99％氧化铍陶瓷活化Mo-Mn金属化机理研究

采用活化Mo-Mn法对99％氧化铍陶瓷进行了金属化实验和抗拉强度实验.封接强度实验结果表明,活化Mo-Mn法适合99％氧化铍陶瓷金属化封接,其焊接强度与氧化铝陶瓷相当.通过对99％氧化铍陶瓷金属化层的显微结构及金属层中的元素在金属层及陶瓷中的分布情况分析,探讨了99％氧化铍陶瓷Mo-Mn金属化机理.研究发现,99％氧化铍陶瓷金属化时,在氧化铍陶瓷和Mo海绵骨架中间形成了一层约3μm的过渡层,金属化层的Mo海绵骨架结构通过过渡层与氧化铍陶瓷基体紧密连接.     

镁铝尖晶石陶瓷的高温Mo-Mn金属化机理研究

采用活化Mo-Mn法对镁铝尖晶石陶瓷进行了金属化封接实验,并通过对镁铝尖晶石陶瓷金属化层的显微结构及金属化层中元素在金属化层与陶瓷中分布情况的分析,探讨了镁铝尖晶石陶瓷的Mo-Mn金属化机理。研究发现,镁铝尖晶石瓷的金属化机理与目前较成熟的95%氧化铝瓷的金属化机理存在很大不同。镁铝尖晶石瓷金属化时,Mn元素沿晶界实现固相扩散迁移,固溶于瓷中,与镁铝尖晶石形成Mn:Mg Al2O4尖晶石相;同时,Mg元素沿晶界析出进入金属化层的玻璃相,填充于Mo海绵骨架中。     

氧化铝基陶瓷Mo-Mn法金属化机理分析及实验研究

本文从玻璃相扩散迁移、Mo的化学态和添加Mn的作用几个方面对氧化铝基陶瓷高温Mo-Mn法金属化机理进行了分析和总结,给出了高纯氧化铝陶瓷（包括99氧化铝陶瓷、透明氧化铝陶瓷）一些实验研究结果。通过对实验结果的分析和讨论,指出了高纯氧化铝陶瓷金属化配方设计、工艺参数控制等方面应把握的技术要点。实验研究结果对工程中高纯氧化铝陶瓷的金属化和封接工作具有一定的指导作用。     

95％Al_2O_3瓷活化Mo-Mn法金属化机理研究

本文以实验证实了95％Al_2O_3瓷活化Mo-Mn法金属化的玻璃迁移机理。所用的9~#金属化配方为添加玻璃的配方,陶瓷金属化烧结时,主要靠金属化层中的一部分玻璃向陶瓷中迁移,冷却时,靠此玻璃把陶瓷和金属化层粘结在一起而完成真空致密封接的。     

氮化铝陶瓷的氧化机理研究

本文研究了不同氧化处理下氮化铝陶瓷的氧化情况,并使用Mo-Mn法进行金属化,测试封接强度及气密性,从而探究氮化铝瓷的氧化机制,氮化铝基瓷与氧化层之间的结合。结果表明:经过1100℃/1h高温氧化处理,氮化铝陶瓷表面几乎没有氧化。在1250℃/1h、1250℃/2h,表面生成了氧化铝,氧化层主晶相为AlN与Al2O3;在1350℃/1h下,氧化层主晶相为Al2O3;氧化层表面有明显的裂纹,均漏气。对不同处理后的氧化铝层表面进行Mo-Mn法金属化,当氧化层厚度较薄时,断裂发生在氧化层。氮化铝瓷与氧化铝层之间的结合机理可能是在两者之间产生了AlON等中间物,从而实现了氮化铝瓷与氧化层之间牢固的连接。     

95%Al2O3陶瓷Mo-Mn金属化层烧结机理研究

通过对95%Al2O3陶瓷Mo-Mn金属化层烧结前后显微结构的分析,对不同Mo含量金属化配方的块状烧结体及高纯高致密Al2O3陶瓷表面金属化层显微结构的研究,探讨了95%Al2O3陶瓷Mo-Mn金属化层的烧结过程,揭示了Mo骨架结构中Mo颗粒间气孔形成的机理.     

