利用新型液固分离技术制备40% (体积分数)-金刚石/Al复合材料封装基板，通过SEM、EPMA和XRD观察和分析复合材料的断口形貌及界面结构，分析金刚石颗粒尺寸(90、106、124和210 µm)对金刚石/Al复合材料热物性的影响。结果表明，复合材料致密度随金刚石颗粒尺寸增加呈现先增加后急剧降低的规律，在颗粒尺寸为106 µm时，致密度达到极大值。复合材料界面处未发现有恶化性能的Al₄C₃生成。复合材料的热膨胀系数随金刚石颗粒尺寸增加略有增大，保持相对稳定，Kerner模型可以准确模拟复合材料热膨胀系数。热导率受金刚石颗粒尺寸和界面行为共同作用，与致密度呈现相同变化规律。金刚石颗粒尺寸为106 µm的金刚石/Al复合材料具有最佳的综合性能，致密度达到97.12%，热膨胀系数为12.4 × 10^-6 K^-1，热导率为153.1 W/(m·K)，达到Maxwell-Eucken模型预测值的69.31%，气密性指标满足电子封装材料军用装配标准。

Rapid development of high-power electronic equipment for 5G and other advanced communication devices leads to a highly compact component size with increased heat flux density in integrated circuits, which requires electronic packaging materials to meet excellent heat dissipation performance. In this work, a novel liquid-solid separation technology was used to prepare a 40% (volume fraction) diamond/Al composite for electronic packaging substrates. By SEM, EPMA, and XRD techniques to investigate the fracture morphology and interface structure of the composite, the influence of diamond particle sizes (90, 106, 124, and 210 μm) on the thermophysical properties of diamond/Al composite was studied. The results showed that with the increase of a diamond particle size, the density of a composite material increased first and then sharply decreased and attained the optimal value when the diamond particle size was 106 μm. No harmful intermetallic Al₄C₃ was generated at the interface of the composite material. Coefficient of thermal expansion ({\alpha }_{\mathrm{c}}) of the composite material increases slightly with increase in diamond particle sizes and remains relatively stable. The Kerner model can accurately simulate the {\alpha }_{\mathrm{c}} of the diamond/Al composite. Thermal conductivity (λ) is also affected by diamond particle sizes and interface behaviors, and the trend of change in λ with the size of the diamond particles follows a similar trend to that between the density of composites and the particle size. The diamond/Al composite with diamond particle size of 106 μm has the best overall performance, relative density and {\alpha }_{\mathrm{c}} attained 97.12% and 12.4 × 10^-6 K^-1, respectively. λ is 153.1 W/(m·K), meeting 69.31% of the Maxwell-Eucken model prediction value. The airtightness value meets the military standard for this type of an electronic packaging material.