High thermal conductive composite material, preparation method and application thereof

Abstract

The application discloses a high-thermal-conductivity composite material and a preparation method and application thereof, and the product is obtained by pouring a ZA27 alloy ingot as a matrix and high-purity AlN ceramic particles as reinforcing bodies. p In the ZA27 / AlN composite material, the mass percentage of the matrix ZA27 alloy is as follows: 70.75% of Zn, 27.20% of Al and 2.05% of Cu; the volume percentage of the reinforcing body AlN ceramic particles is p=2%, 4%, 6% and 8%; and the particle size is 1 micrometer and 40 nanometers; the pouring temperature of the composite material is reasonable, the holding time is appropriate; the AlN ceramic particles can obviously refine the grain size and effectively enhance the hardness of the alloy; and the composite material has a good application prospect in microelectronic packaging materials and large-scale integrated circuit devices.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microelectronic packaging materials, and particularly relates to a high-thermal-conductivity composite material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid progress of semiconductor processing technology, electronic components are developing towards being lighter, smaller and faster. The size of the currently mass-produced semiconductor chips has been reduced from 45nm to 14nm, 7nm or even below 7nm, and the reduction in chip size and the increase in integration level result in a substantial increase in chip heat. For every 10℃ increase in the temperature of commonly used Si and GaAs semiconductors, the possibility of chip failure triples, so it is crucial to select a packaging material with good thermal conductivity and a thermal expansion coefficient matching that of the semiconductor to enhance chip performance and prolong chip service life. At present, widely used chip packaging materials include epoxy glass, ceramics, metals and metal matrix composites, etc. Organic packaging materials are more portable and easy to process, but their lower thermal conductivity and poor heat resistance limit their application, and long-term high operating temperature can significantly reduce the service life of semiconductor chips and the stability of integrated circuits; ceramic packaging materials such as AlN and Al2O3 have high strength, stability and good thermal conductivity, but the production cost of ceramics is high, the manufacturing process is complex and the surface is prone to oxidation, which can also cause failure of semiconductor chips; metal packaging materials mainly include Cu, Al and Zn, which have higher thermal conductivity and are easy to process compared to the other two types of packaging materials, but the thermal expansion coefficient of metals is less suitable for semiconductors, and thermal stress can occur after long-term cold and hot cycle use, leading to chip failure. Therefore, it is of great application prospect to prepare a metal matrix composite with a thermal expansion coefficient matching that of the chip material and excellent thermal conductivity by using a metal as a matrix material and compounding it with an inorganic material with a low thermal expansion coefficient.

[0003] Zinc-aluminum (ZA) alloys have a wide range of applications due to their excellent castability, wear resistance and good thermal conductivity, among which ZA27 alloy has the most excellent performance and is gradually replacing traditional Al and Cu casting alloys in various engineering applications. As a microelectronic packaging material, ZA27 alloy can effectively conduct the heat generated during the use of semiconductor chips to the outside, and is easy to process and low in cost, making it an ideal material for microelectronic packaging. However, the theoretical thermal expansion coefficient of ZA27 alloy is 26.0x10 -6 / K, which is too high for chips and can easily generate large thermal stress and cause chip failure, so it is necessary to compound ZA27 alloy with an inorganic material with a low thermal expansion coefficient to match the thermal expansion coefficient of the chip material.

[0004] AlN has high thermal conductivity, low thermal expansion coefficient, low dielectric constant, and is an ideal material for forming metal matrix composites (MMC) with ZA27 alloy. AlN added to metal matrix composites can also refine the grain, increase the number of grain boundaries, and further enhance the mechanical properties. Studies have shown that AlN p / metal composites have excellent comprehensive performance. However, current research mainly focuses on AlN p / Cu composites and AlN p / Al composites, and there is little research on AlN p / ZA27 composites with ZA27 as the matrix and AlN as the reinforcing body. For metal matrix composites, the strengthening phase is crucial to the mechanical, thermal and electrical properties of the matrix alloy. Therefore, there is an urgent need to explore the microstructure, strengthening phase distribution, thermal conductivity and thermal conduction mechanism of high-thermal-conductivity AlN p / ZA27 composites to accelerate the application of high-thermal-conductivity zinc alloys in the field of microelectronic packaging materials. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a high-thermal-conductivity composite material and its preparation method and application to solve the technical problem of limited application of ZA27 alloy in the field of microelectronic packaging due to insufficient thermal conductivity, high thermal expansion coefficient and insufficient high-temperature strength. By changing the doping amount of AlN ceramic particles, the microstructure and thermal conductivity of AlN p / ZA27 composites are improved. According to the microstructure, there are α-Al phase, β-Zn phase, eutectoid (α+η) structure and AlN reinforcing phase in the AlN p / ZA27 composite. The presence of AlN reinforcing phase effectively improves the hardness of the alloy and refines the grain. At the same time, through subsequent large plastic deformation process, the microstructure of the composite material and the distribution of AlN reinforcing phase are improved, achieving the purpose of significantly improving the mechanical properties and thermal conductivity of the composite material.