95%Al2O3陶瓷Mo-Mn金属化层烧结机理研究

通过对95%Al2O3陶瓷Mo-Mn金属化层烧结前后显微结构的分析,对不同Mo含量金属化配方的块状烧结体及高纯高致密Al2O3陶瓷表面金属化层显微结构的研究,探讨了95%Al2O3陶瓷Mo-Mn金属化层的烧结过程,揭示了Mo骨架结构中Mo颗粒间气孔形成的机理.     

95%Al_2O_3瓷活化Mo-Mn法金属化机理研究

95%Al_2O_3瓷的活化 Mo-Mn 法金属化工艺,在我国已广泛地应用。但由于对陶瓷金属化的机理研究不多,认识比较肤浅,生产中仍存在质量不稳定,出现问题不能及时解决的现象。本课题使用扫描电镜、电子探针等现代分析仪器,对95?_2O_3瓷活化 Mo-Mn 法金属化的机理进行了比较深入、系统的研究,揭示了陶瓷金属化机理。此机理有助于从事陶瓷金属封接的同行们,准确及时地分析废品原因,制定合理的工艺规范,提高质量、降低成本。     

氮化铝陶瓷金属化技术的探讨

本文对目前常用的电子陶瓷(例如,氮化铝陶瓷、氧化铍陶瓷、氧化铝陶瓷)的性能和金属化技术进行了初步的比较,提出了氮化铝陶瓷要加强其应用研究,特别是要进一步提高其Mo-Mn法封接强度,论述了氧化铍陶瓷比氮化铝陶瓷DBC技术上的某些优势。     

活化Mo-Mn法中低温烧成技术研究

以降低活化Mo-Mn法烧成温度为目的,利用MnO-Al₂O₃-SiO₂相图,设计了17组金属化配方,通过拉力测试、X射线衍射物相分析、扫描电镜测试及能谱分析,研究了不同活化剂配方对金属化层力学性能及显微结构的影响。本试验成功将活化Mo-Mn法烧结温度降低至1350℃,得到的金属化层显微结构致密均匀,力学性能及气密性良好,其三点封接强度可达470 MPa,远超行业标准。     

国内外电真空用氧化铝陶瓷金属化层显微结构分析

利用扫描电镜和能谱仪，分析了国内、俄罗斯、英国及德国公司生产的电真空用氧化铝陶瓷的金属化层显微结构和微区成分。比较了4种金属化样品间的差异，并探讨了金属化层显微结构对焊接体焊接性能的影响。     

氧化铝陶瓷的Mo-Mn-Ti-Si-Al系统膏剂金属化工艺研究

用Mo-Mn-Ti-Si-Al系统膏剂金属化两种氧化铝陶瓷材料。封接强度实验结果表明,Mo-Mn-Ti-Si-Al系统膏剂不适宜高纯Al2O3陶瓷的金属化封接,而比较适宜95%Al2O3陶瓷的金属化封接。用该膏剂金属化95%Al2O3陶瓷,其焊接强度最高值可达150MPa以上。通过显微结构分析发现,高纯Al2O3陶瓷的金属化机理与95%Al2O3陶瓷金属化的机理不同,前者中玻璃相仅仅通过高温熔解-沉析与表面的Al2O3晶粒反应,后者金属化层内玻璃相与陶瓷内玻璃相相互迁移渗透。     

氧化铝陶瓷基板化学镀铜金属化及镀层结构

通过化学镀铜在氧化铝陶瓷基板表面实现了金属化,采用SEM研究了镀铜层表面微观形貌以及热处理的影响,检测分析了金属化镀层附着力。结果表明:通过控制镀液中铜离子浓度以及铜沉积速率,在基板表面可形成均匀致密的铜金属化层;热处理后进一步提高镀层致密化和导电性,其方阻由3.6 mΩ/□降为2.3 mΩ/□。划痕法测试表明镀铜层与氧化铝陶瓷基板结合紧密无起翘,可以满足敷铜基板的要求。     

Open-ended metallized ceramic coaxial probe for high-temperaturedielectric properties measurements

