Cu-In composite slurry for chip sintering and preparation method thereof

Abstract

The invention discloses Cu-In composite slurry for chip sintering and a preparation method of the Cu-In composite slurry, and relates to the technical field of conductive slurry. Comprising the following steps that In powder is added into dimethyl silicone oil to be fully stirred, Cu powder continues to be added, and stirring is conducted; the temperature is set to be 130-150 DEG C, and heating is conducted for 85-95 min; standing and cooling for 10-15 hours, and filtering out upper-layer oil to obtain Cu-In composite slurry; in the raw materials of the Cu-In composite slurry, the mass ratio of Cu powder to In powder is (1-5): 1; the raw materials of the Cu-In composite slurry further comprise composite graphene; in the raw materials of the Cu-In composite slurry, the mass ratio of the composite graphene to the Cu powder is (0.02-0.2): (1-5).

Description

Technical Field

[0001] This invention relates to the field of conductive paste technology, specifically a Cu-In composite paste for chip sintering and its preparation method. Background Technology

[0002] As power devices rapidly evolve towards miniaturization and high integration, chip output power continues to rise, placing increasingly stringent demands on the performance of packaging materials. Among these, silver sintering technology, with its excellent thermal and electrical conductivity and high-temperature stability, has garnered significant attention from researchers in recent years. Silver solder paste and copper solder paste, as two typical examples, are considered ideal alternatives to traditional soldering materials due to their ability to achieve sintering and curing at relatively low temperatures while maintaining stable mechanical and electrical properties under high-temperature conditions, and have been extensively studied.

[0003] However, existing chip sintering pastes still face significant technical bottlenecks in practical applications. On the one hand, when using single-component pastes, such as copper-based pastes alone, copper is prone to oxidation during sintering and use, forming an oxide layer. This not only significantly reduces the thermal and electrical conductivity of the paste but also damages the bonding strength of the solder interface, leading to poor soldering performance and limiting its application in high-reliability packaging scenarios. On the other hand, most composite pastes use silver solder paste or silver film as the core component. Although their initial performance is excellent, the high cost of silver makes the packaging process uneconomical. Furthermore, during long-term temperature cycling, silver migration can easily increase the interface resistance, leading to decreased cycle stability and making it difficult to meet the long-life requirements of power devices.

[0004] In summary, to solve the above problems, it is of great significance to prepare a Cu-In composite slurry for chip sintering and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a Cu-In composite paste for chip sintering and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for preparing a Cu-In composite slurry for chip sintering includes the following steps: adding In powder to dimethyl silicone oil and stirring thoroughly, then adding Cu powder and stirring; setting the temperature to 130-150℃ and heating for 85-95 minutes; allowing it to stand and cool for 10-15 hours, then filtering off the upper layer of oil to obtain the Cu-In composite slurry.

[0008] In a more optimized manner, the mass ratio of Cu powder to In powder in the raw materials of the Cu-In composite slurry is (1-5):1.

[0009] In a more optimized manner, the raw materials of the Cu-In composite slurry also include composite graphene; the mass ratio of composite graphene to Cu powder in the raw materials of the Cu-In composite slurry is (0.02~0.2):(1~5).

[0010] A more optimized method for preparing the composite graphene is as follows:

[0011] Step 1: Add urushiol and 3-mercaptopropyltriethoxysilane to tetrahydrofuran, stir and mix, add benzoin dimethyl ether, stir to dissolve, and then react under ultraviolet light at room temperature for 10-20 minutes to obtain the modified silane coupling agent.

[0012] Step 2: Add graphene oxide to an aqueous ethanol solution, add a modified silane coupling agent, set the temperature to 75-80℃, react for 5-7 hours, centrifuge, filter, wash, and dry to obtain modified graphene.

[0013] Step 3: Add the modified graphene and tetrabutyl zirconate sequentially to xylene, stir at room temperature for 2-3 hours, then add 4-butylcatechol-xylene solution, and heat to 130-145℃ at a rate of 0.5-1℃ / min, stirring continuously for 1-2 hours; cool, filter, wash, and dry to obtain composite graphene.

