Adhesion enhancement of polyimide on copper by Ar ion beam etching of copper

Ar ion beam etching (IBE) can be used to roughen a Cu surface and thus improve the adhesion of subsequently spin-coated polyimide (PI) films. During Ar IBE, the surface morphology of sputter-deposited Cu changes from round bumps to a rough cone structure. The ultimate tensile strength (UTS) of the PI/Cu interface is increased for certain specific beam conditions. Under optimal conditions, the UTS of the etched PI/Cu interface (6.2 MPa) is twice that of the unetched PI/Cu interface (3.1 MPa). Cu is detected in the deposited PI by Rutherford backscattering spectrometry (RBS). The amount of Cu at the top surface of the 2.5 μm thick PI film is 0.1 at. %; this is determined by RBS and XPS. While the Cu is dissolved by polyamic acid and diffuses into the PI, an oxygen-rich region is formed in the Cu. The oxygen-rich region in Cu grows from 50 A (approximately Cu₂O) before PI deposition to more than 2000 A (where the oxygen concentration is about 5 at. %) after PI deposition. The oxygen source is not the PI itself but either dissociated oxygen from the water vapor in the PI imidization process or a product of the chemical reaction between Cu and polyamic acid.     

Copper-alumina nanocomposite coating on copper substrate through solution combustion

The main objective of the present research is to investigate the production of Cu-Al₂O₃ nanocomposite coating on a copper substrate using solution combustion synthesis. Solution combustion synthesis is mainly used to produce nanocomposite powders; however, in this study it is applied to produce nanocomposite coat. For this purpose, both copper and aluminum nitrates (Cu (NO₃)₂·3H₂O and Al (NO₃)₃·9H₂O) are used as oxidizers. Also, urea and graphite are respectively used as fuel to synthesize the Cu-Al₂O₃ nanocomposite and as inhibitor to prevent the oxidation of the synthesized copper. The microstructure and morphology of the nanocomposite coating, which includes 25 wt% alumina as the reinforcing phase, was studied using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy at different fuel/oxidizer ratios ranging from 0.9 to 2. The temperature variation during the process was measured as a function of time using a precise thermocouple. Finally, micro-hardness and wear tests were conducted on the nanocomposite coating. The results verified the formation of Cu-Al₂O₃ nanocomposite coating. Time-temperature curve illustrated that the highest temperature was achieved at the fuel/oxidizer ratio of 1.25. The results of the microhardness and wear resistance test showed that these properties depend heavily on the fuel/oxidizer ratio, with the best condition attained at the ratio of 1.25.     

Adhesion of diamond coatings on steel and copper with a titanium interlayer

Adherent diamond coatings on steel and copper were obtained by using a titanium interlayer. The adhesion of the coatings was evaluated by scratch tests and micro-indentation tests. The diamond coating on steel exhibited a much higher critical load than on copper, as revealed by the scratch tests. However, an observation on the back of the scratch-delaminated film and on the corresponding substrate surface showed that the detachment occurred between the diamond film and the titanium interlayer. Therefore, the difference in the critical scratch load is due mainly to a substrate effect, making it difficult to compare the adhesion of different coatings.On the other hand, Knoop indentation tests showed interesting results: a small indentation load causes round spallation in the film with no observable crack. An exponential sink-in deformation under the indentation is proposed, y=−a exp(−bx). The coating adhesion is considered to be equivalent to the deformation stress at the edge of the spallation zone. The adhesion of diamond coatings on steel and copper with a titanium interlayer is evaluated quantitatively using this model. Furthermore, a thermal quench method is proposed to estimate the coating adhesion. The results found are in agreement with the indentation model.     

Study on enhancement of diamond nucleation on fused silica substrate by ultrasonic pretreatment

Fused silica substrates were pretreated by the ultrasonic vibration in the diamond powder slurry (UVDS). The influence of UVDS parameters such as the grain size of diamond powder, the liquid medium used to form the slurry, the weight ratio of diamond powder to liquid medium and the pretreatment time on the diamond nucleation density (DND) were systemically investigated. The grain size of diamond powder greatly affected the DND, the larger the grain size the higher the DND in our experiment conditions. The DND was about the same using acetone or ethanol or hexane medium. The best weight ratio of diamond powder (grain size 20–40 μm) to liquid medium was ∼1/60. Under appropriate pretreatment and CVD conditions, the DND of ∼10¹⁰ cm⁻² was obtained on fused silica substrates. Continuous ultra-thin diamond films with uniform and smooth surface (diamond grain size: ∼150 nm and surface roughness: ∼6 nm) were synthesized in an improved hot filament chemical vapor deposition (HFCVD) system. Nano-damaged sites on the pretreated surface mainly enhanced the DND and shortened the incubation time of nucleation.     

