Journal articles: 'Direct bonded copper'

1

Squires, Matthew B., James A. Stickney, Evan J. Carlson, Paul M. Baker, Walter R. Buchwald, Sandra Wentzell, and Steven M. Miller. "Atom chips on direct bonded copper substrates." Review of Scientific Instruments 82, no. 2 (February 2011): 023101. http://dx.doi.org/10.1063/1.3529434.

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Cavaco, Celso, Lan Peng, Koen De Leersnijder, Stefano Guerrieri, Deniz S. Tezcan, and Haris Osman. "Copper Oxide Direct Bonding of 200mm CMOS Wafers: Morphological and Electrical Characterization." International Symposium on Microelectronics 2015, no. 1 (October 1, 2015): 000594–97. http://dx.doi.org/10.4071/isom-2015-tha26.

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We show for the first time complete data on 200mm wafer to wafer copper oxide direct bonding of two metal levels. Both surface acoustic microscope (SAM) and cross-section scanning electron microscope (X-SEM) images taken across the bonded wafer pairs confirm the good direct bonding quality of the resulting interface. Daisy chains with up to 3200 copper to copper bonded pads and of about 50mOhm/pad, are shown to be connected successfully and its resistance value to match a target value, as well as to scale linearly with the increase of connections in the chain.

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3

Schulz-Harder, Jürgen. "Advantages and new development of direct bonded copper substrates." Microelectronics Reliability 43, no. 3 (March 2003): 359–65. http://dx.doi.org/10.1016/s0026-2714(02)00343-8.

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4

Mei, Yunhui, Guo-Quan Lu, Xu Chen, Chen Gang, Shufang Luo, and Dimeji Ibitayo. "Investigation of Post-Etch Copper Residue on Direct Bonded Copper (DBC) Substrates." Journal of Electronic Materials 40, no. 10 (July 30, 2011): 2119–25. http://dx.doi.org/10.1007/s11664-011-1716-8.

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5

Hagiwara, Naoki, Shinji Koyama, and Ikuo Shohji. "Cu/Cu Direct Bonding by Metal Salt Generation Bonding Technique with Formic Acid and Citric Acid." Advanced Materials Research 922 (May 2014): 219–23. http://dx.doi.org/10.4028/www.scientific.net/amr.922.219.

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The effect of formic acid and citric acid surface modification on the bonded strength of the solid-state direct bonded interface of copper was investigated by SEM observations of interfacial microstructures and fractured surfaces. Copper surfaces were modified by boiling in 98% formic acid for 0.6 ks and 17% aqueous solution of citric acid for 0.96 s. Solid-state bonding was performed in a vacuum chamber at bonding temperature of 423 ~ 673 K under a pressure of 588 N (bonding time of 0.9 ks). As a result of surface modification by formic acid and citric acid, bonded joints were obtained at a bonding temperature 150 K (formic acid) and 100 K (citric acid) lower than that required for non-modified surfaces, and the bond strength was comparable to that of the maximum load.

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6

Grzesiak, Wojciech, Piotr Maćków, Tomasz Maj, Beata Synkiewicz, Krzysztof Witek, Ryszard Kisiel, Marcin Myśliwiec, Janusz Borecki, Tomasz Serzysko, and Marek Żupnik. "Application of direct bonded copper substrates for prototyping of power electronic modules." Circuit World 42, no. 1 (February 1, 2016): 23–31. http://dx.doi.org/10.1108/cw-10-2015-0051.

