A chip package structure

Abstract

In order to overcome the problems of insufficient temperature resistance, reliability and service life of the existing multi-layer chip packaging structure, the application provides a chip packaging structure, which comprises a substrate, a chip and a packaging layer, the packaging layer and the chip are located on the substrate, and the packaging layer covers the chip, the chip comprises a plurality of storage chips, the plurality of storage chips are arranged in a staggered and stacked manner, so that a plurality of stepped surfaces are formed on one side of the storage chips, at least one pad is arranged at the position of the stepped surface of the storage chip, the pads of two adjacent storage chips are connected with each other through the lead wire, the glass transition temperature of the packaging layer is 210-250 DEG C, the dielectric constant is 2.8-3.2, the tensile strength is 115-141 MPa, and the elongation at break is 5.7%-8%.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor chips, and particularly relates to a chip packaging structure. BACKGROUND

[0002] With the rapid development of electronic information technology, especially the continuous progress of chip mounting technology and the fifth generation mobile communication (5G) technology, the requirements for chip packaging materials are increasingly strict. Ladder type multi-layer chip packaging is increasingly widely used in consumer electronics, data centers and other fields because it can effectively improve storage capacity and integration. This packaging structure realizes efficient use of space by integrating multiple chips in a ladder-shaped stack, meeting the urgent needs of modern electronic devices for miniaturization and high performance. Currently, most chip packaging uses epoxy resin as the main packaging material. Epoxy resin has been widely used in traditional electronic packaging due to its good bonding strength with the substrate and excellent weather resistance.

[0003] However, in the face of higher performance requirements for multi-layer chip packaging, epoxy resin gradually exposes its limitations. First, the temperature resistance of epoxy resin is generally only 100 degrees Celsius or more, while some advanced chip mounting processes such as wave soldering require higher temperature resistance, which makes epoxy resin unsuitable for these application scenarios. Second, with the development of 5G communication technology, more stringent requirements are placed on the dielectric constant of the chip packaging layer. Due to the high dielectric constant of the packaging layer itself, its application effect in high-frequency signal transmission is limited, and it cannot meet the low-loss, high-speed requirements of 5G communication.

[0004] In addition, existing packaging layers generally exhibit high rigidity, which is a potential risk for multi-layer chip packaging. Because in actual work, chips will experience volume expansion and contraction caused by temperature changes, which can easily produce thermal stress in multi-layer chip packaging structures. If the packaging material is too rigid, it may cause cracks in the packaging material or form gaps between the packaging material and the substrate, thereby weakening its ability to block moisture and increasing the risk of lead breakage between chips, further affecting the reliability and service life of the chips. SUMMARY

[0005] In view of the problems of insufficient temperature resistance, reliability and service life of existing multi-layer chip packaging structures, the application provides a chip packaging structure.

[0006] The technical scheme adopted by the application to solve the above technical problems is as follows:

[0007] In one aspect, the present application provides a chip packaging structure, comprising a substrate, a chip and a packaging layer, the packaging layer and the chip are located on the substrate, and the packaging layer covers the chip, the chip comprises a plurality of memory chips, the plurality of memory chips are arranged in a staggered and stacked manner to form a stepped surface on one side of each memory chip, at least one pad is arranged on the stepped surface of the memory chip, and the pads of two adjacent memory chips are connected to each other by arranging a lead wire, the glass transition temperature of the packaging layer is 210-250 DEG C, the dielectric constant is 2.8-3.2, the tensile strength is 115-141 MPa, and the elongation at break is 5.7%-8%.

[0008] Optionally, the chip further comprises a control chip, the control chip is located on the substrate, and the control chip is located below the plurality of memory chips, and the control chip is electrically connected to at least one of the memory chips.

[0009] Optionally, the packaging layer is obtained by curing a chip packaging material, the chip packaging material comprises a combination of the following components by weight:

[0010] bisphenol A type epoxy resin 58-67 parts, polyether modified polyamide acid 9-19 parts, acid anhydride curing agent 9-16 parts, imidazole promoter 0.5-2 parts, filler 2-10 parts and active diluent 2-5 parts;

[0011] The polyether modified polyamide acid comprises a block copolymerized polyamide acid segment and a polyether segment, and the polyether modified polyamide acid has an end amino group.

[0012] Optionally, the polyether modified polyamide acid is prepared by the following method:

[0013] Preparation of anhydride-terminated polyimide acid;

[0014] Mixing polyether diamine and anhydride-terminated polyimide acid to carry out block polymerization reaction, and the amount of substance of polyether diamine is greater than that of anhydride-terminated polyimide acid, to obtain polyether modified polyamide acid with end amino group.

[0015] Optionally, the anhydride-terminated polyimide acid is prepared by the following method:

[0016] Polymerization of diacid anhydride and diamine, and the amount of substance of diacid anhydride is greater than that of diamine, to obtain anhydride-terminated polyimide acid.

[0017] Optionally, the diamine includes at least one of 4,4-diaminodiphenoxy ether, 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl and 2-(4-aminophenyl)-5-aminobenzimidazole; the diacid anhydride includes at least one of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride or 2,3,3',4'-diphenoxyethanetetracarboxylic dianhydride.

[0018] Optionally, the acid anhydride curing agent includes one or more of methyl nadic anhydride, methyltetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, trimellitic anhydride, polyazelaic anhydride and dodecenyl succinic anhydride, the imidazole promoter includes one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-phenylimidazole, the filler includes one or more of nanosilica, alumina, calcium carbonate, talc, glass microbeads, and the active diluent includes phenyl glycidyl ether.

[0019] Optionally, the filler is selected from nanosilica, and the surface of the nanosilica is treated with a silane coupling agent.

[0020] Optionally, the chip packaging material further includes 20-100 parts by weight of a solvent, and the solvent includes one or more of N-methylpyrrolidone, dimethylacetamide, dimethylformamide and γ-butyrolactone.

[0021] Optionally, the chip packaging material further includes 2-5 parts by weight of hexamethylene diisocyanate trimer.

