CN113969126A

CN113969126A - Chip-level underfill with low-fat overflow on silicon surface

Info

Publication number: CN113969126A
Application number: CN202111190179.8A
Authority: CN
Inventors: 金涛; 王建斌; 姜贵琳; 陈田安
Original assignee: Yantai Darbond Technology Co Ltd
Current assignee: Yantai Darbond Technology Co Ltd
Priority date: 2021-10-13
Filing date: 2021-10-13
Publication date: 2022-01-25
Also published as: WO2023060639A1

Abstract

The invention relates to a chip-level underfill with a low-fat overflow silicon surface, which comprises the following raw materials in parts by weight: 20-30 parts of epoxy resin, 0.5-1 part of coupling agent, 0.5-1 part of dispersing agent, 0.2-0.6 part of black paste, 65-70 parts of spherical silicon dioxide and 8-10 parts of modified amine curing agent. The invention introduces the self-synthesized dispersant into the formula of the chip-level underfill material, and can obviously reduce the degree of precipitation of the chip-level underfill material on the surface of a silicon wafer in a packaging test.

Description

Chip-level underfill with low-fat overflow on silicon surface

Technical Field

The invention relates to a chip-level underfill material with a low-fat overflow silicon surface, belonging to the field of single-component and thermosetting epoxy electronic adhesive materials.

Background

In the chip packaging technology, a bonding layer of an IC chip and an organic substrate is composed of a large number of welding spots with micro sizes, the welding spots have poor deformation adaptability and are extremely sensitive to thermal stress, and the problem of structural reliability is more prominent. The use of polymer underfill to improve the reliability of packaged chips is a new approach developed in recent years. The method is economical and easy, and during the chip packaging process, the Underfill material (Underfill) is gradually solidified and formed in the slit between the IC chip and the organic substrate by thermosetting action, and the connected welding spots are protected. Meanwhile, the impact load can be effectively reduced, the performances of deformation resistance, moisture resistance, chemical corrosion resistance and the like of the packaged chip are improved, and the fatigue life of the packaged chip can be greatly prolonged, so that the chip packaging structure has great development potential.

The chip-level underfill material is a single-component liquid material before being cured at normal temperature, and mainly comprises epoxy resin and spherical silicon dioxide with a large amount of addition. The chip-level underfill material has a high viscosity at normal temperature, but due to different molecular weight distributions in the resin, relevant additives are inevitably added in the formula design, so that a precipitation phenomenon is easily generated on the silicon surface in the chip in an actual packaging test, and the phenomenon is called as 'fat overflow'. In the whole chip packaging process, other packaging elements are bonded on the surface of the silicon chip by using a heat conduction material, so that the overflowing grease on the surface of the silicon chip can directly influence other processes of chip packaging. As one of the precipitation problems, the problem of the overflowing grease on the surface of the silicon wafer can be solved, and other precipitation failure mode scenes of the semiconductor package can be guided to be solved.

Disclosure of Invention

Aiming at the technical problem, the invention provides a chip-level underfill with a low silicon surface fat overflow and a preparation method thereof. By adding a proper amount of the dispersing agent in the invention, the dispersing degree of the spherical silicon micropowder in the formula is improved, and simultaneously, the occurrence of the phenomenon of grease overflow on the surface of the silicon wafer caused by resin molecular weight distribution or related auxiliary agents is reduced.

The specific technical scheme is as follows:

one of the purposes of the invention is to provide a chip-level underfill with low silicon surface fat overflow, which is characterized by comprising the following raw materials in parts by weight:

20-30 parts of epoxy resin, 0.5-1 part of coupling agent, 0.5-1 part of dispersing agent, 0.2-0.6 part of black paste, 65-70 parts of spherical silicon dioxide and 8-10 parts of modified amine curing agent.

