A multi-phase ceramic material for GaAs chip packaging and a preparation method and application thereof

Abstract

The application belongs to ceramic packaging materials, and particularly discloses a complex-phase ceramic material for GaAs chip packaging, a preparation method and application thereof. 3+ The application discloses a kind of complex-phase ceramics, which is prepared by using ZnAl2O4 spinel doped with ions as matrix phase, SiC or AlN nanowhisker as heat-conducting toughening phase, and rare earth oxide as interface control sintering aid.The nanowhisker is uniformly dispersed by using ultrasonic-assisted low-speed ball milling process.The complex-phase ceramic is obtained by molding, degassing and controllable sintering.The application controls thermal expansion coefficient by ion doping and nanowhisker compounding, constructs three-dimensional heat-conducting network by nanowhisker, and forms low-thermal-resistance amorphous phase on the interface of two phases by using rare earth component, which greatly reduces the heat transfer loss of interface.The thermal conductivity of the obtained ceramic can reach 25-35 W / (mK), the thermal expansion coefficient is highly matched with GaAs chip, the fracture toughness and mechanical strength are significantly improved, and the ceramic has excellent dielectric properties.The ceramic can be used for preparing GaAs chip packaging substrate or heat-dissipating element.

Description

Technical Field

[0001] This invention pertains to ceramic packaging materials, specifically relating to a multiphase ceramic material for GaAs chip packaging, its preparation method, and its applications. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Gallium arsenide (GaAs), as a new generation of high-frequency, high-speed semiconductor material, has irreplaceable advantages in radio frequency devices and optoelectronic devices. However, the coefficient of thermal expansion (CTE) of GaAs chips is approximately 6.97 ppm / °C, which exhibits varying degrees of mismatch with commonly used packaging materials. For example, the CTE of AlN ceramics is approximately 4.5 ppm / °C, and that of Al2O3 ceramics is approximately 7.2-8.0 ppm / °C. This thermal mismatch can lead to thermal stress between the chip and the package, which can affect device performance in mild cases and cause chip cracking or package failure in severe cases.

[0004] ZnAl2O4 spinel ceramics have attracted attention due to their excellent dielectric properties and CTE potential similar to GaAs. (B) 3+ Ion doping to form ZnAl 2-x B x O4 solid solutions can tune CTE to levels close to those of GaAs. However, pure B... 3+ ZnAl₂O₄ doped ceramics have low thermal conductivity, typically around 18 W / (m·K), which is insufficient for the heat dissipation requirements of high-power GaAs chips. Furthermore, they exhibit poor fracture toughness, typically 1.2–1.5 MPa·m. 1 / 2 Cracks can easily form during the packaging process, affecting long-term reliability.

[0005] Introducing a high thermal conductivity second phase is a common strategy to improve thermal conductivity and mechanical properties. However, two key challenges arise in practice: first, nanocrystals are prone to agglomeration, and traditional ball milling processes can damage the whisker structure; second, the interfacial thermal resistance between the second phase and the matrix increases significantly, often resulting in limited or even decreased improvement in actual thermal conductivity. Therefore, how to simultaneously achieve breakthroughs in thermal conductivity and fracture toughness while maintaining precise CTE matching is a pressing technical problem in the field of GaAs chip packaging ceramic materials. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention provides a multiphase ceramic material for GaAs chip packaging, its preparation method, and its applications. This invention utilizes B... 3+By introducing nano-whiskers and rare earth oxide sintering aids into the doped ZnAl2O4 matrix and employing a mild dispersion process of ultrasonic-assisted low-speed ball milling, the whiskers are uniformly dispersed in the matrix and form an amorphous interface phase with low thermal resistance at the interface, thereby simultaneously achieving a comprehensive improvement in high thermal conductivity, low CTE, and high fracture toughness.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a multiphase ceramic material for GaAs chip packaging, comprising the following steps: (1) According to the molecular formula ZnAl 2-x B x O4 uses stoichiometric weighing of ZnO, Al2O3, and B source raw materials, all with a purity ≥98% and ≤0.01%. x ≤0.10, the weighed raw materials are mixed, ball-milled, dried, and sieved, then pre-calcined at high temperature, and ball-milled again to obtain the matrix pre-calcined powder; (2) The matrix pre-calcined powder, nano whiskers and rare earth oxide sintering aid obtained in step (1) are mixed in a dispersion medium and then subjected to ultrasonic treatment and ball milling in sequence to obtain a mixed slurry. (3) Add a binder to the mixed slurry obtained in step (2) and granulate it, then press it into shape to obtain a green body; (4) After removing the binder from the green body obtained in step (3), sinter it in a protective atmosphere or an air atmosphere to obtain the green body.