[0022] According to the chip packaging structure provided by the application, for the multi-chip laminated structure, a packaging layer with a glass transition temperature of 210-250 DEG C, a dielectric constant of 2.8-3.2, a tensile strength of 115-141 MPa, and an elongation at break of 5.7%-8% is designed. The glass transition temperature of the packaging layer reaches 210-250 DEG C, which can better adapt to the high-temperature environment of the multiple storage chips in the manufacturing and use process of the stepwise misaligned laminated structure compared with the traditional epoxy resin packaging material. Whether it is a multiple soldering process or an advanced installation process such as wave soldering, the packaging layer can maintain stable performance, avoid material degradation caused by high temperature, effectively protect the stability of the stepwise multi-layer storage chip packaging structure, and prolong its service life under high-temperature working conditions. Secondly, the dielectric constant of the packaging layer is controlled to be 2.8-3.2, which meets the low-loss requirement of 5G communication technology for high-frequency signal transmission. Furthermore, the tensile strength of the packaging layer is 115-141 MPa, and the elongation at break is 5.7%-8%, which has a certain flexibility while having high strength. For the thermal stress caused by the different degrees of volume expansion and contraction of the stepwise misaligned laminated storage chips due to temperature changes during work, the packaging layer can effectively buffer and release, avoid cracks caused by too high rigidity of the material, and avoid the problem of gaps between the packaging layer and the substrate, and each storage chip layer. This not only enhances the water vapor blocking ability of the packaging layer, but also further improves the reliability of the entire stepwise multi-layer storage chip packaging structure, and protects the long-term stable work of the chip. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 FIG. 1 is a structural schematic diagram of the substrate chip packaging structure provided by the application.

[0024] The reference signs in the drawings of the specification are as follows:

[0025] 1, substrate; 2, control chip; 3, storage chip; 4, solder pad; 5, lead; 6, packaging layer. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects of the application clearer, the application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0027] As Figure 1As shown, an embodiment of the present application provides a chip packaging structure, which comprises a substrate 1, a chip and a packaging layer 6, the packaging layer 6 and the chip are located on the substrate 1, and the packaging layer 6 covers the chip, the chip comprises a plurality of storage chips 3, the plurality of storage chips 3 are arranged in a staggered and stacked manner to form a stepped surface on one side of each of the plurality of storage chips 3, at least one pad 4 is arranged at the position of the stepped surface of the storage chip 3, and the pads 4 of two adjacent storage chips 3 are connected to each other through a lead 5, the glass transition temperature of the packaging layer 6 is 210-250℃, the dielectric constant is 2.8-3.2, the tensile strength is 115-141MPa, and the elongation at break is 5.7%-8%.

[0028] For the multi-chip stacked structure, a packaging layer 6 with a glass transition temperature of 210-250℃, a dielectric constant of 2.8-3.2, a tensile strength of 115-141MPa, and an elongation at break of 5.7%-8% is designed. The glass transition temperature of the packaging layer 6 reaches 210-250℃, which can better adapt to the high-temperature environment of the plurality of storage chips 3 arranged in a staggered and stacked manner during manufacturing and use compared to traditional epoxy resin packaging materials. Whether it is a multiple soldering process or an advanced mounting process such as wave soldering, the packaging layer 6 can maintain stable performance, avoid material degradation caused by high temperature, effectively ensure the stability of the staggered multi-layer storage chip 3 packaging structure, and prolong its service life under high-temperature working conditions. Secondly, the dielectric constant of the packaging layer 6 is controlled to be 2.8-3.2, which meets the low-loss requirement of 5G communication technology for high-frequency signal transmission. Furthermore, the tensile strength of the packaging layer 6 is 115-141MPa, and the elongation at break is 5.7%-8%, which has a certain flexibility while having high strength. For the thermal stress caused by different degrees of volume expansion and contraction of the staggered and stacked storage chips 3 due to temperature changes during work, the packaging layer 6 can effectively buffer and release the stress, avoiding the generation of cracks caused by excessive rigidity of the material and the appearance of gaps between the packaging layer 6, the substrate 1 and the layers of storage chips 3. This not only enhances the moisture blocking ability of the packaging layer 6, but also further improves the reliability of the entire staggered multi-layer storage chip 3 packaging structure, ensuring the long-term stable operation of the chip.

[0029] In an embodiment, the chip further comprises a control chip 2, the control chip 2 is located on the substrate 1, and the control chip 2 is located below the plurality of storage chips 3, and the control chip 2 is electrically connected to at least one of the storage chips 3.

[0030] In an embodiment, the packaging layer 6 is obtained by curing a chip packaging material, and the chip packaging material comprises the following combined raw materials by weight:

[0031] bisphenol A type epoxy resin 58~67 parts, polyether modified polyamide acid 9~19 parts, acid anhydride type curing agent 9~16 parts, imidazole type accelerator 0.5~2 parts, filler 2~10 parts and active diluent 2~5 parts;

[0032] The polyether modified polyamide acid comprises block copolymerized polyamide acid segments and polyether segments, and the polyether modified polyamide acid has terminal amino groups.

[0033] The bisphenol A type epoxy resin gives the chip packaging material good adhesion to the chip or substrate 1, and the polyamide acid segments in the polyether modified polyamide acid are isomerized to polyimide in the subsequent curing process, have high high-temperature stability and low dielectric constant, and can effectively improve the high-temperature resistance of the packaging material, increase the Tg of the chip packaging material from about 140°C to about 230°C, and the dielectric loss of the chip packaging material is <0.008 at 1GHz, which is suitable for high-frequency electronic packaging. At the same time, the polyether segments in the polyether modified polyamide acid have high flexibility, and form a rigid network with the epoxy resin, which can effectively reduce the rigidity of the chip packaging material after curing, adapt to the volume deformation of the chip when the temperature changes, inhibit the generation of cracks, and improve the water vapor barrier effect. Further, in order to solve the problem of insufficient affinity between different resin segments, the polyether segments and the polyamide acid segments are used to form a block copolymer to realize dispersion at the molecular level, and terminal amino groups with electron pairs are formed at the ends of the polyether modified polyamide acid. Before curing, the active hydrogen of the terminal amino group can attack the epoxy group of the bisphenol A type epoxy resin to initiate ring-opening reaction, realize crosslinking between the polyether modified polyamide acid and the bisphenol A type epoxy resin, avoid material stratification, and further improve the crosslinking density between the segments to form a network-like crosslinking network, improve the high-temperature resistance and mechanical properties of the chip packaging material.

[0034] In some embodiments, the polyether modified polyamide acid is prepared by the following method:

[0035] An acid anhydride-terminated polyimide acid is prepared;

[0036] The polyether diamine and the acid anhydride-terminated polyimide acid are mixed to perform block polymerization, and the amount of substance of the polyether diamine is greater than that of the acid anhydride-terminated polyimide acid, to obtain a polyether modified polyamide acid with terminal amino groups.