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Purpose – This paper aims to present certain issues in direct bonded copper (DBC) technology towards the manufacture of Al2O3 or AlN ceramic substrates with one or both sides clad with a copper (Cu) layer. Design/methodology/approach – As part of the experimental work, attempts were made to produce patterns printed onto DBC substrates based on four substantially different technologies: precise cutting with a diamond saw, photolithography, the use of a milling cutter (LPKF ProtoMat 93s) and laser ablation with differential chemical etching of the Cu layer. Findings – The use of photolithography and etching technology in the case of boards clad with a 0.2-mm-thick Cu layer, can produce conductive paths with a width of 0.4 mm while maintaining a distance of 0.4 mm between the paths, and in the case of boards clad with a 0.3-mm-thick copper layer, conductive paths with a width of 0.5 mm while maintaining a distance of 0.5 mm between paths. The application of laser ablation at the final step of removing the unnecessary copper layer, can radically increase the resolution of printed pattern even to 0.1/0.1 mm. The quality of the printed pattern is also much better. Research limitations/implications – Etching process optimization and the development of the fundamentals of technology and design of power electronic systems based on DBC substrates should be done in the future. A limiting factor for further research and its implementation may be the relatively high price of DBC substrates in comparison with typical PCB printed circuits. Practical implications – Several examples of practical implementations using DBC technology are presented, such as full- and half-bridge connections, full-wave rectifier with an output voltage of 48 V and an output current of 50 A, and part of a battery discharger controller and light-emitting diode illuminator soldered to a copper heat sink. Originality/value – The paper presents a comparison of different technologies used for the realization of precise patterns on DBC substrates. The combination of etching and laser ablation technologies radically improves the quality of DBC-printed patterns.

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7

Akhtar, S. S., L. T. Kareem, A. F. M. Arif, M. U. Siddiqui, and A. S. Hakeem. "Development of a ceramic-based composite for direct bonded copper substrate." Ceramics International 43, no. 6 (April 2017): 5236–46. http://dx.doi.org/10.1016/j.ceramint.2017.01.049.

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8

Piekoszewski, J., Wieslawa Olesińska, J. Jagielski, D. Kaliński, M. Chmielewski, Z. Werner, M. Barlak, and Wiesław Szymczyk. "Ion Implanted Nanolayers in AlN for Direct Bonding with Copper." Solid State Phenomena 99-100 (July 2004): 231–34. http://dx.doi.org/10.4028/www.scientific.net/ssp.99-100.231.

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Experiments to directly bond AlN with Cu were conducted for different pre-treatments of the bonded components. AlN substrates were implanted either with oxygen, or titanium or iron ions at low (15 keV) or high (70 keV) energy, or thermally oxidized. Some Ti-implanted samples were also thermally oxidized. The copper component was annealed and thermally oxidized. The best results, with respect to the bond shear strength, were obtained for low-energy implantation of oxygen and titanium.

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9

NING, HONGLONG, USHENG MA, FUXIANG HUANG, YONGGANG WANG, JIMAN ZHU, and ZHITING GENG. "INVESTIGATION OF THE INTERFACE OF THE DCB SUBSTRATE." Surface Review and Letters 10, no. 01 (February 2003): 95–99. http://dx.doi.org/10.1142/s0218625x03004640.

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DCB means direct copper bonding and denotes a process in which copper and a ceramic material are directly bonded. Between the temperature of the metal's melting point and the eutectic temperature of the metal-oxygen, DCB depends on the eutectic compound to join the copper and the ceramic. We do some research to investigate the interface between the copper foils and Al2O3 ceramics; it is the key factor in influencing the performance of the DCB substrate. We also discuss how to get good microstructure of the DCB interface.

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10

Akhtar, S. S., K. T. Lemboye, A. F. M. Arif, and K. S. Al-Athel. "Design and Performance Evaluation of Al2O3-SiC Composite for Direct-Bonded Copper Substrate." Journal of Materials Engineering and Performance 27, no. 11 (October 15, 2018): 5831–44. http://dx.doi.org/10.1007/s11665-018-3702-2.

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11

Akbar, Ahmed Ali Akbar, Sami Abualnoun A. Ajeel, and Safaa Mohammed Hassoni. "Optimization of Diffusion Bonding of Pure Copper (OFHC) with Stainless Steel 304L." Al-Khwarizmi Engineering Journal 14, no. 2 (March 12, 2019): 30–39. http://dx.doi.org/10.22153/kej.2018.11.002.

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This work deals with determination of optimum conditions of direct diffusion bonding welding of austenitic stainlesssteel type AISI 304L with Oxygen Free High Conductivity (OFHC) pure copper grade (C10200) in vacuum atmosphere of (1.5 *10-5 mbr.). Mini tab (response surface) was applied for optimizing the influence of diffusion bonding parameters (temperature, time and applied load) on the bonding joints characteristics and the empirical relationship was evaluated which represents the effect of each parameter of the process. The yield strength of diffusion bonded joint was equal to 153 MPa and the efficiency of joint was equal to 66.5% as compared with hard drawn copper. The diffusion zone reveals high microhardness than copper side due to solid solution phase formation of (CuNi). The failure of bonded joints always occurred on the copper side and fracture surface morphologies are characterized by ductile failure mode with dimple structure. Optimum bonding conditions were observed at temperature of 650 ◦C, duration time of 45 min. and the applied stress of 30 MPa. The maximum depth of diffuse copper in stainless steel side was equal 11.80 µm.