[0014] In a more optimized manner, the raw material of the ethanol-water solution has an ethanol-to-water mass ratio of (100-120):(10-20); the raw material of the modified silane coupling agent comprises, by weight: 170-230 parts urushiol, 130-175 parts 3-mercaptopropyltriethoxysilane, 300-400 parts tetrahydrofuran, and 0.5-1.0 parts benzoin dimethyl ether.

[0015] In a more optimized manner, the mass ratio of graphene oxide, aqueous ethanol solution, and modified silane coupling agent in the raw materials for the modified graphene is (0.5-1.0):(80-100):(1-2).

[0016] In a more optimized manner, the raw materials for the composite graphene contain, by weight, 1-2 parts modified graphene, 0.4-0.8 parts tetrabutyl zirconate, and 1-2 parts 4-butylcatechol.

[0017] A Cu-In composite paste for chip sintering is prepared according to the method described above.

[0018] In a more optimized manner, the Cu-In composite paste for chip sintering is used in the following process: the Cu-In composite paste is printed on a substrate, dried and shaped, bonded with a chip, and sintered under high temperature to obtain a Cu-In sintered composite paste connector.

[0019] In a more optimized manner, during the drying process, the drying temperature is 140–160°C and the drying time is 10–30 min; during the high-temperature hot pressing sintering process, the temperature is 240–280°C and the sintering time is 55–65 min.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the Cu-In composite slurry prepared in this application, through optimization of the composition and addition ratio in the composite slurry, yields a Cu-In composite slurry for chip sintering with high heat dissipation and excellent cycle stability.

[0021] In terms of improving the heat dissipation of the solder layer, Cu powder has high thermal conductivity and can provide the main channel for heat transfer; In powder can fill the gaps between Cu powder during sintering, effectively reducing interfacial thermal resistance and promoting uniform heat conduction within the solder layer; After modification and composite treatment, graphene, based on its inherent layered structure and extremely high thermal conductivity, is endowed with characteristics more suitable for composite slurry systems: First, a mercaptosilane coupling agent is introduced into the long-chain groups of urushiol to obtain a modified silane coupling agent; Second, graphene oxide and the modified silane coupling agent are reacted to graft the long-chain groups onto the graphene, giving the graphene excellent dispersibility in the dispersant dimethyl silicone oil, thus obtaining modified graphene; Third, catechol groups are introduced into the modified graphene to further chelate zirconium metal, thus obtaining composite graphene. With the synergistic effect of the three, Cu powder, as the main thermally conductive component, In powder and composite graphene can synergistically fill the gaps in the composite slurry system. Furthermore, graphene itself has an efficient thermal conduction path, and composite graphene further chelates metallic zirconium, which can work with Cu powder and In powder to significantly improve the heat dissipation performance of the solder layer. The combined effect of the three significantly reduces the overall thermal resistance of the solder layer and significantly improves heat dissipation, enabling the chip to quickly dissipate heat when outputting high power and avoid performance impact due to overheating.

[0022] In terms of improving cycle stability, Cu powder provides structural support for the solder layer, resisting the mechanical stress caused by temperature cycling. The low melting point of In powder allows it to alleviate thermal stress through slight deformation during temperature changes, reducing the risk of solder layer cracking. Graphene itself possesses a certain mechanical strength, and the introduction of long-chain groups into modified graphene allows it to be uniformly dispersed in the solder layer. Furthermore, the layered structure of graphene fills the gaps between Cu and In powders, improving the density of the solder layer and the interfacial bonding strength. Through the synergistic effect of these three components—Cu providing structural support, In ensuring stress buffering, and the reinforcement and interfacial stabilization of the composite graphene—the shear strength decay and thermal resistance increase of the solder layer during temperature cycling are effectively suppressed, significantly improving cycle stability and ensuring reliable bonding performance of the solder layer during long-term operation.

