Heat-conducting epoxy composition capable of eliminating corner cracks of packaged chip and preparation method of heat-conducting epoxy composition

Abstract

The invention relates to a heat-conducting epoxy composition capable of eliminating corner cracks of a packaged chip and a preparation method of the heat-conducting epoxy composition, the heat-conducting epoxy composition comprises the following components in percentage by weight: 17-25% of epoxy resin, and the epoxy resin comprises epoxy resin containing polar groups and flexible resin; 48-62% of a modified heat-conducting filler; 0.1 to 0.95 percent of a coupling agent; 0.5%-4.8% of a flatting agent; 1.0 to 4.0% of an adhesion promoter; 1.3%-3.5% of a reactive diluent; 6-12% of a curing agent; 0.2%-0.8% of a curing accelerator; 1.5%-2.0% of a toughening agent; the invention has the advantages that the combination of the epoxy resin containing polar groups and the flexible resin is matched with the modified heat-conducting filler to construct a uniform and stable resin network structure, so that the stress can be buffered and dispersed, the stress is prevented from being concentrated on weak parts such as the edge of a chip and the like, and cracks are eliminated.

Description

Technical Field

[0001] The present invention relates to an epoxy film, and particularly to a thermally conductive epoxy composition capable of eliminating corner cracks of encapsulated chips and a preparation method thereof. Background Art

[0002] Epoxy film is an organic product mainly composed of epoxy resin and can be applied to chip packaging. With the development of the post-Moore era, chips are developing towards high frequency, high power, high transmission speed, and high storage capacity. Correspondingly, the reliability and stability of packaging materials are improved. Key indicators such as thermal conductivity, coefficient of thermal expansion, modulus, and low warpage and low shrinkage are important evaluation criteria and also the focus of packaging factories' assessment of packaging materials. During the chip packaging process, after steps such as thermal curing and thermal reflow, due to differences in different coefficients of thermal expansion and volume shrinkage during the curing of packaging materials, thermal stress will be generated, especially concentrated at the corners of the chip. When the thermal stress exceeds the bearing capacity of the epoxy film, tearing will occur, ultimately resulting in cracks at the edges of the chip after the film is cured and also during the chip cutting process.

[0003] It should be noted that the information disclosed in the above background art section is only used to enhance the understanding of the background of the present disclosure, and thus may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention discloses a thermally conductive epoxy composition capable of eliminating corner cracks of encapsulated chips and a preparation method thereof.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A thermally conductive epoxy composition capable of eliminating corner cracks of encapsulated chips, characterized in that it includes components in percentage by content: 17-25% of epoxy resin, and the epoxy resin includes epoxy resin containing polar groups and flexible resin; 48-62% of modified thermally conductive filler; 0.1-0.95% of coupling agent; 0.5-4.8% of leveling agent; 1.0-4.0% of adhesion promoter; 1.3-3.5% of reactive diluent; 6-12% of curing agent, 0.2-0.8% of curing accelerator; 1.5-2.0% of toughening agent; 10-22% of solvent.

[0007] Further, the epoxy resin containing polar groups includes at least one of dendritic epoxy resin, polyurethane-modified epoxy resin, and modified CYD-T60 epoxy resin.

[0008] Further, the flexible resin includes at least one of silicone-modified epoxy resin, liquid butadiene rubber-modified epoxy resin, high molecular weight flexible epoxy resin, phenoxy resin, and polyester-type modified epoxy resin.

[0009] Further, the modified CYD-T60 epoxy resin is obtained by pre-polymerization modification of dendritic crosslinker CYD-T60 and bisphenol A epoxy resin. The dendritic crosslinker CYD-T60 is added to the bisphenol A epoxy resin matrix, and the addition ratio of the dendritic crosslinker CYD-T60 accounts for 20-40%. The bisphenol A epoxy resin matrix is pre-polymerization modified at 70-100°C for 1-2 h to obtain a product, and the equivalent weight of the modified CYD-T60 epoxy resin is controlled at 250-300 g / eq.