[0006] The application adopts the following technical solutions:

[0007] A high-thermal-conductivity composite material preparation method, ZA27 alloy is heated, and after the ZA27 alloy is melted, AlN ceramic particles are added for smelting. After refining and slagging, AlN p / ZA27 composite material is obtained. In the AlN p / ZA27 composite material, the volume percentage of ZA27 alloy is 92% to 98%, and the volume percentage of AlN ceramic particles is 2% to 8%.

[0008] Specifically, the AlN ceramic particles are tetragonal AlN ceramic particles.

[0009] Further, the particle size of the AlN ceramic particles is 1 µm or 40 nm.

[0010] Specifically, in the ZA27 alloy, the mass percentage of Zn is 70.75%~71.00, the mass percentage of Al is 27.00%~27.20%, and the mass percentage of Cu is 2.00%~2.05%.

[0011] Specifically, the melting process is as follows:

[0012] The ZA27 alloy is added and heated to 550~600 ℃, the AlN ceramic particles are added after the ZA27 alloy is melted, the temperature is raised to 600~650 ℃, and the temperature is kept for 1~1.5 h, then the temperature is lowered to 500~540 ℃, and the AlN p / ZA27 composite material is obtained by casting.

[0013] Further, the melting process needs to be protected by a gas, and the melting equipment needs to be preheated.

[0014] Further, the protective gas is an argon atmosphere.

[0015] Another technical solution of the present application is a high-thermal-conductivity composite material, and the chemical formula of the high-thermal-conductivity composite material is AlN p / ZA27, and the volume percentage p is 2%, 4%, 6%, or 8%.

[0016] Specifically, the Brinell hardness of the high-thermal-conductivity composite material is 110.20~135.50 HBW.

[0017] Another technical solution of the present application is the application of the high-thermal-conductivity composite material in microelectronic packaging materials.

[0018] Compared with the prior art, the present application has at least the following beneficial effects:

[0019] The present application is a high-thermal-conductivity composite material preparation method, when the volume fraction of the AlN particles is 2%~8%, the AlN p / ZA27 composite material can effectively form a dispersed distribution of square AlN reinforcing phases on the ZA27 alloy substrate, effectively control the volume fraction of the AlN reinforcing phases, explore the influence of the AlN addition amount on the AlN p / ZA27 composite material organization and performance, significantly refine the ZA27 alloy substrate grain size, and introduce the AlN reinforcing phase, which plays a dual role of fine-grain strengthening and dispersion strengthening.

[0020] Further, the AlN reinforcing phase is in the AlN pThe ZA27 composite material contains square AlN ceramic particles. These square AlN ceramic particles can regulate the solute redistribution during the solidification process of the ZA27 alloy, effectively promoting the diffusion of Zn atoms from α-Al to η-Zn in the eutectoid transformation β→(α+η).

[0021] Furthermore, the AlN ceramic particles have a particle size of 1 μm or 40 nm. The introduction of micron- and nano-scale reinforcing phases can significantly refine the matrix grains, improve the alloy hardness, and enhance the AlN... p Uniformity of the microstructure of / ZA27 composite material.

[0022] Furthermore, the ZA27 matrix alloy contains 70.75% Zn, 27.20% Al, and 2.05% Cu. According to the Zn-Al phase diagram, the ZA27 alloy forms primary α-Al phase, β-Zn phase, and eutectoid (α+η) structure during solidification. At room temperature, the primary α-Al phase and eutectoid (α+η) structure are distributed in a lamellar pattern, effectively enhancing the alloy's hardness and wear resistance. The addition of AlN reinforcing phase refines the ZA27 alloy grains and improves its hardness. The AlN particle content is 2.0 / 4.0 / 6.0 / 8.0 vol.%. Excessive AlN content leads to decreased density and thermal conductivity in the composite material; this content setting is beneficial for exploring the effect of AlN content on AlN... p The influence of / ZA27 high thermal conductivity composite material on microstructure and properties, and ensuring a certain volume fraction of AlN reinforcing phase, can improve the mechanical properties of the composite material.

