1. The underfill adhesive for semiconductor packaging comprises epoxy resin, a filler, a curing agent, a toughening agent and an accelerator, and is characterized in that: in the high elongation at break underfill, the content of the epoxy resin is 13-20 wt%, the content of the filler is 60-65 wt%, the content of the curing agent is 10-20 wt%, the content of the toughening agent is 5-15 wt%, the content of the accelerator is 0.5-0.8 wt%, and the toughening agent is selected from a methyl methacrylate-butadiene-styrene terpolymer.

2. The method of claim 1, wherein: the epoxy resin is selected from bisphenol A epoxy resin.

3. The method of claim 1, wherein: the filler comprises silica.

4. The method of claim 1, wherein: the particle size of the silicon dioxide is 0.1-0.5 μm.

5. The method of claim 1, wherein: the curing agent is at least one selected from imidazole epoxy curing agents, dimethylol urea and dicyandiamide.

6. The method of claim 1, wherein: the accelerator is at least one selected from 2,4, 6-tris (dimethylaminomethyl) phenol, N-benzyldimethylamine and 2-ethyl-4-methylimidazole.

7. The method of claim 1, wherein: the underfill also includes a colorant.

8. The method of claim 7, wherein: in the underfill, the content of the colorant is 0.1 to 0.5 wt%.

9. The utility model provides a semiconductor package structure of chip flip-chip, includes the base plate, sets up the chip in the functional surface one side of base plate, and is located a plurality of solder bumps between base plate and the chip, it has underfill material, its characterized in that to fill in the clearance between base plate and the chip: the underfill material is formed by thermally curing the underfill of any one of claims 1 to 8.

Background

The underfill is a low-viscosity and low-temperature curing chemical adhesive for capillary flow underfilling of the bottom, is cured in a heating mode, and is widely applied to circuit board assembly of portable electronic products such as MP3, USB, mobile phones, basket teeth and the like. In chip packaging, the underfill is applied directly to the chip or substrate and then cured by heating. The underfill material is used as a key material for packaging the flip chip, can effectively protect high-density solder balls, disperses the stress borne by the surface of the chip, relieves the internal stress generated by the mismatch of the thermal expansion coefficients of the chip, the solder and the substrate, can protect the chip from being damaged by physical, chemical and other environmental factors, and increases the processability, reliability and service life of the chip and a packaging device.

Along with the development of electronic products towards miniaturization and multi-functionalization, the integration level, the packaging density and the working frequency of a chip are improved, and the ratio of power to volume is increased day by day, so that the heat flux density of the chip is rapidly increased and the heating power is increased under the working state of high function and high transmission rate of the electronic products, thereby the chip is subjected to severe examination and needs underfill with excellent performance at high temperature to package the chip.

In addition, in the geothermal production and petroleum production processes, the temperature usually exceeds 200 ℃, the related electronic equipment needs to use a chip capable of resisting high temperature, and the underfill for packaging the chip capable of resisting high temperature also puts higher requirements.

However, the conventional underfill is not resistant to high temperature or has a low elongation at break at high temperature, resulting in low toughness, inability to absorb stress and strain between the chip and the package substrate, and susceptibility to fracture under strong impact, and inability to meet the package requirements of high temperature resistant chips.

Disclosure of Invention

The application provides an underfill for semiconductor packaging, aiming at improving the problem of low elongation at break of the existing underfill under the high-temperature condition.

The embodiment of the application is realized by that the underfill adhesive for semiconductor packaging comprises epoxy resin, filler, a curing agent, a toughening agent and an accelerator, wherein in the underfill adhesive with high elongation at break, the content of the epoxy resin is 13-20 wt%, the content of the filler is 60-65 wt%, the content of the curing agent is 10-20 wt%, the content of the toughening agent is 5-15 wt%, the content of the accelerator is 0.5-0.8 wt%, and the toughening agent is selected from a methyl methacrylate-butadiene-styrene terpolymer.

Optionally, in some embodiments herein, the epoxy resin is selected from bisphenol a epoxy resins.

Optionally, in some embodiments of the present application, the filler comprises silica.

Optionally, in some embodiments of the present application, the silica has a particle size of 0.1 to 0.5 μm.

Optionally, in some embodiments herein, the curing agent is selected from at least one of imidazole-based epoxy curing agents, dimethylol ureas, and dicyandiamide.