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12

Gaiser, Patrick, Markus Klingler, and Jürgen Wilde. "The influence of strain hardening of copper on the crack path in Cu/Al2O3/Cu direct bonded copper substrates." International Journal of Fatigue 140 (November 2020): 105821. http://dx.doi.org/10.1016/j.ijfatigue.2020.105821.

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13

Jiang, Yun-Bo, Hui-Zhong Kou, Ru-Ji Wang, and Ai-Li Cui. "A sandwich strand supramolecular complex: aquachloro(nitrilotriacetato-κ2 N,O)copper(II) 18-crown-6-ether trihydrate." Acta Crystallographica Section E Structure Reports Online 62, no. 4 (March 17, 2006): m804—m806. http://dx.doi.org/10.1107/s1600536806008427.

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The unexpected title compound, [Cu(C6H8NO6)Cl(H2O)]·C12H24O6·3H2O, was synthesized by crystallization of a mixture containing CuCl2·2H2O, nitrilotriacetic acid (H3NTA), KOH, 18-crown-6 and GdCl3·6H2O. The complex consists of a hydrogen-bonded polymeric structure, in which discrete Cu(H2NTA)(H2O)Cl units interact via the carboxyl groups and the coordinating water molecules with the crown ether molecules. No direct metal–crown ether bond exists in the infinite sandwich-type hydrogen-bonded structure. The copper complex lies on a mirror plane, which passes through Cu and all the coordinating atoms. The crown ether molecule lies on an inversion centre. One water molecule is disordered across the mirror plane.

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14

Olesinska, W., D. Kalinski, and M. Chmielewski. "Influence of Oxygen and Titanium Modification of AlN Surface on the Properties of Direct Bonded AlN-Cu Joints." Advances in Science and Technology 45 (October 2006): 1537–42. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1537.

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The paper presents the results concerning the formation of a ‘barrier’ layer on AlN ceramic during its joining with copper by the Copper Direct Bonding (CDB) technique. Prior to the joining, the AlN surface was modified by isothermal oxidation or by titanium ion implantation. The effects of the oxidation process temperature were examined within the temperature range from 673 to 1473K. The surface of the ceramic was modified by titanium ion implantation at various ion doses and various accelerating voltages. The modified ceramic was joined with oxidized copper in a nitrogen atmosphere with about 1.5ppm of oxygen, using a belt-type furnace at a temperature of 1323K. The microstructure and phase changes induced on the surfaces of the joints were examined. The modification yielded a ‘barrier’ layer (TiN), which ensured a continuous pore-less contact between the materials being joined. The results obtained under all the experimental conditions indicate that the implantation gives better effects than thermal oxidation. Ion implantation seems to be ideally suited for these purposes. The preferential dose appears to be 5*E16ions/cm2 and the preferential accelerating voltage – 15kV.

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15

Gundel, Paul, Anton Miric, Kai Herbst, Melanie Bawohl, Jessica Reitz, Christina Modes, Gabriel Zier, Ilias Nikolaidis, and Mark Challingsworth. "Advanced DBC - Highly Reliable and Conductive Copper Ceramic Substrates." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2016, CICMT (May 1, 2016): 000073–78. http://dx.doi.org/10.4071/2016cicmt-tp2b2.

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Abstract So far Direct Bonded Copper (DBC) substrates have been the standard for power electronics. They provide excellent electrical and thermal conductivity at low cost. Weaknesses of DBC technology are the inevitable warpage and the relatively low reliability under thermal cycling. The low reliability poses a significant hurdle in particular for automotive applications with high lifetime requirements. Thick Print Copper (TPC) substrates with low warpage and excellent reliability overcome these weaknesses, but also provide a reduced conductivity at a higher cost. We present two thick-film/DBC hybrid technologies which combine the best properties of DBC and TPC: excellent conductivity, low cost, reduced warpage and excellent reliability.

