共查询到20条相似文献,搜索用时 46 毫秒
1.
Pressure and pressureless electrical contacts were evaluated by measuring the contact electrical resistivity between copper
mating surfaces. Pressure electrical contacts with a contact resistivity of 2×10−5 Ω·cm2 have been attained using a carbon black paste of a thickness of less than 25 μm as the interface material. In contrast, a
pressureless contact with silver paint as the interface material exhibits a higher resistivity of 3×10−5 Ω·cm2 or above. A pressureless contact with colloidal graphite as the interface material exhibits the same high contact resistivity
(1×10−4 Ω·cm2) as a pressure contact without any interface material. On the other hand, pressureless contacts involving solder and silver
epoxy exhibit lower contact resistivity than carbon black pressure contacts. 相似文献
2.
Silver particle (3 μm) carbon-matrix composites in the form of thick films (around 100 μm thick) on alumina, as prepared from pastes comprising silver and mesophase pitch particles (14 μm), have been attained. The films on alumina were fired at 650°C in nitrogen to convert pitch to carbon. The volume electrical
resistivity attained ranged from 10−5 Ω cm to 104 Ω cm, depending on the silver volume fraction. The percolation threshold was 12 vol% silver. 相似文献
3.
Electrically nonconductive thermal pastes have been attained using carbon (carbon black or graphite) as the conductive component
and ceramic (fumed alumina or exfoliated clay) as the nonconductive component. For graphite particles (5 μm), both clay and alumina are effective in breaking up the electrical connectivity, resulting in pastes with electrical resistivity
up to 1013Ω·cm and thermal contact conductance (between copper surfaces of roughness 15 μm) up to 9 × 104 W/m2·°C. For carbon black (30 nm), clay is more effective than alumina, providing a paste with resistivity 1011 Ω·cm and thermal contact conductance 7 × 104 W/m2·°C. Carbon black increases the thermal stability, whereas either graphite or alumina decreases the thermal stability. The
antioxidation effect of carbon black is further increased by the presence of clay up to 1.5 vol.%. The addition of clay (up
to 0.6 vol.%) or alumina (up to 2.5 vol.%) to graphite paste enhances the thermal stability. 相似文献
4.
Jorge A. Cardenas Sophia Upshaw Nicholas X. Williams Matthew J. Catenacci Benjamin J. Wiley Aaron D. Franklin 《Advanced functional materials》2019,29(1)
Silver nanoparticles (NPs) are the most widely used conductive material throughout the printed electronics space due to their high conductivity and low cost. However, when interfacing with other prominent printed materials, such as semiconducting carbon nanotubes (CNTs) in thin‐film transistors (TFTs), silver is suboptimal when compared to more expensive or less conductive materials. Consequently, there would be significant value to improving the interface of printed silver to CNT films. In this work, the impact of nanostructure morphology on the electrical properties of printed silver and nanotube junctions in CNT‐TFTs is investigated. Three distinct silver morphologies (NPs, nanoflakes – NFs, and nanowires – NWs) are explored with top‐ and bottom‐contact configurations for each. The NF morphology in a top‐contact configuration is found to yield the best electrical interface to CNTs, resulting in an average contact resistance of 1.2 MΩ ? µm. Beyond electrical performance, several trade‐offs in morphology selection are revealed, including print resolution and process temperature. While NF inks produce the best interfaces, NP inks produce the smallest features, and NW inks are compatible with low processing temperatures (<80 °C). These results outline the trade‐offs between silver contact morphologies in CNT‐TFTs and show that contact morphology selection can be tailored for specific applications. 相似文献
5.
