Cu核微焊点液-固界面反应及剪切行为研究

相较于传统Sn基焊点,Cu核焊点具备更好的导热性、导电性及力学性能。为揭示尺寸效应对Cu核焊点界面反应及剪切强度的影响,制备了不同Sn镀层厚度的Cu核焊点(Cu@Ni-Sn/Cu)。观察回流不同时间后Cu核微焊点横截面微观组织,研究了Cu核微焊点在尺寸效应下的液-固界面反应。之后对Cu核微焊点进行剪切测试,结合断口形貌,分析断裂机理。界面反应结果表明:Cu@Ni-Sn/Cu焊点在250℃回流时,Sn/Ni界面生成Ni含量较高的针状(Cu,Ni)_(6)Sn_(5)IMC,Sn/Cu界面生成Ni含量较低的层状(Cu,Ni)_(6)Sn_(5)IMC。剪切测试结果表明:随着Sn镀层厚度增加,Cu@Ni-Sn/Cu焊点的剪切强度先增大后减小。基于Sn镀层厚度对界面(Cu,Ni)_(6)Sn_(5)IMC层体积的直接影响,Sn层厚度的增加提升了焊点剪切强度。然而Cu@Ni-Sn(60μm)/Cu焊点中Cu核位置的偏移,造成剪切强度略有降低。

超重力分离法净化2011型号废旧Al-Cu合金

基于Al-Cu合金中不同杂质相的熔点差异,借助超重力场可强化过滤分离的特点,以2011型号Al-Cu合金为原料,探究合金中杂质元素Fe、Pb和有益元素Al、Cu的分离规律。研究结果表明:原料经过高温重熔再结晶的过程后,杂质聚集到铝基体晶界间,在高温超重力场中,低熔点杂质可穿过晶界间的孔隙分离除去,当超重力分离时间≥1 min时,Fe、Pb含量不再随时间变化;提高超重力系数和温度均有利于Fe、Pb的去除,但Al、Cu回收率降低。综合考虑Fe、Pb含量和Al、Cu回收率,确定较好的超重力分离工艺参数:超重力系数为600、分离温度为610℃、分离时间为1 min,该工艺参数条件下,Fe、Pb含量分别净化至0.06%和0.08%,Al、Cu回收率分别为95.64%、67.90%,废旧Al-Cu合金中的Al和Cu总占比由97.91%提升至99.72%。

柔性精细铜引线Cu/ITO蚀刻液的制备及工艺研究

目的:为实现柔性精细铜引线,通过配制Cu/ITO双膜系蚀刻液并对其蚀刻工艺进行研究,得到蚀刻液的合理配比和最佳的工艺参数。方法:通过配制的蚀刻液进行分析,测试其对Cu膜的蚀刻程度,通过对蚀刻温度、喷淋压力、蚀刻时间、药液浓度等工艺参数进行调整控制,利用蚀刻液的高选择性,使Cu/ITO双膜系刻蚀一步完成图案化。结果:通过试验得到Cu/ITO双膜系蚀刻液的合理配比和最佳的工艺参数,进行批量化试验生产得到线宽线距L/S规格为(35±5)μm的产品,生产的Cu-Film Sensor在外观及功能测试方面可达到规格要求,金属铜线路边缘整齐美观,绝缘性在50 MΩ以上,蚀刻后膜层附着力达到5B,产品高温高湿可靠性均符合规格要求,制程C pK大于1.33。意义:该工艺整个过程操作简练、安全环保而且配制的药液体系更加均匀稳定,可进行批量化稳定生产。

Thermodynamics and Phase Equilibrium of Cu－Ce－O，Cu－Ce－S，Cu－Ce－O－S Liquid Solutions

Thermodynamics of Cu-Ce-O,Cu-Ce-S and Cu-Ce-0-S solutions at 1200℃ were studied by using solid electrolyte cell and chemical equilibrium method.The equilibrium constant of deoxidation,desulfurization and deoxysulfurization by Ce,the Gibbs standard reaction free energies of the formation of Ce_2O_3,CeS and Ce_2O_2S in Cu-base solution,activity interaction coefficients of S and Ce,temperature dependence of standard reaction free energy of solution of Ce in Cu,self-interaction coefficients of Ce in liquid Cu have been obtained.The phase precipitation diagram for Cu-CeS-O system has been plotted.The thermodynamic condition of the existence of Ce_2O_3,CeS and Ce_2O_2S in liquid Cu has been determined.It provides the basis for predicting the sequence and the type of equilibrium inclusions of Ce formed in Cu-base solution.

