CN115945825A - Slurry, preparation method thereof and packaging method of chip heat dissipation structure - Google Patents

Abstract

The application relates to the technical field of electronic packaging interconnection, and provides a slurry, which comprises a first welding slurry and a second welding slurry, wherein the first welding slurry and the second welding slurry are respectively calculated by independent parts by weight, and the first welding slurry comprises: 1-95 parts of first metal powder, wherein the melting point of the first metal powder is less than or equal to 200 ℃, 2-5 parts of first organic solvent, 0.5-1 part of first activator, 0.3-1 part of corrosion inhibitor and 0.1-1 part of first thickener; the second solder paste includes: 10 to 80 parts of micron metal powder, 10 to 70 parts of nano metal powder, 2 to 5 parts of second organic solvent, 0.5 to 1 part of second activator and 0.1 to 1 part of second thickener. The slurry provided by the application has good low-temperature melting fluidity and wettability of the first metal powder in the first welding slurry, can be filled in pores formed by sintering the nano metal powder, and can form an interface material with low porosity, good thermal conductivity, good remelting property and high reliability.

Description

Slurry, preparation method thereof and packaging method of chip heat dissipation structure

Technical Field

The application belongs to the technical field of electronic packaging interconnection, and particularly relates to a slurry, a preparation method thereof and a packaging method of a chip heat dissipation structure.

Background

At present, the maximum service temperature of common packaging materials (such as tin-based solder) is lower than 200 ℃, so in order to deal with high-temperature service environment, transient Liquid Phase (TLP) and low-temperature nano-sintering interconnection technologies are proposed in the industry, which are respectively used for forming full intermetallic compounds and nano-sintering solder joints. However, the all-intermetallic compound is large in brittleness, low in thermal conductivity (not more than 70W/m.k), and poor in reliability; the low-temperature nano sintering has poor wettability and high porosity, and the joint can not bear stress generated by different expansion coefficients of materials when the temperature is raised and lowered, so that the problems of interface parameter cracks and the like are caused.

For example, patent CN104741821A discloses a Sn-based solder paste filled with micro-nano copper particles for high-temperature packaging of electronic modules and a preparation method thereof, which comprises sequentially reducing micro-nano copper and micro-nano tin by a direct liquid-phase multi-element sequential controllable reduction method to obtain micro-nano copper-tin particles, mixing the micro-nano copper-tin particles with a dispersant, a soldering flux, a thixotropic agent and the like, and preparing the solder paste by a mixing and dispersing process. However, the oxidation resistance of the soldering paste is poor, and the addition of the soldering flux brings complicated processes for cleaning welding spots in the later period and causes certain environmental pollution. In addition, the welding point structure prepared by the soldering paste is an all-intermetallic compound (IMC) structure, the IMC has high brittleness, and the heat and electric conductivity has larger difference compared with the sintered silver. The patent CN114429829A discloses a composite paste for power device packaging and a preparation method thereof, the composite paste for power device packaging is prepared from silver-copper filler and an organic carrier, and the silver-copper filler and the organic carrier are stirred to be uniformly mixed to obtain a mixed paste; and then carrying out three-stage dispersion grinding on the mixed paste to obtain a composite paste for packaging the power device, and finally interconnecting the chip and the substrate through the composite paste. However, the composite paste of the scheme has poor interface wettability, is easy to generate holes, has high welding temperature, and can cause mechanical damage to a chip due to higher pressure, so that the application of the composite paste in the field of high-temperature interconnection is limited.

Therefore, it is necessary to develop a solder paste having good interfacial wettability, low porosity, good thermal conductivity and high reliability.

Disclosure of Invention

The application aims to provide a slurry, a preparation method thereof and a packaging method of a chip heat dissipation structure, and aims to solve the problems of poor interface wettability, high porosity and poor heat conductivity of the existing welding slurry.

In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:

in a first aspect, the present application provides a paste comprising a first soldering paste and a second soldering paste, each in independent parts by weight,

the first welding slurry comprises the following components in parts by weight:

the second welding slurry comprises the following components in parts by weight:

in a second aspect, the present application provides a method of preparing a slurry, comprising the steps of:

providing raw material components in the slurry;

carrying out first mixing treatment on a first organic solvent, a first activator, a corrosion inhibitor, a first thickening agent and first metal powder to obtain first welding slurry;

and carrying out second mixing treatment on a second organic solvent, a second activator, a second thickening agent, the micron metal powder and the nanometer metal powder to obtain second welding slurry.

In a third aspect, the present application provides a method for packaging a chip heat dissipation structure, including the following steps:

providing the slurry or the slurry prepared by the preparation method, a chip and a radiating fin;

coating a first welding slurry in the slurries on the surface of a chip to perform first pre-curing treatment to form a first welding film, and coating a second welding slurry in the slurries on the surface of a radiating fin to perform second pre-curing treatment to form a second welding film; or coating the first welding slurry in the slurry on the surface of the radiating fin to perform first pre-curing treatment to form a first welding film, and coating the second welding slurry in the slurry on the surface of the chip to perform second pre-curing treatment to form a second welding film;

and carrying out relative adhesion treatment on the chip and the radiating fin, and enabling the first welding film to be positioned above the second welding film for relative adhesion to obtain the chip radiating structure.