[0023] In summary, by modifying and compounding graphene, and adjusting the proportion of constituent raw materials in the composite slurry, Cu-In composite slurry for chip sintering can be endowed with excellent performance. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that the following quantities are by weight. There are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: graphene oxide (provided by Shanghai Zhongke Yueda Materials Technology Co., Ltd.), urushiol (CAS: 83258-37-1), 3-mercaptopropyltriethoxysilane (CAS: 14814-09-6), dimethyl benzoate (CAS: 24650-42-8), tetrabutyl zirconate (CAS: 1071-76-7), 4-butylcatechol (CAS: 2525-05-5), and other raw materials, all of which are commercially available.

[0026] Example 1: A method for preparing Cu-In composite paste for chip sintering; and the application of this method to prepare Cu-In sintering composite paste connectors, the specific steps of which are as follows:

[0027] I. Preparation of Cu-In composite slurry

[0028] Add In powder to dimethyl silicone oil and stir thoroughly. Then add Cu powder and stir. Heat using a heating platform at 140°C for 90 minutes, stirring continuously during the heating process. Let stand for 13 hours to cool and filter out the upper oil layer to obtain Cu-In composite slurry.

[0029] II. Preparation of Cu-In sintered composite slurry connectors

[0030] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0031] In this comparative example, the mass ratio of Cu powder to In powder in the raw materials of the Cu-In composite slurry is 2:1.

[0032] Example 2: A method for preparing Cu-In composite paste for chip sintering; and the application of this method to prepare Cu-In sintering composite paste connectors, the specific steps of which are as follows:

[0033] I. Preparation of Cu-In composite slurry

[0034] Add In powder to dimethyl silicone oil and stir thoroughly. Then add Cu powder and stir. Heat using a heating platform at 140°C for 90 minutes, stirring continuously during the heating process. Let stand for 13 hours to cool and filter out the upper oil layer to obtain Cu-In composite slurry.

[0035] II. Preparation of Cu-In sintered composite slurry connectors

[0036] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0037] In this comparative example, the mass ratio of Cu powder to In powder in the raw materials of the Cu-In composite slurry is 3:1.

[0038] Example 3: Based on Example 2, composite graphene was further added to the Cu-In composite slurry, specifically including the following steps:

[0039] I. Preparation of Composite Graphene

[0040] Step 1: Add 170 parts of urushiol and 130 parts of 3-mercaptopropyltriethoxysilane to 300 parts of tetrahydrofuran, stir and mix, add 0.5 parts of benzoin dimethyl ether, stir and dissolve, and continue to react at room temperature under ultraviolet light for 10 minutes to obtain the modified silane coupling agent.

[0041] Step 2: Add 0.5 parts of graphene oxide to 80 parts of ethanol aqueous solution, add 1 part of modified silane coupling agent, set the temperature to 75℃, react for 5 hours, centrifuge at 4500 rpm for 25 minutes, filter, wash, and dry to obtain modified graphene.

[0042] Step 3: Add 1 part of modified graphene and 0.4 parts of tetrabutyl zirconate to 100 parts of xylene in sequence, stir at room temperature for 2 hours, and then add 4-butylcatechol-xylene solution (1 part of 4-butylcatechol and 50 parts of xylene). Heat to 138°C at a rate of 1°C / min, while stirring continuously for 1 hour. Cool down, filter, wash, and dry to obtain composite graphene.

[0043] II. Preparation of Cu-In Composite Slurry

[0044] Add In powder to dimethyl silicone oil and stir thoroughly. Then add Cu powder and stir. After stirring, add composite graphene and stir again. Heat using a heating platform at 130°C for 85 minutes, stirring continuously during the heating process. Let stand for 10 hours to cool and filter out the upper oil layer to obtain Cu-In composite slurry.

[0045] III. Preparation of Cu-In sintered composite slurry connectors

[0046] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0047] In this embodiment, the mass ratio of Cu powder, In powder, and composite graphene in the raw materials of Cu-In composite slurry is 2:1:0.04.