[0037] The polyether-modified polyamide acid with terminal amino groups is prepared by first preparing an acid anhydride-terminated polyimide acid and then performing a block polymerization reaction with excess polyether diamine. This method precisely controls the molecular structure, ensures the ratio of polyether segments to polyamide acid segments in the polyether-modified polyamide acid and the presence of terminal amino groups, thereby stably achieving the modification effect on the epoxy resin and further ensuring the performance consistency and stability of the packaging material.

[0038] In the above reaction, the polyimide acid exists in the form of a solution, and the polyether diamine is added in batches and stirred to react in the polyimide acid solution.

[0039] In some embodiments, the polyether diamine is selected from Jeffamine D-230 or Jeffamine D-400.

[0040] In some embodiments, the acid anhydride-terminated polyimide acid is prepared by the following method:

[0041] The binary acid anhydride and the binary amine are subjected to a polymerization reaction, and the amount of substance of the binary acid anhydride is greater than that of the binary amine, thereby obtaining an acid anhydride-terminated polyimide acid.

[0042] The polymerization reaction of the binary acid anhydride and the binary amine is performed in a solvent. Specifically, the binary acid anhydride and the binary amine are respectively dissolved in a solvent to form a solution, and then the binary acid anhydride solution is added dropwise into the binary amine solution.

[0043] By controlling the amount of substance of the binary acid anhydride and the binary amine, the polyimide acid is terminated with an acid anhydride, which provides active sites for the subsequent block polymerization reaction with the polyether diamine, ensuring that the structure of the polyether-modified polyamide acid is controllable, thereby effectively regulating the flexibility, high-temperature resistance, low dielectric properties and other properties of the packaging material.

[0044] In some embodiments, the binary amine includes at least one of 4,4-diamino diphenyl ether, 4,4'-diamino-2,2'-bistrifluoromethyl biphenyl and 2-(4-aminophenyl)-5-aminobenzimidazole; and the binary acid anhydride includes at least one of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride or 2,3,3',4'-diphenyl ether tetra carboxylic dianhydride.

[0045] When the diamine is selected from 4,4'-diamino-2,2'-bistrifluoromethyl diphenyl or 2-(4-aminophenyl)-5-aminobenzimidazole, or when the dianhydride is selected from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, the special groups (such as fluorine atoms, benzimidazole structures, etc.) contained in the molecular structure thereof help to reduce the dielectric constant of the polyimide acid, improve the heat resistance and chemical stability, so that the prepared polyether modified polyamide acid can more significantly improve the dielectric properties and high temperature resistance of the packaging material, meeting the needs of 5G communication and high temperature chip mounting process.

[0046] In some embodiments, the anhydride-based curing agent includes one or more of methyl nadic anhydride, methyl tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, trimellitic anhydride, polyazelaic anhydride, and dodecenyl succinic anhydride.

[0047] The anhydride-based curing agent forms a cross-linked network by reacting with the epoxy group, thereby converting the linear or branched epoxy resin into a three-dimensional polymer network with high strength, heat resistance and chemical stability.

[0048] In some embodiments, the imidazole-based accelerator includes one or more of 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-phenylimidazole.

[0049] The imidazole-based accelerator can accelerate the reaction efficiency of the bisphenol A type epoxy resin with the terminal amino group of the polyether modified polyamide acid and other reactive groups (such as carboxyl groups) during the curing process of the chip packaging material, which is conducive to reducing the reaction temperature, forming a more dense three-dimensional network structure, and ensuring the cross-linking between different polymer segments.

[0050] In some embodiments, the filler includes one or more of nanosilica, alumina, calcium carbonate, talc, and glass microbeads.

[0051] The addition of the filler can enhance the mechanical properties of the packaging material, such as hardness, wear resistance, and thermal conductivity, and different fillers can also bring different additional properties (such as alumina can improve thermal conductivity).

[0052] In some embodiments, the reactive diluent includes phenyl glycidyl ether.

[0053] The reactive diluent phenyl glycidyl ether can effectively reduce the viscosity of the system, making the packaging material more easily coated and filled during the processing process, improving production efficiency and product quality, and not affecting the curing performance and final performance of the material.

[0054] In some embodiments, the filler is selected from nanosilica, and the surface of the nanosilica is treated with a silane coupling agent.

[0055] Nano-silica has high specific surface area and excellent reinforcing effect. After treatment with silane coupling agent, the compatibility of the surface of the nano-silica with epoxy resin and polyether-modified polyamide acid is greatly improved, the nano-silica can be more uniformly dispersed in the system, the mechanical properties and water vapor barrier properties of the reinforcing material are improved, the problem of performance decline caused by filler agglomeration is avoided, and the comprehensive performance of the packaging material is further improved.

[0056] In some embodiments, the chip packaging material further comprises 20-100 parts by weight of a solvent, the solvent comprising one or more of N-methylpyrrolidone, dimethylacetamide, dimethylformamide, gamma-butyrolactone.

[0057] The presence of the solvent can improve the dispersibility of the components, make the raw materials more uniform during mixing, help to form a uniform and stable system, adjust the viscosity of the material, and make the material have better operation performance in coating, printing and other processing processes, facilitate the molding and application of the packaging material.

[0058] In some embodiments, the chip packaging material further comprises 2-5 parts by weight of hexamethylene diisocyanate trimer.

[0059] The hexamethylene diisocyanate trimer contains multiple isocyanate groups, which can react with the terminal amino groups of the polyether-modified polyamide acid, the hydroxyl groups of the epoxy resin, and the like, further strengthen the crosslinking network inside the material, improve the strength and toughness of the packaging material, and help to improve the water vapor barrier properties and long-term stability of the material.

[0060] The curing method of the chip packaging material is as follows: first stage: 120℃ / 2 hours, to promote the reaction of epoxy groups with amino groups, carboxyl groups, hydroxyl groups and the like; second stage: 150℃ / 2 hours, to promote the imidization reaction of polyimide.

[0061] The application will be further described through examples.

[0062] Example 1

[0063] This example is used to illustrate the chip packaging structure disclosed in the application and the preparation method thereof, which comprises the following operation steps:

[0064] Step 1: Preparation of anhydride-terminated polyimide acid

[0065] 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, 5.00 mol) and 4,4-diaminodiphenyl ether (ODA, 4.80 mol) were respectively added to a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, and N-methylpyrrolidone (NMP, 1500 mL) was added respectively, and stirring was performed to obtain a binary anhydride solution and a binary amine solution, respectively;

[0066] The diacid anhydride solution was added dropwise to the diamin solution under nitrogen protection, and the reaction was stirred at 0°C for 4 hours to form an acid anhydride-terminated polyimide acid solution.