Compared with the prior art, the method has the following beneficial effects:

the first aspect of this application provides a thick liquids, it includes first welding thick liquids and second welding thick liquids, wherein, first welding thick liquids contain the melting point of peculiar weight part and are less than or equal to 200 ℃ first metal powder, second welding thick liquids contain micron metal powder and nanometer metal powder of peculiar weight part, through coating first welding thick liquids and second welding thick liquids respectively in chip and fin surface can realize will be with chip and fin relative bonding, because first metal powder in the first welding thick liquids has low temperature melting mobility and wettability good, can effectively fill the hole that nanometer metal powder formed at sintering process, thereby reduce the porosity by a wide margin, promote thermal conductivity. And the first metal powder has low melting point and can form alloy with micron metal powder and nanometer metal powder, so that remelting can not occur at the temperature of 500 ℃, and the high-temperature service requirement is met. In addition, the micron metal powder is used as a framework of a network structure, and the nano metal powder is used as a filler for improving the initial stacking density and bonding the micron metal powder and providing low-temperature sintering property, so that the volume shrinkage rate of the welding slurry can be reduced, the porosity can be further reduced, and the stability of a sintering structure can be further improved. Therefore, the slurry can form an interface interconnection material with low porosity, good thermal conductivity, good remelting performance and high reliability.

According to the preparation method of the slurry provided by the second aspect of the application, a first welding slurry is obtained by carrying out first mixing treatment on a certain weight part of a first organic solvent, a first activating agent, a corrosion inhibitor, a first thickening agent and first metal powder, and a second welding slurry is obtained by carrying out second mixing treatment on a certain weight part of a second organic solvent, a second activating agent, a second thickening agent, micron metal powder and nano metal powder.

The third aspect of the present application provides a method for packaging a chip heat dissipation structure, where a first soldering paste in a paste is first coated on a surface of a chip or a heat sink to perform a first pre-curing process to form a first soldering film, and then a second soldering paste in the paste is coated on a surface of the chip or the heat sink where no soldering film is formed to perform a second pre-curing process to form a second soldering film, and finally the chip and the heat sink are relatively bonded to each other, and the first soldering film is positioned above the second soldering film to perform a relative bonding, so as to obtain the chip heat dissipation structure.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a process flow diagram of a method for preparing a solder paste provided by an embodiment of the present application;

fig. 2 is a process flow diagram of a packaging method of a chip heat dissipation structure according to an embodiment of the present application;

fig. 3 is a structural diagram of a chip heat dissipation structure according to an embodiment of the present application;

fig. 4 is a structural diagram of a heat dissipation structure of a chip according to another embodiment of the present application;

FIG. 5 is an SEM image of a sintering interface of a heat dissipation structure of a chip obtained in example 1 of the present application;

FIG. 6 is an optically enlarged view of a sintering interface of a heat-dissipating structure of a chip manufactured by comparative example 1 of the present application;

fig. 7 is an SEM sectional view of an indium-copper sintered interface of the heat dissipation structure of a chip manufactured in example 3 of the present application.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

In this application, the term "and/or" describes an association relationship of associated objects, which means that there may be three relationships, for example, a and/or B, which may mean: a is present alone, A and B are present simultaneously, and B is present alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (one) of a, b, or c," or "at least one (one) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, and c may be single or plural, respectively.

It should be understood that, in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

The weight of the related components mentioned in the description of the embodiments of the present application may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present application as long as it is scaled up or down according to the description of the embodiments of the present application. Specifically, the mass described in the specification of the embodiments of the present application may be a mass unit known in the chemical industry field such as μ g, mg, g, kg, etc.

The terms "first" and "second" are used for descriptive purposes only and are used for distinguishing purposes such as substances from one another, and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the present application. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

In a first aspect, the embodiments of the present application provide a paste, which includes a first soldering paste and a second soldering paste, the first soldering paste and the second soldering paste are respectively calculated by independent weight portions,

the first welding slurry comprises the following components in parts by weight:

the second welding paste comprises the following components in parts by weight:

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the slurry provided by the embodiment of the application comprises a first welding slurry and a second welding slurry, wherein the first welding slurry contains a first metal powder with a specific weight part and a melting point of less than or equal to 200 ℃, the second welding slurry contains a micron metal powder and a nanometer metal powder with a specific weight part, the first welding slurry and the second welding slurry are respectively coated on the surfaces of a chip and a radiating fin to realize relative adhesion of the chip and the radiating fin, and the first metal powder in the first welding slurry has low-temperature melting fluidity and good wettability and can effectively fill pores formed by the nanometer metal powder in a sintering process, so that the porosity is greatly reduced, and the heat conduction performance is improved. And the first metal powder has low melting point and can form alloy with micron metal powder and nanometer metal powder, so that remelting can not occur at the temperature of 500 ℃, and the high-temperature service requirement is met. In addition, the micron metal powder is used as a framework of a network structure, and the nano metal powder is used as a filler for improving the initial stacking density and bonding the micron metal powder and providing low-temperature sintering property, so that the volume shrinkage rate of the welding slurry can be reduced, the porosity can be further reduced, and the stability of a sintering structure can be further improved. Therefore, the slurry can form an interface interconnection material with low porosity, good thermal conductivity, good remelting performance and high reliability.

