低膨胀系数基板材料的性能及机理研究

发布时间：2018-06-30 06:51

本文选题：低热膨胀系数 + LTCC基板材料　；参考：《电子科技大学》2016年博士论文

【摘要】：随着技术的进步,微电子器件向着高度集成化、小型化方向发展,这对基板材料提出了新的要求。经过多年研究,国外的一些科研机构已经实现了LTCC基板材料的商用化,但是国内在这一领域仍然处于追赶状态。因此,制备出满足LTCC基板要求的材料并研究其机理,已经成为了一个极为重要的课题。Li2O-Al2O3-SiO2(LAS)和CaO-Al2O3-SiO2(CAS)微晶玻璃具有低热膨胀系数、低介电常数的特点,具有应用于LTCC基板材料领域的潜力。因此本文采用玻璃熔融法和固相反应法分别制备了LAS微晶玻璃和CAS微晶玻璃,并研究了玻璃组成、烧结制度对其晶体析出、微观结构、烧结及性能的影响,主要获得了如下成果:一、LAS微晶玻璃1)MgO的添加可以降低微晶玻璃的析晶温度,有利于致密化烧结,并能促进透辉石晶相析出,并使得材料的抗弯强度由75 MPa提高到155 MPa。通过调节MgO的掺杂量及烧结制度,可以改变其中的晶相种类和含量,进而实现热膨胀系数可在0.5~4.3×10-6·K-1之间调节。2)微晶玻璃的玻璃化转变温度和析晶温度随着ZnO含量的增大而降低。过量的ZnO添加会导致ZnAl2O4晶相析出。适量添加ZnO会增大材料密度,有利于材料烧结致密化,最佳烧结温度为800℃,保温时间是30 min。由于Zn2+离子半径大,阻碍碱金属离子的移动,其含量的增大会使材料的介电损耗降低。微晶玻璃的抗弯强度受到晶相性能的影响,具有较大弹性模量的ZnAl2O4晶相的析出使得材料的抗弯强度增大,同时由于较大热膨胀系数的晶相析出,体系的热膨胀系数随着ZnO含量的增大而升高。3)由于CaO的解聚作用,其含量的增大会导致体系析晶倾向增大,并促进透辉石相析出。CaO的添加会降低玻璃的粘度,使得液相含量增多,这有利于致密化烧结。由于析出的透辉石晶相与主晶相的介电常数相差不大,CaO的添加对材料的介电常数影响较小,因此介电常数主要取决于材料的致密化程度。透辉石含量的增大也会导致材料热膨胀系数的增大。4)利用氧化物掺杂和烧结制度的调节,实现了LAS微晶玻璃热膨胀系数在较大范围内可调。在800℃保温烧结30 min的微晶玻璃样品获得了最佳的性能:高的抗弯强度(155 MPa),介电常数较低(7.2),介电损耗较低(2×10-3),低的热膨胀系数(3.2×10-6·K-1)。具有这些优秀性能的LAS微晶玻璃可以满足LTCC基板材料的要求。二、LAS微晶玻璃+Al2O3陶瓷复合材料文献指出,在低热膨胀系数体系中引入高热膨胀系数晶相,会增大微晶玻璃抗弯强度。出于提高材料抗弯强度的目的,将具有较大热膨胀系数的Al2O3陶瓷添加到LAS微晶玻璃中,制备了LAS微晶玻璃+Al2O3陶瓷复合材料。由于来源于玻璃的液相对致密化烧结有利,玻璃的减少会增大材料的析晶温度,使得烧结温度增大。Al2O3陶瓷含量的增大会导致具有大介电常数和热膨胀系数的Al2O3晶相的析出,并使得材料的抗弯强度、介电常数和热膨胀系数均出现增大。Al2O3含量为20 wt%的材料样品具有最佳的性能:高的抗弯强度(173 MPa),低的介电常数(8),低的介电损耗(2.4×10-3),低的热膨胀系数(2.9×10-6·K-1),可以满足LTCC基板材料的要求。三、CAS微晶玻璃1)Al2O3/SiO2比的增大会连接玻璃中的断网,使得析晶变得困难,并降低玻璃的粘度,使得材料的收缩率下降。材料的组成和烧结制度的变化会使得体系中的晶相含量和种类发生变化,从而影响材料的性能。2)调整氧化物ZnO的添加会削弱了网络结构,从而降低玻璃的玻璃化转变温度和析晶温度,并导致石英和钙长石晶相析出量增大。ZnO增大导致高热膨胀系数的晶相析出,使得材料的热膨胀系数增大。3)通过改变玻璃组成和烧结制度,可以调节玻璃中晶相的种类与含量,并获得不同的性能。在900℃保温烧结2 h的CAS微晶玻璃样品具有最佳的性能:高的抗弯强度(145 MPa),低的介电常数(5.5),低的介电损耗(3.4×10-3)以及低的热膨胀系数(5.3×10-6·K-1),可以满足LTCC基板材料的要求。四、热膨胀系数计算和析晶动力学的研究1)通过XRD法测试微晶玻璃中晶相和玻璃相的含量,并以此计算材料的热膨胀系数,结果表明,计算值和实测值大体吻合。这说明微晶玻璃的热膨胀系数主要取决于其晶相的热膨胀系数,控制晶体析出即可获得想要的热膨胀系数。2)ZnO掺杂使LAS微晶玻璃的析晶活化能由219.5 kJ/mol降到143.1 kJ/mol,LAS微晶玻璃的析晶指数n值在3.1~3.5之间,说明该玻璃析晶机制为整体析晶。ZnO掺杂使CAS微晶玻璃的析晶活化能由339 kJ/mol降到275 k J/mol,CAS微晶玻璃的析晶指数n值在1.41~1.82之间,说明该玻璃析晶机制为表面析晶。
[Abstract]:With the progress of technology, microelectronic devices are becoming highly integrated and miniaturized. This has put forward new requirements for substrate materials. After years of research, some research institutions abroad have realized the commercialization of LTCC substrate materials, but in this field the domestic pursuit state is still in the field. Therefore, to prepare the LTCC substrate to meet the requirements. The material obtained and the study of its mechanism have become a very important subject,.Li2O-Al2O3-SiO2 (LAS) and CaO-Al2O3-SiO2 (CAS) glass ceramics have low thermal expansion coefficient, low dielectric constant, and have the potential to be applied in the field of LTCC substrate materials. Therefore, the glass melting method and solid state reaction method have been used to prepare LAS micro respectively. Glass and CAS glass ceramics, and study the composition of glass, the influence of the sintering system on its crystal precipitation, microstructure, sintering and properties, mainly obtained the following results: the addition of LAS microcrystalline glass 1) MgO can reduce the crystallization temperature of glass ceramics, is beneficial to the dense sintering, and can promote the precipitation