[0067] Step 2: Preparation of polyether-modified polyamic acid by block polymerization

[0068] The polyether diamine (Jeffamine D-230) was slowly added dropwise to the acid anhydride-terminated polyimide acid solution, keeping the temperature below 25°C; the reaction intermediates were detected by infrared spectroscopy (FTIR), and the characteristic peaks of the acid anhydride were at 1780 cm -1 and 1850 cm -1 When the characteristic peaks disappeared, the temperature was raised to 50°C and the reaction was continued for 6 hours to form an amino-terminated polyether-modified polyamic acid;

[0069] After the reaction was completed, part of the solvent was evaporated under reduced pressure to make the solid content of the polyether-modified polyamic acid solution 20%.

[0070] Step 3: Preparation of chip packaging material

[0071] Bisphenol A epoxy resin (E-51) 62g

[0072] Polyether-modified polyamic acid solution 60g

[0073] Methyl nadic anhydride (MNA) 10g

[0074] 2-Ethyl-4-methyl imidazole 1.2g

[0075] Nano-silicon dioxide (treated with KH-560) 6g

[0076] Phenyl glycidyl ether 3g

[0077] Hexamethylene diisocyanate trimer 3g

[0078] Operation steps:

[0079] The bisphenol A epoxy resin and the polyether-modified polyamic acid solution were added to the reaction kettle, and stirring was continued at 60°C for 2 hours to ensure uniform dispersion;

[0080] Methyl nadic anhydride, 2-ethyl-4-methyl imidazole and phenyl glycidyl ether were added in turn, and stirring was continued at 50°C for 1 hour;

[0081] Nano-silicon dioxide treated with silane coupling agent (KH-560) was added, and high-speed dispersion (2000 rpm) was continued for 2 hours;

[0082] Finally, hexamethylene diisocyanate trimer was added, and low-speed stirring was continued for 30 minutes;

[0083] Vacuum degassing (-0.1 MPa, 30 minutes) to obtain a uniform chip packaging material, and part of the chip packaging material is taken for detection, and the remaining packaging material is used for step 4 packaging.

[0084] Step 4: Chip packaging

[0085] The control chip and the multi-layer storage chip are staggered and stacked on the substrate, lead wires are arranged on the control chip, the storage chip and the substrate, the chip packaging material is filled on the substrate through a mold, and the packaging material covers the control chip and the storage chip, and a curing operation is performed, and the curing method is as follows: first stage: 120℃ / 2h, promoting the reaction of epoxy group with amino group, carboxyl group and hydroxyl group; second stage: 150℃ / 2h, promoting the imidization reaction of polyimide.

[0086] A chip packaging structure is obtained.

[0087] Example 2

[0088] This example is used to illustrate the chip packaging material and the preparation method thereof disclosed by the application, which comprises the following operation steps:

[0089] Step 1: Preparation of anhydride-terminated polyimide acid

[0090] 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, 5.00 mol) and 4,4-diaminodiphenyl ether (ODA, 4.80 mol) are respectively added to a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, and N-methyl pyrrolidone (NMP, 1500 mL) is added respectively, and stirring and dissolution are performed respectively to obtain a binary anhydride solution and a binary amine solution;

[0091] The binary anhydride solution is added dropwise to the binary amine solution under nitrogen protection, and stirring reaction is performed at 0℃ for 4 hours to form an anhydride-terminated polyimide acid solution.

[0092] Step 2: Preparation of polyether-modified polyamide acid by block polymerization

[0093] The polyether diamine (Jeffamine D-230) is slowly added dropwise to the above-mentioned anhydride-terminated polyimide acid solution, and the temperature is kept below 25℃; the reaction intermediate is detected by infrared spectroscopy (FTIR), and the characteristic peaks of anhydride are at 1780cm -1 and 1850cm -1 , and the dropping end point is reached when the characteristic peaks disappear, and the temperature is raised to 50℃ for continuous reaction for 6 hours to generate an amino-terminated polyether-modified polyamide acid;

[0094] After the reaction is completed, part of the solvent is evaporated under reduced pressure, and the solid content of the polyether-modified polyamide acid solution is 20%.

[0095] Step 3: Preparation of the chip packaging material

[0096] Bisphenol A epoxy resin (E-51) 58 g

[0097] Polyether modified polyamide acid solution 50 g

[0098] Methyl nadic anhydride (MNA) 16 g

[0099] 2-Ethyl-4-methyl imidazole 0.5 g

[0100] Nano-silica (treated with KH-560) 5 g

[0101] Phenyl glycidyl ether 5 g

[0102] Hexamethylene diisocyanate trimer 5 g

[0103] Operation steps:

[0104] The bisphenol A epoxy resin and the polyether modified polyamide acid solution were added to a reaction kettle, and stirring was continued at 60℃ for 2 hours to ensure uniform dispersion;

[0105] Methyl nadic anhydride, 2-ethyl-4-methyl imidazole and phenyl glycidyl ether were added in sequence, and stirring was continued at 50℃ for 1 hour;

[0106] Nano-silica treated with silane coupling agent (KH-560) was added, and high-speed dispersion (2000 rpm) was carried out for 2 hours;

[0107] Finally, hexamethylene diisocyanate trimer was added, and low-speed stirring was carried out for 30 minutes;

[0108] Vacuum degassing (-0.1 MPa, 30 minutes) was carried out to obtain a uniform chip packaging material, and part of the chip packaging material was taken for detection, and the remaining packaging material was used for step 4 packaging.

[0109] Step 4: Chip packaging

[0110] The control chip and the multi-layer storage chip were arranged in a staggered and stepped manner on the substrate, and lead wires were arranged to electrically connect the control chip, the storage chip and the substrate. The chip packaging material was filled on the substrate by a mold, and the packaging material was wrapped around the control chip and the storage chip. After vacuum degassing, a solidification operation was carried out, and the solidification method was as follows: first stage: 120℃ / 2 hours; second stage: 150℃ / 2 hours.

[0111] A chip packaging structure was obtained.