[0010] Further, the modified thermal conductive filler includes filler A and filler B. Filler A is modified diamond with a D50 particle size range of 1-10 μm. Filler B includes at least one of modified spherical aluminum nitride, modified spherical boron nitride, and modified spherical aluminum oxide, and the D50 particle size range of the modified spherical aluminum nitride, modified spherical boron nitride, and modified spherical aluminum oxide is 20-50 μm.

[0011] Further, the curing agent includes at least one of phenolic curing agents, amine curing agents, and imidazole curing agents.

[0012] Further, the adhesion promoter is a dendritic adhesion promoter.

[0013] Further, the coupling agent is a silane coupling agent; the reactive diluent is at least one of resorcinol diglycidyl ether, cashew nut oil-modified monoglycidyl ether, and the polymer of 1,6-hexanediol and epichlorohydrin; the leveling agent includes at least one of silicone leveling agents and acrylate leveling agents.

[0014] Further, the curing accelerator includes at least one of 2,4,6-tris(dimethylaminomethyl)phenol, dimethylbenzylamine, or quaternized polyvinylimidazole; the toughening agent includes at least one of reactive liquid nitrile rubber, core-shell toughening agents, and polyvinyl formal; the solvent includes at least one of propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, toluene, and butyl acetate.

[0015] A preparation method of a thermal conductive epoxy composition capable of eliminating corner cracks of encapsulated chips includes the following steps:

[0016] Step S1, modification of the thermal conductive filler. Prepare the raw materials of the thermal conductive filler and put them into a stirrer. While stirring, spray in the silane coupling agent. The stirring speed is controlled at 200-400 r / min, the reaction temperature is 90-100°C, and the stirring time is 2-3 h.

[0017] Step S2: Preparation of Adhesive A. First, mix an epoxy resin containing polar groups and a flexible resin. Put the obtained epoxy resin after mixing into a reaction kettle, then add a solvent and a toughening agent. Control the stirring speed at 800 - 1000 r / min, the stirring time at 2 - 5 h, and the stirring temperature at 60 - 90 °C.

[0018] Step S3: Preparation of Adhesive B. Put the modified thermal conductive filler, curing agent, curing accelerator, adhesion promoter, leveling agent, and reactive diluent into a reaction kettle and stir - mix with the mixed solution of Adhesive A. Control the stirring speed at 500 - 700 r / min and stir at 25 °C for 1 - 3 h to obtain Adhesive B.

[0019] Step S4: Film - forming and Rewinding of the Adhesive Film. Use the doctor - blade coating method to coat Adhesive B on a release film, then send it into an oven for drying and forming. The temperature range of the oven is 80 - 120 °C, the film - feeding speed in the oven is 1 - 2 m / s, and finally wind up the obtained product.

[0020] The beneficial effects of the present invention are as follows:

[0021] 1. The polar groups in the epoxy resin containing polar groups can easily form intermolecular forces with other materials, making their combination more compact and stable, improving their compatibility, forming a uniform and stable overall network structure after curing, reducing defects and stress concentration points caused by poor bonding between resins, and helping to eliminate cracks. In addition, the flexible resin has a flexible and tensile - resistant molecular structure. When subjected to external forces, the resin network structure can buffer and disperse stress, avoiding stress concentration at weak parts such as the edges of chips and further eliminating cracks.

[0022] 2. The resin system contains a large number of polar groups such as hydroxyl groups (-OH) and epoxy groups (—CH(O)CH—). The thermal conductive filler modified with a silane coupling agent introduces polar groups on the surface of the thermal conductive filler. Due to the action of polar functional groups, the epoxy resin molecules can interact with the molecules on the surface of the modified thermal conductive filler, significantly improving the bonding force and compatibility between the two, enabling them to form a stable structure in the composite material, and significantly helping the thermal conductivity, thermal performance, and crack elimination of the material.