[0023] Furthermore, the melting point of ZA27 alloy is 509℃, therefore, it is suitable for preparing AlN. p When preparing the ZA27 composite material, ZA27 alloy is added and the temperature is raised to 550–600℃. After the ZA27 is fully melted, AlN ceramic particles are added, and the temperature is raised to 600–650℃ and held for 1–1.5 hours. Then, the temperature is lowered to 500–540℃. At this temperature, the viscosity of the alloy melt is suitable, which is beneficial for casting. The resulting AlN composite material is then cast. p / ZA27 composite material. This casting process can reduce the melting temperature and oxygen absorption of the composite material, reduce the formation of oxide inclusions, and effectively control the amount of reinforcing phase in the composite material. At this melting temperature, AlN is better wetted by the molten zinc-aluminum alloy, while AlN does not react with the molten zinc-aluminum alloy, avoiding the formation of inferior interfaces by interfacial reactions, and effectively increasing the mechanical and thermal conductivity properties of the composite material.

[0024] Furthermore, Zn / Al is easily oxidized in air, so a protective gas is introduced during the smelting process to isolate oxygen and reduce the formation of oxide inclusions; at the same time, preheating the equipment can effectively prevent the crucible from cracking during high-temperature smelting.

[0025] Further, argon is an inert gas, commonly used as a protective gas in the smelting process, can effectively isolate oxygen, prevent the formation of oxide inclusions in the smelting process.

[0026] A high-thermal-conductivity composite material, the addition of AlN ceramic particles effectively forms a uniform distribution, controllable quantity, and various forms of AlN reinforcing phase, which can significantly refine the grain size and form a uniform distribution of strengthening phase, effectively enhance the Brinell hardness of the alloy; further develop a reliable service in the field of microelectronic packaging high-thermal-conductivity composite material provides research ideas.

[0027] In summary, the method of the application has reasonable composite material casting temperature, proper holding time; the addition of AlN ceramic particles can significantly refine the ZA27 alloy grain, while introducing the dispersion distribution of the strengthening phase, effectively improving the hardness of the composite material; has good application prospect in the field of microelectronic packaging materials.

[0028] The technical solutions of the application will be further described in detail below by means of the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 1 μm-AlN p / ZA27 as-cast optical microstructure (100x) schematic diagram, wherein (a) is the volume fraction of AlN 0%, (b) is the volume fraction of AlN 2%, (c) is the volume fraction of AlN 4%, (d) is the volume fraction of AlN 8%;

[0030] Figure 2 1 μm-2 vol.% AlN p / ZA27 as-cast optical microstructure (500x) schematic diagram, wherein (a) is the distribution of eutectoid (alpha + eta) organization, (b) is the distribution of eutectoid (alpha + eta) organization;

[0031] Figure 3 1 μm-8 vol.% AlN p / ZA27 as-cast microstructure SEM diagram, wherein (a) is (500x) AlN particle morphology, (b) is (1000x) AlN particle morphology. DETAILED DESCRIPTION

[0032] The technical solutions of the application will be further described in detail below by means of the drawings and examples.

[0033] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0034] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0035] In the present application, percentage (%) or part refers to the percentage by weight or weight parts of the composition, if not otherwise specified.

[0036] In the present application, each component or its preferred component involved can be combined to form new technical solutions, if not otherwise specified.

[0037] In the present application, unless otherwise specified, the numerical range "a~b" represents a shorthand notation for any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range "6~22" represents that all the real numbers between "6~22" have been listed herein, and "6~22" is only a shorthand notation for these numerical combinations.

[0038] The lower limit and upper limit of the range disclosed in the present application can be one or more lower limits and one or more upper limits, respectively.

[0039] In the present application, the term "and / or" used herein refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0040] In the present application, unless otherwise specified, each reaction or operation step can be carried out sequentially or according to the sequence. Preferably, the reaction method herein is carried out sequentially.

[0041] Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied in the present application.

[0042] The present application provides a high-thermal-conductivity composite material and a preparation method and application thereof, which is obtained by casting ZA27 alloy ingot and AlN ceramic particles as raw materials. The AlN pThe mass percentage of the matrix ZA27 alloy in the ZA27 composite material is respectively 70.75% of Zn, 27.20% of Al and 2.05% of Cu, the volume percentage of the matrix ZA27 is 98%, 96%, 94% and 92%, the volume percentage p of the reinforcing body AlN ceramic particles is 2%, 4%, 6% and 8%, the composite material has reasonable pouring temperature and proper holding time, the AlN ceramic particles can significantly refine the grain size, introduce the strengthening phase and increase the hardness of the alloy, and has good application prospect in the field of microelectronic packaging materials.