[0112] Example 3

[0113] This example is used to illustrate the chip packaging material and the preparation method thereof disclosed in the present application, which comprises the following operation steps:

[0114] Step 1: Preparation of anhydride-terminated polyimide acid

[0115] 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 5.00 mol) and 4,4'-oxydianiline (ODA, 4.80 mol) were added into a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, respectively, and N-methyl pyrrolidone (NMP, 1500 mL) was added, respectively, to obtain a dianhydride solution and a diamine solution, respectively, which were stirred to dissolve;

[0116] The dianhydride solution was added dropwise into the diamine solution under nitrogen protection, and the reaction was stirred at 0°C for 4 hours to form an anhydride-terminated polyimide acid solution.

[0117] Step 2: Preparation of polyether-modified polyamide acid by block polymerization

[0118] The polyether diamine (Jeffamine D-230) was slowly added dropwise into the above-mentioned anhydride-terminated polyimide acid solution, and the temperature was kept below 25°C; the reaction intermediate was detected by infrared spectroscopy (FTIR), and the characteristic peaks of anhydride were at 1780 cm -1 and 1850 cm -1 , and the dropping was stopped when the characteristic peaks disappeared, and the temperature was raised to 50°C for further reaction for 6 hours to form an amino-terminated polyether-modified polyamide acid;

[0119] After the reaction was completed, part of the solvent was evaporated under reduced pressure to make the solid content of the polyether-modified polyamide acid solution 20%.

[0120] Step 3: Preparation of a chip packaging material

[0121] Bisphenol A epoxy resin (E-51) 65 g

[0122] Polyether-modified polyamide acid solution 70 g

[0123] Methyl nadic anhydride (MNA) 12 g

[0124] 2-Ethyl-4-methylimidazole 1 g

[0125] Nano-silicon dioxide (treated with KH-560) 4 g

[0126] Phenyl glycidyl ether 3 g

[0127] Hexamethylene diisocyanate trimer 3 g

[0128] Operation steps:

[0129] The bisphenol A epoxy resin and the polyether-modified polyamide acid solution were added into a reaction kettle, and stirring was continued at 60°C for 2 hours to ensure uniform dispersion;

[0130] Methyl nadic anhydride, 2-ethyl-4-methyl imidazole and phenyl glycidyl ether were added successively, and stirred at 50℃ for 1 hour;

[0131] Nano-silica treated with silane coupling agent (KH-560) was added, and dispersed at high speed (2000 rpm) for 2 hours;

[0132] Hexamethylene diisocyanate trimer was finally added, and stirred at low speed for 30 minutes;

[0133] Vacuum degassing was performed (-0.1 MPa, 30 minutes), and a uniform chip packaging material was obtained. Part of the chip packaging material was taken for detection, and the remaining packaging material was used for step 4 packaging.

[0134] Step 4: Chip packaging

[0135] The control chip and the multi-layer storage chip were arranged in a staggered and stepped manner on the substrate, lead wires were arranged on the control chip, the storage chip and the substrate, the chip packaging material was filled on the substrate through a mold, and the packaging material was wrapped around the control chip and the storage chip. After vacuum degassing, a solidification operation was performed. The solidification method was as follows: first stage: 120℃ / 2 hours; second stage: 150℃ / 2 hours.

[0136] A chip packaging structure was obtained.

[0137] Example 4

[0138] This example is used to illustrate the chip packaging material and the preparation method thereof disclosed in the present application, which comprises the following operation steps:

[0139] Step 1: Preparation of anhydride-terminated polyimide acid

[0140] 3,3',4,4'-benzophenone tetracarboxylic dianhydride (5.00 mol) and 4,4-diamino diphenyl ether (ODA, 4.80 mol) were respectively added to a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, and N-methyl pyrrolidone (NMP, 1500 mL) was added respectively, and stirring was performed to obtain a binary acid anhydride solution and a binary amine solution respectively;

[0141] The binary acid anhydride solution was added dropwise to the binary amine solution under nitrogen protection, and stirring was performed at 0℃ for 4 hours to form an anhydride-terminated polyimide acid solution.

[0142] Step 2: Preparation of polyether modified polyamide acid by block polymerization

[0143] Polyether diamine (Jeffamine D-230) was slowly added dropwise to the above-mentioned anhydride-terminated polyimide acid solution, and the temperature was kept below 25℃; the reaction intermediate was detected by infrared spectroscopy (FTIR), and the characteristic peak of anhydride was at 1780 cm -1and 1850 cm -1 The dropping was stopped when the characteristic peak disappeared, and the temperature was raised to 50°C to continue the reaction for 6 hours to form an amino-terminated polyether-modified polyamic acid;

[0144] After the reaction was completed, part of the solvent was evaporated under reduced pressure to make the solid content of the polyether-modified polyamic acid solution 20%.

[0145] Step 3: Preparation of the chip packaging material

[0146] Bisphenol A epoxy resin (E-51) 62 g

[0147] Polyether-modified polyamic acid solution 60 g

[0148] Methyl nadic anhydride (MNA) 10 g

[0149] 2-Ethyl-4-methylimidazole 1.2 g

[0150] Nano-silicon dioxide (treated with KH-560) 6 g

[0151] Phenyl glycidyl ether 3 g

[0152] Hexamethylene diisocyanate trimer 3 g

[0153] Operation steps:

[0154] The bisphenol A epoxy resin and the polyether-modified polyamic acid solution were added to the reaction kettle, and stirring was continued at 60°C for 2 hours to ensure uniform dispersion;

[0155] Methyl nadic anhydride, 2-ethyl-4-methylimidazole, and phenyl glycidyl ether were added in sequence, and stirring was continued at 50°C for 1 hour;

[0156] Nano-silicon dioxide treated with silane coupling agent (KH-560) was added, and high-speed dispersion (2000 rpm) was continued for 2 hours;

[0157] Finally, hexamethylene diisocyanate trimer was added, and low-speed stirring was continued for 30 minutes;

[0158] Vacuum degassing (-0.1 MPa, 30 minutes) was performed to obtain a uniform chip packaging material, and part of the chip packaging material was taken for detection, and the remaining packaging material was used for step 4 packaging.

[0159] Step 4: Chip packaging

[0160] The control chip and the multi-layer storage chip are staggered and stacked in a step-by-step manner on the substrate, lead wires are arranged on the control chip, the storage chip and the substrate, the chip packaging material is filled on the substrate through a mold and the packaging material covers the control chip and the storage chip, vacuum degassing is performed, and then solidification is performed, the solidification method being: first stage: 120℃ / 2 hours; second stage: 150℃ / 2 hours.

[0161] A chip packaging structure is obtained.

[0162] Example 5

[0163] The chip packaging material and the preparation method thereof are described in the embodiment, and the following operation steps are included.