紫铜基体上组合电刷镀厚镍层的工艺

研究了快速镍、低应力镍刷镀时间对紫铜表面镍镀层的厚度、显微硬度及结合强度的影响。单层快速镍及单层低应力镍较适宜的刷镀时间为15～20min。采用15min快速镍与15min低应力镍交替组合刷镀镍,所得镍镀层的厚度、显微硬度及耐淬火次数分别达50μm、400HV及46次,镀层组织清晰而均匀,镀层与镀层之间、镀层与基体之间结合良好,符合理想厚镍镀层的性能要求。     

Investigation of plasma jet gas-dynamic effect on a substrate in conditions of diamond coating synthesis

Experimentally, it was shown that using a gas-dynamic correction in the plasma torch operation mode of jet expansion absence increases the efficiency of DC synthesis more than 10 times. Moreover, the diameter of the homogeneous part of a coating is increased not less than twice in relation to the diameter of the plasma jet.The theoretical explanation of the obtained result is given. It was shown that at subsonic speed of plasma flow spreading along the substrate radius, this effect can only be obtained at Reynolds numbers not exceeding the critical value R_r≤R_r cr=13456.The maximum area of uniform thickness DC is not less than 6 cm².     

Adhesion enhancement of evaporated copper on HDPE surface modified by plasma polymerization of glycidyl methacrylate

Surface modification of high‐density polyethylene (HDPE) surfaces by plasma polymerization of glycidyl methacrylate (GMA) (the pp‐GMA‐HDPE surfaces), in the absence and presence of Ar plasma pre‐activation of the HDPE substrates, was carried out to enhance the adhesion of the polymer with evaporated copper. THe FTIR and X‐ray photoelectron spectroscopy (XPS) results suggested that the epoxide functional groups on the pp‐GMA‐HDPE surfaces had been preserved to various extents, depending on the RF power used during plasma polymerization. Ar plasma pre‐activation of the HDPE surface led to the strong interaction of the pp‐GMA layer with the HDPE substrate. GMA plasma polymerization at low RF powers and in the presence of Ar plasma pre‐activation was shown to be an effective method for enhancing the adhesion of HDPE with the evaporated Cu. An optimum adhesion strength of about 16 N/cm was achieved between the evaporated Cu and the pp‐GMA‐HDPE surface prepared by plasma polymerization of GMA at 5 W, 100 Pa, 20 sccm for 5 s on the HDPE surface pre‐activated by Ar plasma at 35 W, 100 Pa 20 sccm for 20 s. The adhesion enhancement of the Cu/pp‐GMA‐HDPE assemblies in the presence of Ar plasma pre‐activation of the HDPE substrate was attributed to the covalent bonding of the plasma‐polymerized GMA (pp‐GMA) layer with the HDPE surface, the preservation of the epoxide functional groups in the pp‐GMA layer, and the spatial interactions of pp‐GMA chains with the evaporated Cu matrix.     

Adhesion enhancement of thin copper film on polyimide modified by oxygen reactive ion beam etching

Polyimide (PI) films were modified by O₂ reactive ion beam etching (RIBE) to enhance the adhesion of subsequently deposited copper films. The adhesion of evaporated copper on the O₂ RIBE-modified PI consisted of three different regimes. The first regime involved chemical reaction between PI and Cu atoms; the second regime involved the mechanical interlocking of the grass-like structure of the modified PI with Cu; and in the third regime, overetching was observed. The locus of failure was also analyzed to understand the adhesion mechanism of Cu on the PI. A 10% decrease in adhesion strength was observed after thermal cycling. Furthermore, humidity tests showed that the adhesion enhancement by mechanical interlocking of the grass-like structure is not affected by the presence of moisture.     

Molecular dynamics investigation on the atomic-scale indentation and friction behaviors between diamond tips and copper substrate

Classical molecular dynamic (MD) simulations are used to investigate the atomic-scale indentation and friction behaviors of the spherical diamond(111) or diamond(001) tip in contact with a flat copper(001) substrate. In the indentation simulations, six radii ranging from 5 to 30 nm are adopted for each tip and the contact radius is examined as a function of normal load. The results demonstrate that the contact radii calculated from the MD simulation always deviate from the continuum theory predictions and the deviation varies with the tip surface atomic structure, tip radius, and normal load. Furthermore, the atomic-scale friction behaviors are investigated using 10 nm and 30 nm diamond(111) tips sliding over the copper(001) surface with a variety of loads. Apparent atomic stick–slip behavior is observed on such ordered but incommensurate contact interface; moreover, it does not disappear with increasing tip radius. It is also revealed that the friction versus load relationship is approximately linear, which is not in agreement with the continuum theory predictions and many reported atomic force microscope (AFM) experiments.     