[0008] In a second aspect, the present invention provides a multiphase ceramic material for GaAs chip packaging, which is prepared by the preparation method described in the first aspect.

[0009] Thirdly, the present invention provides the application of the above-mentioned multiphase ceramic material for GaAs chip packaging in the preparation of GaAs chip packaging substrates or heat dissipation elements.

[0010] The beneficial effects of one or more of the above technical solutions are: The preparation method provided by this invention involves mixing pre-sintered matrix powder, nanofibers, and rare earth oxide sintering aids in a specific ratio, followed by sequential ultrasonic treatment and low-speed ball milling. This process achieves uniform dispersion without damaging the whisker structure. Ultrasonic treatment effectively breaks up initial whisker agglomeration, while low-speed ball milling prevents whisker breakage, ensuring the formation of a continuous three-dimensional thermally conductive and toughening network within the matrix. Simultaneously, during sintering, the rare earth oxides form an amorphous interface phase at the whisker-matrix interface. This interface phase reduces the interfacial thermal resistance due to phonon scattering, significantly increasing thermal conductivity from 18 W / (m·K) to 25-35 W / (m·K). Furthermore, it enhances interfacial bonding strength. Combined with whisker pull-out and bridging mechanisms, this results in fracture toughness increasing from 1.2-1.5 MPa·m. 1 / 2 Increased to 1.8-2.5 MPa·m 1 / 2 Furthermore, through B 3+ By controlling both doping concentration and whisker content, the CTE can be precisely adjusted within the range of 6.5-7.5 ppm / °C, achieving a high degree of thermal matching with GaAs chips (difference ≤0.5 ppm / °C). Therefore, the technical challenge of simultaneously achieving high thermal conductivity, low CTE, and high toughness is solved. Attached Figure Description

[0011] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0012] Figure 1 The X-ray diffraction pattern of the multiphase ceramic material prepared in Example 1 of this invention; Figure 2 The images shown are SEM and EDS images of the multiphase ceramic material prepared in Example 2 of this invention, where a is 5 μm, b is 1 μm, c is 500 nm, and d is the EDS image. Figure 3 The thermal expansion curves of Embodiment 1, Comparative Examples 1-3, and GaAs chips of the present invention are shown. Figure 4 This is a graph showing the trend of the coefficient of thermal expansion of the present invention. Detailed Implementation

[0013] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0014] This invention provides a method for preparing a multiphase ceramic material for GaAs chip packaging, comprising the following steps: (1) According to the molecular formula ZnAl 2-x B x O4 uses stoichiometric weighing of ZnO, Al2O3, and B source raw materials, all with a purity ≥98% and ≤0.01%. x ≤0.10, the weighed raw materials are mixed, ball-milled, dried, and sieved, then pre-calcined at high temperature, and ball-milled again to obtain the matrix pre-calcined powder; (2) The matrix pre-calcined powder, nano whiskers and rare earth oxide sintering aid obtained in step (1) are mixed in a dispersion medium and then subjected to ultrasonic treatment and ball milling in sequence to obtain a mixed slurry. (3) Add a binder to the mixed slurry obtained in step (2) and granulate it, then press it into shape to obtain a green body; (4) After removing the binder from the green body obtained in step (3), sinter it in a protective atmosphere or an air atmosphere to obtain the green body.

[0015] In one or more embodiments, in step (1), the B source material is boric acid or boron oxide. Boric acid and boron oxide are common boron doping sources that decompose and dissolve into the ZnAl2O4 lattice during the pre-calcination process, replacing Al. 3+ This reduces the CTE of the matrix phase by targeting specific sites. These two raw materials are low-cost, easy to weigh, and produce no harmful residues from their decomposition.

[0016] In one or more embodiments, in step (1), the ball milling speed is 250–350 r / min, and the milling time is 4–12 h; the drying temperature is 80–120℃, and the drying time is 12–24 h; the pre-calcination temperature is 900–1100℃, and the pre-calcination holding time is 2–6 h. Within the above parameter range, the raw materials can be fully and uniformly mixed without phase change, and a pure phase solid solution is formed after pre-calcination.