[0023] 3. A variety of heat-conducting fillers such as modified diamond are used in combination. Among them, modified diamond has extremely high thermal conductivity and is one of the materials with the highest thermal conductivity among known materials. Moreover, its own coefficient of thermal expansion is low, which can effectively reduce the elastic modulus of the resin system, making the cured epoxy adhesive have a certain toughness and can better relieve internal stress, thereby helping to eliminate crack problems; modified spherical aluminum nitride also has good thermal conductivity and certain electrical insulation properties; modified spherical boron nitride not only has good thermal conductivity but also has high-temperature stability. When they are used in combination, a more efficient heat conduction is formed in the resin system.

[0024] 4. The active groups of the dendritic adhesion promoter can chemically react with the resin containing polar groups to form chemical bonds, which can improve the adhesion between the epoxy adhesive film and the chip and help reduce cracks caused by thermal stress.

[0025] 5. The molecular chains of reactive liquid nitrile rubber contain active groups at both ends or on the side chains that can react with the epoxy groups of epoxy resin, so that the molecular chains of nitrile rubber are connected to the cross-linked network of epoxy resin in the form of chemical bonds, forming an interpenetrating network structure. When the material is subjected to external forces, the rubber phase can absorb and dissipate energy through the stretching and deformation of molecular chains, thereby reducing the stress of the system and shrinkage during curing and improving the cracking problem; core-shell tougheners usually consist of a rubber core and a plastic shell. The rubber core is responsible for absorbing impact energy, and the plastic shell provides flexibility and toughness; the hydrogen bonds formed by the acetal bonds and residual hydroxyl groups in the chemical structure of polyvinyl formaldehyde improve the toughness of the material and are also beneficial to improving the cracking problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the steps of the preparation method of the epoxy adhesive film in Example 1.

[0027] Figure 2 It is a rheological curve diagram of the product in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] The following will describe the specific embodiments of the present invention with reference to the accompanying drawings.

[0029] Example 1:

[0030] A heat-conducting epoxy composition capable of eliminating corner cracks of encapsulated chips, comprising:

[0031] 18% of epoxy resin, which includes 5% dendritic epoxy resin CYE-001, 5% modified CYD-T60 epoxy resin and 8% flexible resin polyester-type modified epoxy resin: polyester-type modified epoxy resin with a polysulfide backbone.

[0032] The modified CYD-T60 epoxy resin is obtained by pre-polymerization modification of dendritic crosslinking agent CYD-T60 and bisphenol A epoxy resin, with an epoxy equivalent of 280 g / eq.

[0033] The modified thermal conductive filler is 54.8%. The modified thermal conductive filler includes filler A and filler B. Filler A is modified diamond with a D50 particle size of 1.8 μm, and filler B is modified spherical aluminum nitride with a D50 particle size of 30 μm. The ratio of the two is a compound of 28.8% modified diamond and 26% modified spherical aluminum nitride.

[0034] The coupling agent is 0.5%. The coupling agent used is silane coupling agent KBM-3600.

[0035] The leveling agent is 1.0%. The leveling agent used is silicone-based leveling agent AKN-1050.

[0036] The adhesion promoter is 2.0%. The adhesion promoter is dendritic adhesion promoter CYD-T57 (Weihai Chenyuan).

[0037] The reactive diluent is 2.2%. The reactive diluent used is resorcinol diglycidyl ether.

[0038] The curing agent is 9.0%. The curing agent used is phenolic curing agent Shengquan SH7090.

[0039] The curing accelerator is 0.5%. The curing accelerator used is 2,4,6-tris(dimethylaminomethyl)phenol.

[0040] The toughening agent is 1.8%. The toughening agent used is reactive liquid nitrile rubber RA1340.

[0041] The solvent is 12.2%. The solvent includes 6% propylene glycol methyl ether acetate and 6.2% toluene.