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16

Pietrzak, K., W. Olesinska, D. Kalinski, and A. Strojny-Nedza. "The relationship between microstructure and mechanical properties of directly bonded copper-alumina ceramics joints." Bulletin of the Polish Academy of Sciences: Technical Sciences 62, no. 1 (March 1, 2014): 23–32. http://dx.doi.org/10.2478/bpasts-2014-0003.

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Abstract The effect of phase transformations induced in the surface layer of alumina ceramics during its direct joining with copper activated with oxygen or titanium on the mechanical strength of the ceramic/copper joints was examined. The materials used in the experiments were an alumina single crystal, alumina ceramics (97.5 wt% Al2O3), the cermet mixtures: Cu-Cu2O with 10-50 wt% of Cu2O, copper with 5 wt% of Ti, and copper with 5 wt% of Ti and 10 wt% of Ag. The microstructure of the transition layer was examined by the X-ray diffraction method (XRD), scanning electron microscopy method (SEM) and energy dispersive x-ray spectroscopy (EDX). The mechanical strength of the joints was measured using the three-point bending method. The amount of oxygen optimal for the joining process was determined. It has been demonstrated that the cohesion of the joints depends not only on the formation of the individual phases but also, or even primarily, on the microstructure of the transition layer formed between them.

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17

Agbim, Kenechi A., Darshan G. Pahinkar, and Samuel Graham. "Integration of Jet Impingement Cooling With Direct Bonded Copper Substrates for Power Electronics Thermal Management." IEEE Transactions on Components, Packaging and Manufacturing Technology 9, no. 2 (February 2019): 226–34. http://dx.doi.org/10.1109/tcpmt.2018.2863714.

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18

Ivanova, Mariya, Yvan Avenas, Christian Schaeffer, Jean-Bernard Dezord, and Juergen Schulz-Harder. "Heat Pipe Integrated in Direct Bonded Copper (DBC) Technology for Cooling of Power Electronics Packaging." IEEE Transactions on Power Electronics 21, no. 6 (November 2006): 1541–47. http://dx.doi.org/10.1109/tpel.2006.882974.

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19

Pak, Han-ryong, Chung-wen Chen, O. T. Inal, and Kali Mukerjee. "Microstructures of straight and wavy interfaces formed in explosively bonded copper single crystals." Proceedings, annual meeting, Electron Microscopy Society of America 44 (August 1986): 426–27. http://dx.doi.org/10.1017/s0424820100143717.

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Explosive welding is essentially a solid-phase bonding process, hence any metal can be bonded even if they are totally dissimilar physically and chemically. Our group recently found that a straight interface is superior, with respect to plastic deformation behavior, to a wavy one, in direct contrast to a model that an interlocking structure of a wavy interface produces strong bonds. To obtain some insight into the superiority of such a straight interface, microstructures of copper single crystals (size: 4 x 40 x 130 mm) explosively welded in a parallel standoff configuration are investigated by means of transmission electron microscopy.

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20

Janák, Karel, and Jaroslav Janák. "Preparation and properties of epoxided Separon-based ion exchangers with bonded 8-hydroxyquinoline." Collection of Czechoslovak Chemical Communications 51, no. 3 (1986): 650–56. http://dx.doi.org/10.1135/cccc19860650.

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The direct fixation of copper(II) 5-(4-hydroxyphenylazo)-8-quinolinate and the indirect fixation of 8-hydroxyquinoline to Separon H 40Emax and Separon H 1000 Emax were compared from the point of view of the practical sorption capacities of the resulting ion exchangers. For the ion exchanger obtained by indirect fixation of the reagent to Separon H 40 Emax, the rate of Cu2+ ions, and the stability were determined and compared with those of a G-gel-based ion exchanger.

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21

Patterson, Brian, Srikanth Kulkarni, Aicha Elshabini, and Fred Barlow. "Evaluation of Direct Bond Aluminum Substrates for Power Electronic Applications in Extreme Environments." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, CICMT (September 1, 2012): 000012–17. http://dx.doi.org/10.4071/cicmt-2012-ta12.