Further, the dispersant is one or more than two of styrene maleic anhydride copolymer (SMA), hyperbranched styrene maleic anhydride copolymer (BPSMA) and hyperbranched styrene maleic anhydride copolymer ester (BPSME); preferably BPSMA and/or BPSME; most preferred is a combination of BPSMA and BPSME, wherein the mass ratio of BPSMA to BPSME is preferably 1: (1-2).

Wherein the styrene maleic anhydride copolymer (SMA) can be SZ25010 of Polyscope company in the Netherlands.

And further, the hyperbranched styrene maleic anhydride copolymer is prepared by jointly reacting and polymerizing 8-12 parts of styrene, 1-2 parts of azobisisobutyronitrile, 2-3 parts of vinyl benzyl mercaptan and 10-12 parts of maleic anhydride by weight.

And further, the hyperbranched styrene maleic anhydride copolymer ester is prepared by the joint reaction of 3-5 parts by weight of hyperbranched styrene maleic anhydride copolymer, 0.3-0.5 part by weight of p-benzenesulfonic acid and an esterifying agent.

Specifically, the preparation method of the hyperbranched styrene maleic anhydride copolymer (BPSMA) comprises the following steps:

dissolving styrene, azodiisobutyronitrile and vinyl benzyl mercaptan in toluene to obtain a mixed solution A; heating maleic anhydride and toluene to 50-60 ℃, stirring until the maleic anhydride is completely dissolved, and then heating to 70-80 ℃ to obtain a solution B; adding the mixed solution A into the solution B, and reacting for 4-6 h at the temperature of 70-80 ℃; and after the reaction is finished, performing suction filtration on the product, washing the product with toluene, dissolving the product in acetone, precipitating and separating the product with ethanol, and drying the product to obtain the BPSMA. The equation for the above reaction is as follows:

specifically, the preparation method of the hyperbranched styrene maleic anhydride copolymer ester (BPSME) comprises the following steps:

mixing the obtained BPSMA, the p-benzenesulfonic acid and the butanone, adding an esterifying agent, and stirring and reacting at the temperature of 70-80 ℃ for 2-4 h; after the reaction is finished, evaporating and concentrating the mixed solution, settling and separating by using petroleum ether to finally obtain a white flocculent substance, and drying to obtain an esterified substance BPSME;

wherein the esterifying agent comprises methanol, dodecanol and n-butanol. The molar ratio of methanol to n-butanol is preferably 1: the volume ratio of the total amount of methanol and n-butanol to dodecanol is preferably (1-2): 1.

the equation for the above reaction is as follows:

further, the epoxy resin comprises 15-20 parts by weight of bisphenol epoxy resin and 5-10 parts by weight of special epoxy resin;

wherein the bisphenol type epoxy resin is bisphenol A type epoxy resin or/and bisphenol F type epoxy resin; specifically, it may be one or a combination of two or more of EXA-830 CRP (bisphenol F epoxy resin), EXA-830 LVP (bisphenol A/bisphenol F mixed epoxy resin), EXA-835 LV (bisphenol A/bisphenol F mixed epoxy resin), Korea Koron KF-8110 (bisphenol A/bisphenol F mixed epoxy resin), and Shanghai Kawayao 328 (bisphenol A epoxy resin) of DIC of Japan. In the above resins, bisphenol a epoxy resin and bisphenol F epoxy resin are main resins of the entire adhesive, and as a skeleton function, the bisphenol a epoxy resin has higher strength but higher viscosity, and the bisphenol F epoxy resin has lower viscosity but lower strength, compared with the bisphenol a epoxy resin and the bisphenol F epoxy resin.