[0017] In one or more embodiments, in step (2), the nanowhiskers are selected from at least one of SiC whiskers or AlN whiskers, with a whisker diameter of 0.1–0.8 μm and an aspect ratio of 15–30. Both SiC and AlN whiskers have high thermal conductivity and low CTE, making them suitable as phases for enhancing thermal conductivity and regulating CTE. Limiting the range of diameter and aspect ratio ensures that the whiskers form an effective network in the matrix without excessive aggregation.

[0018] In one or more embodiments, in step (2), the rare earth oxide sintering aid is selected from at least one of Y2O3, La2O3, or Sm2O3. These rare earth oxides can react with oxides on the matrix or whisker surface during sintering to generate an amorphous interface phase, effectively reducing interfacial thermal resistance. Y2O3 shows the best effect, while La2O3 and Sm2O3 can achieve similar effects at a lower cost.

[0019] In one or more embodiments, in step (2), the weight ratio of the pre-sintered matrix powder, nanocrystals, and rare earth oxide sintering aid is 80-90:5-20:0.5-5. Within this ratio range, the matrix phase can stably ensure the thermal matching characteristics with the GaAs chip, the sufficient amount of nanocrystals can construct a continuous three-dimensional thermally conductive network, and the appropriate amount of rare earth aid can fully exert the interface regulation and sintering aid effects without causing the precipitation of impurity phases due to excessive aid, thus avoiding damage to the overall dielectric and mechanical properties of the ceramic.

[0020] In one or more embodiments, in step (2), the ultrasonic treatment time is 30–90 min, the ultrasonic power is 150–200 W, and the ultrasonic frequency is 30–50 kHz; the low-speed ball milling speed is 100–150 r / min, and the ball milling time is 2–4 h. Ultrasonic treatment utilizes the cavitation effect to open up whisker agglomerates, while low-speed ball milling avoids whisker breakage. Within this parameter range, the whiskers are uniformly dispersed and structurally intact.

[0021] In one or more embodiments, in step (3), the adhesive is an aqueous solution of polyvinyl alcohol with a mass concentration of 5-10. wt The molding pressure is 50–200 MPa, and the holding time is 30–60 s. Polyvinyl alcohol is a commonly used binder in ceramic granulation, and leaves no residue after firing. Within this pressure range, the green body has sufficient strength and is not prone to delamination.

[0022] In one or more embodiments, the debinding temperature in step (4) is 400–600°C, the heating rate is 0.5–1°C / min, and the debinding holding time is 1–2 h; the protective atmosphere is N2 atmosphere; the sintering temperature is 1350–1500°C, and the holding time is 2–8 h. Slow heating and debinding can prevent cracking of the green body. When AlN whiskers are used, N2 protection is required to prevent oxidation; SiC whiskers can be sintered in an air atmosphere. Sintering temperatures below 1350°C result in insufficient densification, while temperatures above 1500°C lead to excessive grain growth and performance degradation.

[0023] This invention provides a multiphase ceramic material for GaAs chip packaging, which is prepared using the above-described method.

[0024] In one or more embodiments, the multiphase ceramic material comprises B 3+ The matrix phase is doped with ZnAl2O4, and the second phase of nanocrystals is uniformly dispersed at the grain boundaries of the matrix; an amorphous interface phase derived from rare earth oxides is formed between the second phase of nanocrystals and the matrix phase.

[0025] In one or more embodiments, the multiphase ceramic material has a thermal conductivity of 25–35 W / (m·K), a coefficient of thermal expansion of 6.5–7.5 ppm / °C, and a fracture toughness of 1.8–2.5 MPa·m. 1 / 2 .

[0026] This invention provides the application of the above-mentioned materials in the preparation of GaAs chip packaging substrates or heat dissipation elements.

[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and experimental examples.

[0028] It should be noted that the present invention is not limited to the above preparation process. Commercially available modified polypropylene films and water-based polypropylene coatings can be used as substitutes, as long as the additive content and mechanical property parameters are consistent.

[0029] Example 1 This embodiment provides a multiphase ceramic material for GaAs chip packaging and its preparation method.

