BeO高导热陶瓷金属化浆料配方与批产工艺研究

研究了适合于Be O高导热陶瓷的"钨锰法"金属化浆料配方和批产工艺,并利用扫描电镜等手段对金属化层的表面形貌进行表征,重点探讨了金属化浆料中活化剂占比、金属化最高烧结温度以及浆料细度对金属化层表面形貌和结合强度的影响和机理。结果表明:当活化剂质量分数为11%,最高烧结温度为1450℃,浆料细度控制在12μm时,Be O高导热陶瓷金属化层表面形貌和结合强度最优。     

陶瓷的钨金属化

实验测定了钨金属化陶瓷的封接特性。纯钨粉成功地用于金属化94％氧化铝瓷。获得的平均封接强度为12000磅/吋~2。对金属化层进行了分析,发现钨没有扩散到陶瓷中去。陶瓷-金属封接最常采用烧结金属粉末法。此工艺所用的金属化配方之主要成份是钼和一些为增加封接强度而用的种种附加物,这些附加物我们都熟悉,常用金属氧化物来代替其纯金属。除某些临界条件应用外,如果涂层厚度和密度能保持各片都均匀,则用这些金属化混合物会得到良好的效果。而在某些条件下,钼-锰或钼-钛金属化的性能反而不利。虽然所用的钼本身并不向陶瓷扩散,但共它成分如锰,     

钨浆料的稳定性研究

研究了用于质量分数为96%的氧化铝陶瓷的钨金属化配方以及相应的钨浆料生产工艺。为了提高钨浆料的稳定性,对浆料各组分的形貌、工艺进行了分析,发现粉体形貌、分散工艺、树脂性能对钨浆稳定性影响很大,提出了延长载体制备时间、提高载体黏度、选择粒度分布合理且比表面积较小的粉体等改善措施。结果表明,采用改善措施后在实际生产中取得了良好效果,制得的钨浆料印刷在陶瓷基片上于1 300℃烧结,平均封接强度达到39 MPa。     

毫米波真空电子器件用陶瓷金属化技术

综述了毫米波真空电子器件用金属化技术,着重强调了金属化组分(氢化钛)和烧结工艺对金属化层介电损耗的影响。     

LTCC互连基板金属化孔工艺研究

LTCC基板互连金属化孔工艺技术是低温共烧陶瓷工艺过程中的关键技术,它直接影响陶瓷基板的成品率和可靠性。文章从影响互连金属化孔的因素出发,介绍了金属化通孔填充工艺及控制技术、金属化通孔材料热应力的影响、金属化通孔材料收缩率的控制等三方面技术,并给出了如下的解决方案。采用合适的通孔填充工艺技术和工艺参数;合理设计控制通孔浆料的收缩率和热膨胀系数,使通孔填充浆料与生瓷带的收缩尽量一致,以便降低材料的热应力;金属化通孔烧结收缩率的控制可以通过导体层的厚度、烧结曲线与基板烧结收缩率的关系、叠片热压的温度和压力等方面来实现。     

高纯氧化铝陶瓷的金属化工艺研究

采用CaO-Al_2O_3-SiO_2玻璃体系作为金属化中的玻璃活化剂,在高纯(99%)氧化铝陶瓷表面烧结Mo金属化层。研究了金属化烧结温度、CaO及Al_2O_3含量和TiO_2的加入对于金属化层烧结强度的影响。结果表明Ca-Al-Si玻璃系统可在1450℃左右进行金属化烧结,同时在提高CaO与Al_2O_3含量后有助于金属化烧结,TiO_2的加入则对金属化烧结有不利影响。     

99%BeO陶瓷两种金属化膏系的研究

我国自六十年代初期开始对氧化铍陶瓷及其金属化工艺进行研究,最初BeO陶瓷金属化是在Al_2O_3陶瓷金属化的Mo-Mn-Si膏系的基础上进行的。99%BeO陶瓷具有良好的导热与绝缘性能,应用范围十分广泛。但用户对其金属化层的抗拉强度及热阻都提出了相当苟刻的要求,而采用Mo-Mn-Si膏系是难以达到的。因此,必须研究新的膏系。本文所研究的金属化膏中,采用导热更好的钨粉来代替钼粉,进行了W-Y_2O_3和W-La_2O_3两种金属化膏系的研究。研究结果表明:两种膏系均在含钨量为90%时,使金属化层抗拉强度达到最大值。此时,W-10%Y_2O_3膏的σ_B=194.7MPa(19.85kgf.mm~(-2));W-10%La_2O_3膏的σ_B=133.8MPa(13.64kgf·mm~(-2)),其烧结温度分别为1740℃和1880℃。在上述两种金属化膏中,W-10%Y_2O_3膏比W-10%La_2O_3膏金属化层抗拉强度大,金属化层烧结温度低,金属化工艺更为稳定,涂膏时对环境温度不敏感,并且抗拉强度值的分散也较小。所以,W-10% Y_2O_3膏是99% BeO陶瓷金属化较为理想的膏料。该两种膏的BeO陶瓷金属化制品,均已用于微波功率晶体管产品中。本文还对BeO陶瓷金属化层拉力试验件及其模具夹具进行了研究和设计,研究结果表明其设计结构合理,操作方便,可保证金属化层抗拉强度具有很好的重复性。     