Post curing of electrically conductive adhesives (silver filled epoxy) by heating at an elevated temperature significantly
enhances the thermal and mechanical stability of conductive adhesive joints. The contact electrical resistivity and thickness
of a joint with epoxy or silicone based adhesive tend to decrease cycle to cycle upon thermal cycling between 30°C and 50°C
and upon compression (up to 0.55 MPa), except for the silicone joint in the absence of compression. The effect of compression
is significant in epoxy joint without post curing and in silicone joint, but is insignificant in epoxy joint after post curing,
The effect of thermal cycling is significant in epoxy joint without post curing, less significant in silicone joint, and insignificant
in epoxy joint after post curing. 相似文献
6.
Improving the electrical and mechanical behavior of electrically conductive paint by partial replacement of silver by carbon black 总被引:2,自引:0,他引:2
Partial replacement of silver particles by carbon black (low cost) in electrically conductive paint was found to decrease
the electrical resistivity and increase the scratch resistance of the resulting thick film, which is for use in electrical
interconnections. An effective carbon black content is 0.055 of the total filler volume. By using a total solid volume fraction
of 0.1969 and a silane-propanol (1:1 by weight) solution as the vehicle, a paint that gives a thick film with resistivity
2 × 10−3 Ω·cm has been attained. 相似文献
7.
环氧树脂–银粉复合导电银浆的制备 总被引:3,自引:1,他引:2
导电油墨(导电银浆等)是以全印制电子技术制作印制电路板的关键材料。研究了以环氧树脂为连结剂、自制超细银粉为填料、聚乙二醇等材料为添加剂的复合导电银浆配方及制备方法。研究获得的最佳配方为:w(银粉)为70%~80%,其他各组分之间的质量比ζ(环氧树脂∶四氢呋喃∶固化剂∶聚乙二醇)=1.00∶(2.00~3.00)∶(0.20~0.30)∶(0.05~0.10)。在最佳配方范围内,复合导电银浆室温固化后电阻率小于100Ω/cm,有机物挥发少,对环境友好,符合实际应用要求。 相似文献
8.
Manepalli R. Stepniak F. Bidstrup-Allen S.A. Kohl P.A. 《Advanced Packaging, IEEE Transactions on》1999,22(1):4-8
Silver metal has the highest room-temperature electrical conductivity of any substance; however, it has found limited acceptance in the electronic industry (e.g., silver filled epoxy) due to the high rate of metal corrosion and migration causing dendrites and electrical failures. With decreasing transistor feature sizes, device-operating voltages have scaled down considerably. In this paper, the reliability of silver and potential benefits of silver metallization are discussed in terms of future trends in microelectronic interconnections. Experimental data supports existing reliability models indicating that electrochemical migration failure modes may not be operative at low voltages. Silver metal corrosion and migration are studied under accelerated test conditions to obtain a qualitative understanding of the failure mechanism 相似文献
9.
Silver oxide pastes were formulated from silver oxide powder, silver α-neodecanoate, and solvents, which lowers the sintering
temperature of printed silver films to 150°C. In this paper, solvent effects were investigated through the formulation of
silver oxide pastes using various solvents with high boiling points such as glycol, ether, and terpineol. Solvent structures
such as terminal methyl and alkoxyl groups affected the solubility of silver α-neodecanoate and the swelling of the polydimethylsiloxane
(PDMS) blanket. Particularly, higher solubility induced uniform mixing of the silver oxide powder and silver α-neodecanoate,
which resulted in higher conductivity after sintering. Glycols and monoalkyl ethers reacted with the silver oxide or silver
salt, which deteriorated the pot life of the paste. Among the various candidates, α-terpineol satisfied all the requirements
such as printability and stability, exhibiting a solubility of 47.8 g in 100 g of solvent, PDMS swelling of 4.6%, and conductivity
of 1.8 × 105 S/cm after sintering at 150°C for 30 min. 相似文献
10.