In an embodiment, the first and second solder pastes are each independently portioned; the first welding slurry comprises the following components in parts by weight: 1-95 parts of first metal powder with the melting point less than or equal to 200 ℃, 2-5 parts of first organic solvent, 0.5-1 part of first activator, 0.3-1 part of corrosion inhibitor and 0.1-1 part of first thickener; the second welding slurry comprises the following components in parts by weight: 10-80 parts of micron metal powder, 10-70 parts of nano metal powder, 2-5 parts of second organic solvent, 0.5-1 part of second activator and 0.1-1 part of second thickener; when used, the first and second solder pastes may be used in a weight ratio selected according to the thickness ratio ((0.3 to 0.5: 1) of the first and second solder films to be used, for example, the weight ratio of the first and second solder pastes may be 0.3.

In the embodiment, the first metal powder with the melting point within 200 ℃ is added, so that the surface tension and viscosity can be reduced, and the fluidity and wettability of the first welding slurry are increased, so that pores formed by sintering the micro-nano metal powder are effectively filled, the porosity can be greatly reduced, the thermal conductivity is good, the welding strength after thermal shock is small in change, the welding strength can also form an alloy with the micro-nano metal powder, remelting can not occur at the temperature as high as 500 ℃, and the high-temperature service requirement is met. Specifically, the first metal powder may be at least one or a mixture of indium powder, tin bismuth alloy powder, tin bismuth silver copper alloy powder, tin bismuth silver alloy powder, tin indium alloy powder, silver indium alloy powder, and silver zinc indium alloy powder, and preferably, the first metal powder is selected from indium powder and tin bismuth silver copper alloy powder. The first metal powder has a particle diameter of 0.5 to 10 μm, preferably 3 to 8 μm, and for example, the average particle diameter of the first metal powder may be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or the like. The first metal powder may be present in an amount of 50 to 80 parts by weight, for example 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, etc.

In an embodiment, the first organic solvent is an ether solvent, and may be selected from at least one or a mixture of more of ethylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, and propylene glycol ethyl ether, and the weight part of the first organic solvent may be 2 to 5 parts, for example, 2 parts, 3 parts, 4 parts, 5 parts, and the like. The addition of the first activator can remove the oxide on the surfaces of the chip, the heat sink and the soldering paste at the soldering temperature, thereby improving the wettability among the chip, the heat sink and the soldering paste, the first activator can be selected from at least one or a mixture of more of L-malic acid, glutaric acid, adipic acid and itaconic acid, and the weight part of the first activator can be 0.5-1 part, such as 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part and the like. The corrosion inhibitor is added to protect the substrate and the device-free lead, has moisture-proof, mildew-proof and corrosion-proof properties, can keep excellent weldability, can be selected from any one of benzotriazole and methyl benzotriazole, and can be 0.5-1 part by weight, such as 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part and the like. The first thickener may be any one selected from polyethylene glycol, polyvinyl butyral and polyvinyl pyrrolidone, and may be present in an amount of 0.1 to 1 part by weight, for example, 0.1 part, 0.3 part, 0.5 part, 0.7 part, 0.9 part, 1 part, etc.

Micron-sized metal powders are understood to be metal powders of micron-scale dimensions, including dimensions of 1 μm to 1000 μm. The micron metal powder is mainly used as a framework of a network structure, can reduce the volume shrinkage rate of the welding slurry, and reduces the porosity, thereby improving the stability of a sintered structure and improving the heat-conducting property. In the examples, the particle size of the micrometric metal powder is between 1 and 10 μm, preferably between 5 and 8 μm, for example 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm and the like. The parts by weight of the micron metal powder may be 30-50 parts, such as 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, and the like. The micron metal powder can be selected from at least one or more of micron silver powder, micron copper powder, micron silver-copper alloy powder, micron aluminum powder and micron silver-coated copper powder, and preferably, the micron metal powder is selected from the micron silver powder.

Nano-metal powder is understood to be metal powder of nano-scale dimensions, including dimensions of 1nm to 1000 nm. The nano metal powder serves as a filler for increasing the initial bulk density and binding the micro metal powder, and provides low-temperature sinterability. In the examples, the particle size of the nano metal powder is 20 to 200nm, for example, 20nm, 50nm, 100nm, 150nm, 200nm, etc. The nano metal powder may be 30-50 parts by weight, such as 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, and the like. The nano metal powder may be at least one or more selected from nano copper powder, nano silver powder and nano silver-copper alloy powder, and preferably, the nano metal powder is selected from nano silver powder and nano copper powder. The nano metal powder and the micron metal powder are added to form a metal compound with better comprehensive performance, so that the comprehensive performance of the welding slurry can be further improved.

In an embodiment, the second organic solvent is an ether solvent, and may be selected from at least one or a mixture of more of ethylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, and propylene glycol ethyl ether, and the weight part of the second organic solvent may be 2 to 5 parts, for example, 2 parts, 3 parts, 4 parts, 5 parts, and the like. The addition of a second activator, which may be selected from a mixture of at least one or more of L-malic acid, glutaric acid, adipic acid, and citric acid, may remove oxides from the surface of the chip, heat sink, and solder paste at the soldering temperature, thereby improving the wettability between the chip, heat sink, and solder paste, and may be in the range of 0.5 to 1 part by weight, e.g., 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, etc. The second thickener may be any one selected from polyethylene glycol, polyvinyl butyral and polyvinyl pyrrolidone, and may be present in an amount of 0.1 to 1 part by weight, for example, 0.1 part, 0.3 part, 0.5 part, 0.7 part, 0.9 part, 1 part, etc.