[0042] The preparation method of the thermal conductive epoxy composition is as Figure 1 shown, and includes the following steps:

[0043] Step S1, modification of the thermal conductive filler. Prepare the raw materials of the thermal conductive filler and put them into a stirrer. While stirring, spray in the silane coupling agent. The stirring speed is controlled at 200 r / min, the reaction temperature is 90 °C, and the stirring time is 2 h;

[0044] Step S2, preparation of glue solution A. First, mix the epoxy resin containing polar groups and the flexible resin. Take the obtained epoxy resin after mixing and put it into a reaction kettle. Then, add the solvent and the toughening agent. The stirring speed is controlled at 800 r / min, the stirring time is 2 h, and the stirring temperature is 60 °C;

[0045] Step S3: Preparation of Adhesive B. Put the modified thermal conductive filler, curing agent, curing accelerator, adhesion promoter, leveling agent, and active diluent into a reaction kettle and stir and mix them with the mixed solution of Adhesive A. Control the stirring speed at 500 r / min and stir at 25°C for 1 h to obtain Adhesive B;

[0046] Step S4: Film Forming and Rewinding of Adhesive Film. Coating Adhesive B on the release film by means of knife coating, then sending it into an oven for drying and forming. The temperature range of the oven is 80°C, the film feeding speed in the oven is 1 m / s, and finally wind up the obtained product.

[0047] Example 2:

[0048] The difference from Example 1 lies in: different amounts of fillers

[0049] Thermal conductive epoxy composition, including:

[0050] Epoxy resin 19%, modified thermal conductive filler 48.55%, coupling agent 0.95%, leveling agent 3.5%, adhesion promoter 1.5%; active diluent 2.0%; curing agent 11.0%; curing accelerator 0.5%; toughening agent 2.0%; solvent 11%.

[0051] The preparation process of the adhesive film is the same as that of Example 1.

[0052] Example 3:

[0053] The difference from Example 1 lies in: different amounts of fillers

[0054] Thermal conductive epoxy composition, including:

[0055] Epoxy resin 17%, modified thermal conductive filler 58%, coupling agent 0.1%, leveling agent 1.6%, adhesion promoter 1.5%; active diluent 1.5%; curing agent 8.0%; curing accelerator 0.2%; toughening agent 1.5%; solvent 10.6%.

[0056] The preparation process of the adhesive film is the same as that of Example 1.

[0057] Example 4:

[0058] The difference from Example 1 lies in:

[0059] Epoxy resin 18%, and the epoxy resin adopts 5% dendritic epoxy resin CYE-001, 5% polyurethane epoxy resin, and 8% flexible resin polyester-modified epoxy resin.

[0060] Example 5:

[0061] The difference from Example 1 lies in:

[0062] Epoxy resin: 18%, including 3% dendritic epoxy resin CYE-001, 3% polyurethane epoxy resin, 2% modified CYD-T60 epoxy resin, and 10% flexible resin polyester-modified epoxy resin.

[0063] Example 6:

[0064] The difference from Example 1 is:

[0065] Epoxy resin: 18%, including 5% dendritic epoxy resin CYE-001, 5% modified CYD-T60 epoxy resin, and 8% silicone-modified epoxy resin.

[0066] Example 7:

[0067] The difference from Example 1 is:

[0068] Epoxy resin: 18%, including 5% dendritic epoxy resin CYE-001, 5% modified CYD-T60 epoxy resin, and 8% liquid butadiene rubber-modified epoxy resin.

[0069] Example 8:

[0070] The difference from Example 1 is:

[0071] Epoxy resin: 18%, including 5% dendritic epoxy resin CYE-001, 5% modified CYD-T60 epoxy resin, and 8% high molecular weight flexible epoxy resin EP1700 (complexed).

[0072] Example 9:

[0073] The difference from Example 1 is:

[0074] Epoxy resin: 18%, including 5% dendritic epoxy resin CYE-001, 5% modified CYD-T60 epoxy resin, 3% silicone-modified epoxy resin, 2% liquid butadiene rubber-modified epoxy resin, and 3% flexible resin polyester-modified epoxy resin.

[0075] Example 10:

[0076] The difference from Example 1 is:

[0077] Epoxy resin: 18%, including 5% dendritic epoxy resin CYE-001, 5% modified CYD-T60 epoxy resin, 3% silicone-modified epoxy resin, 2% liquid butadiene rubber-modified epoxy resin, and 3% phenoxy resin.