Hiroshi Ogura Minoru Maruyama Ryo Matsubayashi Tetsuya Ogawa Shigeyoshi Nakamura Teruo Komatsu Hiroshi Nagasawa Akio Ichimura Seiji Isoda 《Journal of Electronic Materials》2010,39(8):1233-1240
Lead-free silver nanoparticle pastes have been tested as a replacement for high temperature lead-rich solders used in electronic
manufacturing. The pastes contain a small amount of solvent, and primarily consist of submicron-silver powder and passivated
silver nanoparticles. The nanoparticles were synthesized from Ag2CO3 and a long-chain alcohol by a method that produced a passivating layer consisting almost exclusively of the carboxylate of
the reactant alcohol. The pastes were used to connect a silicon diode chip to copper bases without applied pressure when sintered
at 350°C under nitrogen. Diode packages made with sintered silver interconnects had electrical and thermal properties equal
to those with lead-soldered interconnects, even after 3000 thermal cycles between −55°C and +150°C. The mechanical strength
was half that of lead-rich solder joints, but still strong enough for practical use. 相似文献
11.
An air-fireable, glass-free, electrically conductive thick-film material (96.6% Ag, 1.38% Cu, 0.28% Al, 0.35% Ti, and 1.39%
Sn by weight) and a conventional glass-containing, electrically conductive thick-film materials (96.6% Ag and 3.4% glass frit
by weight), both on alumina substrates, were studied by electrical, mechanical, thermal, and microscopic methods. The volume
electrical resistivity of the glass-free thick film (2.5×10−6 Ω·cm, 30-μm thick) is lower than that of the glass-containing thick film (3.9×10−6 Ω·cm, 19-μm thick), with each film processed at its optimum firing temperature. The optimum firing temperature is 930°C and
850°C for glass-free and glass-containing thick films, respectively, as indicated by the criteria of low resistivity and high
scratch resistance. The glass-free thick film has a higher scratch resistance than the glass-containing thick film, both fired
at their respective optimum temperatures, suggesting that the former has higher bond strength to the alumina substrate. The
formation process of the glass-free and glass-containing thick films is similar. The process involves solid-state diffusion
of silver, which results in a silver network and grain boundaries. However, the sintering of silver particulates in the glass-containing
thick film is enhanced by the viscous flow of glass. 相似文献
12.
Yu-Chou Shih Yeong-Her Lin Jiun-Pyng You Frank G. Shi 《Journal of Electronic Materials》2013,42(3):410-416
In this study, silver pastes containing different sizes of glass frits were employed to form the front-side electrodes in order to examine the size effect of the glass frits on the interfacial microstructures between the front-side silver contacts and the n-type silicon emitter layers, which will subsequently affect the electrical performance of silicon solar cells. The interfacial microstructures at the Ag/Si interfaces were investigated by advanced electron microscopy techniques. The transfer length method (TLM) was used to measure the specific contact resistivity of silver electrodes screen-printed on the n-type silicon substrates. The particle size of the glass frits was found to strongly affect the interfacial microstructures and therefore resulted in different specific contact resistivities (ρ c) of the fabricated silver ohmic contacts. Nanosized glass frits showed excellent etching ability during engineered thermal treatments. The samples made with silver pastes containing microsized glass frits showed a thick residual glass layer at the Ag/Si interface, while the silver paste with nanosized glass frits was found to form an interface with less glass residue, which led to lower resistance after otherwise identical processing. 相似文献
13.
Shallown
+ andp
+ doped source/drain contacts to silicon as small as 300 × 200 nm have been fabricated using an optimized silicided (TiSi2) contact technology. Well behaved structural and electrical characteristics were found. The electrical series resistance
through two of such contacts from metal to metal through the semiconductor contacts increases rapidly for contact sizes below
the transfer length of the contact (about 0.5 μm). This resistance increase is critically dependent on the contact resistivity
and three-dimensional current flow patterns. 相似文献
14.