Wherein the special epoxy resin is one or a mixture of more of ELM-100H of Sumitomo Japan, MY720 and MY0500 of Hunsmann, SW-0510, SW-70 and SW-80 of Sailwei Hunan, EBA-65 of the Wallace of Shanghai, KF-8110 of Korea, YLSE-900S of Korea GLK and HP-4032D of Japan DIC. The resin contains a multifunctional group structure, can improve the curing crosslinking density and the strength of the cured material, and contains a rigid structure, can improve the strength of the cured material, and further reduces the thermal expansion coefficient, wherein the coupling agent is one or more than two of gamma-aminopropyltriethoxysilane, gamma-mercaptopropyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-glycidyloxypropyltrimethoxysilane and gamma-aminopropyltrimethoxysilane. The black paste is preferably carbon black.

Further, the modified amine curing agent is one or more than two of 4, 4 '-diamino-3, 3' -diethyl diphenylmethane, diethyl toluenediamine, diamino diphenyl sulfone, m-amino methylamine, xylylene diamine tripolymer, dibenzyl amino ether and diethyl toluenediamine.

Further, the spherical silica is one or more than two of FE920ASQ, FEB 25G-SED, SC 220G-SQ, SE 6050-STE, SO-E2 and SO-E2/24C of Yadama, Japan. In the spherical silica, the average particle size is 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, and the maximum particle size is 5 μm, 10 μm, 20 μm, and the optimal filler compounding ratio can be obtained by calculation through a Horsfield spherical stacking model, so that more fillers can be added into the whole system, lower viscosity can be obtained, the filling fluidity at high temperature is better, and the process operability and reliability characterization results of the material can be directly influenced.

Another object of the present invention is to provide a method for preparing the chip-scale underfill adhesive, which comprises the following steps:

blending epoxy resin, coupling agent, dispersant and black paste, stirring for 1-3 h, adding spherical silicon dioxide, heating at 70-90 deg.C, stirring for 3-5 h, cooling to normal temperature, adding modified amine curing agent, controlling temperature at 25-30 deg.C, and stirring for 1-3 h.

Further, the whole preparation process is carried out under vacuum condition, preferably, the whole process is maintained at vacuum degree of not less than-0.08 MPa.

The invention has the beneficial effects that: the self-synthesized dispersant is introduced into the formula of the chip-level underfill material, so that the degree of precipitation of the chip-level underfill material on the surface of a silicon wafer in a packaging test can be obviously reduced. The novel and special point in the patent is that the dispersant is self-prepared and synthesized, the preparation process is simple, the operation is easy, and no special equipment is needed.

In a packaging test, the conventional chip-level underfill material is gradually heated to 165 ℃ after being glued, is maintained at 165 ℃ for 120min, and is gradually cooled to a room temperature state. The surface of the cured silicon wafer generally has 800-1000 μm flash, and the serious length can reach over 1000 μm, which exceeds the requirement standard of standard packaging test. The chip-level underfill prepared in the patent can control the overflowing length of the surface of a silicon chip to be below 100 mu m or even lower under the same test condition.

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.

In each example, hyperbranched styrene maleic anhydride copolymer (BPSMA) was prepared by the following method:

in parts by weight, 10 parts of styrene (St), 1.5 parts of Azobisisobutyronitrile (AIBN), 2 parts of Vinylbenzylmercaptan (VBT) were added to a flask and dissolved in 56 parts of toluene to obtain a mixed solution a; in addition, 12 parts of Maleic Anhydride (MA) and 85 parts of toluene are added into a three-neck flask provided with a magnetic stirring device, a condensing tube and a temperature sensor, the temperature is increased to 50 ℃, the mixture is stirred until the Maleic Anhydride (MA) is completely dissolved, and then the temperature is increased to 70 ℃; adding the mixed solution A at the upper part into a three-neck flask by a peristaltic pump at the speed of 2mL/min, and reacting for 6h under the condition of heat preservation; and after the reaction is finished, performing suction filtration on the product, washing the product for a plurality of times by using hot toluene, dissolving the product in acetone, performing precipitation separation by using ethanol, repeating the operation for 3 times, and drying the product in a vacuum oven to obtain the BPSMA.