[0078] Example 11:

[0079] The heat-conducting epoxy composition has the same content of each component as in Example 1, and the difference is:

[0080] Modified thermal conductive filler: 54.8%, the modified thermal conductive filler includes filler A and filler B. Filler A is modified diamond with a D50 particle size of 10 μm. Filler B is a mixture of modified spherical aluminum nitride and modified spherical boron nitride. The D50 particle size of the modified spherical aluminum nitride is 20 μm, and the D50 particle size of the modified spherical boron nitride is 30 μm. The proportion of the modified thermal conductive filler is 16% of modified diamond, 20% of modified spherical aluminum nitride, and 18.8% of modified spherical boron nitride.

[0081] Example 12:

[0082] The thermal conductive epoxy composition has the same content of each component as in Example 1, and the difference is that:

[0083] Modified thermal conductive filler: 54.8%, the modified thermal conductive filler includes filler A and filler B. Filler A is modified diamond with a D50 particle size of 5 μm. Filler B is a mixture of modified spherical aluminum nitride, modified spherical boron nitride, and modified spherical aluminum oxide. The D50 particle size of the modified spherical aluminum nitride is 30 μm, the D50 particle size of the modified spherical boron nitride is 25 μm, and the D50 particle size of the modified spherical aluminum oxide is 50 μm. The proportion of each filler is 17% of modified diamond, 12% of modified spherical aluminum nitride, 9% of modified spherical boron nitride, and 16.8% of modified spherical aluminum oxide.

[0084] Example 13:

[0085] The thermal conductive epoxy composition has the same content of each component as in Example 1, and the difference is that:

[0086] The curing agent is selected as a complex of ammonia curing agent Dow D.E.H.52 modified amine and imidazole curing agent Complex EH-15LS.

[0087] Example 14:

[0088] The thermal conductive epoxy composition has the same content of each component as in Example 1, and the difference is that:

[0089] The curing agent is selected as a complex of phenolic curing agent SH7090 (Shengquan) and ammonia curing agent Dow D.E.H.52 modified amine (Dow).

[0090] Example 15:

[0091] The thermal conductive epoxy composition has the same content of each component as in Example 1, and the difference is that:

[0092] The curing agent is selected as a complex of phenolic curing agent SH7090 (Shengquan), ammonia curing agent Dow D.E.H.52 modified amine (Dow), and imidazole curing agent EH-15LS, (Complex).

[0093] Example 16:

[0094] The heat-conducting epoxy composition has the same component contents as those in Example 1, with the difference that:

[0095] DMP-30 is selected as the curing accelerator.

[0096] Example 17:

[0097] The heat-conducting epoxy composition has the same component contents as those in Example 1, with the difference that:

[0098] An acrylate leveling agent BYK-358N is selected as the leveling agent.

[0099] Example 18:

[0100] The heat-conducting epoxy composition has the same component contents as those in Example 1, with the difference that:

[0101] X-12-1056ES is selected as the coupling agent.

[0102] Example 19:

[0103] The heat-conducting epoxy composition has the same formulation as that in Example 1, with the difference that:

[0104] The preparation method of the heat-conducting epoxy composition is as Figure 1 shown, and includes the following steps:

[0105] Step S1, modification of the heat-conducting filler. Prepare the raw materials of the heat-conducting filler and put them into a stirrer. While stirring, spray in the silane coupling agent. The stirring speed is controlled at 300 r / min, the reaction temperature is 100 °C, and the stirring time is 2 h;

[0106] Step S2, preparation of adhesive solution A. First, mix the epoxy resin containing polar groups and the flexible resin. Take the obtained epoxy resin after mixing and put it into a reaction kettle. Then, add the solvent and the toughening agent. The stirring speed is controlled at 900 r / min, the stirring time is 3 h, and the stirring temperature is 80 °C;

[0107] Step S3, preparation of adhesive solution B. Put the modified heat-conducting filler, curing agent, curing accelerator, adhesion promoter, leveling agent, and reactive diluent into the reaction kettle and stir and mix them with the mixed solution of adhesive solution A. The stirring speed is controlled at 600 r / min, and stir at 25 °C for 2 h to obtain adhesive solution B;

[0108] Step S4, forming and winding of the adhesive film. Use the doctor blade coating method to coat adhesive solution B on the release film, and then send it into the oven to dry and form. The temperature range of the oven is 100 °C, the film feeding speed in the oven is 1 m / s, and finally, wind the obtained product.