[0048] Example 4: Based on Example 2, composite graphene was further added to the Cu-In composite slurry, specifically including the following steps:

[0049] I. Preparation of Composite Graphene

[0050] Step 1: Add 200 parts of urushiol and 155 parts of 3-mercaptopropyltriethoxysilane to 350 parts of tetrahydrofuran, stir and mix, add 0.75 parts of benzoin dimethyl ether, stir and dissolve, and continue to react at room temperature under ultraviolet light for 15 minutes to obtain the modified silane coupling agent.

[0051] Step 2: Add 0.75 parts of graphene oxide to 90 parts of ethanol aqueous solution, add 1.5 parts of modified silane coupling agent, set the temperature to 80℃, react for 6 hours, centrifuge at 4500 rpm for 25 minutes, filter, wash, and dry to obtain modified graphene.

[0052] Step 3: Add 1.5 parts of modified graphene and 0.6 parts of tetrabutyl zirconate to 100 parts of xylene in sequence, stir at room temperature for 2.5 h, and then add 4-butylcatechol-xylene solution (1.5 parts of 4-butylcatechol and 50 parts of xylene). Heat to 138°C at a rate of 1°C / min, while stirring continuously for 1.5 h. Cool down, filter, wash, and dry to obtain composite graphene.

[0053] II. Preparation of Cu-In Composite Slurry

[0054] In powder was added to dimethyl silicone oil and stirred thoroughly. Cu powder was then added and stirred. Composite graphene was then added and stirred. The mixture was heated using a heating platform at 140°C for 90 minutes, with stirring maintained during the heating process. The mixture was allowed to stand for 13 hours to cool and the upper oil layer was filtered off to obtain Cu-In composite slurry.

[0055] III. Preparation of Cu-In sintered composite slurry connectors

[0056] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0057] In this embodiment, the mass ratio of Cu powder, In powder, and composite graphene in the raw materials of Cu-In composite slurry is 3:1:0.12.

[0058] Example 5: Based on Example 2, composite graphene was further added to the Cu-In composite slurry, specifically including the following steps:

[0059] I. Preparation of Composite Graphene

[0060] Step 1: Add 230 parts of urushiol and 175 parts of 3-mercaptopropyltriethoxysilane to 400 parts of tetrahydrofuran, stir and mix, add 1 part of benzoin dimethyl ether, stir and dissolve, and continue to react at room temperature under ultraviolet light for 20 minutes to obtain the modified silane coupling agent.

[0061] Step 2: Add 1 part graphene oxide to 100 parts ethanol aqueous solution, add 2 parts modified silane coupling agent, set the temperature to 85℃, react for 7h, centrifuge at 4500rpm for 25min, filter, wash, and dry to obtain modified graphene.

[0062] Step 3: Add 2 parts of modified graphene and 0.8 parts of tetrabutyl zirconate to xylene in sequence, stir at room temperature for 3 hours, and then add 4-butylcatechol-xylene solution (2 parts of 4-butylcatechol, 50 parts of xylene). Heat to 138°C at a rate of 1°C / min, stirring continuously for 2 hours. Cool down, filter, wash, and dry to obtain composite graphene.

[0063] II. Preparation of Cu-In Composite Slurry

[0064] Add In powder to dimethyl silicone oil and stir thoroughly. Then add Cu powder and stir. After stirring, add composite graphene and stir again. Heat using a heating platform at 150°C for 95 minutes while stirring. Let stand for 15 hours to cool and filter out the upper oil layer to obtain Cu-In composite slurry.

[0065] III. Preparation of Cu-In sintered composite slurry connectors

[0066] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0067] In this embodiment, the mass ratio of Cu powder, In powder, and composite graphene in the raw materials of Cu-In composite slurry is 4:1:0.2.