In each example, hyperbranched styrene maleic anhydride copolymer ester (BPSME) was prepared as follows:

adding 4g of BPSMA, 0.4g of p-benzenesulfonic acid and 80mL of butanone into a flask provided with a condenser tube, then adding 30mL of esterifying agent (methanol and n-butanol are dropwise added according to a molar ratio of 1: 1, and dodecanol is added into the flask at one time for reaction for 3 hours under stirring at 80 ℃; after the reaction is finished, evaporating and concentrating the mixed solution, settling and separating by using petroleum ether to finally obtain a white flocculent substance, and drying the white flocculent substance in a vacuum oven at the temperature of 30 ℃ to obtain the esterified substance BPSME.

In each example, the styrene maleic anhydride copolymer (SMA) used was SZ25010 from Polyscope, Netherlands.

Example 1

18g of EXA-835 LV resin, 5.5g of ELM-100H resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent, 0.5g of dispersing agent SMA and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer for three times, the temperature is set to be 85 ℃, the stirring is heated for 4 hours, the heating is closed, the stirrer is cooled to the normal temperature by condensed water, 8g of curing agent diethyl toluenediamine is added, after the stirring is maintained at the normal temperature for 2 hours, the preparation process is finished, and the vacuum degree is kept to be not lower than-0.08 Mpa in the whole process.

Example 2

18g of EXA-835 LV resin, 5.5g of ELM-100H resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent, 0.5g of dispersing agent BPSMA and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer for three times, the temperature is set to be 85 ℃, the stirring is heated for 4 hours, the heating is closed, the stirrer is cooled to the normal temperature by condensed water, 8g of curing agent diethyl toluenediamine is added, after the stirring is maintained at the normal temperature for 2 hours, the preparation process is finished, and the vacuum degree is kept to be not lower than-0.08 Mpa in the whole process.

Example 3

18g of EXA-835 LV resin, 5.5g of ELM-100H resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent, 0.5g of dispersing agent BPSME and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer for three times, the temperature is set to be 85 ℃, the stirring is carried out for 4 hours by heating, the heating is closed, the stirrer is cooled to the normal temperature by condensed water, 8g of curing agent diethyl toluene diamine is added, after the stirring is carried out for 2 hours under the condition of temperature control, the preparation process is finished, and the vacuum degree is kept to be not lower than-0.08 Mpa in the whole process.

Example 4

18g of EXA-835 LV resin, 5.5g of ELM-100H resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent, 0.2g of dispersing agent SMA, 0.3g of dispersing agent BPSMA and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer in three times, the temperature is set to 85 ℃, the stirring is carried out for 4 hours by heating, the heating is closed, the stirrer is cooled to the normal temperature by condensed water, 8g of curing agent diethyltoluenediamine is added, after the stirring is carried out for 2 hours at the normal temperature by controlling the temperature, the preparation process is ended, and the vacuum degree is not lower than-0.08 MPa in the whole process.

Example 5

18g of EXA-835 LV resin, 5.5g of ELM-100H resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent, 0.2g of dispersing agent SMA, 0.3g of dispersing agent BPSME and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer in three times, the temperature is set to 85 ℃, the stirring is carried out for 4 hours by heating, the heating is closed, the stirrer is cooled to the normal temperature by introducing condensed water, 8g of curing agent diethyl toluene diamine is added, after the stirring is carried out for 2 hours at the normal temperature by controlling the temperature, the preparation process is ended, and the vacuum degree is not lower than-0.08 MPa in the whole process.

Example 6

18g of EXA-835 LV resin, 5.5g of ELM-100H resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent, 0.2g of dispersing agent BPSMA, 0.3g of dispersing agent BPSME and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer for three times, the temperature is set to 85 ℃, the stirring is carried out for 4 hours by heating, the heating is closed, the stirrer is cooled to the normal temperature by introducing condensed water, 8g of curing agent diethyl toluene diamine is added, after the stirring is carried out for 2 hours at the normal temperature by controlling the temperature, the preparation process is ended, and the vacuum degree is not lower than-0.08 MPa in the whole process.

