modified silicon dioxide, wherein the molar ratio of the silicon dioxide to the gamma-methacryloxypropyl trimethoxysilane is 5: 1;

slowly dropping a certain amount of styrene at the speed of 2 drops per second, dropping an initiator of ammonium persulfate after the addition, continuously maintaining the reaction for 6 hours, filtering the suspension, and drying at the low temperature of 50 ℃ to obtain the silane coupling agent and the styrene monomer modified silica, wherein the molar ratio of the modified silica to the styrene to the ammonium persulfate is 5:1: 0.1.

Example 2

The underfill adhesive for the electronic packaging device in the embodiment is composed of the following raw materials by mass:

the preparation method of the modified silica is the same as that of example 1.

Example 3

The underfill adhesive for the electronic packaging device in the embodiment is composed of the following raw materials by mass:

the preparation method of the modified silica is the same as that of example 1, and the only difference is that the molar ratio of the silica to the gamma-methacryloxypropyltrimethoxysilane is 2: 1.

Example 4

The underfill adhesive for the electronic packaging device in the embodiment is composed of the following raw materials by mass:

the preparation method of the modified silica is the same as that of the modified silica in the embodiment 1, and the only difference is that the molar ratio of the modified silica to the styrene to the ammonium persulfate is 8:1: 0.1.

Example 5

The underfill adhesive for the electronic packaging device in the embodiment is composed of the following raw materials by mass:

the preparation method of the modified silica was the same as in example 1.

Comparative example 1

The underfill in this comparative example is composed of the following raw materials by mass:

comparative example 2

The underfill in this comparative example is composed of the following raw materials by mass:

comparative example 3

The underfill in this comparative example is composed of the following raw materials by mass:

comparative example 4

The underfill in this comparative example is composed of the following raw materials by mass:

the preparation method of the modified silica was the same as in example 1.

Comparative example 5

The underfill in this comparative example is composed of the following raw materials by mass:

the preparation method of the modified silica was the same as in example 1.

Comparative example 6

The underfill in this comparative example is composed of the following raw materials by mass:

the preparation method of the modified silica is the same as that of example 1.

The underfill for electronic package devices of examples 1 to 5 and the underfill of comparative examples 1 to 6 were subjected to the TMA thermal expansion coefficient CTE1/2 test, the flow test, and the DMA storage modulus test. The TMA thermal expansion coefficient CTE1 test method comprises the following steps: after the underfill for electronic packaging devices of examples 1-5 and the underfill of comparative examples 1-6 were cured at 150 ℃/1 hour, samples meeting the requirements of the standard ASTM E831-2019 were prepared, and then the thermal expansion coefficients of the samples were tested, taking the values of the temperatures of 30 ℃ -50 ℃ and 150 ℃ -200 ℃, respectively. The fluidity test method comprises the following steps: the method comprises the steps of adhering four corners of a square glass sheet with the width of 20mm and the thickness of 0.5mm to four corners of the glass sheet by using a double-sided adhesive tape with the thickness of 30um, then placing the glass sheet on an electric heating plate with the temperature of 90 ℃, preheating for 3min, transversely coating an underfill material to be detected along one side of the square glass sheet by using a thin steel needle, starting timing at the same time, enabling the underfill material to flow at the bottom of the glass sheet under the action of capillary force, and recording the time of flowing the underfill material to half (10mm) of the side length of the glass sheet and the time of flowing the underfill material to full (20 mm). The storage modulus takes the value of 25-250 ℃ respectively. The detection results are shown in the following table I:

table one:

as can be seen from the above table, the thermal expansion coefficient of the underfill for electronic packaging devices with modified silica added of examples 1 to 5 is significantly lower than that of the underfill without modified silica added of comparative examples 1 to 3.

The underfill of comparative example 4, in which the amount of modified silica added was less than 75%, had a significantly higher coefficient of thermal expansion than the underfill for electronic packaging devices of examples 1-5.

The modified silica was added in the underfill of comparative examples 5-6 in too high an amount that the underfill was no longer flowable.

The underfill for electronic package devices provided in the embodiments of the present application is described in detail above, and the principles and embodiments of the present application are explained herein by applying specific examples, and the description of the embodiments above is only used to help understand the method and the core concept of the present application; meanwhile, for those skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.