Low-precipitation photo-thermal dual-curing 2.5 D packaging underfill adhesive and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, in particular to a low-precipitation photo-thermal dual-curing 2.5 D packaging underfill adhesive and a preparation method thereof. The low-precipitation photo-thermal dual-curing 2.5 D packaging underfill adhesive is prepared from the following raw materials in parts by weight: 10 to 20 parts of bisphenol F type epoxy resin, 5 to 10 parts of bisphenol A type epoxy resin, 5 to 10 parts of alicyclic epoxy resin, 0.5 to 1 part of black paste, 0.8 to 1.2 parts of a coupling agent, 50 to 55 parts of spherical filler, 10 to 15 parts of an amine curing agent and 0.1 to 0.5 part of a photoinitiator. According to the invention, the photoinitiator and the amine curing agent are introduced at the same time, firstly, photocuring, pre-curing and tackifying are carried out, or a semi-gel state is formed, so that precipitated small molecular substances can be fixed, and a large number of small molecules cannot be precipitated even in subsequent thermocuring. And the width of precipitates on the substrate and the silicon wafer can be reduced to the lowest level while the manufacturability and the reliability are met.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to a low-precipitation light-heat dual-curing 2.5D packaging bottom filling adhesive and a preparation method thereof. Background Art

[0002] As Moore's Law slows down, the semiconductor industry is increasingly using chip design and heterogeneous integrated packaging to continue to drive performance improvements. This method is to divide a large silicon chip into multiple smaller chips, design, manufacture and optimize them separately, and then integrate them into a single package. Among them, 2D, 2.1D, 2.3D, 2.5D and 3D integration use heterogeneous integrated packaging technology to assemble independent chips into a cohesive package. In particular, 2.5D and 3D integrated packaging are relatively advanced packaging technology types at present. Among them, 2.5D packaging arranges multiple chips of different sizes on the same plane, leaving a gap of 100-200μm between each chip. This involves that when the bottom filler is used for filling, the bottom filler needs to flow through multiple chips of different sizes. To ensure uniform flow rate, it is also necessary to ensure that there will be no serious precipitates on the substrate and the gaps between different chips during the flow filling and curing process of the bottom filler. Because if the degree of precipitation is large, it will not only affect the appearance, but also may affect other processes in the packaging process. Summary of the invention

[0003] In view of the above shortcomings of the prior art, an object of the present invention is to provide a low-precipitation light-thermal dual-curing 2.5D packaging bottom filling glue and a preparation method thereof.

[0004] To achieve the above objectives, the technical solutions adopted are:

[0005] One of the purposes of the present invention is to provide a low precipitation light-thermal dual-curing 2.5D package bottom filling glue, the raw materials include by weight:

[0006] 10-20 parts of bisphenol F epoxy resin, 5-10 parts of bisphenol A epoxy resin, 5-10 parts of alicyclic epoxy resin, 0.5-1 parts of black paste, 0.8-1.2 parts of coupling agent, 50-55 parts of spherical filler, 10-15 parts of amine curing agent, and 0.1-0.5 parts of photoinitiator.

[0007] Preferably, the photoinitiator is a free radical photoinitiator or a cationic photoinitiator. When the photoinitiator is a free radical photoinitiator, the corresponding amine curing agent is at least one of a primary amine curing agent, a secondary amine curing agent, and a tertiary amine curing agent; when the photoinitiator is a cationic photoinitiator, the corresponding amine curing agent is a tertiary amine curing agent.

[0008] Preferably, the primary amine curing agent comprises at least one of ethylenediamine, hexamethylenediamine, metaphenylenediamine, monoethanolamine (MEA), dimethylthiotoluenediamine (DMTDA), and diethyltoluenediamine (DETDA).

[0009] Preferably, the secondary amine curing agent comprises at least one of diethylamine, dihexylamine, N-methylaniline, hexahydropyridine, diethyltetramethylimidazole (2E4MZ), and 1-cyanoethyl-2-ethyl-4-methylimidazole (2E4MZ-CN).

[0010] Preferably, the tertiary amine curing agent comprises at least one of N, N-dimethylaniline (DMPA), diethanolamine (DEA), N-methyldiethanolamine (MDEA), triethanolamine (TEA), triethylamine (TEA), and trihexylamine (THA).

[0011] Preferably, the bisphenol F type epoxy resin includes: at least one of 830S, 830CRP of Japan DIC, RE-303S-L of Nippon Kayaku, and DER354 of Dow Chemical; the bisphenol A type epoxy resin includes: at least one of 850-S, 850CRP of Japan DIC, RE-310S of Nippon Kayaku, DER383, and DER332 of Dow Chemical; the alicyclic epoxy resin is at least one of 2021P, S28E, PB3600, GT401, and 2028 of Japan Daicel.