[0030] (1) Preparation of pre-calcined matrix powder: according to the molecular formula ZnAl 1.96 B 0.04 O4 ( x Weigh ZnO (99.9% purity), Al2O3 (99.9% purity), and H3BO3 (99.9% purity) to a weight of 0.04 g. Place the raw materials in a planetary ball mill, using anhydrous ethanol as the medium, zirconium oxide balls (5 mm:10 mm = 1:1), a ball-to-material ratio of 3:1, and a rotation speed of 300 r / min for 6 h. Dry the slurry at 100℃ for 24 h and pass it through a 200-mesh sieve. Pre-calcine the resulting powder at 1000℃ for 4 h at a heating rate of 5℃ / min, and then cool it with the furnace. Ball mill the pre-calcined material again (under the same conditions) to obtain the matrix pre-calcined powder.

[0031] (2) Mixing: Take 90 parts of pre-calcined matrix powder, 10 parts of SiC nanocrystals (diameter 0.1-0.5 μm, aspect ratio 20-30, purity ≥99%) and 2 parts of Y2O3 (purity 99.99%), and add them to anhydrous ethanol. Place the mixed slurry in an ultrasonic cleaner and ultrasonically treat it for 60 minutes at a power of 200W and a frequency of 40kHz. Then transfer the ultrasonicated slurry into a ball mill jar with a ball-to-powder ratio of 1:1 and a rotation speed of 120 r / min for 3 hours to obtain a mixed slurry.

[0032] (3) Granulation and molding: Add 5g of granulation material to the mixed slurry. wt Granulation was performed using a % polyvinyl alcohol aqueous solution, which was then passed through a 40-mesh sieve and aged for 12 hours. The granules were then uniaxially dry-pressed into Φ10 mm × 5 mm round green sheets under a pressure of 150 MPa for 60 seconds.

[0033] (4) Debinding and sintering: The green body is debinded at 500℃ for 2 h with a heating rate of 1℃ / min. Then it is sintered at 1480℃ for 4 h in air with a heating rate of 3℃ / min and cooled with the furnace.

[0034] Example 2 This embodiment is basically the same as Embodiment 1, except that: in step (2), AlN nanocrystals (diameter 0.2-0.8 μm, aspect ratio 15-25) are used instead of SiC whiskers, and the amount of whiskers remains unchanged; in step (4), the sintering atmosphere is changed to a flowing N2 atmosphere (flow rate 0.5 L / min) to prevent AlN oxidation. The remaining steps are the same as in Embodiment 1.

[0035] Example 3 This embodiment is basically the same as Embodiment 1, except that the weight ratio of the pre-calcined matrix powder, SiC whiskers and Y2O3 in step (2) is adjusted to 80:20:2. The remaining steps are the same as in Embodiment 1.

[0036] Example 4 This embodiment is basically the same as Embodiment 1, except that in step (1), the molecular formula ZnAl is used. 1.9 B 0.1 Weigh the raw materials using O4 (x=0.10). The remaining steps are the same as in Example 1.

[0037] Example 5 This embodiment is basically the same as Embodiment 1, except that in step (2), Y2O3 is replaced with an equal amount of La2O3. The remaining steps are the same as in Embodiment 1.

[0038] Example 6 This embodiment is basically the same as Embodiment 1, except that in step (2), Y2O3 is replaced with an equal amount of Sm2O3. The remaining steps are the same as in Embodiment 1.

[0039] Example 7 This embodiment is basically the same as Embodiment 1, except that the weight ratio of the pre-calcined matrix powder, SiC whiskers and Y2O3 in step (2) is adjusted to 90:10:0.5. The remaining steps are the same as in Embodiment 1.

[0040] Example 8 This embodiment is basically the same as Embodiment 1, except that the weight ratio of the pre-calcined matrix powder, SiC whiskers and Y2O3 in step (2) is adjusted to 90:10:5. The remaining steps are the same as in Embodiment 1.

[0041] Comparative Example 1 (pure matrix, without whiskers and rare earth elements) The difference between this comparative example and Example 1 is that SiC whiskers and Y2O3 are not added in step (2); only the pre-calcined matrix powder is granulated, shaped, and sintered. The remaining steps are the same as in Example 1. The resulting material is pure ZnAl. 1.96 B 0.04 O4 ceramic material.

[0042] Comparative Example 2 (with whiskers but no rare earth elements) The difference between this comparative example and Example 1 is that Y2O3 is not added in step (2). The remaining steps are the same as in Example 1.