Oxidation and thermal shock resistant properties of Al-modified environmental barrier coating on SiCf/SiC composites

SiC_f/SiC ceramic matrix composites (CMCs) are being widely used in the hot-sections of gas-turbines, especially for aerospace applications. These CMCs are subjected to surface recession if exposed to heat-corrosion. In this research, an alternative environmental barrier coating (EBC) is introduced to protect the SiC_f/SiC CMC from high temperature degradation that is, Al film was deposited on the surface of SiC_f/SiC CMC followed by heat-treatment in a vacuum. After that, a dense Al₂O₃ overlay was in-situ synthesized on the surface of CMC, and in this process the microstructure evolution of SiC_f/SiC CMC was analyzed. The oxidation and thermal shock resistance were characterized, showing that the Al-modified SiC_f/SiC CMC has a better oxidation resistance, because the dense Al₂O₃ overlay can hinder oxygen diffusion from environment. What is more, the water-quenching testes show that the Al-modified SiC_f/SiC CMC has a good spallation resistance.     

Transparent ultrananocrystalline diamond films on quartz substrate

Highly transparent ultrananocrystalline diamond (UNCD) films were deposited on quartz substrates using microwave plasma enhanced chemical vapor deposition (MPECVD) method. Low temperature growth of high quality transparent UNCD films was achieved by without heating the substrates prior to the deposition. Additionally, a new method to grow NCD and microcrystalline diamond (MCD) films on quartz substrates has been proposed. Field emission scanning electron microscopy (FESEM) and Raman spectroscopy were used to analyze the surface and structural properties of the films. The surface morphology of UNCD film shows very smooth surface characteristics. The transparent property studies of UNCD film on quartz substrate showed 90% transmittance in the near IR region. The transparent and dielectric properties of UNCD, NCD, and MCD films on quartz substrates were compared and reported.     

电镀金刚石工具镀层脱落的原因分析

文章针对电镀金刚石工具在使用过程中镀层脱落常见的三种类型,讨论了镀层脱落的影响因素,提出了解决镀层脱落的基本对策。     

Overgrowth of diamond layers on diamond microneedles: New concept for freestanding diamond substrate by heteroepitaxy

A new concept for producing freestanding diamond substrate by heteroepitaxy is proposed. Thick diamond growth by heteroepitaxy is often prevented by heteroepitaxial-strain-related substrate bowing as it leads to substrate cracking. The possibility of using diamond microneedles as a mechanism to neglect and/or exploit substrate bowing is discussed in this new concept; the self-breaking effect of the microneedles is proposed as an application to prevent the main bulk diamond layers from cracking. With an aim toward the realization of this concept, the present study shows the first two important experimental verifications through a homoepitaxial experiment with a high-pressure high-temperature diamond substrate: (1) fabrication of high-aspect-ratio diamond microneedles (2 and 100 μm in diameter and length, respectively) by a thermo-chemical etching reaction and (2) overgrowth of diamond on the microneedles with air gaps remaining between microneedles after continuous diamond film overgrowth. We also detail a growth scheme that illustrates how continuous diamond films are created from the microneedles. The strong feasibility for applying the concept in actual heteroepitaxy is suggested through the present study.     

Adhesion optimization for catalyst coating on silicon-based reformer

CMZ (ca. 30.0 wt.% Cu, 20 wt.% Mn, and 50 wt.% Zn) catalyst was chosen for the partial oxidation of methanol (POM) reaction. To enhance adhesion between a silicon-based reactor and catalysts, boehmite and bentonite were used as binders. Changes in conditions such as pH value, ratio of bentonite/boehmite, amount of solid contents per area of substrate, and aging time have crucial effects on adhesion and result in variable performance of catalyst in POM reaction. Regarding optimized adhesion conditions, 13 wt.% weight loss was observed and methanol conversion could be kept at ca. 80–90% of original catalyst performance in a packed-bed reactor. However, poor performance was observed in the micro-channel reactor. The methanol conversion (C_MeOH), H₂ selectivity (S_H2), and H₂ yield (Y_H2) achieved 58%, 67%, 5.7 × 10^?6 mol/min in micro-channel reformer at 250 °C, respectively.     