[0012] Preferably, the coupling agent is γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ- ― At least one of aminopropyltrimethoxysilane, more preferably at least one of KBM-403, KBE-403, KBM-303, KBM-802, KBM-803, KBM-903 and KBE-903 produced by Shin-Etsu of Japan.

[0013] Preferably, the spherical filler is at least one of SE6050-STE, SO-E2, SO-E2 / 24C, FE920ASQ, 200SE-E4, SC2500-SQ, SE5050, SE2050, SE5050-SEJ, SE2050-SEJ, and SE203G-SEJ produced by Japan Admatechs Company.

[0014] The free radical photoinitiator includes: at least one of TR-TPO, TR-TPO-L, TR-DETX of Changzhou Qiangli New Materials and GR-TPO, GR-TPO-L, GR-DETX, GR-XBPO, GR-FMT, GR-1173 of Gurun Chemical; the cationic photoinitiator includes: at least one of TR-PAG-20101, TR-PAG-20201P, TR-PAG-30101, TR-PAG-30201 of Qiangli New Materials and GR-261, GR-262, GR-IS051, GR-IS052, GR-SS058, GR-SS061, GR-SS263 of Gurun Chemical.

[0015] More preferably, the black paste is 90EXPX04 from PolyOne Corporation of the United States.

[0016] The second object of the present invention is to provide a method for preparing the low precipitation light-thermal dual-curing 2.5D package bottom filling glue, comprising the following steps:

[0017] Add bisphenol A epoxy resin, bisphenol F epoxy resin, alicyclic epoxy resin, coupling agent and black paste into a reaction container, then stir for 2 hours, then add spherical fillers in batches, stir and mix thoroughly and then disperse and grind; then continue to heat and stir at 70-90°C in the reaction container for 4 hours, then cool to room temperature; under a yellow light environment, add a photoinitiator, control the temperature to maintain at 25-30°C and stir for 1 hour; then add an amine curing agent, control the temperature to maintain at 25-30°C and stir for 1 hour to obtain the low-precipitation photothermal dual-curing 2.5D packaging bottom filling glue.

[0018] Preferably, the entire preparation process is carried out under vacuum conditions, and more preferably the vacuum degree is maintained at not less than -0.08Mpa during the entire process.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention introduces both photoinitiator and amine curing agent into the formula, and utilizes their respective curing characteristics. It innovatively performs light pre-curing first, and then completely cures the bottom filling material in the entire bottom filling area by heating. First, the light curing pre-curing increases viscosity or forms a semi-gel state, which will fix the precipitated small molecules. Even in the subsequent thermal curing, there will not be a large number of small molecules precipitated. The low-precipitation substance finally obtained can be used for a new 2.5D bottom filling glue, which is a light-curing and thermal-curing dual-curing single-component epoxy adhesive. It can reduce the width of the precipitates on the substrate and silicon wafer to the minimum level while meeting the processability and reliability. DETAILED DESCRIPTION

[0021] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0022] Add bisphenol A epoxy resin, bisphenol F epoxy resin, alicyclic epoxy resin, coupling agent and black paste into a high-speed planetary stirring kettle, then stir for 2 hours, then add spherical fillers in batches, stir and mix thoroughly, and then disperse and grind them through a three-roll grinder; then continue to heat and stir at 70-90°C in the high-speed planetary stirring kettle for 4 hours, and cool to room temperature; under a yellow light environment, add a photoinitiator, control the temperature to maintain at 25-30°C and stir for 1 hour; then add an amine curing agent, control the temperature to maintain at 25-30°C and stir for 1 hour, and then obtain the low-precipitation photothermal dual-curing 2.5D packaging bottom filling glue.

[0023] According to the above preparation process, the specific examples and comparative examples are shown in Table 1 below, and the dosage units are grams:

[0024] Table 1. Examples and comparative examples preparation formula

[0025]

[0026]

[0027] test

[0028] 1. Precipitation width measurement: mainly carried out on self-made simulation samples, with the substrate heating temperature of 110°C and the nozzle heating temperature of 60°C. The precipitation width is measured for the edge of the silicon wafer on the glue-applied side and the substrate surface on the glue-applied side. After the glue is applied and filled, the initial precipitation width is measured first; then the simulated sample after the glue is filled is irradiated with a 365-wavelength LED light for preliminary curing for 60 seconds, and then the precipitation width is measured again; finally, the preliminary light-cured sample is placed in an oven, heated to 165°C, and after thermal curing for 2 hours, the final precipitation width is measured.