Enrique Cabrera Sara Olibet Dominik Rudolph Per Erik Vullum Radovan Kopecek Daniel Reinke Carmen Herzog Daniel Schwaderer Gunnar Schubert 《Progress in Photovoltaics: Research and Applications》2015,23(3):367-375
Good quality contacts between metal and silicon emitter are crucial for high crystalline solar cell efficiencies. We investigate the impact of defects originating from electrically inactive phosphorus on contact formation within silver thick film metallized silicon solar cells. For this purpose, emitters with varying sheet resistance, depth, and dead layer were metallized with silver pastes from different generations. Macroscopic contact resistivity measurements were compared with the microscopic contact configurations studied by scanning electron microscopy. The density of direct contacts between Ag crystallites grown into Si and the Ag finger bulk is essential for low contact resistivity. The presence of glass‐free regions needed for such direct contacts depends on the paste composition and on the surface texture, and does not vary with the Si emitter properties. Indeed, the decrease in contact resistivity correlates with increasing density of Ag crystallites embedded in the Si surface. Furthermore, the density of Si surface‐embedded Ag crystallites scales proportional to the electrically inactive P and is independent of the sheet resistance. Using the newest silver paste, the Ag crystallite density is independent of the emitter doping, but the Ag crystallite size increases as a function of the thickness of the dead layer. Transmission electron microscopy characterization of the excess P‐doped Si crystal lattice shows that significant strain and Si bond weakening may play a major role for both Ag crystallite nucleation and growth. Finally, we studied Si crystal defects by metallizing nanocracks, dislocations, and grain boundaries and found that Ag crystallite nucleation is defect‐property dependent. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
15.
Hyun Chul Jung Su-Hwan Cho Jae Woo Joung Yong-Soo Oh 《Journal of Electronic Materials》2007,36(9):1211-1218
Inkjet printing is considered one of the most promising methods for patterning and materials deposition. The feasibility of
employing inkjet technology for the creation of conductive pathways on printed circuit boards is addressed herein. Prediction
of the width, length, and thickness of printed lines as a function of the dot diameter, resolution, and volume fraction of
the particles in the ink is presented. Surface treatment of the substrate to promote desirable adhesion and wetting properties
as well as the adjustment of the curing process to reduce the surface roughness of the printed traces were studied. In a sintering
study, samples sintered at 250°C for 20 min showed a resistivity of 4.2 μΩ cm, which is approximately 2.6 times that of bulk silver. A low-temperature sintering method through the reduction of a
metal salt is presented. The resistivity of printed samples sintered at 140°C for 30 min in the presence of silver nitrate
with N,N-dimethylformamide showed a resistivity of 22.5 μΩ cm. 相似文献
16.
Ying-Jung Chiang Sea-Fue Wang Chun-An Lu Hong-Ching Lin 《Journal of Electronic Materials》2014,43(9):3397-3403
Silver powders were synthesized by reducing a silver organometallic compound, silver 2-ethylhexanoate, with di-n-octylamine. The effects of preparation conditions on the characteristics of the powders were investigated. Silver powders prepared from silver 2-ethylhexanoate and di-n-octylamine in the ratio 2:1 (MA21) at 150°C for 3 h had the best characteristics (average particle size 277 nm, narrow particle-size distribution, high tap density of 4.0 g/cm3), and were also obtained in high yield (98%). Use of an excessive amount of di-n-octylamine resulted in intense thermolysis and a low yield of silver powders of irregular morphology with a wide particle-size distribution. As the proportion of silver 2-ethylhexanoate was increased, the silver powders obtained had a bimodal particle-size distribution and a relatively low tap density. Silver films seemed to have high resistivity when the temperature used for synthesis of the silver powders was too low or reaction time was insufficient. The electrical resistivities of silver films prepared from MA21 powders and sintered at 300°C and 500°C for 30 min were 3.8 × 10?6 Ω cm and 2.3 × 10?6 Ω cm, respectively, close to that of bulk silver. 相似文献
17.