[0164] Step 1: Preparation of anhydride-terminated polyimide acid

[0165] 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, 5.00 mol) and 4,4-diaminodiphenyl ether (ODA, 4.80 mol) are respectively added to a four-necked flask provided with a mechanical stirrer, a thermometer and a nitrogen inlet, and N-methyl pyrrolidone (NMP, 1500 mL) is respectively added, so as to obtain a binary anhydride solution and a binary amine solution respectively after stirring and dissolving;

[0166] The binary anhydride solution is added dropwise to the binary amine solution under the protection of nitrogen, and the anhydride-terminated polyimide acid solution is formed after stirring and reacting at 0℃ for 4 hours.

[0167] Step 2: Preparation of polyether-modified polyamide acid by block polymerization

[0168] The polyether diamine (Jeffamine D-230) is slowly added dropwise to the anhydride-terminated polyimide acid solution, and the temperature is kept below 25℃; the reaction intermediate is detected by infrared spectroscopy (FTIR), and the characteristic peaks of anhydride are at 1780 cm -1 and 1850 cm -1 When the characteristic peaks disappear, the dropping is stopped, the temperature is raised to 50℃, and the reaction is continued for 6 hours to obtain an amino-terminated polyether-modified polyamide acid;

[0169] After the reaction is completed, part of the solvent is evaporated under reduced pressure, and the solid content of the polyether-modified polyamide acid solution is 20%.

[0170] Step 3: Preparation of the chip packaging material

[0171] Bisphenol A type epoxy resin (E-51) 62g

[0172] Polyether-modified polyamide acid solution 60g

[0173] Methyl nadic anhydride (MNA) 10g

[0174] 2-ethyl-4-methylimidazole 1.2 g

[0175] Nano-silica (treated by KH-560) 6 g

[0176] Phenyl glycidyl ether 3 g

[0177] Operation steps:

[0178] The bisphenol A type epoxy resin and the polyether modified polyamide acid solution are added into a reaction kettle, and stirring is continued at 60°C for 2 hours to ensure uniform dispersion;

[0179] Methyl nadic anhydride, 2-ethyl-4-methylimidazole and phenyl glycidyl ether are added in sequence, and stirring is continued at 50°C for 1 hour;

[0180] Nano-silica treated by silane coupling agent (KH-560) is added, and high-speed dispersion (2000 rpm) is carried out for 2 hours;

[0181] Vacuum degassing is carried out (-0.1 MPa, 30 minutes) to obtain a uniform chip packaging material, and part of the chip packaging material is taken for detection, and the remaining packaging material is used for packaging in step 4.

[0182] Step 4: Chip packaging

[0183] The control chip and the multi-layer storage chip are arranged in a staggered and stepped manner on the substrate, lead wires are arranged on the control chip, the storage chip and the substrate, the chip packaging material is filled on the substrate through a mold, and the packaging material covers the control chip and the storage chip, vacuum degassing is carried out, and then solidification is carried out, the solidification method being: first stage: 120°C / 2 hours; second stage: 150°C / 2 hours.

[0184] A chip packaging structure is obtained.

[0185] Comparative Example 1

[0186] This comparative example is used to illustrate the chip packaging material and the preparation method thereof disclosed in the present application, and includes the following operation steps:

[0187] Preparation of the chip packaging material

[0188] Bisphenol A type epoxy resin (E-51) 62 g

[0189] N-methylpyrrolidone 50 g

[0190] Methyl nadic anhydride (MNA) 10 g

[0191] 2-ethyl-4-methylimidazole 1.2 g

[0192] Nano-silica (treated by KH-560) 6 g

[0193] phenyl glycidyl ether 3 g

[0194] Operation steps:

[0195] The bisphenol A type epoxy resin and N-methyl pyrrolidone were added to a reaction kettle, and stirring was continued at 60℃ for 2 hours to ensure uniform dispersion;

[0196] Methyl nadic anhydride, 2-ethyl-4-methyl imidazole and phenyl glycidyl ether were added in sequence, and stirring was continued at 50℃ for 1 hour;

[0197] Nano-silicon dioxide treated with silane coupling agent (KH-560) was added, and high-speed dispersion (2000 rpm) was carried out for 2 hours;

[0198] Vacuum degassing (-0.1 MPa, 30 minutes) was carried out to obtain a uniform chip packaging material, and part of the chip packaging material was taken for detection, and the remaining packaging material was used for packaging.

[0199] The control chip and the multi-layer storage chip were arranged in a staggered and stepped manner on the substrate, lead wires were arranged on the control chip, the storage chip and the substrate, the chip packaging material was filled on the substrate through a mold, and the packaging material was wrapped around the control chip and the storage chip, vacuum degassing was carried out, and then solidification operation was carried out, the solidification method being: first stage: 120℃ / 2 hours; second stage: 150℃ / 2 hours.

[0200] A chip packaging structure was obtained.

[0201] Comparative Example 2

[0202] This comparative example is used to illustrate the chip packaging material and the preparation method thereof disclosed in the present application, and includes the following operation steps:

[0203] Step 1: Preparation of anhydride-terminated polyimide acid

[0204] 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, 5.00 mol) and 4,4-diaminodiphenyl ether (ODA, 4.80 mol) were respectively added to a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, and N-methyl pyrrolidone (NMP, 1500 mL) was added, and stirring dissolution was carried out to obtain a binary anhydride solution and a binary amine solution, respectively;

[0205] The binary anhydride solution was added dropwise to the binary amine solution under nitrogen protection, and stirring reaction was carried out at 0℃ for 4 hours to form an anhydride-terminated polyimide acid solution, after the reaction was completed, part of the solvent was evaporated under reduced pressure to make the solid content of the polyimide acid solution 20%.

[0206] Step 2: Preparation of the chip packaging material

[0207] Bisphenol A type epoxy resin (E-51) 62 g

[0208] Polyamic acid solution 60 g

[0209] Methyl nadic anhydride (MNA) 10 g

[0210] 2-Ethyl-4-methylimidazole 1.2 g

[0211] Nano-silica (treated with KH-560) 6 g

[0212] Phenyl glycidyl ether 3 g

[0213] Hexamethylene diisocyanate trimer 3 g

[0214] Operation steps:

[0215] The bisphenol A type epoxy resin and the polyamic acid solution are added to a reaction kettle, and stirring is continued at 60°C for 2 hours to ensure uniform dispersion;

[0216] Methyl nadic anhydride, 2-ethyl-4-methylimidazole, and phenyl glycidyl ether are added in sequence, and stirring is continued at 50°C for 1 hour;

[0217] Nano-silica treated with a silane coupling agent (KH-560) is added, and high-speed dispersion (2000 rpm) is performed for 2 hours;

[0218] Hexamethylene diisocyanate trimer is finally added, and low-speed stirring is performed for 30 minutes;

[0219] Vacuum degassing is performed (-0.1 MPa, 30 minutes) to obtain a uniform chip packaging material, and part of the chip packaging material is taken for detection, and the remaining packaging material is used for step 3 packaging.