[0043] Comparative Example 3 (with rare earth elements but no whiskers) The difference between this comparative example and Example 1 is that SiC whiskers are not added in step (2). The remaining steps are the same as in Example 1.

[0044] Comparative Example 4 The difference between this comparative example and Example 1 is that in step (1), the molecular formula ZnAl2O4 ( x =0) Weigh the raw materials, without adding H3BO3, and do not add SiC whiskers and Y2O3 in step (2). Only granulate, shape and sinter the pre-fired matrix powder. The remaining steps are the same as in Example 1. The obtained material is pure ZnAl2O4 ceramic material.

[0045] Performance testing methods The following performance tests were conducted on Examples 1-7 and Comparative Examples 1-4, and the test results are shown in Table 1.

[0046] Relative density: Archimedes electronic hydrometer; Thermal conductivity: Laser thermal conductivity meter; Coefficient of thermal expansion (CTE): Laser thermal expansion meter; Fracture toughness: Universal testing machine; Bending strength: universal testing machine; Dielectric properties: Network vector analyzer; Quality factor: Network vector analyzer.

[0047] Microstructure: Observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

[0048] like Figure 1 As shown, the multiphase ceramic material prepared in Example 1 of this invention mainly consists of B 3+ It consists of a doped cubic spinel phase (ZnAl2O4 phase, JCPDS No. 05-0669) and a second phase (α-SiC phase, JCPDS No. 29-1129).

[0049] like Figure 2As shown, the multiphase ceramic material prepared in Example 1 of this invention exhibits a microscopic structure in which whiskers are uniformly and interwoven between the matrix grains. Since nitrogen is a light element, its detection signal is weak, so only Al can be used to indicate the presence of AlN. The results show that the Al element is uniformly distributed, indicating that the whiskers are uniformly dispersed. AlN nanocrystals are uniformly dispersed at the matrix grain boundaries and triplex grain boundaries, forming a three-dimensional network without obvious agglomeration. The matrix grain size is 2–5 μm. Y₂O₃ forms an amorphous interface phase of approximately 2–5 nm thick at the interface between the whiskers and the matrix.

[0050] Table 1 Test results of Examples 1-7

[0051] Table 2 Test results for comparative examples 1-4

[0052] As shown in Table 1, the composite ceramic material prepared by this invention possesses the characteristics of high reliability (high strength and toughness), high thermal conductivity, and high-precision thermal matching. Its relative density is ≥ 95%, thermal conductivity is 25 – 35 W / (m•K) (range 25-300°C), and coefficient of thermal expansion (CTE, range 25-300°C) is 6.5-7.5 ppm / °C. CTE difference with GaAs chip (6.97 ppm / °C): ≤0.5 ppm / °C, fracture toughness: 1.8 – 2.5 MPa•m 1 / 2 Dielectric constant ( ε r ): 7.8 – 9.5 (at 1 MHz frequency), dielectric loss Q × f Value: ≥45,000 GHz.

[0053] As can be seen from Examples 1 and 2, the intrinsic thermal conductivity of AlN whiskers (theoretically about 300 W / (m•K)) is higher than that of SiC (about 200-250 W / (m•K)). However, the actual thermal conductivity of Example 2 is lower than that of the SiC whiskers used in Example 1. This may be because AlN undergoes slight oxidation at high temperatures or reacts with the matrix to form interface defects. SiC whiskers exhibit better chemical stability under air sintering conditions.

[0054] As can be seen from Examples 1 and 3, a high whisker content can further enhance the thermal conductivity and toughening effect, but it has an adverse effect on densification and slightly degrades the dielectric properties.

[0055] As can be seen from Examples 1 and 4, high boron doping can further reduce the CTE of the matrix, but the resulting lattice distortion leads to a significant decrease in thermal conductivity. The thermal conductivity remains above 25 W / (m·K) after compositing with SiC whiskers, verifying the compensating effect of the whisker thermal network on the increase in matrix thermal resistance. x =0.04 is the optimal doping amount for overall performance.

[0056] As can be seen from Examples 1 and 5, La2O3 can also effectively promote densification and form an amorphous phase at the interface, although the effect is slightly less than that of Y2O3, it is still within an acceptable range. Its advantage lies in its lower cost, making it suitable for industrial-scale promotion.