Comparative example 1

18g of EXA-835 LV resin, 5.5g of ELM-100H resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer for three times, the temperature is set to be 85 ℃, the stirring is heated for 4 hours, the heating is closed, the stirrer is cooled to the normal temperature by condensed water, 8g of curing agent diethyl toluenediamine is added, after the temperature is controlled and maintained to be stirred for 2 hours at the normal temperature, the preparation process is ended, and the vacuum degree is kept to be not lower than-0.08 MPa in the whole process.

Comparative example 2

18g of EXA-835 LV resin, 5.5g of ELM-100 resin, 2g of HP-4032D resin, 0.5g of KH560 silane coupling agent, 0.5g of SZ25010 dispersing agent and 0.5g of carbon black are added into a high-speed planetary stirrer, after stirring for 2 hours, 65g of SE 6050-STE silicon dioxide is added into the stirrer for three times, the temperature is set to be 85 ℃, the stirring is heated for 4 hours, the heating is stopped, the stirrer is cooled to the normal temperature by condensed water, 8g of curing agent diethyl toluene diamine is added, after the stirring is maintained for 2 hours at the controlled temperature, the preparation process is finished, and the vacuum degree is kept to be not lower than-0.08 Mpa in the whole process at the normal temperature.

Testing

The viscosities of the products obtained in examples 1 to 6 and comparative examples 1 and 2 are shown in Table 1; the results of the bleed length test on the surface of the silicon wafer before and after curing are shown in table 2.

And (3) viscosity testing: measuring at room temperature for 20s with Haake viscometer (Thermofeisher, USA) and C20/2 rotor^-1Viscosity of water; the viscosity at 110 ℃ was measured using a TA rheometer.

A sample preparation process: selecting a bare silicon wafer with the specification size of 15mm x 0.735mm, and fixing the bare silicon wafer on a PCB (printed circuit board) by using solder paste ball planting, wherein the bare silicon wafer is called as a simulation chip; placing the simulation chip on a heating platform at 110 ℃, preheating for ten minutes, dispensing on one side of the simulation chip by using an air-powered dispensing machine until the climbing height of glue on the opposite side meets the requirement basically, stopping dispensing, and standing on the heating platform for ten minutes.

And (3) curing process: and (3) placing the analog chip after dispensing into a blast oven, raising the temperature from room temperature to 165 ℃ at the speed of 5 ℃/min, maintaining the temperature at 165 ℃ for 2 hours, and naturally cooling to room temperature to finish curing.

The method for measuring the length of the overflowing grease on the silicon surface comprises the following steps: observing and measuring the prepared simulation sample before and after curing under a high power microscope, respectively taking five position points on the other three edges except the dispensing edge on the bare silicon wafer, and measuring the distance from the outermost edge of the bare silicon wafer to the outermost edge of the grease overflow, namely the lengths of the grease overflow before and after curing are L respectively₀And L.

TABLE 1 Normal temperature viscosity and 110 ℃ viscosity test results

TABLE 2 measurement results of the length of the flash on the surface of bare silicon wafer

As can be seen from the data in Table 1, after the dispersant is added into the formula, the viscosity of the glue at normal temperature and 110 ℃ can be reduced, particularly the trend of the viscosity reduction at normal temperature is obvious, and for a single dispersant, the viscosity reduction capability is sequentially BPSME (beta-methyl phenyl isocyanate) Y19268 > BPSMA > from large to small, but the viscosity reduction degree is larger when two dispersants are added simultaneously, particularly when the BPSME and the BPSMA are added simultaneously, compared with the comparative example 1, the viscosity reduction degree is the largest.