[0220] Step 3: Chip packaging

[0221] The control chip and the multi-layer storage chip are arranged in a staggered and stepped manner on the substrate, lead wires are arranged on the control chip, the storage chip, and the substrate, the chip packaging material is filled on the substrate through a mold, and the packaging material covers the control chip and the storage chip, vacuum degassing is performed, and then solidification is performed, the solidification method being: first stage: 120°C / 2 hours; second stage: 150°C / 2 hours.

[0222] A chip packaging structure is obtained.

[0223] Comparative Example 3

[0224] This comparative example is used to illustrate the chip packaging material and the preparation method thereof disclosed in the present application, and includes the following operation steps:

[0225] Step 1: Preparation of anhydride-terminated polyimide acid

[0226] Into a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 5.00 mol) and 4,4'-diaminodiphenyl ether (ODA, 4.80 mol) were added into N-methyl pyrrolidone (NMP, 1500 mL) respectively, and stirred to dissolve to obtain a dianhydride solution and a diamine solution respectively;

[0227] The dianhydride solution was added dropwise into the diamine solution under nitrogen protection, and stirred at 0°C for 4 hours to form an acid anhydride-terminated polyimide acid solution.

[0228] Step 2: Preparation of a polyimide acid and polyether mixture

[0229] Polyethylene glycol 200 (PEG200) (0.50 mol) was added into the acid anhydride-terminated polyimide acid solution to obtain a polyimide acid and polyether mixture, and part of the solvent was evaporated under reduced pressure to make the solid content of the polyimide acid and polyether mixture solution 20%.

[0230] Step 3: Preparation of a chip packaging material

[0231] Bisphenol A epoxy resin (E-51) 62 g

[0232] Polyimide acid and polyether mixture solution 60 g

[0233] Methyl nadic anhydride (MNA) 10 g

[0234] 2-Ethyl-4-methylimidazole 1.2 g

[0235] Nano-silicon dioxide (treated with KH-560) 6 g

[0236] Phenyl glycidyl ether 3 g

[0237] Hexamethylene diisocyanate trimer 3 g

[0238] Operation steps:

[0239] The bisphenol A epoxy resin and the polyimide acid and polyether mixture solution were added into a reaction kettle, and stirred at 60°C for 2 hours to ensure uniform dispersion;

[0240] Methyl nadic anhydride, 2-ethyl-4-methylimidazole and phenyl glycidyl ether were added in sequence, and stirred at 50°C for 1 hour;

[0241] Nano-silicon dioxide treated with silane coupling agent (KH-560) was added, and dispersed at high speed (2000 rpm) for 2 hours;

[0242] Finally, hexamethylene diisocyanate trimer was added, and stirred at low speed for 30 minutes;

[0243] Vacuum degassing (-0.1 MPa, 30 minutes) to obtain a uniform chip packaging material, and part of the chip packaging material is taken for detection, and the remaining packaging material is used for step 4 packaging.

[0244] Step 4: Chip packaging

[0245] The control chip and the multi-layer storage chip are arranged in a staggered and stepped manner on the substrate, lead wires are arranged on the control chip, the storage chip and the substrate, the chip packaging material is filled on the substrate through a mold, and the packaging material covers the control chip and the storage chip, vacuum degassing is performed, and then solidification is performed, and the solidification method is: first stage: 120°C / 2 hours; second stage: 150°C / 2 hours.

[0246] A chip packaging structure is obtained.

[0247] Comparative Example 4

[0248] This comparative example is used to illustrate the chip packaging material and the preparation method thereof disclosed by the present application, which comprises the following operation steps:

[0249] Step 1: Preparation of anhydride-terminated polyimide acid

[0250] 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA, 5.00 mol) and 4,4-diaminodiphenyl ether (ODA, 4.80 mol) are respectively added to a four-necked flask equipped with a mechanical stirrer, a thermometer and a nitrogen inlet, and N-methyl pyrrolidone (NMP, 1500 mL) is added, and the binary anhydride solution and the binary amine solution are respectively obtained by stirring and dissolving.

[0251] The binary anhydride solution is added dropwise to the binary amine solution under nitrogen protection, and the reaction is stirred at 0°C for 4 hours to form an anhydride-terminated polyimide acid solution.

[0252] Step 2: Preparation of polyether-modified polyamide acid by block polymerization

[0253] The polyether diamine (Jeffamine D-230) is slowly added to the above-mentioned anhydride-terminated polyimide acid solution, and the temperature is kept below 25°C; the reaction intermediate is detected by infrared spectrum (FTIR), and the characteristic peaks of anhydride are at 1780 cm -1 and 1850 cm -1 , and the dropping is stopped before the characteristic peaks disappear, and the temperature is raised to 50°C for continuous reaction for 6 hours to generate an anhydride-terminated polyether-modified polyamide acid, and the sample is detected by infrared spectrum (FTIR) to confirm the appearance of anhydride characteristic peaks (1780 cm -1 and 1850 cm -1 );

[0254] After the reaction, the solvent was evaporated under reduced pressure to make the solid content of the polyether-modified polyamic acid solution 20%.

[0255] Step 3: Preparation of the chip packaging material

[0256] Bisphenol A epoxy resin (E-51) 62g

[0257] Polyether-modified polyamic acid solution 60g

[0258] Methyl nadic anhydride (MNA) 10g

[0259] 2-Ethyl-4-methylimidazole 1.2g

[0260] Nano-silica (treated with KH-560) 6g

[0261] Phenyl glycidyl ether 3g

[0262] Hexamethylene diisocyanate trimer 3g

[0263] Operation steps:

[0264] The bisphenol A epoxy resin and the polyether-modified polyamic acid solution were added to the reaction kettle, and stirring was continued at 60°C for 2 hours to ensure uniform dispersion;

[0265] Methyl nadic anhydride, 2-ethyl-4-methylimidazole, and phenyl glycidyl ether were added in sequence, and stirring was continued at 50°C for 1 hour;

[0266] Nano-silica treated with silane coupling agent (KH-560) was added, and high-speed dispersion (2000 rpm) was carried out for 2 hours;

[0267] Finally, hexamethylene diisocyanate trimer was added, and low-speed stirring was carried out for 30 minutes;

[0268] Vacuum degassing (-0.1 MPa, 30 minutes) was carried out to obtain a uniform chip packaging material. Part of the chip packaging material was taken for testing, and the remaining packaging material was used for step 4 packaging.