Liquid phase separation of Cu-Cr alloys during rapid cooling

The ribbons of Cu-Cr alloys with high Cr content (15%- 35%, mass fraction) were prepared by rapid solidification. The microstructures of solidified samples were analyzed by scanning electron microscopy and transmission electron microscopy. The results reveal that a representative liquid phase separation microstructures are observed in Cu75Cr25 ribbons solidified at a cooling rate of about 104K/s. The liquid phase separation is not restrained when the cooling rate is enhanced to about 107K/s. However, the size of Cr particles solidified from Cr-rich liquid or Cr-rich regions in alloy melts could be refined by increasing the cooling rates. The size of Cr particles increases with increasing Cr contents when the ribbons contain 15% to 35%Cr.

Gapped Spin-1/2 Spinon Excitations in a New Kagome Quantum Spin Liquid Compound Cu_3Zn(OH)_6FBr

We report a new kagome quantum spin liquid candidate CuaZn（OH）6FBr, which does not experience any phase transition down to 50inK, more than three orders lower than the antiferromagnetic Curie-Weiss temperature （-200 K）. A clear gap opening at low temperature is observed in the uniform spin susceptibility obtained from 19F nuclear magnetic resonance measurements. We observe the characteristic magnetic field dependence of the gap as expected for fractionalized spin-1/2 spinon excitations. Our experimental results provide firm evidence for spin fractionalization in a topologically ordered spin system, resembling charge fraetionalization in the fractional quantum Hall state.

Optimization of methane conversion to liquid fuels over W-Cu/ZSM-5 catalysts by response surface methodology

The conversion of methane to liquid fuels is still in the development process. The modified HZSM-5 by loading with Tungsten （W） enhanced its heat resistant performance, and the high reaction temperature （800℃） did not lead to the loss of W component by sublimation. The loading of ZSM-5 with Tungsten and Copper （Cu） resulted in an increment in the methane conversion, CO2, and C5＋ selectivities. The high methane conversion and C5＋ selectivity, and low H2O selectivity are obtained by using W/3.0Cu/ZSM-5. The optimization of methane conversion over 3.0 W/3.0Cu/ZSM-5 under different temperature and oxygen concentration using response surface methodology （RSM） are studied. The optimum point for methane conversion is 19% when temperature is 753 ℃, and oxygen concentration is 12%. The highest C5＋ selectivity is 27% when temperature is 751 ℃. and oxwen concentration is 11%.

Transport Study of Cu （Ⅱ） Through Hollow Fiber Supported Liquid Membrane

The transport of Cu(II)from aqueous solutions containing buffer media through hollow fiber supported liquid membrane(HFSLM)using di(2-ethylhexyl)phosphoric acid(D2EHPA)dissolved in kerosene as membrane phase and hydrochloric acid as striping phase was investigated.A set of factors were studied,including tube side velocity,shell side velocity,pH of the feed phase,Cu(II)concentration in the feed phase,buffer media concentration and D2EHPA concentration in the membrane phase.Experimental results indicate that the mass transfer coefficient increases with increasing both carrier concentration in the organic phase and flow rates on the tube side and shell side,and decreases with increasing initial Cu(II)concentration in the feed phase.With increasing pH value and acetate concentration in the feed phase,the mass transfer coefficient reaches a maximum value then decreases.The optimal operating conditions are obtained at pH value of 4.44 and 0.1 mol·L -1 acetic ion concentration in feed phase,and carrier volume fraction of around 10%in kerosene as organic phase.A mathematical model of the transport mechanism through HFSLM is developed.The modeled results agree well with the experimental ones.