[0043] Please refer to Figure 1 The application discloses a preparation method of a high-thermal-conductivity composite material.

[0044] S1, ZA27 alloy ingots and AlN ceramic particles are used as raw materials, and the ZA27 alloy ingots are cleaned after removing surface oxide scales and are reserved;

[0045] S2, the ZA27 alloy and the AlN ceramic particles obtained in the step S1 are used as raw materials, and the matrix ZA27 alloy has a volume percentage of 98%, 96%, 94% and 92%, and the reinforcing body AlN ceramic particles have a volume percentage of 2%, 4%, 6% and 8%.

[0046] The particle size of the AlN ceramic particles is 1 mu m and 40 nm.

[0047] The addition of the AlN ceramic particles can significantly refine the matrix grain of the ZA27 alloy, the addition of the dispersedly-distributed tetragonal AlN ceramic particles can effectively enhance the Brinell hardness of the ZA27 alloy.

[0048] S3, the ingredients obtained in the step S2 are melted to obtain AlN p ZA27 composite material, the crucible, the pouring mold and the raw materials are preheated in an argon gas atmosphere furnace, argon protective gas is introduced in a melting process, the ZA27 alloy is added and is heated to 550-600 DEG C, the AlN ceramic particles are added after the ZA27 alloy is melted, the temperature is increased to 600-650 DEG C, the temperature is kept for 1-1.5 h, then the temperature is decreased to 500-540 DEG C, the slag is refined, and the AlN p ZA27 composite material is obtained.

[0049] The high-thermal-conductivity composite material is prepared by the method, and the chemical formula of the high-thermal-conductivity composite material is AlN p ZA27, and the volume percentage p is 2%, 4%, 6% and 8%.

[0050] According to the mass percentage, the Zn accounts for 70.75% in the ZA27 alloy, the Al accounts for 27.20% and the Cu accounts for 2.05%.

[0051] AlN p The Brinell hardness value of the / ZA27 composite material gradually increases with the increase of the volume fraction of the reinforcing AlN ceramic particles (110.20~135.50HBW), reaching a peak of 135.50HBW at p=8vol.%. The addition of AlN ceramic particles can significantly refine the grain size and introduce reinforcement, effectively enhancing the hardness of the alloy, making it suitable for use in packaging materials for microelectronic packaging.

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] Argon gas was introduced, and ZA27 alloy and AlN ceramic particles were used as raw materials, with ZA27 alloy accounting for 98% by volume and AlN ceramic particles with a particle size of 1μm accounting for 2% by volume. ZA27 was added and the temperature was raised to 550℃. After the ZA27 alloy melted, AlN ceramic particles were added, the temperature was raised to 600℃, and the temperature was held for 1 hour. After the melt was homogenized for 5 minutes, the temperature was lowered to 520℃, and the mixture was cast to obtain a 1μm-2% AlN / ZA27 composite material.

[0055] Example 2

[0056] Argon gas was introduced, and ZA27 alloy and AlN ceramic particles were used as raw materials, with ZA27 alloy accounting for 96% by volume and AlN ceramic particles with a particle size of 1μm accounting for 4% by volume. ZA27 was added and the temperature was raised to 550℃. After the ZA27 alloy melted, AlN ceramic particles were added, the temperature was raised to 600℃, and the temperature was held for 1 hour. After the melt was homogenized for 5 minutes, the temperature was lowered to 520℃, and the mixture was cast to obtain a 1μm-4% AlN / ZA27 composite material.

[0057] Example 3

[0058] ZA27 alloy and AlN ceramic particles as raw materials, according to the volume fraction of ZA27 alloy is 94%, the volume fraction of 1 μm AlN ceramic particles is 6%. Add ZA27 and heat to 580°C, after ZA27 alloy is melted, add AlN ceramic particles, heat to 630°C, keep for 1 h, after melt homogenization for 10 minutes, then cool to 520°C, cast to get 1 μm-6% AlN / ZA27 composite material.

[0059] Example 4

[0060] ZA27 alloy and AlN ceramic particles as raw materials, according to the volume fraction of ZA27 alloy is 92%, the volume fraction of 1 μm AlN ceramic particles is 8%. Add ZA27 and heat to 580°C, after ZA27 alloy is melted, add AlN ceramic particles, heat to 630°C, keep for 1.5 h, after melt homogenization for 10 minutes, then cool to 540°C, cast to get 1 μm-8% AlN / ZA27 composite material.