Optionally, in some embodiments herein, the promoter is selected from at least one of 2,4, 6-tris (dimethylaminomethyl) phenol, N-benzyldimethylamine, and 2-ethyl-4-methylimidazole.

Optionally, in some embodiments of the present application, the underfill further comprises a colorant.

Optionally, in some embodiments herein, the colorant is present in an amount of 0.1 to 0.5 wt%.

Correspondingly, the embodiment of the application also provides a semiconductor packaging structure of chip flip-chip, including the base plate, set up at the chip of the functional surface one side of base plate, and be located a plurality of solder bumps between base plate and the chip, it has underfill material to fill in the clearance between base plate and the chip, underfill material forms by above-mentioned underfill glue thermosetting back.

The underfill of the present application includes a toughening agent of methyl methacrylate-butadiene-styrene terpolymer. The methyl methacrylate-butadiene-styrene terpolymer has a core-shell structure, is easy to disperse in an epoxy resin system, and can effectively reduce the crosslinking density of the epoxy resin at a high temperature of more than 200 ℃, so that the toughness of the underfill is improved, and the underfill has a high elongation at break of 8-25%. In addition, the toughening agent can achieve the effect of improving the elongation at break of the underfill when the addition amount is only 5-15 wt%, the dispersion effect of the two toughening agents is good, and the addition of the two toughening agents does not affect other mechanical properties of the underfill.

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 schematic diagram of a semiconductor flip-chip structure according to an embodiment of the present disclosure.

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. 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 with high elongation at break, which is mainly used for packaging high-temperature-resistant chips. The high elongation at break underfill comprises epoxy resin, a filler, a curing agent, a toughening agent colorant and an accelerator.

In the high elongation at break underfill, the content of the epoxy resin is 13-20 wt%, the content of the filler is 60-65 wt%, the content of the curing agent is 10-20 wt%, the content of the toughening agent is 5-15 wt%, the content of the coloring agent is 0.1-0.5 wt%, and the content of the accelerator is 0.5-0.8 wt%.

The epoxy resin may be selected from, but is not limited to, bisphenol a epoxy resins. In at least one preferred embodiment, the bisphenol a epoxy resin is selected from at least one of the dow DER332, taiwan vinpocetine D810 and taiwan vinpocetine D822.

The filler comprises silica. In at least one preferred embodiment, the silica has a particle size of 0.1 to 0.5 μm.

The curing agent is at least one selected from imidazole epoxy curing agent, dimethylol urea (DMU) and Dicyandiamide (DICY). In at least one preferred embodiment, the imidazole-based epoxy hardener is selected from at least one of the Japanese monosodium glutamate PN-23 and the four national chemical 2 MZ-A. The curing agent is a high-temperature resistant curing agent which can resist the high temperature of 245 ℃. The addition of the curing agent can improve the heat resistance of the underfill, so that the underfill still has good performances at high temperature, such as high elongation at break, low expansion coefficient, high fluidity and the like.

The structural formula of the ajinomoto PN-23 is as follows:

the dimethylol urea DMU has the following structural formula:

the dicyandiamide DICY has the following structural formula:

the structural formula of the 2MZ-A is as follows:

the toughening agent is selected from methyl methacrylate-butadiene-styrene terpolymer (MBS). The methyl methacrylate-butadiene-styrene terpolymer has a core-shell structure, is easy to disperse in an epoxy resin system, and can effectively reduce the crosslinking density of the epoxy resin at a high temperature of more than 200 ℃, so that the toughness of the underfill is improved, and the underfill has a high elongation at break of 8-25%. In addition, the toughening agent can achieve the effect of improving the elongation at break of the underfill when the addition amount is only 5-15 wt%, the dispersion effect of the two toughening agents is good, and the addition of the two toughening agents does not affect other mechanical properties of the underfill.

In at least one preferred embodiment, the methacrylate-butadiene-styrene terpolymer (MBS) is selected from at least one of akoma cleartrength XT100 and akoma E920.

The colorant may be selected from carbon black and the like colorants conventionally used in underfills.

The accelerant is at least one selected from 2,4, 6-tris (dimethylaminomethyl) phenol (DMP-30), N-Benzyldimethylamine (BDMA) and 2-ethyl-4-methylimidazole. The accelerant has a curing promoting effect on the underfill, and simultaneously can reduce the crosslinking density of epoxy resin in the underfill, weaken the rigidity of the underfill, enhance the toughness of the underfill and increase the elongation at break.