[0057] As can be seen from Examples 1 and 6, Sm2O3 has the weakest effect in terms of sintering aid and interface regulation among the three, but it is still far superior to the traditional rare earth-free additive scheme. All three rare earth oxides are effective, with Y2O3 being the optimal choice, and La2O3 and Sm2O3 being alternatives.

[0058] As can be seen from Example 1 and Comparative Example 1, the thermal conductivity increased from 18.6 W / (m·K) to 31.5 W / (m·K) (+69%) and the fracture toughness increased from 1.35 to 2.32 MPa·m after the simultaneous introduction of SiC whiskers and Y2O3. 1 / 2 (+72%), while CTE remains within the matching range of 6.98 ppm / °C.

[0059] As can be seen from Example 1 and Comparative Example 2, without rare earth additives, the bonding between the whiskers and the matrix is ​​poor, and the interfacial thermal resistance is high, resulting in almost no improvement in thermal conductivity, only increasing from 18.6 to 19.5 W / (m·K), and densification is difficult. This strongly demonstrates that the interfacial control of rare earth oxides is the key to achieving high thermal conductivity in this invention.

[0060] As can be seen from Example 1 and Comparative Example 3, the only difference between Comparative Example 3 and Example 1 is that SiC whiskers are not added (the matrix of both examples is ZnAl). 1.96 B 0.04 O4 (all with 2% Y2O3 added). The CTE of Comparative Example 3 was 7.20 ppm / °C. Compared with Example 1 (6.98 ppm / °C), the introduction of whiskers further reduced the CTE by 0.22 ppm / °C, demonstrating the secondary reduction effect of low CTE whiskers on overall thermal expansion. More significantly, the thermal conductivity of Example 1 (31.5 W / (m·K)) was 64% higher than that of Comparative Example 3 (19.2 W / (m·K)), and the fracture toughness (1.42 MPa·m) was also improved. 1 / 2The performance improvement is 63%. This directly proves that the three-dimensional thermally conductive network and toughening mechanism constructed by SiC whiskers are the core driving force for the performance leap, while the Y2O3 interface regulation is the key prerequisite for ensuring that the whisker effect is fully utilized (without Y2O3, the whisker effect will be offset by the interface thermal resistance).

[0061] As can be seen from Example 1 and Comparative Example 4, Comparative Example 4 is a pure ZnAl2O4 ceramic ( x =0), its CTE is as high as 10.7 ppm / °C, and the difference with the GaAs chip (6.97 ppm / °C) is 3.73 ppm / °C, indicating a serious thermal mismatch. In Example 1, through B 3+ Doping to form ZnAl 1.96 B 0.04 The O4 solid solution showed a precise CTE reduction to 6.98 ppm / °C, almost perfectly matching GaAs. This is because B 3+ Partially substituted Al (ionic radius approximately 0.27 Å) 3+ After reducing the ionic radius to approximately 0.53 Å, the BO bond length is shorter and the bond energy is stronger, and the lattice contraction effect significantly suppresses thermal expansion. Meanwhile, the thermal conductivity of Example 1 (31.5 W / (m·K)) is more than twice that of Example 4 (15.2 W / (m·K)), and the fracture toughness (2.32 vs. 1.28 MPa·m) is also significantly higher. 1 / 2 This represents an 81% increase. This comparison proves that: B 3+ Doping is a necessary condition for CTE matching, and the introduction of whiskers and rare earth elements has enabled a leap in thermal conductivity and toughness.

[0062] like Figure 3 As shown, the thermal expansion curves of the rare-earth-whisker co-doped multiphase ceramic material (solid red line) prepared in Example 1 of this invention almost perfectly coincide with the reference curve (dashed black line) of the GaAs chip in the range of 25-300℃. Specifically, the average linear coefficient of thermal expansion (CTE) of this working material is 6.98 × 10⁻⁶. -6 / ℃, while the CTE of the GaAs chip is 6.97 × 10 -6 / ℃, and the two values ​​are highly consistent. In contrast, the purple curve of the undoped matrix material in Comparative Example 1 is 7.21 × 10 -6 / ℃, the CTE of the blue curve for Comparative Example 2 (whisker reinforcement only, no rare earth) is 7.35 × 10⁻⁶. -6 / ℃, the green curve for Comparative Example 3, with only rare earth doping (no whiskers), is 7.20 × 10⁻⁶. -6The values ​​of / ℃ all significantly deviate from the expansion behavior of GaAs. This result strongly demonstrates that the co-doping strategy of rare earth elements and whiskers has successfully achieved precise control over the thermal expansion properties of multiphase ceramic materials, enabling excellent thermal matching with GaAs chips and effectively avoiding stress cracking caused by thermal mismatch during packaging.