A second aspect of the embodiments of the present application provides a method for preparing a slurry, as shown in fig. 1, including the following steps:

s01: providing raw material components in the slurry;

s02: carrying out first mixing treatment on a first organic solvent, a first activator, a corrosion inhibitor, a first thickening agent and first metal powder to obtain first welding slurry;

s03: and carrying out second mixing treatment on a second organic solvent, a second activator, a second thickening agent, micron metal powder and nanometer metal powder to obtain second welding slurry.

According to the preparation method of the slurry, a first welding slurry is obtained by carrying out first mixing treatment on a certain weight part of a first organic solvent, a first activator, a corrosion inhibitor, a first thickening agent and first metal powder, and a second welding slurry is obtained by carrying out second mixing treatment on a certain weight part of a second organic solvent, a second activator, a second thickening agent, micron metal powder and nanometer metal powder.

In the above step S01, the raw material components and contents of the first soldering paste and the second soldering paste are described in detail above, and are not repeated herein.

In the step S02, the step of performing the first mixing process on the first organic solvent, the first activator, the corrosion inhibitor, the first thickener, and the first metal powder includes: mixing, stirring and heating a first organic solvent, a first activating agent, a corrosion inhibitor and a first thickening agent to obtain a first mixed material; and then uniformly stirring the first metal powder and the first mixed material. Thus, the first metal powder can be better dispersed in the first welding paste to obtain the first welding paste with sufficient and uniform dispersion.

In the step S03, the step of performing the second mixing process on the second organic solvent, the second activator, the second thickener, the micro metal powder, and the nano metal powder includes: mixing, stirring and heating a second organic solvent, a second activating agent and a second thickening agent to obtain a second mixed material; mixing (5-15) wt% of the second mixed material with micron metal powder, and then sequentially stirring and grinding to obtain a third mixed material; dispersing the nano metal powder in the rest of the second mixed material to obtain a fourth mixed material; and mixing the third mixed material and the fourth mixed material, and uniformly stirring. Thus, the micron metal powder and the nanometer metal powder can be better dispersed in the welding slurry to obtain the second welding slurry which is fully and uniformly dispersed.

A third aspect of the embodiments of the present application provides a method for encapsulating a chip heat dissipation structure, as shown in fig. 2, including the following steps:

s11: providing the slurry or the slurry prepared by the preparation method, a chip and a radiating fin;

s12: coating a first welding slurry in the slurries on the surface of a chip to perform first pre-curing treatment to form a first welding film, and coating a second welding slurry in the slurries on the surface of a radiating fin to perform second pre-curing treatment to form a second welding film; or coating the first welding slurry in the slurry on the surface of the radiating fin to perform first pre-curing treatment to form a first welding film, and coating the second welding slurry in the slurry on the surface of the chip to perform second pre-curing treatment to form a second welding film;

s13: and carrying out relative adhesion treatment on the chip and the radiating fin, and enabling the first welding film to be positioned above the second welding film for relative adhesion to obtain the chip radiating structure.

The packaging method of the chip heat dissipation structure provided by the embodiment of the application comprises the steps of firstly coating first welding slurry in the slurry on the surface of a chip or a heat dissipation sheet to carry out first pre-curing treatment to form a first welding film, then coating second welding slurry in the slurry on the surface of the chip or the heat dissipation sheet which is not provided with the welding film to carry out second pre-curing treatment to form a second welding film, and finally carrying out relative bonding treatment on the chip and the heat dissipation sheet, and enabling the first welding film to be located above the second welding film to carry out relative bonding to obtain the chip heat dissipation structure.

In the above step S11, the raw material components and contents of the first soldering paste and the second soldering paste are described in detail above, and are not repeated herein. In an embodiment, the chip is selected from any one of a silicon carbide chip, a silicon-based chip, and an insulated gate bipolar transistor. The heat sink is selected from any one of a substrate including a metalized layer, a metal substrate, an alumina substrate, and an aluminum nitride substrate.

In the step S12, the temperature of the first pre-curing treatment is 90 to 120 ℃, and the first welding paste is pre-cured in the temperature range, which is beneficial to complete volatilization of the solvent in the first welding paste, so that the initial setting is started to form the first welding film. The temperature of the second pre-curing treatment is 90-120 ℃, and the second welding slurry is pre-cured within the temperature range, so that the solvent in the second welding slurry is completely volatilized, and the initial sizing is started to form a second welding film.

In the embodiment, the thickness ratio of the first welding film to the second welding film is (0.3-0.5): 1, for example, 0.3. Specifically, when the thickness of the first soldering film is 20 μm, the thickness of the second soldering film may be 40 μm.

In the step S13, the step of performing the relative adhesion process between the chip and the heat sink includes: after being laminated, the chip and the radiator are placed in a hot press with the pressure of 2-5 MPa and the temperature of 180-250 ℃ for baking for 2-2.5 h.