[0109] Comparative Example 1:

[0110] Replace the epoxy resin with polar groups and the flexible resin in Example 1 with novolac epoxy resin, and the remaining components and percentages are the same as those in Example 1, and the same preparation process conditions are adopted.

[0111] Comparative Example 2:

[0112] Replace the epoxy resin with polar groups and the flexible resin in Example 1 with a combination of bisphenol F type epoxy resin and aliphatic epoxy resin, and the remaining components and percentages are the same as those in Example 1, and the same preparation process conditions are adopted.

[0113] Comparative Example 3:

[0114] Replace the thermal conductive filler in Example 1 with alumina and aluminum nitride, and the remaining components and percentages are the same as those in Example 1, and the same preparation process conditions are adopted.

[0115] Comprehensive performance test of epoxy adhesive film:

[0116] Experimental detection standard:

[0117] The glass transition temperature and coefficient of thermal expansion are tested with reference to ASTM D696.

[0118] The thermal conductivity is tested with reference to ASTM D5470-2012.

[0119] The elastic modulus is tested with reference to ASTM D638.

[0120] The water absorption is tested with reference to GB / T1462-2005.

[0121] The thermal stress is tested with reference to IPC-TM-650 2.4.13.1 at 288 °C, solder float, for 60 min.

[0122] The situation of corner cracks is observed and judged through a microscope.

[0123] Sampling: Randomly select sample adhesive films from Examples 1 to 19 and Comparative Examples 1 to 3 for testing.

[0124]

[0125]

[0126]

[0127]

[0128] Analysis of experimental results:

[0129] As can be seen from the results in the table, the thermal conductivity of the experimental samples in Examples 1 to 19 is between 6.6 and 7.9 W / mK, the glass transition temperature of the experimental samples is ≥170 °C, the linear expansion coefficients in two directions of the experimental samples are low, the water absorption rate of the experimental samples is ≤0.3, there are no cracks at the corners of the experimental samples, and no cracks appear during the thermal stress test of the experimental samples. From a macroscopic perspective, it is proved that the material has a uniform and stable resin network structure, which can effectively disperse and relieve stress, avoiding cracks due to excessive stress concentration at the corners of the adhesive film. Thus, it can be seen that the resin selected in the present invention has a good effect on improving cracking, plays an important role in the formulation system, is irreplaceable, and the modified thermal conductive filler is stably combined in the resin network structure, significantly improving its thermal performance.

[0130] Comparing Example 1 with Comparative Examples 1 to 2, without using the combination of epoxy resin containing polar groups and flexible resin, stress concentration points will be generated after curing, increasing the risk of crack generation, and it will also have a greater impact on properties such as thermal conductivity and thermal expansion coefficient.

[0131] Comparing Example 1 with Comparative Example 3, in addition to affecting the thermal conductivity, the elastic modulus and thermal expansion coefficient of the system also become higher, resulting in the generation of corner cracks.

[0132] Rheological curve measurement:

[0133] Take the product manufactured in Example 1 as the experimental sample.

[0134] Experimental instrument: Rotational rheometer.

[0135] Test temperature range: 20 - 140 °C.

[0136] Obtain the rheological curve diagram as Figure 2 shown.

[0137] Result analysis:

[0138] It can be seen from the rheological curve that under heating conditions, the viscosity of the adhesive film drops significantly and is relatively low, indicating that the adhesive film has excellent fluidity under heating conditions and is not prone to problems such as lack of glue and incomplete filling during the chip encapsulation process; at around 118 °C, the viscosity of the adhesive film begins to rise and the adhesive film begins to gel. The temperature range of the vacuum heating and laminating process can be set according to the viscosity rising point, providing a meaningful reference for optimizing the chip encapsulation process.