Interfacial phase formation of Al-Cu bimetal by solid-liquid casting method

The solid-liquid method was used to prepare the continuous casting of copper cladding aluminium by liquid aluminum alloy and solid copper, and the interfacial phase formation of Al-Cu bimetal at different pouring temperatures(700, 750, 800 oC) was investigated by means of metallograph, scanning electron microscopy(SEM) and energy dispersive spectrometry(EDS) methods. The results showed that the pouring temperature of aluminum melt had an important influence on the element diffusion of Cu from the solid Cu to Al alloy melt and the reactions between Al and Cu, as well as the morphology of the Al-Cu interface. When the pouring temperature was 800 oC, there were abundant Al-Cu intermetallic compounds(IMCs) near the interface. However, a lower pouring temperature(700 oC) resulted in the formation of cavities which was detrimental to the bonding and mechanical properties. Under the conditions in this study, the good metallurgical bonding of Al-Cu was achieved at a pouring temperature of 750 oC.

Effect of Zn/Mg/Cu Additions on Hot Cracking Tendency and Performances of Al-Cu-Mg-Zn Alloys for Liquid Forging

During the process of liquid forging, a host of hot cracking defects were found in the Al-CuMg-Zn aluminum alloy. Therefore, mechanical tests and analyses by optical microscope, scanning electron microscope, and X-ray diffraction were performed to research the influences of zinc, magnesium, and copper(three main alloying elements) on hot cracking tendency and mechanical properties. It was concluded that all the three alloying elements exerted different effects on the performances of newly designed alloys. And the impact of microstructures on properties of alloys was stronger than that of solution strengthening. Among new alloys, Al-5 Cu-4.5 Mg-2.5 Zn alloy shows better properties as follows: σb=327 MPa, δ=2.7%, HB=107 N/mm^2, and HCS=40.

Improvement of Joint Strength of SiCp/Al Metal Matrix Composite in Transient Liquid Phase Bonding Using Cu/Ni/Cu Film Interlayer

The compact oxide on the surface of SiCp/Al metal matrix composite （SiCp/Al MMC） greatly depends on the property of the joint. Inlaid sputtering target was applied to etch the oxide completely on the bonding surface of SiCp/Al MMC by plasma erosion. Cu/Ni/Cu film of 5μm in thickness was prepared by magnetron sputtering method on the clean bonding surface in the same vacuum chamber, which was acted as an interlayer in transient liquid phase （TLP） bonding process. Compared with the same thickness of single Cu foil and Ni foil interlayer, the shear strength of 200 MPa was obtained using Cu/Ni/Cu film interlayer during TLP bonding, which was 89.7% that of base metal. In addition, homogenization of the bonding region and no particle segregation in interfacial region were found by analysis of the joint microstructure. Scanning electron microscopy （SEM） was used to observe the micrograph of the joint interface. The result shows that a homogenous microstructure of joint was achieved, which is similar with that of based metal.

INTERACTION BETWEEN Cu AND LIQUID Sn—Also on Physical Meaning of Wetting Curve

The interaction between Cu and liquid Sn was studied by microstructure observation.The curve of the dipping time with related to dissolving and diffusion of Cu in liquid Sn is given. The Cu dissolves rapidly in liquid Sn at the beginning,then an intermetallic compound Cu_6Sn_5 forms,and the dissolving follows to slow down.At temperature up to 350℃,the hard feather-like Cu_6Sn_5 is sharply growing up and speads through the dipped Sn laver.The way to inhibit the growth of the intermetallic compound Cu_6Sn_5 was also approached.Thus,on the above mentioned basis,the physical meaning of the wetting curve traced by the meniscograph wettability tester has been derived as film detaching,Cu dissolying and Cu_6Sn_5 growing.

INTERACTION BETWEEN Cu AND LIQUID Sn(II)——SEM OBSERVATION OF INTERMETALLIC GROWTH

The features of Cu_6Sn_5 growing slowly at lower temperature and growing rapidly up over 350℃,and or Cu_3Sn growing at higher temperatures,bave been detailedly observed under SEM.The increase of Pb content seems to inhibit sequentially the growth of Cu_6Sn_5 in Pb-Sn alloy.

THERMODYNAMICS AND PHASE EQUILIBRIUM OF Cu－Y－O，Cu－Y－S，Cu－Y－O－S LIQUID SOLUTIONS

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Formation process of liquid in interface of Ti/Cu contact reaction couple

By using the Ti/Cu contact reaction couples, the dissolution behavior of Ti and Cu in the eutectic reaction process was investigated under different conditions. The results show that the formation of eutectic liquid phase has a directional property, i.e. the eutectic liquid phase forms first at the Cu side and then spreads along the depth direction of Cu. The width of the eutectic liquid zone when Ti is placed on Cu is wider than that when Ti is placed under Cu. The shape of the upside liquid zone is wave-like. This phenomenon indicates that the formation process and spreading behavior in the upside are different from those in the underside, and there exists void effect in the Cu side of underside liquid zone, this will result in the delaying phenomenon of the contact reaction between Ti and Cu, and distinctly different shapes of the both liquid zones. The formation process of Ti/Cu eutectic liquid zone is similar to that of the traditional solid-state diffusion layer, and the relationship between the width of liquid zone and holding time obeys a square root law.