[0068] Comparative Example 1: No modified silane coupling agent was used in the composite graphene; only 3-mercaptopropyltriethoxysilane was used; the rest was the same as in Example 4; the specific steps are as follows:

[0069] I. Preparation of Composite Graphene

[0070] Step 1: Add 0.75 parts of graphene oxide to 90 parts of ethanol aqueous solution, add 1.5 parts of 3-mercaptopropyltriethoxysilane, set the temperature to 80℃, react for 6 h, centrifuge at 4500 rpm for 25 min, filter, wash, and dry to obtain modified graphene.

[0071] Step 2: Add 1.5 parts of modified graphene and 0.6 parts of tetrabutyl zirconate to 100 parts of xylene in sequence, stir at room temperature for 2.5 h, and then add 4-butylcatechol-xylene solution (1.5 parts of 4-butylcatechol and 50 parts of xylene). Heat to 138°C at a rate of 1°C / min, while stirring continuously for 1.5 h. Cool down, filter, wash and dry to obtain composite graphene.

[0072] II. Preparation of Cu-In Composite Slurry

[0073] In powder was added to dimethyl silicone oil and stirred thoroughly. Cu powder was then added and stirred. Composite graphene was then added and stirred. The mixture was heated using a heating platform at 140°C for 90 minutes, with stirring maintained during the heating process. The mixture was allowed to stand for 13 hours to cool and the upper oil layer was filtered off to obtain Cu-In composite slurry.

[0074] III. Preparation of Cu-In sintered composite slurry connectors

[0075] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0076] In this embodiment, the mass ratio of Cu powder, In powder, and composite graphene in the raw materials of Cu-In composite slurry is 3:1:0.12.

[0077] Comparative Example 2: No modification was made to the graphene composite; only graphene oxide was used. The rest was the same as in Example 4. The specific steps are as follows:

[0078] I. Preparation of Composite Graphene

[0079] 1.5 parts of modified graphene and 0.6 parts of tetrabutyl zirconate were added sequentially to 100 parts of xylene, and stirred at room temperature for 2.5 h. Then, a 4-butylcatechol-xylene solution (1.5 parts of 4-butylcatechol and 50 parts of xylene) was added, and the temperature was increased to 138 °C at a rate of 1 °C / min while stirring. The stirring was continued for 1.5 h. The mixture was then cooled, filtered, washed, and dried to obtain composite graphene.

[0080] II. Preparation of Cu-In Composite Slurry

[0081] In powder was added to dimethyl silicone oil and stirred thoroughly. Cu powder was then added and stirred. Composite graphene was then added and stirred. The mixture was heated using a heating platform at 140°C for 90 minutes, with stirring maintained during the heating process. The mixture was allowed to stand for 13 hours to cool and the upper oil layer was filtered off to obtain Cu-In composite slurry.

[0082] III. Preparation of Cu-In sintered composite slurry connectors

[0083] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0084] In this embodiment, the mass ratio of Cu powder, In powder, and composite graphene in the raw materials of Cu-In composite slurry is 3:1:0.12.

[0085] Comparative Example 3: The composite graphene did not contain tetrabutyl zirconate; the rest was the same as in Example 4; the specific steps are as follows:

[0086] I. Preparation of Composite Graphene

[0087] Step 1: Add 200 parts of urushiol and 155 parts of 3-mercaptopropyltriethoxysilane to 350 parts of tetrahydrofuran, stir and mix, add 0.75 parts of benzoin dimethyl ether, stir and dissolve, and continue to react at room temperature under ultraviolet light for 15 minutes to obtain the modified silane coupling agent.

[0088] Step 2: Add 0.75 parts of graphene oxide to 90 parts of ethanol aqueous solution, add 1.5 parts of modified silane coupling agent, set the temperature to 80℃, react for 6 hours, centrifuge at 4500 rpm for 25 minutes, filter, wash, and dry to obtain modified graphene.

[0089] Step 3: Add 1.5 parts of modified graphene and 0.6 parts of tetrabutyl zirconate to 100 parts of xylene in sequence, stir at room temperature for 2.5 h, and then add 4-butylcatechol-xylene solution (1.5 parts of 4-butylcatechol and 50 parts of xylene). Heat to 138°C at a rate of 1°C / min, while stirring continuously for 1.5 h. Cool down, filter, wash, and dry to obtain composite graphene.