[0063] like Figure 4 As shown, "Optimal rare earth oxide (2.0)" wt The CTE corresponding to the % (i.e., the green curve) is the smallest, and it can be achieved in "13-17 wt The "% whisker" range falls exactly within the yellow GaAs matching window. The blue dashed line (5.0) wt %): CTE is the highest and the decline trend is the slowest; the red dashed line (0.5%) wt %): CTE is at an intermediate level; solid green line (2.0) wt %): CTE is the lowest (lowest position), and the downward slope is obvious. Increasing nanofibers can effectively reduce CTE; however, more rare earth elements are not necessarily better, there is an optimal addition amount (approximately 2.0%). wt At this point, the material's thermal expansion is minimal (%). This means that when the rare earth element content is 2.0%, the material's thermal expansion is at its minimum. wt %, whisker addition amount is 13-17% wt When the CTE of the multiphase ceramic falls within the yellow matching zone, it achieves optimal thermal matching with the GaAs chip.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a multiphase ceramic material for GaAs chip packaging, characterized in that, (1) According to the molecular formula ZnAl 2-x B x O4 uses stoichiometric weighing of ZnO, Al2O3, and B source raw materials, all with a purity ≥98% and ≤0.01%. x ≤0.10, the weighed raw materials are mixed, ball-milled, dried, and sieved, then pre-calcined at high temperature, and ball-milled again to obtain the matrix pre-calcined powder; (2) The matrix pre-calcined powder, nano whiskers and rare earth oxide sintering aid obtained in step (1) are mixed in a dispersion medium and then subjected to ultrasonic treatment and ball milling in sequence to obtain a mixed slurry. (3) Add a binder to the mixed slurry obtained in step (2) and granulate it, then press it into shape to obtain a green body; (4) After removing the binder from the green body obtained in step (3), sinter it in a protective atmosphere or an air atmosphere to obtain the green body.

2. The preparation method according to claim 1, characterized in that, In step (1), the B source material is boric acid or boron oxide.

3. The preparation method according to claim 1, characterized in that, In step (1), the ball milling speed is 250-350 r / min and the ball milling time is 4-12 h; the drying temperature is 80-120℃ and the drying time is 12-24 h; the pre-firing temperature is 900-1100℃ and the pre-firing holding time is 2-6 h.

4. The preparation method according to claim 1, characterized in that, In step (2), the nano whiskers are selected from at least one of SiC whiskers or AlN whiskers, with a whisker diameter of 0.1 to 0.8 μm and an aspect ratio of 15 to 30; The rare earth oxide sintering aid is selected from at least one of Y2O3, La2O3 or Sm2O3.

5. The preparation method according to claim 1, characterized in that, In step (2), the weight ratio of the matrix pre-calcined powder, nano whiskers and rare earth oxide sintering aid is 80-90:5-20:0.5-5.

6. The preparation method according to claim 1, characterized in that, In step (2), the ultrasonic treatment time is 30-90 min, the ultrasonic treatment power is 150-200 W, and the ultrasonic treatment frequency is 30-50 kHz; the ball milling speed is 100-150 r / min, and the ball milling time is 2-4 h.

7. The preparation method according to claim 1, characterized in that, In step (3), the adhesive is an aqueous solution of polyvinyl alcohol with a mass concentration of 5-10%. wt %; molding pressure 50-200MPa, holding time 30-60s.

8. The preparation method according to claim 1, characterized in that, In step (4), the glue removal temperature is 400-600℃, the heating rate is 0.5-1℃ / min, and the glue removal holding time is 1-2h; the protective atmosphere is N2 atmosphere; the sintering temperature is 1350℃-1500℃, and the holding time is 2-8h.

9. A multiphase ceramic material for GaAs chip packaging, characterized in that, It is prepared by the preparation method according to any one of claims 1-8.

10. The application of the multiphase ceramic material for GaAs chip packaging as described in claim 9 in the preparation of GaAs chip packaging substrates or heat dissipation elements.

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