[0269] Step 4: Chip packaging

[0270] The control chip and the multi-layer storage chip were arranged in a staggered and stepped manner on the substrate, and lead wires were connected on the control chip, the storage chip, and the substrate. The chip packaging material was filled on the substrate through a mold and wrapped around the control chip and the storage chip. After vacuum degassing, solidification was carried out. The solidification method was as follows: first stage: 120°C / 2 hours; second stage: 150°C / 2 hours.

[0271] A chip packaging structure was obtained.

[0272] Performance test

[0273] After the chip packaging material prepared above is heat cured, the following performance tests are carried out:

[0274] I. Glass transition temperature (Tg) test

[0275] Sample preparation: 5-10 mg of the cured packaging material is taken and cut into a thin piece;

[0276] Test conditions: differential scanning calorimeter, nitrogen atmosphere (50 mL / min); heating rate: 10℃ / min; temperature range: 30℃-300℃, two heating scans are carried out; the inflection point (midpoint) of the second scan curve is taken as the Tg value.

[0277] II. Dielectric constant test

[0278] The dielectric constant test of the cured packaging material is carried out according to the standard ASTM D2520.

[0279] III. Tensile strength and elongation at break test

[0280] The tensile strength and elongation at break test of the cured packaging material is carried out according to the standard ASTM D638.

[0281] The test results obtained are filled in Table 1.

[0282] Table 1

[0283]

[0284] As can be seen from the test results in Table 1, the chip packaging material provided by the present application has a high glass transition temperature, indicating that it has good high temperature resistance, is beneficial to maintaining stability at high temperatures, is suitable for chip packaging in complex application environments and high-end processes such as wave soldering, and at the same time has a low dielectric constant, which can reduce signal loss in high frequency environments and is suitable for 5G high frequency chips. In addition, the chip packaging material has good mechanical properties, mainly in the improvement of elongation at break, indicating that it has high flexibility, can avoid material fatigue caused by volume expansion and contraction, reduce the occurrence of cracks, and ensure its packaging performance.

[0285] As can be seen from the test results of Comparative Example 1 and Example 4, the use of fluorine-containing dibasic anhydride (such as 6FDA) as the polymerization monomer of the polyamic acid in Example 1 is beneficial to reducing the dielectric constant of the material, and the non-fluorine-containing Example 4 will cause the dielectric constant to rise due to the influence of the material polarity.

[0286] The test results of Comparative Example 1 and Example 5 show that the addition of hexamethylene diisocyanate trimer promotes the formation of multi-branched crosslinking between the bisphenol A type epoxy resin and the polyether modified polyamide acid, which is beneficial to further improve the high temperature resistance and mechanical properties of the material.

[0287] The above description is merely the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A chip package structure, characterized by, The chip includes a substrate, a chip and a packaging layer, the packaging layer and the chip are located on the substrate, and the packaging layer covers the chip, the chip includes a plurality of memory chips, the plurality of memory chips are arranged in a staggered manner, and a stepped surface is formed on one side of each memory chip, at least one pad is arranged on the stepped surface of the memory chip, and the pads of two adjacent memory chips are connected to each other through a lead.

2. The chip package structure of claim 1, wherein, The chip also includes a control chip, the control chip is located on the substrate, and the control chip is located below the plurality of memory chips, and the control chip is electrically connected to at least one of the memory chips.

3. The chip package structure of claim 1, wherein, The packaging layer is obtained by curing a chip packaging material, and the chip packaging material includes the following combined raw materials by weight: Bisphenol A type epoxy resin 58-67 parts, polyether modified polyamide acid 9-19 parts, acid anhydride curing agent 9-16 parts, imidazole promoter 0.5-2 parts, filler 2-10 parts and active diluent 2-5 parts; The polyether modified polyamide acid includes block copolymerized polyamide acid segments and polyether segments, and the polyether modified polyamide acid has terminal amino groups.

4. The chip package structure of claim 3, wherein, The polyether modified polyamide acid is prepared by the following method: Preparation of anhydride-terminated polyimide acid; Mixing polyether diamine and anhydride-terminated polyimide acid to carry out block polymerization, and the amount of substance of polyether diamine is greater than that of anhydride-terminated polyimide acid, to obtain polyether modified polyamide acid with terminal amino groups.

5. The chip package structure of claim 4, wherein, The polyether modified polyamide acid is prepared by the following method: Polymerization of diacid anhydride and diamine, and the amount of substance of diacid anhydride is greater than that of diamine, to obtain anhydride-terminated polyimide acid.

6. The chip package structure of claim 5, wherein, The diamine includes at least one of 4,4-diamino diphenyl ether, 4,4'-diamino-2,2'-bis-trifluoromethyl diphenyl and 2-(4-aminophenyl)-5-aminobenzimidazole; and the diacid anhydride includes at least one of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride or 2,3,3',4'-diphenyl ether tetraformic acid dianhydride.

7. The chip package structure of claim 3, wherein, The acid anhydride curing agent includes one or more of methyl nadic anhydride, methyl tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, trimellitic anhydride, polyazelaic anhydride and dodecenyl succinic anhydride, the imidazole promoter includes one or more of 2-methyl imidazole, 2-ethyl-4-methyl imidazole and 2-phenyl imidazole, the filler includes one or more of nano silicon dioxide, aluminum oxide, calcium carbonate, talc powder and glass beads, and the active diluent includes phenyl glycidyl ether.

8. The chip package structure of claim 7, wherein, The filler is selected from nano silicon dioxide, and the surface of the nano silicon dioxide is treated with a silane coupling agent.

9. The chip package structure of claim 3, wherein, The chip packaging material further includes 20 to 100 parts by weight of a solvent including one or more of N-methylpyrrolidone, dimethylacetamide, dimethylformamide, and gamma-butyrolactone.

10. The chip package structure of claim 3, wherein, The chip packaging material further includes 2 to 5 parts by weight of a hexamethylene diisocyanate trimer.

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