[0061] Example 5

[0062] ZA27 alloy and AlN ceramic particles as raw materials, according to the volume fraction of ZA27 alloy is 98%, the volume fraction of 40 nm AlN ceramic particles is 2%. Add ZA27 and heat to 600°C, after ZA27 alloy is melted, add AlN ceramic particles, heat to 650°C, keep for 1.5 h, after melt homogenization for 15 minutes, then cool to 540°C, cast to get 40 nm-2% AlN / ZA27 composite material.

[0063] See Figure 1 , AlN p / ZA27 (p = 0 / 2 / 4 / 6 / 8 vol.%) composite material OM (100x) photo. The addition of AlN ceramic particles significantly refines the matrix grain of ZA27 alloy, and with the increase of AlN content, the grain refinement effect is more and more significant. The grain shape of ZA27 alloy changes, from dendritic grains with aspect ratio close to 1:1 to feather-like grains with aspect ratio far greater than 1:1.

[0064] See Figure 2 , AlN pOM (500x) photo of ZA27 (p=0 / 2 / 4 / 6 / 8 vol.%) composites. According to the Zn-Al alloy phase diagram, the phases and microstructure formed during solidification of ZA27 mainly include: primary alpha-Al phase, peritectic beta-Zn phase, eutectoid (alpha+eta) structure. The grayish white dendritic part in the figure is the primary alpha-Al phase, the dark gray part is the peritectic beta-Zn phase formed around the alpha-Al phase, and the eutectoid (alpha+eta) structure is distributed between the crystals, wherein the darker black part has higher contrast and is the eta-Zn phase, and the lighter gray part has lower contrast and is the alpha-Al phase, and the two phases are distributed in lamellar form.

[0065] See Figure 3 , AlN p SEM photo of ZA27 (p=0 / 2 / 4 / 6 / 8 vol.%) composites. On the substrate ZA27 alloy, there are dispersedly distributed black tetragonal phases with diameters ranging from 1 to 10 microns, which are AlN particles added in the composite, most of the AlN particles have diameters of about 1 to 3 microns, and a small number of AlN particles have agglomerated and have diameters of 10 microns.

[0066] In summary, the high-thermal-conductivity composite material, the preparation method and the application thereof, by changing the addition amount of AlN ceramic particles, can improve the dispersion and orientation of AlN p The microstructure of the ZA27 composite. According to the phase diagram, the phases and microstructure in the ZA27 alloy substrate of the composite mainly include primary alpha-Al phase, peritectic beta-Zn phase and eutectoid (alpha+eta) structure. AlN particles are dispersedly distributed on the ZA27 alloy substrate in the form of complete or incomplete black tetragonal phases with diameters ranging from 1 to 10 microns. The addition of AlN particles significantly refines the grains and improves the mechanical properties such as hardness of the alloy, and through subsequent large plastic deformation process, the distribution and orientation of AlN ceramic particles are improved, and the thermal conductivity of the composite material is improved.

[0067] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of preparing a high thermal conductivity composite material, characterized by, The smelting process needs to pass argon, and the smelting equipment is preheated, ZA27 alloy is added and heated to 550-600 DEG C, after ZA27 alloy is melted, the four square AlN ceramic particles with a particle size of 1 mu m or 40 nm are added, the temperature is raised to 600-650 DEG C, and the temperature is kept for 1-1.5 h, then the temperature is lowered to 500-540 DEG C, after refining and slagging, AlN p / ZA27 composite material, in the ZA27 alloy, the mass percentage of Zn is 70.75%, the mass percentage of Al is 27.20%, the mass percentage of Cu is 2.05%, AlN p / ZA27 composite material, the volume percentage of ZA27 alloy in the ZA27 composite material is 92%-98%, and the volume percentage of AlN ceramic particles is 2%-8%.

2. A high thermal conductivity composite material, characterized by, The high-thermal-conductivity composite material is prepared by the method according to claim 1, and the chemical formula of the high-thermal-conductivity composite material is: AlN p / ZA27, volume percentage p = 2%, 4%, 6%, 8%.

3. The high thermal conductivity composite of claim 2, wherein, The Brinell hardness of the high-thermal-conductivity composite material is 110.20-135.50 HBW.

4. Application of the high-thermal-conductivity composite material according to claim 2 to microelectronic packaging materials.

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