In a specific embodiment, as shown in fig. 3, a first soldering paste is coated on the surface of a chip by a screen printing method, and is pre-cured at 90-120 ℃ to form a first soldering film; coating the second welding slurry on the surface of the radiating fin by using a screen printing mode, and performing second pre-curing at 90-120 ℃ to form a second welding film; and relatively bonding the chip and the radiating fin, enabling the first welding film to be positioned right above the second welding film (namely the first welding film is positioned on the upper layer, and the second welding film is positioned on the lower layer), relatively bonding, putting into a hot press, and baking for 2-2.5 h under the conditions that the pressure is 2-5 MPa and the temperature is 180-250 ℃.

In a specific embodiment, as shown in fig. 4, a first soldering paste is coated on the surface of the heat sink by a screen printing method, and is pre-cured at 90-120 ℃ to form a first soldering film; coating the second welding slurry on the surface of the chip by utilizing a screen printing mode, and performing second pre-curing at 90-120 ℃ to form a second welding film; and relatively bonding the chip and the radiating fin, enabling the first welding film to be positioned right above the second welding film (namely, the first welding film is positioned on the upper layer, and the second welding film is positioned on the lower layer), relatively bonding, putting into a hot press, and baking for 2-2.5 h under the conditions that the pressure is 2-5 MPa and the temperature is 180-250 ℃.

The following description is given with reference to specific examples.

Example 1

The embodiment provides a slurry, a preparation method thereof and a packaging method of a chip heat dissipation structure. The slurry comprises a first welding slurry and a second welding slurry, and the first welding slurry and the second welding slurry are respectively and independently counted;

the first welding slurry comprises the following components in parts by weight:

the second welding slurry comprises the following components in parts by weight:

the preparation method of the slurry comprises the following steps:

s001: measuring raw material components in the slurry of the embodiment;

s002: preparing first welding slurry:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid, benzotriazole and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a first mixed material;

adding indium powder with the average particle size of 8 mu m and the first mixed material into a planetary stirrer, and uniformly stirring to obtain first welding slurry;

s003: preparing a second welding paste:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a second mixed material;

adding 10wt% of the second mixed material and micron silver powder with the average particle size of 5 microns into a planetary stirrer, uniformly stirring, and grinding and dispersing by using a three-roll grinder to obtain a third mixed material;

mixing the remaining (90 wt%) second mixed material with the nano silver powder with the average particle size of 80nm, and performing ultrasonic dispersion to obtain a fourth mixed material;

and uniformly mixing and stirring the third mixed material and the fourth mixed material to obtain second welding slurry.

The packaging method of the chip heat dissipation structure comprises the following steps:

s011: coating the first welding paste in the paste of the embodiment on the surface of a chip by using a screen printing mode, and performing pre-curing at 120 ℃ to form a first welding film;

s012: coating the second welding paste in the paste of the embodiment on the surface of the radiating fin by using a screen printing mode, and performing pre-curing at 120 ℃ to form a second welding film;

s013: and (3) relatively attaching the chip and the radiating fin up and down, relatively attaching the first welding film above the second welding film, then placing the chip and the radiating fin into a hot press, maintaining the pressure for 3MPa, heating to 200 ℃, and keeping the temperature and pressure for baking for 1.5 hours to obtain the chip radiating structure.

Example 2

The embodiment provides a slurry, a preparation method thereof and a packaging method of a chip heat dissipation structure. The slurry comprises a first welding slurry and a second welding slurry, and the first welding slurry and the second welding slurry are respectively and independently counted;

the first welding slurry comprises the following components in parts by weight:

the second welding slurry comprises the following components in parts by weight:

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the preparation method of the slurry of the embodiment comprises the following steps:

s001: measuring raw material components in the slurry of the embodiment;

s002: preparing first welding slurry:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid, benzotriazole and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a first mixed material;

adding tin-bismuth alloy powder with the average grain size of 8 mu m and the first mixed material into a planetary stirrer, and uniformly stirring to obtain first welding slurry;

s003: preparing a second welding paste:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a second mixed material;

adding 10wt% of the second mixed material and micron silver powder with the average particle size of 5 microns into a planetary stirrer, uniformly stirring, and grinding and dispersing by using a three-roll grinder to obtain a third mixed material;

mixing the remaining (90 wt%) second mixed material with the nano silver powder with the average particle size of 80nm, and performing ultrasonic dispersion to obtain a fourth mixed material;

and uniformly stirring the third mixed material and the fourth mixed material to obtain second welding slurry.

The packaging method of the chip heat dissipation structure comprises the following steps:

s011: coating the first welding paste in the paste of the embodiment on the surface of the radiating fin by using a screen printing mode, and performing pre-curing at 120 ℃ to form a first welding film;

s012: coating the second welding paste in the paste of the embodiment on the surface of the chip by using a screen printing mode, and performing pre-curing at 120 ℃ to form a second welding film;

s013: and (3) relatively laminating the chip and the radiating fin up and down, relatively laminating the first welding film above the second welding film, then putting the first welding film into a hot press, maintaining the pressure at 3MPa, heating to 200 ℃, and baking for 1.5 hours under the condition of heat preservation and pressure maintenance to obtain the chip radiating structure.

