氮气氛下LTCC基板Cu共烧金属化研究

从PMMA型LTCC素坯膜的制备和PMMA的排胶机理两方面,研究了LTCC基板Cu共烧金属化.结果表明,采用PMMA作为粘结剂的流延浆料具有剪切变稀行为,所得的流延坯膜微观组织均匀,叠压后坯体内部无分层现象.热失重、差热和傅立叶红外光谱联用分析结果表明高纯N2气氛中PMMA以解聚机理热解,热解后释放的主要产物为丙烯酸甲酯.在高纯N2气氛中LTCC与Cu共烧后Cu金属化膜平整、致密,连通良好.经测试,基板表面Cu导体方阻小于5 mΩ/□.     

基于低温共烧陶瓷技术的SIP工艺研究

系统集成封装技术(SIP)是将一个电子系统进行集成封装,而基于低温共烧陶瓷工艺(LTCC)的高密度基板技术是其中的关键。本文研究了收发(T/R)组件微波多层互连基板的制作工艺及其优化,基于LTCC工艺,制备出一种应用于X波段T/R组件的SIP基板,并着重对影响基板特性的信号孔和散热孔填充、通孔金属化、异质材料匹配工烧、内埋腔体技术和组装等关键技术进行了研究。获得了一套内埋置腔体LTCC多层互连基板的工艺参数,并已成功研制出满足T/R组件微波电路性能要求的LTCC多层互连基板。     

流延法制备Metal/Al_2O_3复合基板及其导热性能

采用流延法制备Metal(Al,Mo,Ni)/Al_2O_3复合基板,优化了流延成型工艺,表征了不同复合基板的相组成、致密度和热导率,并对其导热机理进行讨论。结果表明:固含量为60%时浆料流动性较好,基板的相对密度高。经1550℃烧结后复合基板中的金属相均发生了不同程度的氧化,其中Ni/Al_2O_3复合基板的抗氧化性能最好,其相对密度在95%以上,热导率为29.1 W/(m·K),有望作为散热基板应用于LED组件中。     

回流焊冷却过程中LTCC基板的热力分析

建立了某航天电子产品焊接组件冷却过程的有限元热分析模型,研究了硅铝管壳与铅锡焊料的热物理参数随温度变化的规律。以降低低温共烧陶瓷(LTCC)基板第一主应力为优化目标,采用正交试验法得到了优化的冷却工艺参数,在该工艺参数下对回流焊冷却过程进行了仿真和试验研究。结果表明,LTCC基板的整体变形表现为自基板底部向管壳内部凸起,与检测结果一致。LTCC基板第一主应力的最大值分布在基板的圆角处,但不足以引起裂纹。采用文中所提出的冷却工艺参数,可以有效提高LTCC基板的焊接质量。     

热处理对PI基板铜薄膜金属化TiN阻挡层的影响

聚酰业胺(PI)材料具有介电常数低，分解温度高及化学稳定性好等优点，是很有前途的电子封装材料。Cu具有低的电阻和高的抗电迁移能力，足PI基板金属化的首选材料。采用物理气相沉积(PVD)方法在PI基板上沉积Cu薄膜，利用TiN陶瓷薄膜阻挡Cu向PI基板内部扩散。研究热处理条件下TiN陶瓷薄膜阻挡层的阻挡效果、Cu膜电阻变化以及Cu膜的结合强度，俄歇谱图分析表明TiN可以有效地阻挡Cu向PI内的扩散。300℃热处理消除了Cu膜内应力，提高了Cu膜的结合强度。     

含钡玻璃陶瓷LTCC粉体的表面修饰及其对玻璃陶瓷性能的影响

为了降低BaO-TiO2-B2O3-SiO2玻璃陶瓷中钡离子的析出，通过化学沉淀法和硫酸处理法对玻璃陶瓷粉体进行了表面修饰，在玻璃陶瓷粉体的表面形成了一层不溶于水的无机膜（氧化铝或BaSO4），不仅阻断了LTCC中钡离子与水的接触途径，使LTCC玻璃陶瓷粉体制备可适用于水基流延工艺的浆料，且操作简便，无毒副作用。研究发现用共沉淀法包覆氧化铝对玻璃陶瓷的性能影响不大，但是硫酸包覆处理后大大提高了玻璃陶瓷的烧结温度，限制了LTCC的应用。     