陶瓷与金属的封接

单晶和多晶陶瓷能用几种工艺和金属可靠的接合。陶瓷金属化就是先将陶瓷和烧结金属以固溶相粘结在一起,然后再用焊料钎焊到金属零件上。活性合金法省略了中间金属化工序。这两种工艺可用化学和冶金等理论来分析。     

BeO瓷的金属化和封接

综述了氧化铍瓷的金属化及其封接技术,指出氧化铍瓷和Al2O3瓷在金属化工艺上的差异,论文最后汇集了国内外常用烧结金属粉末法15种配方和工艺参数,以资同行专家参考.     

均匀沉淀法制备陶瓷金属化层的微观结构研究

利用均匀沉淀法制备了混合均匀并且钼粉粒度达到纳米级的陶瓷金属化粉末,使用该粉末进行了陶瓷金属化层制备,获得了比较理想的陶瓷金属化层显微结构。同时研究了Mo的含量及烧结温度对陶瓷金属化层显微结构的影响,并将该工艺生产的制品与国内现有制品的微观结构进行了对比。     

晶体硅太阳能电池烧结工艺用炉体热功率设计

介绍太阳电池的原理及烧结工艺,通过研究烧结工艺与前道工序的关联因素,结合烧结工艺对温度曲线的要求,确定烧结炉的内部结构及温区分布,最后利用热工理论计算,得出炉体功率分布,找到最佳的烧结工艺状态,进而确定炉体的设计关键参数。     

Review of silver nanoparticle based die attach materials for high power/temperature applications

There has been a significant rise in the number of research papers on silver nanoparticle based solutions for harsh environment die attach. However, sintering nanoparticles is a complex process, affected by many different factors, such as the sintering temperature profile, particle size, sintering pressure, sintering environment, and organic compounds inside the nanoparticle paste used for stabilisation of the particles and easier processing. Therefore, numerous routes exist for establishment of sintered structures, and each lab has selected their own techniques and criteria for sintering silver nanoparticles. This has resulted in formation of a significant amount of knowledge and data in this field, but without appropriate correlation between utilised parameters. In this review data has been collected from a wide range of researchers in the field and an attempt made to correlate the results. By finding connections between the datasets, we present a broad and general understanding of the sintering processes to help researchers produce desired sintered structures. The collected data and investigated parameters include sintering pressure, metallisation, effect of thermal aging and cycling, highest sintering temperature, and particle size distributions. Some particularly interesting innovations in the field to address the shortcomings of sintering silver joints are investigated and some insights on sintering process are also provided, such as the understanding that higher sintering pressure causing improved strength might potentially reduce the long term thermal resistance of the die attach.     

选区激光烧结聚苯乙烯粉的基础实验研究

为了探寻选区激光烧结工艺参量对聚苯乙烯粉烧结质量影响的规律,并通过工艺参量的优化来提高其烧结精度与强度,采用对聚苯乙烯粉进行热重/差示扫描量热法实验分析、利用SLS300快速成型机对聚苯乙烯粉烧结等方法,进行了理论分析和实验验证,发现烧结温度在150℃～260℃之间时,试样烧结尺寸精度较高。结果表明,聚苯乙烯粉烧结件的x向和y向尺寸精度受工艺参量影响较小,而z向尺寸精度受工艺参量影响较大;弯曲强度表现为随激光功率、扫描间隔、分层厚度的增大而减小的变化趋势。这对于工艺参量优化选择来提高聚苯乙烯粉的烧结质量提供了实验依据。     

工程塑料粉末激光烧结三维温度场的理论和实验研究

粉末材料激光烧结的温度场对工艺参数优化和烧结成形物质量有着直接影响。从瞬时点热源三维传热出发,建立了高斯面热源激光扫描烧结过程的非稳态导热温度场的三维解析模型,利用理论和实验相结合,计算了随温度变化的尼龙粉末的有效导热系数,给出了热扩散率与激光烧结能量的关联表达式,通过温度场的模拟和实验结果的比较,验证了模型求解及参数拟合的有效性。     

工艺参数对激光烧结铁粉温度场演变的影响

综合考虑金属粉末激光直接烧结的热流施加和材料高温下热学性能参数与温度关系的非线性,基于ANSYS平台建立了移动高斯热源作用下激光烧结的三维瞬态有限元温度场模型,利用APDL语言编制程序实现热源移动,同时考虑相变潜热对温度场的影响.重点分析了激光功率、扫描速度和预热温度这三个重要的工艺参数不同组合下温度场的分布规律及传热学行为.模拟结果与先前实验结果吻合较好,表明可以利用此模型进行工艺参数优化,并为后续的应力场分析做好准备.     