SiC涂层对金刚石刀头性能的影响

探索了在金刚石表面镀覆SiC涂层的工艺方法,并以机械合金化铁合金粉末为基体,采用热压烧结工艺制备了长条形金刚石刀头,测试分析了刀头的硬度、抗弯强度和微观组织.结果表明:用金刚石+Si+I2混合粉末(工艺A)、或金刚石+聚碳硅烷(PCS)溶液(工艺B)于1000℃～1200℃真空反应,均能在金刚石表面制备出SiC涂层;在基体中添加Zn、Sn等低熔点元素,会降低刀头的硬度和强度;而添加少量B4C,可以起弥散强化的作用;对金刚石先镀Ti、再镀SiC,可使刀头的硬度和强度进一步提高,最高硬度为HRB118,抗弯强度为543MPa.     

金刚石化学镀铜工艺研究

介绍了金刚石化学镀铜工艺流程、工艺配方。研究了不同络合剂体系对镀液稳定性以及不同预处理方法对化学镀铜层表面形貌的影响。探讨了硫酸铜质量浓度、络合剂物质的量之比和不同pH下甲醛质量浓度对金刚石表面沉积铜速率的影响。结果表明:使用胶体钯敏化活化能显著提高金刚石表面镀铜质量,多元络合剂的加入可以增加镀液的稳定性。获得了化学镀铜最佳工艺条件:CuSO4·5H2O15g/L,甲醛(w(HCHO)=36%)15g/L,酒石酸钾钠14g/L,EDTA14.6g/L,NaOH适量,二联吡啶0.02g/L,亚铁氰化钾0.01g/L,温度(43±0.5)°C,pH=12.5。采用此工艺在金刚石颗粒表面获得了良好的镀铜层。     

镁合金基体上镍磷镀层的退除

提出了一种采用HF与HNO3退除镁合金上化学镀镍磷镀层的方法。测试了不同HF与HNO3组合的退镀液的性能,并分别测定了不同HF与HNO3含量对退镀效果的影响。结果表明,退镀液中含有一定含量的F^-,可保护基体不受腐蚀,其生成的保护膜主要为MgF2。当退镀液中ω(HF)：ω(HNO3)：ω(H2O)为4：3：3时,效果最好。由于HF有剧毒,因此操作过程应采取相应的防护措施。     

Effect of polymer coating on ammonium nitrate substrate

Prilled, spheroidized, and granular ammonium nitrates (AN) were coated with poly(chloro-p-xylylene) (parylene C) by a vapor deposition polymerization technique. Particles of AN with a 0.2% coating remain free flowing after long exposure to ambient conditions. The effectiveness of the coating as a moisture barrier on the three forms of AN was found to be in the order spheroids > prills > granules. Water adsorption isotherms and hygroscopicity determinations indicate that a 0.7% coating hydrophobes the surface of AN by approximately one order of magnitude. The parylene C/AN interface exhibits chemical and physical stability at elevated temperatures.     

金属基抗菌涂层发展现状

对金属材料表面有机抗菌涂层、无机抗菌涂层(包括金属离子型抗菌涂层和光催化剂型抗菌涂层)以及复合抗菌涂层等进行了论述.综述了国内外抗菌涂层的研究现状,指出其发展趋势.     

Quality enhancement of copper oxide thin film synthesized under elevated gravity acceleration by two-axis spin coating

Two-Axis spin coating as a new modified technique is employed to enhance the quality and surface leveling of thin films. The modified technology utilizes a synthetic centrifugal force perpendicular to the surface which generates an elevated gravity acceleration while spreading the coating on the entire wafer surface. In this paper, copper acetate sol-gel is coated by conventional and Two-Axis spin coating techniques. The coated layers are sintered in an air furnace at 275 °C. The fabricated layers are characterized by GIXRD, EDX, AFM and SEM devices. Wettability and Surface Free Energy (SFE) of sintered films using the contact angle technique are measured, and evaluated by the Owens-Wendt method. XRD and EDX spectra show a higher intensity of copper oxide phase using Two-Axis spin coating technology. AFM micrographs showed an improvement in the surface leveling within the Two-Axis spin coated layer. A comparison between the SFE of conventional and Two-Axis spin coated layers shows an increase in SFE of the layer synthesized under 200g artificial gravity acceleration.