[0029] 2. Main physical and chemical performance test: The present invention needs to carry out physical and chemical performance test of curing, and the curing conditions are: first use 365 wavelength LED light for preliminary curing for 60s, then put it in an oven, heat it to 165℃, and heat cure it for 2h. It should be noted that the high-temperature pudding mold adhesion belongs to the adhesion in the initial state after curing. The following three reflow soldering, uHast192h (130℃ temperature / 85% humidity), TCB 1000 cycles (-55℃-125℃, 30min / 1 cycle, 1000 cycles), HTST 1000h (150℃) are three different reliability conditions. When testing, they are not accumulated, but are carried out separately after curing.

[0030] 3. Electrical reliability test of simulated samples: After the simulated samples are filled with glue, they are cured according to the above curing conditions, and then the above reliability conditions are respectively carried out, and then the power-on test is carried out in turn. The results are shown in Table 2-Table 4.

[0031] Table 2. Comparison of precipitation width between Examples 1-6 and Comparative Examples 1-3

[0032]

[0033] Table 3. Comparison of main physical and chemical properties of Examples 1-6 and Comparative Examples 1-3

[0034]

[0035]

[0036] Table 4. Comparison of reliability electrical measurements of simulated samples of Examples 1-6 and Comparative Examples 1-3

[0037]

[0038] As shown in the data in Table 2, it can be intuitively seen that in the precipitation on the edge of the silicon wafer, in Examples 1-6, no precipitated material climbed onto the silicon wafer at the beginning, and no precipitate appeared on the silicon wafer after preliminary photocuring and further thermal curing. However, in Comparative Examples 1-3, precipitates appeared on the surface of the silicon wafer after preliminary photocuring and further thermal curing. Comparative Example 1 does not contain a photoinitiator component, so there is no photocuring reaction. Compared with Examples 1-6, by observing the colloidal morphology of Examples 1-6 after preliminary photocuring, compared with before photocuring, although it is not completely cured, it can be seen that the viscosity has increased, or is close to a semi-gel state. It can be explained that containing a suitable photoinitiator can make the formula product in the present invention have a part of the photocuring reaction, increase the viscosity or form a semi-gel state, and can "lock" the small molecule substances in the formula. In this way, after thermal curing, although the overall viscosity will be reduced to a certain extent, there will be no precipitation of small molecules, so that low precipitation or even no precipitation is achieved.

[0039] Comparative Examples 2 and 3 contain photoinitiators, but the viscosity is basically not increased by precipitation performance and colloid morphology observation after preliminary photocuring. It is further explained that the primary amine and secondary amine curing agents in Comparative Examples 2 and 3 cause the cationic photoinitiator to be poisoned and inactivated, so there is no photocuring reaction. Comparative Examples 1-3 do not have a preliminary photocuring reaction, so the initial viscosity of the thermal curing process is reduced to the minimum, and small molecules are easily precipitated.

[0040] Similarly, for the precipitation on the substrate surface, the overall rules shown in Table 2 are similar to those on the edge of the silicon wafer. Slightly different is that compared with other embodiments, the precipitation performance of Examples 5 and 6 before and after curing is at the lowest level. This is because Examples 5 and 6 both introduce GT401, a multi-branched functional group alicyclic epoxy resin, which has a lower viscosity than conventional alicyclic epoxy resins. At the same time, during the initial light curing and subsequent heat curing process, the multi-functional group can react to a high degree, and more small molecules can be "locked" at the same time.

[0041] It should be noted here that: based on the formula design of the present invention, when a free radical photoinitiator is selected, primary amines, secondary amines, and tertiary amines can be used in combination at will, because the free radical photoinitiator will not be deactivated. When a cationic photoinitiator is selected, it cannot be used in combination with primary amines and secondary amines, because the nitrogen in the original amine curing agent will deactivate it, and the more hydrogen atoms are carried on the nitrogen atom, the greater the degree of deactivation. After formula design research, the present invention has selected GR-SS058 cationic photoinitiator, which has poisoning and deactivation phenomenon for primary amines, secondary amines, and tertiary amines, but for primary amines and secondary amines, it is completely inactivated, and for tertiary amines, it is not completely inactivated. The colloid viscosity after initial photocuring increases, and it has the effect of "locking" small molecular precipitates.

[0042] As shown in the data in Table 3, the physical and chemical properties related to reliability need to focus on the fracture strain and stress at high temperature of 245°C, high temperature adhesion, and adhesion under different reliability conditions. The high temperature fracture strain and stress show the material's bulk toughness at high temperature, which can be related to the warpage performance after the bottom filler is filled with actual chips, and directly affects the reliability. High temperature adhesion and adhesion under different reliability conditions are also directly related to the reliability after glue filling.