Ni/Cu电极MLCC烧成工艺的研究

通过各项工艺对比实验,研究了烧成工艺参数对成品性能的影响。给出了最佳工艺参数:烧结温度为1280～1300℃,保温2h,用N2/H2/H2O的混合气控制P(O2)为10–8～10–10MPa,回火温度900～1100℃,保温2～5h,回火气氛氧含量(5～50)×10–6;1000℃以上的升降温速率控制在2～4℃/min。在此工艺条件下,选用合适的烧炉,可以得到性能合格的Ni/Cu电极MLCC。     

制备工艺对Co_2Z六方晶系铁氧体电磁特性的影响

采用普通陶瓷工艺,制备了3BaO·2CoO·10.8Fe2O3六方晶系铁氧体。对各种工艺参数进行了正交设计,分析了其对Co2Z六方晶系铁氧体电磁特性的影响。结果表明:在一磨时间2.0h,预烧温度1280℃,二磨时间4.0h,烧结温度1240℃的工艺条件下,材料在2.0GHz下的磁导率的实部为7.4,虚部为7.2,截止频率达到2.0GHz,样品密度达到了4.8g·cm–3。     

Microwave sintering process model.

In order to simulate and optimize the microwave sintering of a silicon nitride and tungsten carbide/cobalt toolbits process, a microwave sintering process model has been built. A cylindrical sintering furnace was used containing a heat insulating layer, a susceptor layer, and an alumina tube containing the green toolbit parts between parallel, electrically conductive, graphite plates. Dielectric and absorption properties of the silicon nitride green parts, the tungsten carbide/cobalt green parts, and an oxidizable susceptor material were measured using perturbation and waveguide transmission methods. Microwave absorption data were measured over a temperature range from 20 degrees C to 800 degrees C. These data were then used in the microwave process model which assumed plane wave propagation along the radial direction and included the microwave reflection at each interface between the materials and the microwave absorption in the bulk materials. Heat transfer between the components inside the cylindrical sintering furnace was also included in the model. The simulated heating process data for both silicon nitride and tungsten carbide/cobalt samples closely follow the experimental data. By varying the physical parameters of the sintering furnace model, such as the thickness of the susceptor layer, the thickness of the allumina tube wall, the sample load volume and the graphite plate mass, the model data predicts their effects which are helpful in optimizing those parameters in the industrial sintering process.     

Pressure-assisted low-temperature sintering of silver paste as an alternative die-attach solution to solder reflow

Pressure-assisted low-temperature sintering of silver paste is shown to be a viable alternative to solder reflow as a die-attachment solution. A quasihydrostatic pressure is used to lower the sintering temperature. The effect of parameters such as temperature and pressure are investigated. Characterization of the silver-attached samples shows a significant improvement in electrical conductivity, thermal conductivity and mechanical strength of the joint. Given that silver deforms with little accumulation of inelastic strains, and given the absence of large voids in the attachment layer, it is also expected that the joint to be more resistant to fatigue failure than a solder attached junction. Due to the high melting temperature of silver, this alternative process is also suitable for high temperature packages.     

Recent Progress in Applications of the Cold Sintering Process for Ceramic–Polymer Composites

Ceramic–polymer composites are of interest for designing enhanced and unique properties. However, the processing temperature windows of sintering ceramics are much higher than that of compaction, extrusion, or sintering of polymers, and thus traditionally there has been an inability to cosinter ceramic–polymer composites in a single step with high amounts of ceramics. The cold sintering process is a low‐temperature sintering technology recently developed for ceramics and ceramic‐based composites. A wide variety of ceramic materials have now been demonstrated to be densified under the cold sintering process and therefore can be all cosintered with polymers from room temperature to 300 °C. Here, the status, understanding, and application of cold cosintering, with different examples of ceramics and polymers, are discussed. One has to note that these types of cold sintering processes are yet new, and a full understanding will only emerge after more ceramic–polymer examples emerge and different research groups build upon these early observations. The general processing, property designs, and an outlook on cold sintering composites are outlined. Ultimately, the cold sintering process could open up a new multimaterial design space and impact the field of ceramic–polymer composites.