| Nowadays,high density and multifunction of integrated circuits are driving the rapid development of electronic packaging technology,and thus advanced packaging substrate materials have become the hotspot of relevant research.At present,there are two main problems in the research of MgO-Al2O3-SiO2?MAS?glass-ceramics,which seriously affected the application in the field of integrated circuits.First,because the sintering temperature is higher than 1100?,it is difficult to meet the requirements of low temperature co-fired ceramics.Second,it is difficult to achieve high flexural strength and low thermal expansion coefficient at the same time.In this thesis,the modification of MAS glass-ceramics have been researched.Moreover,the relationship between microstructure,crystal phase composition,thermal expansion coefficient,flexural strength,and dielectric properties were discussed systematically.And the sintering kinetics and crystallization kinetics were carried out for the further theoretical analysis.The result showed that an appropriate amount of CaO doping reduced the softening temperature and promoted the crystallization of MAS glass.The main crystalline phase was Mg2Si5Al4O18.A high CaO content changed the crystallization tendency of MAS glass.For the sample doped with 3wt%CaO,the production of high-thermal-expansion phase(MgAl2Si3O18)0.6 increased the coefficient of thermal expansion to 3.52×10–6/?,which behaved a good match with silicon chip.Meanwhile,flexural strength of 152MPa,dielectric constant of 5.87,dielectric loss of 1.81×10–3,and resistivity of 2.0×1011?·m,were achieved.However,a complex crystallization process occurred in the study of MnO doping.The main crystal phase was changed from Mg2Si5Al4O188 to(MgAl2Si3O18)0.6,the secondary crystal phase was Mg2Si5Al4O18 and MgSiO3.When MnO content is 0.5wt%,the sample with a large bulk density and good comprehensive performances,including flexural strength of 247MPa,thermal expansion coefficient of 5.40×10–6/?,dielectric constant of 6.27,dielectric loss of 2.40×10–3 and resistivity of 2.0×1011?·m was obtained.In addition,1wt%La2O3 promoted the refinement of grain and contributed to the densification of microstructure.The sample possessed flexural strength of 163MPa,thermal expansion coefficient of 3.28×10–6/?,dielectric constant of 5.45,dielectric loss of 1.79×10–3 and resistivity of 2.0×1011?·m.Besides,CeO2 doping can't affect the composition of crystal phases,and scarcely has an effect on the performance of MAS glass-ceramics.Finally,theoretical studies on sintering kinetics and crystallization kinetics of CaO or MnO doped MAS glass-ceramics were further carried out in this thesis.A constant heating rate model based on the Arrhenius equation was used to study shrinkage variation curve of glass-ceramics,and sintering activation energy is calculated.The results show that 1wt%3wt%CaO or 0.250.5wt%MnO can reduce sintering activation energy of system and contribute to densification of MAS glass-ceramics.The Kissinger model was used to study DSC curves of glass-ceramics,and crystallization activation energy was calculated.The results show that 3wt%CaO increased the crystallization activation energy,resulting in a decrease of Mg2Si5Al4O18.The addition of MnO reduced the crystallization activation energy,and the main crystal phase changed from Mg2Si5Al4O18to(MgAl2Si3O18)0.6,which also indirectly show that the energy required for precipitation of(MgAl2Si3O18)0.6 was lower than that of Mg2Si5Al4O18. |
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