[0139] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0140] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips, characterized in that: Including the components in percentage: 17-25% of epoxy resin, wherein the epoxy resin includes epoxy resin containing polar groups and flexible resin; Modified thermal conductive filler 48-62%; Coupling agent 0.1~0.95%; Leveling agent 0.5~4.8%; Adhesion promoter 1.0-4.0%; Active diluent 1.3~3.5%; Curing agent 6-12%; Curing accelerator 0.2~0.8%; Toughening agent 1.5-2.0%; Solvent 10-22%.

2. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 1, characterized in that: The polar group epoxy resin includes at least one of a dendritic epoxy resin, a polyurethane modified epoxy resin and a modified CYD-T60 epoxy resin.

3. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 1, characterized in that: The flexible resin includes at least one of an organic silicon modified epoxy resin, a liquid butadiene rubber modified epoxy resin, a high molecular weight flexible epoxy resin, a phenoxy resin and a polyester modified epoxy resin.

4. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 2, characterized in that: The modified CYD-T60 epoxy resin is obtained by prepolymerization modification of a dendritic crosslinking agent CYD-T60 and a bisphenol A epoxy resin. The dendritic crosslinking agent CYD-T60 is added to a bisphenol A epoxy resin matrix, the addition ratio of the dendritic crosslinking agent CYD-T60 is 20-40%, and the bisphenol A epoxy resin matrix is ​​prepolymerized at 70-100° C. for 1-2 hours to obtain a product. The modified CYD-T60 epoxy resin equivalent is controlled at 250-300 g / eq.

5. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 1, characterized in that: The modified thermal conductive filler includes filler A and filler B, wherein filler A is modified diamond, and its D50 particle size ranges from 1 to 10 μm, and filler B includes at least one of modified spherical aluminum nitride, modified spherical boron nitride and modified spherical aluminum oxide, and the D50 particle size ranges from 20 to 50 μm.

6. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 1, characterized in that: The curing agent includes at least one of a phenolic curing agent, an ammonia curing agent and an imidazole curing agent.

7. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 1, characterized in that: The adhesion promoter is a dendritic adhesion promoter.

8. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 1, characterized in that: The coupling agent is a silane coupling agent; the active diluent is at least one of resorcinol diglycidyl ether, cashew nut oil modified monoglycidyl ether, and a polymer of 1,6-hexanediol and epichlorohydrin; and the leveling agent includes at least one of an organic silicon leveling agent and an acrylate leveling agent.

9. The thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips according to claim 1, characterized in that: The curing accelerator includes at least one of 2,4,6-tris(dimethylaminomethyl)phenol, dimethylbenzylamine or quaternized polyvinyl imidazole; the toughening agent includes at least one of reactive liquid nitrile rubber, core-shell toughening agent and polyvinyl formal; the solvent includes at least one of propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, toluene and butyl acetate.

10. A method for preparing a thermally conductive epoxy composition capable of eliminating cracks at corners of packaged chips as claimed in any one of claims 1 to 9, comprising the following steps: Step S1, thermal conductive filler modification, prepare thermal conductive filler raw materials and put them into a stirrer, spray silane coupling agent while stirring, the stirring speed is controlled at 200-400 r / min, the reaction temperature is 90-100° C., and the stirring time is 2-3 h; Step S2, preparing glue A, pre-mixing the epoxy resin containing polar groups and the flexible resin, putting the epoxy resin obtained after mixing into a reaction kettle, then adding the solvent and the toughening agent, controlling the stirring speed at 800-1000 r / min, the stirring time at 2-5 h, and the stirring temperature at 60-90° C.; Step S3, preparing glue liquid B, adding the modified thermal conductive filler, curing agent, curing accelerator, adhesion promoter, leveling agent and active diluent into a reaction kettle and stirring with the mixed liquid of glue liquid A, the stirring speed is controlled at 500-700 r / min, stirring at 25° C. for 1-3 hours, to obtain glue liquid B; Step S4, film forming and winding, using a doctor blade coating method, the adhesive liquid B is coated on the release film, and then sent to an oven for drying and forming. The oven temperature range is 80-120°C, and the film feeding speed in the oven is 1-2m / s. Finally, the obtained product is wound up.

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