of diopside crystal phase, and make the material The bending strength is increased from 75 MPa to 155 MPa. by adjusting the doping amount and sintering system of MgO, the type and content of crystalline phase can be changed, and then the thermal expansion coefficient can be adjusted to.2 between 0.5~4.3 * 10-6. K-1. The glass transition temperature and crystallization temperature of glass ceramics can be reduced with the increase of ZnO content. The excess ZnO addition will be added. The ZnAl2O4 crystal phase precipitates. Proper addition of ZnO will increase the density of the material, which is beneficial to the densification of the material, the optimum sintering temperature is 800 C, the holding time is 30 min. because of the large radius of the Zn2+ ion, which hinders the movement of alkali metal ions. The increase of the content will reduce the dielectric loss of the material. The bending strength of the glass ceramics is subjected to the crystalline phase properties. The effect of the precipitation of ZnAl2O4 crystal phase with larger modulus of elasticity increases the bending strength of the material. At the same time, the thermal expansion coefficient of the system increases with the increase of the content of ZnO because of the crystallization of the larger thermal expansion coefficient. Because of the depolymerization of CaO, the increase of the content of the system will lead to the increase of the crystallization tendency of the system and promote the diopside. The addition of.CaO will reduce the viscosity of the glass and increase the content of the liquid phase, which is beneficial to the densification and sintering. As the precipitated diopside crystal phase differs little from the permittivity of the main crystal phase, the addition of CaO has little influence on the dielectric constant of the material, so the dielectric constant is mainly determined by the densification degree of the material. The thermal expansion coefficient of material is increased by.4). Using the regulation of oxide doping and sintering, the thermal expansion coefficient of LAS glass ceramics can be adjusted in a larger range. The optimum performance of the glass ceramics samples at 800 C for 30 min is obtained: high flexural strength (155 MPa), low dielectric constant (7.2) and dielectric loss Low (2 * 10-3), low thermal expansion coefficient (3.2 x 10-6. K-1). The LAS glass ceramics with these excellent properties can meet the requirements of LTCC substrate materials. Two, LAS glass ceramics +Al2O3 ceramic composite materials indicate that the introduction of high thermal expansion coefficient crystal phase in the low thermal expansion coefficient system will increase the flexural strength of glass ceramics. For the purpose of bending strength, the Al2O3 ceramics with large thermal expansion coefficient were added to LAS glass ceramics to prepare LAS glass ceramics +Al2O3 ceramic composites. The crystallization temperature of the materials will be increased because of the relative densification of the liquid source from the glass, and the sintering temperature increases the content of.Al2O3 ceramics. It will lead to the precipitation of Al2O3 crystalline phase with large dielectric constant and thermal expansion coefficient, and the material samples with increased flexural strength, dielectric