不同分散剂对水系流延氧化铝基片的影响

研究了2种不同类型的分散剂对水系流延氧化铝基片的影响。研究发现：从浆料的分散性、所流延坯片的质量、烧结后基片的密度及其微观结构的比较，流延氧化铝浆料以聚丙烯酸（PAA）为分散剂明显优于以阿拉伯树胶为分散剂。以阿拉伯树胶为分散剂的浆料分散性较差，流延出的坯片生坯密度较低、坯片的柔软性较差，烧结后相对密度较低，同时，由于分散剂对塑化剂的影响，使得粘结剂PVA在浆料中没有凝胶化，从而在坯片上表面产生C富集层。     

反应磁控溅射TiN/AlON纳米多层膜的微结构与显微硬度

采用Ti靶和Al2O3靶在Ar、 N2混合气氛中进行反应磁控溅射的方法,制备了一系列不同AlON层厚度的TiN/AlON纳米多层膜,利用EDS、XRD、HRTEM和微力学探针研究了AlON的形成条件以及AlON调制层厚的改变对多层膜生长方式和显微硬度的影响.结果表明,在Ar、N2混合气氛中对Al2O3进行溅射,N原子会部分取代Al2O3中的O原子,形成非晶态的AlON化合物.在TiN/AION纳米多层膜中,由于TiN晶体层的模板效应,AlON层在厚度小于0.6 nm时被强制晶化并与TiN形成共格外延生长结构,多层膜显示出最高硬度达40.5 Gpa的超硬效应;进一步增加AlON的层厚,其生长模式由晶态向非晶态转变,破坏了多层膜的共格外延生长结构,多层膜的硬度随之降低.     

热处理对氮化铝化学镀铜组织性能的影响

目的优化化学镀铜氮化铝(AlN)基板的综合性能,掌握热处理对其镀层致密度、界面结合强度和热导率的作用机理,并对划痕膜层失效行为进行分析。方法采用化学镀铜法实现AlN陶瓷基板表面金属化,对其进行200~500℃热处理。利用X射线衍射仪、扫描电镜、激光导热仪,对Cu-AlN基板的物相结构、显微形貌、热学性能进行分析。采用划痕法对镀层结合力进行评价,并通过划痕形貌对膜层失效行为进行分析。结果未热处理的Cu-AlN基板表面存在鼓泡现象,结合强度为24.7 N,热导率为156.8 W/(m K)。热处理消除了Cu-AlN基板的鼓泡现象,300℃热处理的Cu-AlN基板综合性能优异,表面Cu颗粒分布均匀,结构较为致密,结合强度为32.6 N,热导率达163.8 W/(m K);当500℃热处理时,Cu-AlN基板表面存在氧化现象,形成CuO,结合强度急剧降低为18.5 N,热导率为161.2 W/(m K)。Cu-AlN基板的基膜失效方式为点剥离,随着载荷的增加,点剥离增多,膜层开裂,AlN逐渐裸露,Cu膜层磨损形貌宏观上表现为由塑性变形引起的犁沟磨损,芯部发生拉伸变形,边界呈现卷曲变形。结论对Cu-AlN进行合理热处理,可改善镀层表面组织与致密度,提高结合强度和导热性能。     

基板材料对QFP焊点应力应变影响的数值模拟

采用粘塑性有限元法,针对三种不同基板材料,对Sn3.8Ag0.7Cu焊点的应力及应变进行分析.结果表明,FR-4基板对应焊点的最大应力集中在焊点最内侧的尖角处;LTCC基板对应焊点的最大应力集中在焊点最外侧的尖角处;PTFE基板对应焊点的最大应力集中在焊点和引线交界的尖角处.三种基板材料中,FR-4基板对应焊点的残余应力最小,LTCC基板对应焊点残余应力最大,PTFE基板对应焊点居中.运用Anand方程计算得出Sn37Pb钎料的分析结果和Sn3.8Ag0.7Cu钎料对应的结果具有相同的规律.对基板厚度进行的优化模拟计算结果表明,基板厚度为0.8mm时对应焊点的残余应力最大.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.