[0090] II. Preparation of Cu-In Composite Slurry

[0091] In powder was added to dimethyl silicone oil and stirred thoroughly. Cu powder was then added and stirred. Composite graphene was then added and stirred. The mixture was heated using a heating platform at 140°C for 90 minutes, with stirring maintained during the heating process. The mixture was allowed to stand for 13 hours to cool and the upper oil layer was filtered off to obtain Cu-In composite slurry.

[0092] III. Preparation of Cu-In sintered composite slurry connectors

[0093] The Cu-In composite paste was printed on the substrate, dried at 150°C for 20 minutes to set its shape, and then bonded with a chip. The substrate was then hot-pressed and sintered at 260°C for 60 minutes to obtain the Cu-In sintered composite paste connector.

[0094] In this embodiment, the mass ratio of Cu powder, In powder, and composite graphene in the raw materials of Cu-In composite slurry is 3:1:0.12.

[0095] Performance testing:

[0096] The Cu-In sintered composite slurry connectors prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to resistivity testing according to GB / T351-2019 "Methods for Measurement of Resistivity of Metallic Materials". According to JESD22-A104C standard, the Cu-In sintered composite slurry connectors were subjected to 500 cycles at a temperature of -40 to +130°C for 2 hours. The shear strength after the cycles was tested to characterize their cyclic stability. The lower the shear strength after the cycles, the worse the cyclic stability.

[0097] sample Thermal resistivity (Ω·m) <![CDATA[Shearing strength( MPa )]]> Example 1 <![CDATA[2.25×10 -8 ]]> 32.7 Example 2 <![CDATA[2.16×10 -8 ]]> 36.2 Example 3 <![CDATA[1.61×10 -8 ]]> 60.2 Example 4 <![CDATA[1.54×10 -8 ]]> 62.8 Example 5 <![CDATA[1.57×10 -8 ]]> 61.5 Comparative Example 1 <![CDATA[1.97×10 -8 ]]> 38.4 Comparative Example 2 <![CDATA[2.07×10 -8 ]]> 42.9 Comparative Example 3 <![CDATA[1.82×10 -8 ]]> 45.7

[0098] Conclusion: The data in the table above shows that, comparing the performance data of the composite slurries prepared in Examples 1-5, the performance of Examples 1-2 is significantly weaker than that of Examples 3-5. This is because Examples 1-2 lack the bridging and mechanical reinforcement effects on the heat-conducting network, resulting in increased interfacial thermal resistance and decreased resistance to cyclic stress. This indicates that composite graphene can enhance the heat dissipation and cyclic stability of the solder layer. Comparing the data from Examples 3-5, the appropriate addition ratio of Cu powder, In powder, and composite graphene improves the excellent performance of the solder layer. According to the data from Examples 3-5 in the table, as the proportion of Cu powder increases, its role as the main heat conductor becomes more prominent, and the thermal resistance decreases significantly. The appropriate increase in the proportion of composite graphene further optimizes the heat-conducting network and interfacial bonding. Although the proportion of In powder remains stable, its effect on filling voids and relieving stress varies with different proportions of Cu powder and composite graphene. The synergistic effect of the three components can be more fully exerted when the proportions are appropriate, thus enabling the slurry to have low thermal resistance and high shear strength.

[0099] Comparing the performance of Example 4 with Comparative Examples 1-3, it can be seen that Example 4 outperforms the comparative examples. Because it did not use a modified silane coupling agent, but only 3-mercaptopropyltriethoxysilane, the interfacial compatibility between graphene and Cu and In was insufficient, making it impossible to effectively construct a continuous thermally conductive network, and the interfacial bonding was weak. Directly using unmodified graphene oxide resulted in the surface oxygen-containing groups being difficult to form stable bonds with other components, easily leading to agglomeration and impairing thermal conductivity and mechanical properties. The absence of tetrabutyl zirconate resulted in insufficient mechanical properties and interfacial stability of the composite graphene, making it prone to structural degradation during cycling. In summary, Cu powder, In powder, and composite graphene synergistically constructed a highly efficient thermally conductive network and a stable structure, exhibiting superior heat dissipation and cycling stability.