As shown in the data in Table 2, after the graft type dispersant is added, the silicone surface grease overflow length is obviously reduced, for a single dispersant, the capability of controlling the silicone surface grease overflow length is that BPSME is larger than BPSMA is larger than SMA in sequence from large to small, and when the BPSMA and the BPSME are added simultaneously, the silicone surface grease overflow length is minimum.

In addition, the two types of special epoxy resins used in the comparative examples are domestic resins, which are more prone to grease overflow due to their lower purity and their relatively low molecular weight polymer segments contained therein.

The reason for the ability of controlling the length of the spilled grease in this patent is that the graft dispersant can also "lock" a considerable amount of small molecules while dispersing the resin and the filler, mainly through esterification or end group combination, and the graft dispersant with surface treatment is superior to the graft dispersant without surface treatment, i.e. the reason why BPSME is superior to BPSMA; the different types of small molecule substances are superior to those in the formula, so when different types of graft type dispersing agents act synergistically, different types of small molecules can be respectively locked, and the reason why the effect is best by only using BPSMA and BPSME at the same time is that the different types of small molecules are different in type, and the different types of graft type dispersing agents are different in type.

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.

Claims

1. The chip-level underfill with the silicon surface low in fat overflow is characterized by comprising the following raw materials in parts by weight:

2. The chip scale underfill according to claim 1, wherein the dispersant is one or more of styrene maleic anhydride copolymer, hyperbranched styrene maleic anhydride copolymer, and esterified hyperbranched styrene maleic anhydride copolymer.

3. The chip scale underfill of claim 2,

the hyperbranched styrene-maleic anhydride copolymer is prepared by carrying out combined reaction and polymerization on 8-12 parts of styrene, 1-2 parts of azobisisobutyronitrile, 2-3 parts of vinyl benzyl mercaptan and 10-12 parts of maleic anhydride in parts by weight;

the hyperbranched styrene maleic anhydride copolymer esterified substance is generated by reacting 3-5 parts of hyperbranched styrene maleic anhydride copolymer, 0.3-0.5 part of p-benzenesulfonic acid and an esterifying agent.

4. The chip scale underfill according to claim 3, wherein the esterification agent comprises methanol, dodecanol, and n-butanol.

5. The chip-scale underfill according to claim 1, wherein the epoxy resin comprises 15-20 parts by weight of bisphenol epoxy resin and 5-10 parts by weight of special epoxy resin;

the bisphenol type epoxy resin is bisphenol A type epoxy resin or/and bisphenol F type epoxy resin;

the special epoxy resin is one or a mixture of more of ELM-100H of Sumitomo of Japan, MY720 and MY0500 of Hunsmann, SW-0510, SW-70 and SW-80 of Sailva of Hunan, EBA-65 of the friendship of Shanghai, KF-8110 of Korea, YLSE-900S of GLK of Korea and HP-4032D of DIC of Japan.

6. The chip-scale underfill according to claim 1, wherein the coupling agent is one or more of γ -aminopropyltriethoxysilane, γ -mercaptopropyltrimethoxysilane, γ -mercaptopropyltriethoxysilane, γ -glycidoxypropyltrimethoxysilane, and γ -aminopropyltrimethoxysilane.

7. The chip scale underfill according to claim 1, wherein the modified amine curing agent is one or more of 4, 4 '-diamino-3, 3' -diethyldiphenylmethane, diethyltoluenediamine, diaminodiphenylsulfone, m-aminomethane, xylylenediamine trimer, dibenzylaminoether, diethyltoluenediamine.

8. A method of preparing the chip scale underfill according to any one of claims 1 to 7, comprising the steps of:

blending epoxy resin, coupling agent, dispersant and black paste, stirring for 1-2 h, adding spherical silicon dioxide, heating and stirring at 70-90 ℃ for 4-6 h, cooling to normal temperature, adding modified amine curing agent, controlling the temperature to be 25-30 ℃, and stirring for 1-2 h to obtain the epoxy resin black paste.

9. The method of claim 8, wherein the entire process is performed under vacuum.