Example 3

The embodiment provides a slurry, a preparation method thereof and a packaging method of a chip heat dissipation structure. The slurry comprises a first welding slurry and a second welding slurry, and the first welding slurry and the second welding slurry are respectively and independently counted;

the first welding slurry comprises the following components in parts by weight:

the second welding paste comprises the following components in parts by weight:

the preparation method of the slurry comprises the following steps:

s001: measuring raw material components in the slurry of the embodiment;

s002: preparing first welding slurry:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid, benzotriazole and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a first mixed material;

adding indium powder with the average grain diameter of 8 mu m and the first mixed material into a planetary stirrer, and uniformly stirring to obtain first welding slurry;

s003: preparing second welding slurry:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a second mixed material;

adding 10wt% of the second mixed material and micron silver powder with the average particle size of 5 microns into a planetary stirrer, uniformly stirring, and grinding and dispersing by using a three-roll grinder to obtain a third mixed material;

mixing the remaining (90 wt%) second mixed material with nano copper powder with the average particle size of 80nm, and performing ultrasonic dispersion to obtain a fourth mixed material;

and uniformly stirring the third mixed material and the fourth mixed material to obtain second welding slurry.

The packaging method of the chip heat dissipation structure of the present embodiment is the same as that of embodiment 1.

Example 4

The embodiment provides a slurry, a preparation method thereof and a packaging method of a chip heat dissipation structure. The slurry comprises a first welding slurry and a second welding slurry, and the first welding slurry and the second welding slurry are respectively and independently counted;

the first welding slurry comprises the following components in parts by weight:

the second welding paste comprises the following components in parts by weight:

the preparation method of the slurry comprises the following steps:

s001: measuring raw material components in the slurry of the embodiment;

s002: preparing first welding slurry:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid, benzotriazole and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a first mixed material;

adding the tin-bismuth alloy powder with the average grain diameter of 8 mu m and the first mixed material into a planetary stirrer, and uniformly stirring to obtain first welding slurry;

s003: preparing second welding slurry:

uniformly mixing diethylene glycol monobutyl ether, glutaric acid and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a second mixed material;

adding 10wt% of the second mixed material and micron silver powder with the average particle size of 5 microns into a planetary stirrer, uniformly stirring, and grinding and dispersing by using a three-roll grinder to obtain a third mixed material;

mixing the remaining (90 wt%) second mixed material with the nano silver powder with the average particle size of 80nm, and performing ultrasonic dispersion to obtain a fourth mixed material;

and uniformly stirring the third mixed material and the fourth mixed material to obtain second welding slurry.

The packaging method of the chip heat dissipation structure of the present embodiment is the same as that of embodiment 1.

Example 5

The embodiment provides a slurry, a preparation method thereof and a packaging method of a chip heat dissipation structure. The slurry comprises a first welding slurry and a second welding slurry, and the first welding slurry and the second welding slurry are respectively and independently counted;

the first welding slurry comprises the following components in parts by weight:

the second welding slurry comprises the following components in parts by weight:

the preparation method of the slurry comprises the following steps:

s001: measuring raw material components in the slurry of the embodiment;

s002: preparing first welding slurry:

uniformly mixing propylene glycol ethyl ether, adipic acid, methyl benzotriazole and polyvinylpyrrolidone, and heating until the mixture is completely dissolved to obtain a first mixed material;

adding tin-bismuth alloy powder with the average grain size of 8 mu m and the first mixed material into a planetary stirrer, and uniformly stirring to obtain first welding slurry;

s003: preparing a second welding paste:

uniformly mixing propylene glycol ethyl ether, adipic acid and polyvinylpyrrolidone, and heating until the mixture is completely dissolved to obtain a second mixed material;

adding 10wt% of the second mixed material and micron silver powder with the average particle size of 5 microns into a planetary stirrer, uniformly stirring, and grinding and dispersing by using a three-roll grinder to obtain a third mixed material;

mixing the remaining (90 wt%) second mixed material with the nano silver powder with the average particle size of 80nm, and performing ultrasonic dispersion to obtain a fourth mixed material;

and uniformly stirring the third mixed material and the fourth mixed material to obtain second welding slurry.

The packaging method of the chip heat dissipation structure of the present embodiment is the same as that of embodiment 1.

Comparative example 1

The comparative example provides a soldering paste, a preparation method thereof and a packaging method of a chip heat dissipation structure. The welding slurry comprises the following components in parts by weight:

the preparation method of the welding paste of the comparative example comprises the following steps:

s1a: uniformly mixing diethylene glycol monobutyl ether, glutaric acid and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a mixed material a;

s2a: adding 10wt% of the mixed material a and micron silver powder with the average particle size of 5 microns into a planetary stirrer, uniformly stirring, and grinding and dispersing by using a three-roll grinder to obtain a mixed material b;

s3a: mixing the remaining (90 wt%) mixed material a with the nano silver powder with the average particle size of 80nm, and performing ultrasonic dispersion to obtain a mixed material c;

s4a: and uniformly stirring the mixed material b and the mixed material c to obtain the welding slurry.

The packaging method of the chip heat dissipation structure comprises the following steps:

s1b: coating the welding paste of the comparative example on the surface of a chip by utilizing a screen printing mode, and performing precuring at 120 ℃ to form a first welding film;

s2b: coating the welding paste of the comparative example on the surface of the radiating fin by using a screen printing mode, and performing pre-curing at 120 ℃ to form a second welding film;

s3b: and (3) relatively laminating the chip and the radiating fin up and down, putting the chip and the radiating fin into a hot press, maintaining the pressure for 3MPa, heating to 200 ℃, and baking for 1.5 hours under the condition of heat preservation and pressure maintenance to obtain the chip radiating structure.