The chemical structural formula of the 2,4, 6-tris (dimethylaminomethyl) phenol is as follows:

the chemical structural formula of the N-benzyldimethylamine is as follows:

the chemical structural formula of the 2-ethyl-4-methylimidazole is as follows:

the underfill comprises 13-20 wt% of epoxy resin, 60-65 wt% of filler, 10-20 wt% of curing agent, 5-15 wt% of toughening agent, 0.1-0.5 wt% of coloring agent and 0.5-0.8 wt% of accelerating agent, wherein the curing agent is at least one of Japanese gourmet powder PN-23, DMU, DICY and 2MZ-A, and the toughening agent is methyl methacrylate-butadiene-styrene terpolymer withA core-shell structure. Under the synergistic effect of the components and contents, the underfill has the characteristic of high end-column elongation at high temperature.

Referring to fig. 1, the present embodiment further provides a flip chip semiconductor package structure 100, which includes a substrate 10, a chip 20 disposed on one side of a functional surface of the substrate 10, and a plurality of solder bumps 30 disposed between the substrate 10 and the chip 20. A plurality of contact pads 11 are arranged on the functional surface of the substrate 10, a plurality of bottom touch metals 21 are arranged in a corresponding area of the surface of the chip 20 adjacent to one side of the substrate 10, each contact pad 11 corresponds to one bottom touch metal 21, and the corresponding contact pad 11 and the bottom touch metal 21 are electrically connected through a solder bump 30.

The gap between the substrate 10 and the chip 20 is filled with an underfill material 40, and the underfill material 40 is formed by thermally curing the high elongation at break underfill.

The underfill material 40 of the flip-chip semiconductor package structure 100 of the present application is formed by curing the high elongation at break underfill of the present application, has a characteristic of high elongation at break at high temperature, and can absorb stress and strain between the chip 20 and the substrate 10 under a high temperature condition, so that the substrate 10 and the chip 20 are not easily broken even under strong impact, and the package requirement of a high temperature resistant chip can be satisfied.

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 composition of the high elongation at break underfill of this example is:

example 2

The composition of the high elongation at break underfill of this example is:

example 3

The composition of the high elongation at break underfill of this example is:

example 4

The composition of the high elongation at break underfill of this example is:

example 5

The composition of the high elongation at break underfill of this example is:

example 6

The composition of the high elongation at break underfill of this example is:

example 7

The composition of the high elongation at break underfill of this example is:

example 8

The composition of the high elongation at break underfill of this example is:

example 9

The composition of the high elongation at break underfill of this example is:

example 10

The composition of the high elongation at break underfill of this example is:

comparative example 1

The underfill of this comparative example had the composition:

comparative example 2

The underfill of this comparative example had the composition:

comparative example 3

The underfill of this comparative example had the composition:

comparative example 4

The underfill of this comparative example had the composition:

comparative example 5

The underfill of this comparative example had the composition:

comparative example 6

The underfill of this comparative example had the composition:

comparative example 7

The underfill of this comparative example had the composition:

comparative example 8

The underfill of this comparative example had the composition:

comparative example 9

The underfill of this comparative example had the composition:

comparative example 10

The underfill of this comparative example had the composition:

the high elongation at break underfill of examples 1-10 and the underfill of comparative examples 1-10 were tested for high temperature elongation at break, flow, DMA storage modulus, and TMA expansion coefficient. The high-temperature elongation at break test method comprises the following steps: the high elongation at break underfill of examples 1-10 and the underfill of comparative examples 1-10 were applied to a strip mold, respectively, and cured at 150 ℃ for 1 hour to obtain a sample strip of 30mm in length, 2mm in width and 0.3mm in thickness, and the elongation at break and the breaking strength of the sample strip were recorded by raising the tensile force to 18N at a rate of 5N/min at a temperature of 245 ℃ using DMA (dynamic mechanical thermal analyzer). 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 is respectively the value of 25-250 ℃, and the expansion coefficient CTE1/2 is respectively the value of 30-50 ℃ and 150-200 ℃. The test results are shown in the following table I:

table one:

as can be seen from the above table, compared with the underfill in comparative examples 1 to 8, the underfill in examples 1 to 10 with high elongation at break still has stronger elongation at break and breaking strength at 245 ℃, and can meet the packaging requirements of the high temperature resistant chip. The high elongation at break underfill of examples 1-10 had higher elongation at break and breaking strength than the underfill of comparative examples 9-10 with the addition of the non-toughening agent of the present application.

The underfill provided by 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 is only used to help understanding 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.