constant and thermal expansion coefficient that increase.Al2O3 content to 20 wt% have the best properties: high bending strength (173 MPa), low dielectric constant (8), low dielectric loss (2.4 x 10-3), low thermal expansion. The expansion coefficient (2.9 x 10-6. K-1) can meet the requirements of the LTCC substrate material. Three, CAS glass 1) the increase of the Al2O3/SiO2 ratio will connect the broken net in the glass, make the crystallization difficult, reduce the viscosity of the glass, and reduce the shrinkage of the material. The composition of the material and the change of the sintering system will make the crystal phase content and type in the system The addition of ZnO will weaken the network structure, thus reduce the glass transition temperature and crystallization temperature, and lead to the increase of the precipitation of quartz and calcite crystal phase and the increase of.ZnO, resulting in the crystallization of the high thermal expansion coefficient and the increase of the thermal expansion coefficient of the material by the modification of the crystal phase, and the increase of the thermal expansion coefficient of the material by the modification of the crystal phase, and the increase of the thermal expansion coefficient of the material by the modification of the crystal phase, and the increase of the thermal expansion coefficient of the material by the modification of the crystal phase, and the increase of the thermal expansion coefficient of the material by the modification of the crystal phase, and the increase of the thermal expansion coefficient of the material by the modification of the crystal phase. The variable glass composition and sintering system can adjust the type and content of glass MICROTEK phase and obtain different properties. The CAS glass ceramics samples of 2 h heat preservation and sintering at 900 C have the best properties: high bending strength (145 MPa), low dielectric constant (5.5), low dielectric loss (3.4 * 10-3) and low thermal expansion coefficient (5.3 * 10-6. K-1), It can meet the requirements of LTCC substrate materials. Four, thermal expansion coefficient calculation and Crystallization Kinetics Study 1) test the content of glass phase and MICROTEK phase in glass ceramics by XRD method, and calculate the thermal expansion coefficient of the material. The results show that the calculated value is in agreement with the measured value. This shows that the thermal expansion coefficient of glass ceramics depends mainly on the thermal expansion coefficient of glass ceramics. The thermal expansion coefficient of crystal phase can be obtained by controlling the crystal precipitation. The desired thermal expansion coefficient.2) ZnO doping can reduce the crystallization activation energy of LAS glass ceramics from 219.5 kJ/mol to 143.1 kJ/mol, and the crystallization exponent n value of LAS glass ceramics is between 3.1~3.5. It shows that the crystallization mechanism of the glass is the crystallization of.ZnO doped CAS microcrystalline glass. It can be reduced from 339 kJ/mol to 275 K J/mol, and the crystallization index n value of CAS glass ceramics is between 1.41~1.82, indicating that the crystallization mechanism of the glass is surface crystallization.
【学位授予单位】：电子科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN405;TQ171.733

【参考文献】