Comparative example 2

The comparative example provides a soldering paste, a preparation method thereof and a packaging method of a chip heat dissipation structure. The welding slurry comprises the following components in parts by weight:

the preparation method of the welding paste of the comparative example comprises the following steps:

s1: uniformly mixing diethylene glycol monobutyl ether, benzotriazole, glutaric acid and polyethylene glycol, and heating until the mixture is completely dissolved to obtain a mixed material a;

s2: adding indium powder with the average particle size of 8 microns, micron silver powder with the average particle size of 5 microns and half of the mixed material a into a planetary stirrer, uniformly stirring, and grinding and dispersing by using a three-roll grinder to obtain a mixed material b;

s3: mixing the nano silver powder with the average particle size of 80nm with the other half of the mixed material a, and performing ultrasonic dispersion to obtain a mixed material c;

s4: and uniformly stirring the mixed material b and the mixed material c to obtain the welding slurry.

The packaging method of the chip heat dissipation structure of the comparative example is the same as that of comparative example 1.

And (3) relevant performance test analysis:

the pastes of examples 1-5 and the soldering pastes of comparative examples 1-2 were characterized, and the performance characterization included:

(1) Welding strength testing process: the chip heat dissipation structures prepared in examples 1 to 5 and comparative examples 1 to 2 were cut into 2mm × 2mm cubes at 5 positions by wire cutting, and the cubes were soldered and fixed to a copper substrate with 305 solder paste, and the uppermost copper sheet was pushed with a thrustometer to test the thrust strength.

(2) And (3) testing the heat conductivity coefficient: the first and second solder pastes of examples 1 to 5 were respectively tack-dried and laminated together (the first solder paste was positioned on the upper layer), and cured blocks were prepared under the conditions of 200 ℃ and 3MPa, and the solder pastes of comparative examples 1 to 2 were prepared into cured blocks under the conditions of 200 ℃ and 3MPa, and were cut into pieces by wire cutting

And testing the heat conductivity coefficient of the module with the thickness of 2mm by a laser flash method.

(3) And (3) remelting characteristic test: the first and second solder pastes of examples 1 to 5 were respectively laminated together (the first solder paste was located on the upper layer) after being surface-dried, and cured blocks were prepared under the conditions of 200 ℃ and 3MPa, the solder pastes of comparative examples 1 to 2 were prepared under the conditions of 200 ℃ and 3MPa, and a small amount of the cured product was taken to test DSC and repeatedly scanned 10 times to see the reflow characteristics of the solder paste.

(4) And (3) testing the cold and hot impact reliability: the chip heat dissipation structures of examples 1 to 5 and comparative examples 1 to 2 were placed in an environment of-40 ℃ and 150 ℃ to perform a cold-hot cycle test, and after 300 cycles, the thrust change was measured according to the above-described weld strength test procedure.

The corresponding evaluation items and criteria are shown in table 1, and the test results are shown in table 2:

TABLE 1

TABLE 2

Item	Strength of welding	Coefficient of thermal conductivity	Remelting behaviour	Cold and hot shock test of weld strength variation
					Example 1	18MPa	240W/m·K	Is free of	10％
Example 2	12MPa	190W/m·K	Is free of	40％
					Example 3	10MPa	180W/m·K	Is free of	60％
Example 4	8MPa	170W/m·K	Is composed of	20％
					Example 5	7MPa	169W/m·K	Is free of	21％
Comparative example 1	20MPa	200W/m·K	Is free of	120％
					Comparative example 2	7MPa	140W/m·K	With remelting	10％

As can be seen from table 2, the change of the welding strength of the sintering interface (welding layer) of the chip heat dissipation structures in embodiments 1 to 5 after being subjected to thermal shock is significantly lower than that in comparative example 1, which indicates that the first welding paste containing the first metal powder with the melting point of not more than 200 ℃ can improve the wettability of the sintering interface, can improve the change of the welding strength after being subjected to thermal shock, and has good reliability. The heat conductivity coefficient of the sintering interface of the chip heat dissipation structure of the embodiments 1 to 5 is significantly higher than that of the comparative example 2, the sintering interface of the chip heat dissipation structure of the embodiments 1 to 5 is not remelted, and the comparative example 2 has remelting, which shows that by coating the first welding slurry containing the first metal powder with the melting point of not more than 200 ℃ and the second welding slurry containing the micron metal powder and the nanometer metal powder on the chip and the heat sink respectively to form the first welding film and the second welding film, and then relatively bonding the chip and the heat sink through the first welding film and the second welding film, the first metal powder with the low melting point of the first welding slurry on the upper layer can effectively fill the gap formed by sintering the nanometer metal powder of the second welding slurry, so that the porosity can be greatly reduced, the heat conductivity coefficient can be improved, and the first metal powder with the low melting point of the first welding slurry on the upper layer can form an alloy with the micro-nanometer metal powder, so that the sintering interface does not occur, and thus the high-temperature service requirement can be satisfied.

