Microstructure and properties of electronic packaging shell with high silicon carbide aluminum-base composites by semi-solid thixoforming

The electronic packaging shell with high silicon carbide aluminum-base composites was prepared by semi-solid thixoforming technique. The flow characteristic of the Si C particulate was analyzed. The microstructures of different parts of the shell were observed by scanning electron microscopy and optical microscopy, and the thermophysical and mechanical properties of the shell were tested. The results show that there exists the segregation phenomenon between the Si C particulate and the liquid phase during thixoforming, the liquid phase flows from the shell, and the Si C particles accumulate at the bottom of the shell. The volume fraction of Si C decreases gradually from the bottom to the walls. Accordingly, the thermal conductivities of bottom center and walls are 178 and 164 W·m-1·K-1, the coefficients of thermal expansion（CTE） are 8.2×10-6 and 12.6×10-6 K-1, respectively. The flexural strength decreases slightly from 437 to 347 MPa. The microstructures and properties of the shell show gradient distribution.     

液固分离法制备Al-65vol%Si电子封装材料组织及性能

采用液固分离法制备了Al-65vol%Si电子封装材料,借助扫描电镜、透射电镜等手段分析了合金中Si相的形态分布、界面及断口形貌,测定了合金的热膨胀系数、热导率及抗弯强度。结果表明:Al-65vol%Si合金组织中硅相颗粒分布均匀,形状规则呈近团球状和短杆状,Al/Si两相界面光滑、平直,无缺陷。合金密度2.4 g/cm3,室温下的热导率(TC)为119.5 W/(m.K),热膨胀系数(CTE)从50℃到400℃在6.5×10-6～11.3×10-6/K范围内稳定增加,抗弯强度为132 MPa,Si相的脆性断裂为主要断裂方式。Al-65vol%Si合金性能满足电子封装要求。     

半固态触变成形制备高硅铝基电子封装盒体的组织与性能

利用半固态触变成形工艺制备高硅铝电子封装盒体,分析盒体中Si相的分布特征.采用金相显微镜和扫描电镜观察盒体不同部位的显微组织,并测定其热物理性能及力学性能.结果表明,Al-25％Si(质量分数)合金在半固态触变成形中Si相和液相产生分离流动,液相从盒体中流出,Si相在盒体中聚集,其体积分数从盒体底面向四壁逐渐降低.盒体底面中心和四壁的热导率分别为107.6和131.5W/(m.K),热膨胀系数分别为7.9×10-6和10.6×10-6 K,抗弯强度由167MPa缓慢增加至180MPa.组织和性能呈现梯度变化.