A metallized ceramic coaxial probe has been developed for high temperature complex permittivity measurements. The probe is made of alumina and metallized with a 3.0-mil-thick layer of moly-manganese, and a 0.5-mil-thick protective coating of nickel plating. It is shown that based on carrying out the network analysis calibration procedure up to 1000°C, and on actual dielectric properties measurements, the probe provides accurate dielectric measurements over a broad frequency range (500 MHz to 3 GHz) and for temperatures up to 1000°C. An uncertainty analysis based on two different calibration techniques was also given to help quantify possible measurement errors     

Thermomechanical fatigue behavior of Sn-Ag solder joints

Microstructural studies of thermomechanically fatigued actual electronic components consisting of metallized alumina substrate and tinned copper lead, soldered with Sn-Ag or 95.5Ag/4Ag/0.5Cu solder were carried out with an optical microscope and environmental scanning electron microscope (ESEM). Damage characterization was made on samples that underwent 250 and 1000 thermal shock cycles between −40°C and 125°C, with a 20 min hold time at each extreme. Surface roughening and grain boundary cracking were evident even in samples thermally cycled for 250 times. The cracks were found to originate on the free surface of the solder joint. With increased thermal cycles these cracks grew by grain boundary decohesion. The crack that will affect the integrity of the solder joint was found to originate from the free surface of the solder very near the alumina substrate and progress towards and continue along the solder region adjacent to the Ag₃Sn intermetallic layer formed with the metallized alumina substrate. Re-examination of these thermally fatigued samples that were stored at room temperature after ten months revealed the effects of significant residual stress due to such thermal cycles. Such observations include enhanced surface relief effects delineating the grain boundaries and crack growth in regions inside the joint.     

Thermocompression bonding of external package leads on integrated circuit substrates

A new technique for attaching external package leads to metallized substrates is presented. Gold-plated copper lead frames and gold-plated headed leads of various compositions are thermocompression bonded to metallized alumina substrates. The generated patterns on the substrates consist of an evaporated layer of gold over an evaporated layer of titanium. The leads are bonded simultaneously to form gold diffusion bonds between the leads and the metallized substrate. The lead frames are stamped from 0.005 inch and 0.010 inch thick copper. The headed leads range in size from 0.017 inch in diameter to 0.025 inch square. The various problems encountered in the development of this technique and their related solutions will be discussed. The bonding tool consists of a base for positioning the substrate and a bonding tip which applies the necessary pressure and temperature to produce a bond. The base and bonding tip for lead frames can compensate for camber and nonuniform thickness in the ceramic while the base and bonding tip for headed leads are noncompensating. The various parameters of bonding time, bonding temperature, bonding force, and bond strengths will be presented. In addition, hermetic seal evaluations will be discussed. A comparative cost analysis will be made between attaching leads individually by welding versus attaching all package leads simultaneously by the thermocompression bonding technique. This investigation has opened additional avenues toward determining the full scope and capability of thermocompression bonding in an area previously dominated by brazing and the sealing of metal to glass and/or ceramics.     

Nanopore Characterization and Optical Modeling of Transparent Polycrystalline Alumina

Production of transparent ceramics has become a topic of resurgent interest in recent years, with its promise of near‐net shaping appealing to applications ranging from biomedicine to solar energy. However, the mechanisms governing ceramic transparency, translucency, and opaqueness are not entirely understood. Models of both grain boundary and pore scattering have been proposed, but too often without sufficient experimental corroboration. An extensive experimental analysis of transparent alumina samples is presented, establishing a first direct link between the observed transparency, defect size, and porosity. Given the unprecedented experimental detail from the full 3D pore reconstruction from the FIB tomography, how to correctly interpret the experimentally observed transparency is additionally shown. The unprecedented experimental and theoretical agreement for the first time identifies the relative contributions of different scattering mechanisms, thereby paving the way forward for microstructural tuning of transparent polycrystalline alumina.     

A hybrid liquid-crystal display with a small number of interconnections

A numerical display cell (nine digits of seven segments) with nematic liquid crystals can be driven in a dynamic or a static mode. The static mode combines a flicker-free display with optimum contrast, but it has the drawback of a large number of interconnections (63). This paper describes a method to reduce this number to only four: a 63-b buffer memory in the form of an I²L shift register is attached directly to the glass plate carrying the electrode pattern. The required transparent electrode patterns provided with metallized contacts are prepared by means of thin-film techniques.