[0043] It can be seen from the data table that the high-temperature fracture stress-strain of Examples 1-6 is significantly higher than that of Comparative Examples 1-3. This is because Examples 1-6 all have a preliminary photocuring pre-reaction, and then thermal curing is performed, so that the overall polymer segment structure will be more complex than that of Comparative Examples 1-3, the molecular chain length and entanglement degree will be higher, and the microscopic toughness and flexibility will be better. At the same time, the stress-strain level of Examples 5 and 6 will be higher than that of Examples 1-4, because the introduction of GT401, a multi-branched functional group alicyclic epoxy resin, can further increase the complexity of the polymer segment structure after curing, the molecular chain length and entanglement degree, microscopic toughness and flexibility.

[0044] It can be seen from the data table that the performance of high-temperature adhesion and adhesion retention after different reliability in Examples 1-6 is slightly better than that in Comparative Example 1, and is significantly better than that in Comparative Examples 2 and 3. The reasons are the same as above, because Examples 1-6 are preliminarily photocured and then thermally cured, the microscopic flexibility is better and the curing stress is very low, which will also affect the high-temperature adhesion and the adhesion after different reliability. At the same time, Comparative Examples 2 and 3 also contain photoinitiators, but due to the matching primary and secondary amines, the photoinitiators therein have no effect, but this photoinitiator is a small molecule substance, which will directly affect the adhesion performance. At the same time, the stress-strain levels of Examples 5 and 6 are higher than those of Examples 1-4, which is also directly related to the introduction of GT401 as described above.

[0045] As shown in Table 4, the electrical test performance of the actual chip after different reliability tests, the feedback rules and mechanisms are consistent with the above analysis conclusions.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low precipitation light-thermal dual-curing 2.5D package bottom filling glue, characterized in that: The raw materials include by weight: 10-20 parts of bisphenol F epoxy resin, 5-10 parts of bisphenol A epoxy resin, 5-10 parts of alicyclic epoxy resin, 0.5-1 parts of black paste, 0.8-1.2 parts of coupling agent, 50-55 parts of spherical filler, 10-15 parts of amine curing agent, and 0.1-0.5 parts of photoinitiator.

2. The low precipitation light-thermal dual-curing 2.5D packaging bottom filling glue according to claim 1, characterized in that: When the photoinitiator is a free radical photoinitiator, the corresponding amine curing agent is at least one of a primary amine curing agent, a secondary amine curing agent, and a tertiary amine curing agent; when the photoinitiator is a cationic photoinitiator, the corresponding amine curing agent is a tertiary amine curing agent.

3. The low precipitation light-thermal dual-curing 2.5D packaging bottom filling glue according to claim 2, characterized in that: The primary amine curing agent comprises at least one of ethylenediamine, hexamethylenediamine, metaphenylenediamine, monoethanolamine, dimethylthiotoluenediamine and diethyltoluenediamine.

4. The low precipitation light-thermal dual-curing 2.5D packaging bottom filling adhesive according to claim 2, characterized in that: The secondary amine curing agent comprises at least one of diethylamine, dihexylamine, N-methylaniline, hexahydropyridine, diethyltetramethylimidazole and 1-cyanoethyl-2-ethyl-4-methylimidazole.

5. The low precipitation light-thermal dual-curing 2.5D packaging bottom filling glue according to claim 2, characterized in that: The tertiary amine curing agent comprises at least one of N, N-dimethylaniline, diethanolamine, N-methyldiethanolamine, triethanolamine, triethylamine and trihexylamine.

6. The low precipitation light-thermal dual-curing 2.5D packaging bottom filling adhesive according to claim 1, characterized in that: The alicyclic epoxy resin is at least one of 2021P, S28E, PB3600, GT401 and 2028 produced by Daicel of Japan.

7. The low precipitation light-thermal dual-curing 2.5D packaging bottom filling adhesive according to claim 6, characterized in that: The coupling agent is γ-aminopropyl triethoxysilane, γ-mercaptopropyl trimethoxysilane, γ-mercaptopropyl triethoxysilane, γ-glycidyloxypropyl trimethoxysilane, γ ― At least one of aminopropyltrimethoxysilane.

8. A method for preparing the low precipitation light-thermal dual-curing 2.5D packaging bottom filling adhesive according to any one of claims 1 to 7, characterized in that: The steps include: Add bisphenol A epoxy resin, bisphenol F epoxy resin, alicyclic epoxy resin, coupling agent and black paste into a reaction container, then stir for 2 hours, then add spherical fillers in batches, stir and mix thoroughly and then disperse and grind; then continue to heat and stir at 70-90°C in the reaction container for 4 hours, then cool to room temperature; under a yellow light environment, add a photoinitiator, control the temperature to maintain at 25-30°C and stir for 1 hour; then add an amine curing agent, control the temperature to maintain at 25-30°C and stir for 1 hour to obtain the low-precipitation photothermal dual-curing 2.5D packaging bottom filling glue.

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