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Power packages that require large current capacities typically employ some form of thick conductive traces attached to a thermally conductive ceramic material to create a suitable package substrate. The most common substrate currently used in high power applications is Direct Bonded Copper (DBC). Though this is a well established, reliable, and commonly used substrate, DBC suffers from poor long term mechanical reliability when exposed to extreme temperature excursions. In an attempt to improve on this technology, substrate materials such as Active Metal Bond / Braze (AMB) and Direct Bonded Aluminum (DBA) are being investigated. Previous work has shown that the accelerated aging / thermal shock lifetimes of DBC and AMB are significantly shorter than that of DBA substrates. Though DBA substrates last longer, they still have some issues that require attention before it can be accepted as an improved alternative to DBC substrates in these types of applications. The main issues that have been observed are DBA's increase in surface roughness during aging and aluminum's poor solderability when compared to copper or nickel. The emphasis of this paper is to investigate the dramatic increase in DBA's surface roughness and its' possible causes due to thermal cycling as well as present a thermal cycling lifetime comparison of the three different substrate. To evaluate this, a DBA sample with one side raw aluminum and one side electroless nickel plated (high phosphorous) was thermally shocked from −40°C to 200°C with surface roughness measurements preformed every 300 cycles. Another batch of samples was thermally shocked to 6000 cycles and lifetimes were compared. One nickel plated DBA sample shocked to 4000 cycles was cross-sectioned and analyzed with SEM and EDAX to evaluate any changes in the metal. The grain structure of a thermally cycled sample was also examined with a Scanning Electron Microscope (SEM).

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22

Kabaar, A. Ben, C. Buttay, O. Dezellus, R. Estevez, A. Gravouil, and L. Gremillard. "Characterization of materials and their interfaces in a direct bonded copper substrate for power electronics applications." Microelectronics Reliability 79 (December 2017): 288–96. http://dx.doi.org/10.1016/j.microrel.2017.06.001.

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23

Molisani, André Luiz, and Humberto Naoyuki Yoshimura. "Intermediate Oxide Layers for Direct Bonding of Copper (DBC) to Aluminum Nitride Ceramic Substrates." Materials Science Forum 660-661 (October 2010): 658–63. http://dx.doi.org/10.4028/www.scientific.net/msf.660-661.658.

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DBC is a process where copper foils are bonded to ceramic substrates for manufacturing hybrid electronic circuits and packages with high power-handling capabilities. For aluminum nitride (AlN) ceramics, a heat-treatment is required to grow an oxide layer to promote the bonding with copper. The oxidation treatment, however, must be conducted in special conditions to avoid the occurrence of severe cracking. In this work, an alternative method is proposed to form an intermediate oxide layers for DBC to AlN substrates. By this method, eutectic powder mixtures (CuO-CaO and CuO-Al2O3 systems) were applied to dense AlN substrates and then heat-treated at 1200 °C for 1 h in air. Different types of AlN ceramics sintered between 1650 and 1700 °C for 4 h in nitrogen atmosphere with additives of the system Y2O3-CaO-SrO-Li2O were investigated. The prepared oxide layers (thickness of ~25 m) presented good microstructural joining with the AlN substrates (characterized by SEM and EDS analysis), and did not affect significantly the thermal conductivity in the working temperature range of electronic devices (~100 to 50 W/m.K determined by laser flash method between 100 and 200 °C) compared to the AlN substrates.

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24

Persons, Ryan, and Paul Gundel. "Print Copper on Ceramic for High Reliability Electronics." International Symposium on Microelectronics 2015, no. 1 (October 1, 2015): 000330–35. http://dx.doi.org/10.4071/isom-2015-wp12.

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In the power electronics world, Direct Bonded Copper (DBC) is the primary substrate technology. In this paper, we will discuss an alternative technology utilizing screen printable copper pastes (Thick Printed Copper - TPC) on a variety of substrate technologies including Alumina (Al2O3) and Aluminum Nitride (AlN). These materials when processed, look and perform similar to DBC, but exhibit superior reliability and excellent design flexibility. DBC has drawbacks when it comes to thermal mechanical reliability and lacks the flexibility to have multiple copper thicknesses for power and signal circuits within the same design, which is easily achieved via screen printing. The benefits of this TPC system will be demonstrated through data generated on passive thermal shock tests in comparison to high end DBC. Furthermore, this Thick Print Copper technology has the excellent potential for replacing high end Metal Core Printed Circuit Board (MCPCB) technology due to utilization of higher thermal conductive dielectric materials like Al2O3 and AlN. This will allow for designers to drive their LED's harder and effectively producing LED modules with higher power densities.