Controlled growth of Mo2C pyramids on liquid Cu surface

Precise spatial control of 2D materials is the key capability of engineering their optical,electronic,and mechanical properties.However,growth of novel 2D Mo2C on Cu surface by chemical vapor deposition method was revealed to be seed-induced 2D growth,limiting further synthesis of complex Mo2C spatial structures.In this research,we demonstrate the controlled growth of Mo2C pyramids with numerous morphologies,which are characterized with clear terraces within the structures.The whole evolution for Mo2C pyramids in the coursed of CVD process has been detected,posing significant potential in probing growth mechanism.The formation of the Mo2C pyramids arises from the supersaturation-induced nucleation and concentration-gradient driven diffused growth of a new Mo2C layer on the edged areas of intrinsic ones,as supported by STEM imaging.This work provides a novel Mo2C-based pyramid structure and further reveals a sliding growth mechanism,which could offer impetus for the design of new 3D spatial structures of Mo2C and other 2D materials.

Preparation and characterization of Mo-Cu nanocomposite powders by chemical liquid reduction process

A novel chemical liquid reduction process was employed to prepare nanosized Mo-Cu powders.The precipitates were first obtained by adding ammonium heptamolybdate((NH4)6Mo7O24·4H2O) solution into excess hydrazine hydrate solution,and then mixed the copper chloride solution.The precipitates were subsequently washed,dried,followed by reducing in H2 atmosphere to convert into Mo-Cu composite powders.The composition,morphology and particle size of the Mo-Cu composite powders were characterized by the XRD,SEM and TEM.The effects of the chemical reaction temperature and the magnetic stirring on the morphology of the Mo-Cu powders were also studied.The results show that Mo-Cu powders produced by the chemical liquid reduction process are nearly spherical shape and dispersive distribution state,with particle size ranging from 50 to 100 nm.The chemical reaction temperature and magnetic stirring will change the particle feature of the powders.Because of the Cu3Mo2O9,the reduction process in H2 is the one-stage reduction from the precipitates to the Mo-Cu composite powders.

Studying Cu Alloy Corrosion Products in Cooling Liquid

The effect of cooling liquid used for heat exchangers on the Cu alloy corrosion products has been examined using potential-time measurements under applied current condition (anodizing), potentiodynamic polarization, X-ray diffraction (XRD) and infrared spectroscopy (IR) The corrosion products formed on the Cu alloy surface during anodizing, are Cu2O, Cu2(OH)3Cl, and Cu2S. NaCl is detected in the corrosion products. The film formation depends on the applied current and the shift of potential to nobler direction indicates its formation progress.

THERMODYNAMIC CALCULATION WITH MODELS FOR LIQUID COPPER

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Liquid structure and viscosity of In_(80) Cu_(20) alloy

The structure and dynamic viscosity of In 80 Cu 20 alloy melt in the temperature range from 600 ℃ to 1 000 ℃ were investigated by using a high temperature X ray diffractometer and a torsional oscillation viscometer. The experiments show that there exist medium range order (MRO) structures in In 80 Cu 20 alloy melt in a low temperature range above liquidus. The MRO structures are weakened with increasing temperature and disappear when the temperature surpasses 800 ℃. The nearest interatomic distance r 1 and the coordination number N s of In 80 Cu 20 alloy melt decrease as temperature increases from 650 ℃ to 1 000 ℃. Thermal contraction of atom clusters can be found in the heating process. The viscosity of In 80 Cu 20 alloy melt drops as temperature increases and meets with the exponential relation. No sudden change in structure occurs in the measured temperature range. DSC curve of In 80 Cu 20 alloy during cooling process was measured. It is found that there is no noticeable variation of heat during cooling from 1 000 ℃ to 600 ℃, which testifies further that there is no sudden change in structure of In 80 Cu 20 alloy melt.