[0100] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a Cu-In composite paste for chip sintering, characterized in that: The process includes the following steps: adding In powder to dimethyl silicone oil and stirring thoroughly, then adding Cu powder and stirring; setting the temperature to 130–150°C and heating for 85–95 minutes; allowing it to stand and cool for 10–15 hours, then filtering out the upper layer of oil to obtain Cu-In composite slurry.

2. The method for preparing a Cu-In composite paste for chip sintering according to claim 1, characterized in that: In the raw materials of the Cu-In composite slurry, the mass ratio of Cu powder to In powder is (1-5):

1.

3. The method for preparing a Cu-In composite paste for chip sintering according to claim 2, characterized in that: The raw materials of the Cu-In composite slurry also include composite graphene; the mass ratio of composite graphene to Cu powder in the raw materials of the Cu-In composite slurry is (0.02~0.2):(1~5).

4. The method for preparing a Cu-In composite paste for chip sintering according to claim 3, characterized in that: The preparation method of the composite graphene is as follows: Step 1: Add urushiol and 3-mercaptopropyltriethoxysilane to tetrahydrofuran, stir and mix, add benzoin dimethyl ether, stir to dissolve, and then react under ultraviolet light at room temperature for 10-20 minutes to obtain the modified silane coupling agent. Step 2: Add graphene oxide to an aqueous ethanol solution, add a modified silane coupling agent, set the temperature to 75-80℃, react for 5-7 hours, centrifuge, filter, wash, and dry to obtain modified graphene. Step 3: Add the modified graphene and tetrabutyl zirconate sequentially to xylene, stir at room temperature for 2-3 hours, then add 4-butylcatechol-xylene solution, and heat to 130-145℃ at a rate of 0.5-1℃ / min, stirring continuously for 1-2 hours; cool, filter, wash, and dry to obtain composite graphene.

5. The method for preparing a Cu-In composite paste for chip sintering according to claim 4, characterized in that: In the raw materials of the ethanol-water solution, the mass ratio of ethanol to water is (100-120):(10-20); in the raw materials of the modified silane coupling agent, by weight parts: 170-230 parts of urushiol, 130-175 parts of 3-mercaptopropyltriethoxysilane, 300-400 parts of tetrahydrofuran, and 0.5-1.0 parts of benzoin dimethyl ether.

6. The method for preparing a Cu-In composite paste for chip sintering according to claim 4, characterized in that: In the raw materials for the modified graphene, the mass ratio of graphene oxide, aqueous ethanol solution, and modified silane coupling agent is (0.5-1.0):(80-100):(1-2).

7. The method for preparing a Cu-In composite paste for chip sintering according to claim 4, characterized in that: The raw materials for the composite graphene, by weight, consist of 1-2 parts modified graphene, 0.4-0.8 parts tetrabutyl zirconate, and 1-2 parts 4-butylcatechol.

8. A Cu-In composite paste for chip sintering, characterized in that: The Cu-In composite paste for chip sintering is prepared according to any one of claims 1 to 7.

9. The Cu-In composite paste for chip sintering according to claim 8, characterized in that: The process of using Cu-In composite paste for chip sintering is as follows: the Cu-In composite paste is printed on a substrate, dried and shaped, then bonded with a chip, and sintered at high temperature to obtain a Cu-In sintered composite paste connector.

10. The Cu-In composite paste for chip sintering according to claim 9, characterized in that: During the drying process, the drying temperature is 140–160℃ and the drying time is 10–30 min; during the high-temperature hot pressing sintering process, the temperature is 240–280℃ and the sintering time is 55–65 min.