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1.
现代电子封装迫切需要开发新型高导热陶瓷(玻璃)基复合材料.本文在对镀钛金刚石进行镀铜和控制氧化的基础上,利用放电等离子烧结方法制备了金刚石增强玻璃基复合材料,并观察了其微观形貌和界面结合情况,测定了复合材料的热导率和热膨胀系数.实验结果表明:复合材料微观组织均匀,Ti/金刚石界面是复合材料中结合最弱的界面,复合材料的热导率随着金刚石粒径和含量的增大而增加,而热膨胀系数随着金刚石含量的增加而降低.当金刚石粒径为100μm、体积分数为70%时,复合材料热导率最高达到了40.2W·m-1·K-1,热膨胀系数为3.3×10-6K-1,满足电子封装材料的要求.  相似文献   

2.
文章综述了微电子封装外壳和基板材料的最新发展及其应用,总结了LTCC和特种聚合物基复合材料的研究和其在高频模块中的应用,对复合电子封装与基板材料的发展趋势进行了分析和评述.  相似文献   

3.
SPS方法制备铜/金刚石复合材料   总被引:1,自引:0,他引:1  
采用放电等离子烧结(SPS)方法制备出高体积分数的铜/金刚石复合材料,并对复合材料的致密度、热导率和热膨胀系数等进行了研究.结果表明,采用该方法制备的铜/金刚石复合材料微观组织均匀,致密度分布为94%~99%,最高热导率为305W.(m.K)-1,热膨胀系数与常见电子半导体材料相匹配,能够满足电子封装材料的要求.  相似文献   

4.
对高储能密度电容器复合介质材料作了研究.在采用介电陶瓷/有机聚合物作复合介质材料的实验中,研究了复合材料的介电系数与组成成分的关系,研究发现,ε随陶瓷成分的增加而增大,并且存在一个临界组分,在此组分时,ε有突变.研究表明,用介电陶瓷与有机聚合物复合可制出储能密度较高的电容器介质材料.  相似文献   

5.
氮化铝陶瓷属优质陶瓷材料,自身热导率高、电绝缘性良好、介电常数及损耗低,受到高功率电子生产行业广泛欢迎。氮化铝陶瓷主要应用在高导热基板材料和高功率电子器件封装上,其自身优势性能对促进机械电子行业发展有重要作用。该文就高质量氮化铝陶瓷粉体制备进行详细分析,分析其技术进展,旨在为深入了解氮化铝陶瓷粉体制备方式,为相关部门深入氮化铝陶瓷研究提供有力参考。  相似文献   

6.
Ba_xSr_(1-x)TiO_3(BST)薄膜具备高的介电可调特性(介电常数在外加电场的作用下会发生改变)和低的介电损耗,这使得BST薄膜成为高速宽带可调微波器件(如相移器、可调带通和带阻滤波器、谐波发生器等)的首选材料,近年来受到世界各国多个研究小组的关注与研究.此研究工作报道采用成分梯度多层膜结构、受主掺杂和复合掺杂方法调控薄膜内部的应力以及电子结构,有效地优化BST薄膜的介电和电学等性能的最新进展.采用脉冲激光沉积(PLD)方法在MgO基片上制备高Sr组分的Ba0.02Sr0.98Ti O3薄膜.通过改善沉积生长的工艺条件,成功克服了MgO基片与薄膜之间大的晶格失配度(7%),在特定的温度和气压获得了外延生长BST薄膜.详细研究了(Ba0.8Sr0.2)(Ti1-xZrx)O3(BSTZ)薄膜的非线性介电特性,发现随着Zr含量的增加,薄膜介电调制率降低,薄膜的损耗和漏电流也显著减小.我们制备了具有不同成分梯度的BSTZ多层膜.介电特性研究表明,随成分梯度(gradients of composition)的增大,介电系数和介电可调性得到增强,铁电回线得到抑制;同时薄膜介电系数的温度稳定性有了显著改善....  相似文献   

7.
纳米金刚石颗粒涂层的场电子发射   总被引:3,自引:0,他引:3  
金刚石具有优异的电子、机械和化学性能,特别是表面的负电子亲和势(NEA)特征使其成为真空微电子器件的理想冷阴极材料,可望在平面显示器等领域得到广泛的应用.近十年来对天然金刚石、CVD金刚石膜和类金刚石碳(DLC)膜以及它们在Si和Mo等基材上的涂层[...  相似文献   

8.
本文研究了硅橡胶介电弹性体复合材料的热力学和热机电稳定性.考虑温度、掺杂和电致伸缩变形的耦合影响,建立介电弹性体复合材料的介电常数模型,从而构建系统的电场能,基于此耦合发展的Ogden模型研究复合材料的热力学性能和热机电稳定性性能.结果表明,当电致伸缩系数减小,或材料常数比减小,或温度增加,或唯象学参数增加,或电致伸缩系数比增加时,介电弹性体临界名义电场增加,从而热力学系统的稳定性增强.这些结论对于硅橡胶纳米复合材料的设计和制备及其应用器件研究有巨大帮助.  相似文献   

9.
随着集成电路.微型组件与大功率半导体器件生产的迅速发展,电子工业对高电气绝缘性能和高导热性能的陶瓷基板和封装材料的需求量日益增加。高频、高效IC(集成电路)越来越高度集成化,耗电量也越来越高。因此.解决器件散热的问题尤为急迫。  相似文献   

10.
高储能密度电容器复合介质材料的研究   总被引:2,自引:0,他引:2  
对高储能密度电容器复合介质材料作了研究。采用介电陶瓷/有机聚合物作复合介质材料的实验中,研究了复合材料的介电系数与组成成分的关系,研究发现,ε随陶瓷成分的增加而增大,并且存在一个临界组。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

16.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

17.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

20.
1 Rise of studies on climate change's effects on biodiversity
Until the 1980s, climate change and biodiversity were studied as two independent disciplines for more than a century. In 1992, the Ecological Society of America's annual report named climate change, biodiversity, and the sustainable ecological system as the three major global environmental issues of the twenty-first century [1].  相似文献   

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