Fig. 5 is an SEM image of a sintering interface of the heat dissipation structure for a chip manufactured in example 1, fig. 6 is an optically enlarged view of the sintering interface of the heat dissipation structure for a chip manufactured in comparative example 1, and fig. 7 is an SEM cross-sectional view of an indium-copper sintering interface of the heat dissipation structure for a chip manufactured in example 3, and it can be seen from fig. 5 and 6 that the first soldering paste containing the first metal powder having a melting point of 200 ℃ or less, which is the soldering paste of example 1 of the present application, shows that the porosity of the sintering interface can be reduced.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. The slurry is characterized by comprising a first welding slurry and a second welding slurry which are respectively calculated by independent parts by weight,

the first welding slurry comprises the following components in parts by weight:

the second welding slurry comprises the following components in parts by weight:

2. the slurry of claim 1, wherein the first metal powder is 50 to 80 parts; and/or

The grain diameter of the first metal powder is 0.5-10 mu m; and/or

The first metal powder is at least one selected from indium powder, tin-bismuth alloy powder, tin-bismuth-silver-copper alloy powder, tin-bismuth-silver alloy powder, tin-indium alloy powder, silver-indium alloy powder and silver-zinc-indium alloy powder.

3. The slurry of claim 1, wherein the first organic solvent is selected from at least one of ethylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether, and propylene glycol ethyl ether; and/or

The first activator is selected from at least one of L-malic acid, glutaric acid, adipic acid and itaconic acid; and/or

The corrosion inhibitor is selected from any one of benzotriazole and tolyltriazole; and/or

The first thickening agent is selected from any one of polyethylene glycol, polyvinyl butyral and polyvinyl pyrrolidone.

4. The slurry according to any one of claims 1 to 3, wherein 30 to 50 parts of the micro metal powder and 30 to 50 parts of the nano metal powder; and/or

The particle size of the micron metal powder is 1-10 μm; and/or

The particle size of the nano metal powder is 20-200 nm; and/or

The micron metal powder is selected from at least one of micron silver powder, micron copper powder, micron silver-copper alloy powder, micron aluminum powder and micron silver-coated copper powder; and/or

The nano metal powder is at least one selected from nano copper powder, nano silver powder and nano silver-copper alloy powder.

5. The slurry according to any one of claims 1 to 3, wherein the second organic solvent is at least one selected from the group consisting of ethylene glycol butyl ether, propylene glycol methyl ether, diethylene glycol butyl ether and propylene glycol ethyl ether; and/or

The second activator is selected from at least one of L-malic acid, glutaric acid, adipic acid and citric acid; and/or

The second thickening agent is selected from any one of polyethylene glycol, polyvinyl butyral and polyvinyl pyrrolidone.

6. A method for preparing slurry is characterized by comprising the following steps:

providing the feedstock components in the slurry of any one of claims 1 to 5;

carrying out first mixing treatment on the first organic solvent, the first activator, the corrosion inhibitor, the first thickener and the first metal powder to obtain first welding slurry;

and carrying out second mixing treatment on the second organic solvent, the second activator, the second thickener, the micron metal powder and the nano metal powder to obtain second welding slurry.

7. The method of claim 6, wherein the step of subjecting the first organic solvent, the first activator, the corrosion inhibitor, the first thickener, and the first metal powder to a first mixing process comprises: mixing, stirring and heating the first organic solvent, the first activator, the corrosion inhibitor and the first thickener to obtain a first mixed material; then uniformly stirring the first metal powder and the first mixed material; and/or

The step of subjecting the second organic solvent, the second activator, the second thickener, the micro metal powder, and the nano metal powder to a second mixing process includes: mixing, stirring and heating the second organic solvent, the second activator and the second thickener to obtain a second mixed material; mixing (5-15) wt% of the second mixed material with the micron metal powder, and then sequentially stirring and grinding to obtain a third mixed material; dispersing the nano metal powder in the rest of the second mixed material to obtain a fourth mixed material; and mixing the third mixed material and the fourth mixed material, and uniformly stirring.

8. A packaging method of a chip heat dissipation structure is characterized by comprising the following steps:

providing the paste according to any one of claims 1 to 5 or the paste produced by the production method according to any one of claims 6 to 7, and a chip and a heat sink;

coating the first welding slurry in the slurry on the surface of the chip to perform first pre-curing treatment to form a first welding film, and coating the second welding slurry in the slurry on the surface of the radiating fin to perform second pre-curing treatment to form a second welding film; or coating the first welding slurry in the slurry on the surface of the heat radiating fin to perform first pre-curing treatment to form a first welding film, and coating the second welding slurry in the slurry on the surface of the chip to perform second pre-curing treatment to form a second welding film;

and carrying out relative bonding treatment on the chip and the radiating fin, and enabling the first welding film to be positioned above the second welding film for relative bonding to obtain the chip radiating structure.

9. The packaging method according to claim 8, wherein a thickness ratio of the first soldering film to the second soldering film is (0.3-0.5): 1; and/or

The radiating fin is selected from any one of a substrate containing a metalized layer, a metal substrate, an aluminum oxide substrate and an aluminum nitride substrate; and/or

The chip is selected from any one of a silicon carbide chip, a silicon-based chip and an insulated gate bipolar transistor.

10. The encapsulation method according to claim 8, wherein the temperature of the first pre-curing process is 90 to 120 ℃; and/or

The temperature of the second pre-curing treatment is 90-120 ℃; and/or

The step of performing a relative adhesion process on the chip and the heat sink includes: and stacking the chip and the radiator, and then baking the stacked chip and radiator in a hot press with the pressure of 2-5 MPa and the temperature of 180-250 ℃ for 2-2.5 h.

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