Testing of the relative effectiveness of various thermal interface materials for improving the thermal contact between the
well-aligned mating surfaces of an operating computer microprocessor (with an integrated heat spreader) and its heat sink
shows that carbon black paste, whether by itself or as a coating on aluminum or flexible graphite, is more effective than
silver paste (Arctic Silver), but is comparable in effectiveness to aluminum paste (Shin-Etsu). The carbon black paste by
itself is as effective as the Shin-Etsu paste coated aluminum. The Shin-Etsu paste is more effective than Arctic Silver, whether
by itself or as a coating. The relative performance is mostly consistent with that assessed by measuring the thermal contact
conductance. The correlation is particularly strong for conductance below 3×104 W/m2·°C. The discrepancy is attributed to the difference in surface roughness between computer and guarded hot plate surfaces.
In the case in which the mating surfaces of microprocessor and heat sink are not well aligned, Shin-Etsu and Arctic Silver
are more effective than carbon black. 相似文献
18.
Jian Zhou Weiping Gan Yingfen Li Lin Luo Qiaoyun Pan Zhijun Xiong 《Journal of Electronic Materials》2014,43(9):3389-3396
Micro-sized silver powders were decorated with nano-scaled Ag/AgI clusters on the surface via a simple reaction with iodine and subsequent exposure to sunshine. Surface morphologies, crystal structures, and thermal properties of the powders were characterized. The powders with different mole ratios of I:Ag (0:100, 2:100, 10:100) were employed in silver pastes to evaluate sinterability and electrical conductivity of thick films. Microstructures and sheet resistance of the films were investigated by scanning electron microscopy and the four-point probe method. The particles coated with and without nano-sized Ag/AgI clusters showed different sintering behaviors. Moreover, clear necks were formed between the Ag particles with the ratio of 2:100 even at 570°C, whereas those untreated remained discrete. However, over-decoration lowered sinterability and electrical conductivity. 相似文献
19.
Many optoelectronic devices require contacts top-doped epitaxial layers. To achieve low contact resistance, the semiconductor has to be doped to high levels. Thep-dopants most commonly used are Be, Mg, and Zn. The contacts were formed by the sequential e-beam evaporation of 10 nm Pd,
≤5 nm Zn, 20 nm Pd and 40 nm Au layers onto a 0.2 μm thick Be-doped (5 × 1018 cm) GaAs layer grown by MBE. The minimum contact resistance of 0.04Ω-mm (≤1 × 10−7
Ω-cm2), as measured using the transmission line method, was obtained for contacts annealed at 500° C for 30s. These are the lowest
contact resistance values reported to date for alloyed contacts top-GaAs. 相似文献
20.
Cu‐nanowire‐doped graphene (Cu NWs/graphene) is successfully incorporated as the back contact in thin‐film CdTe solar cells. 1D, single‐crystal Cu nanowires (NWs) are prepared by a hydrothermal method at 160 °C and 3D, highly crystalline graphene is obtained by ambient‐pressure CVD at 1000 °C. The Cu NWs/graphene back contact is obtained from fully mixing the Cu nanowires and graphene with poly(vinylidene fluoride) (PVDF) and N‐methyl pyrrolidinone (NMP), and then annealing at 185 °C for solidification. The back contact possesses a high electrical conductivity of 16.7 S cm?1 and a carrier mobility of 16.2 cm2 V?1 s?1. The efficiency of solar cells with Cu NWs/graphene achieved is up to 12.1%, higher than that of cells with traditional back contacts using Cu‐particle‐doped graphite (10.5%) or Cu thin films (9.1%). This indicates that the Cu NWs/graphene back contact improves the hole collection ability of CdTe cells due to the percolating network, with the super‐high aspect ratio of the Cu nanowires offering enormous electrical transport routes to connect the individual graphene sheets. The cells with Cu NWs/graphene also exhibit an excellent thermal stability, because they can supply an active Cu diffusion source to form an stable intermediate layer of CuTe between the CdTe layer and the back contact. 相似文献