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25

Ogasawara, Katsuyuki, Yuji Mochizuki, Takeshi Noro, and Kiyoshi Tanaka. "Electronic structure of lower singlet states of binuclear copper acetate monohydrate." Canadian Journal of Chemistry 70, no. 2 (February 1, 1992): 393–98. http://dx.doi.org/10.1139/v92-056.

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The electronic structures of the ground state and the excited states due to the 3d–3d transition of copper acetate monohydrate are investigated by abinitio calculations. No direct bond is obtained between the two Cu ions, but they are bonded by bridges of the four acetates. The excited states represented by the one-electron excitation of an occupied 3d electron to an unoccupied 3d orbital in either of the two Cu's are located around 1.6-1.8 eV, which corresponds to the energy region of band I. Those of the simultaneous one-electron 3d–3d excitation in both Cu's (i.e., two-electron excitation) are located around 3.2–3.4 eV. They correspond to the energy region of band II. Keywords: copper acetate monohydrate, binuclear compound, bridged bond, 3d → 3d excited states.

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26

Toth Pal, Zsolt, Ya Fan Zhang, Ilja Belov, Hans Peter Nee, and Mietek Bakowski. "Investigation of Pressure Dependent Thermal Contact Resistance between Silver Metallized SiC Chip and DBC Substrate." Materials Science Forum 821-823 (June 2015): 452–55. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.452.

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– Thermal contact resistances between a silver metallized SiC chip and a direct bonded copper (DBC) substrate have been measured in a heat transfer experiment. A novel experimental method to separate thermal contact resistances in multilayer heat transfer path has been demonstrated. The experimental results have been compared with analytical calculations and also with 3D computational fluid dynamics (CFD) simulation results. A simplified CFD model of the experimental setup has been validated. The results show significant pressure dependence of the thermal contact resistance but also a pressure independent part.

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Rashid, S. J., C. Mark Johnson, F. Udrea, Andrej Mihaila, G. Amaratunga, and Rajesh Kumar Malhan. "Analysis of Novel Packaging Techniques for High Power Electronics in SiC." Materials Science Forum 556-557 (September 2007): 971–74. http://dx.doi.org/10.4028/www.scientific.net/msf.556-557.971.

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A novel high temperature wire bondless packaging technique is numerically investigated in this paper. Extraction of device effective resistivity with temperature from numerical characteristics of 1.2kV 4H-SiC MOSFETs at a current density of 400A/cm2 have demonstrated a T−2 temperature dependence. Electro-thermal finite element analysis (FEA) of 1.2kV 4H-SiC MOSFETs sandwiched between two etched direct-bonded-copper substrate tiles has been performed. The thermal resistance of the ceramic sandwich package shows a 75% reduction in thermal resistance compared to conventional wire bonded assemblies. Mechanical analysis of the assembly has been used to investigate the residual stresses in the SiC dies at room temperature, which are then alleviated at higher temperatures during device operation. Mismatch of the expansion coefficients of the auxiliary materials in the assembly result in elevated stresses at full load operation, however these are well below the tensile strength of the respective materials and hence do not compromise the mechanical integrity of the package.

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Kang, Hyejun, Ashutosh Sharma, and Jae Pil Jung. "Recent Progress in Transient Liquid Phase and Wire Bonding Technologies for Power Electronics." Metals 10, no. 7 (July 11, 2020): 934. http://dx.doi.org/10.3390/met10070934.

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Transient liquid phase (TLP) bonding is a novel bonding process for the joining of metallic and ceramic materials using an interlayer. TLP bonding is particularly crucial for the joining of the semiconductor chips with expensive die-attached materials during low-temperature sintering. Moreover, the transient TLP bonding occurs at a lower temperature, is cost-effective, and causes less joint porosity. Wire bonding is also a common process to interconnect between the power module package to direct bonded copper (DBC). In this context, we propose to review the challenges and advances in TLP and ultrasonic wire bonding technology using Sn-based solders for power electronics packaging.

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29

Nowak, Iwona, Izabella Krucińska, and Łukasz Januszkiewicz. "Metallic Electroconductive Transmission Lines Obtained on Textile Substrates by Magnetron Sputtering." Fibres and Textiles in Eastern Europe 27, no. 3(135) (June 30, 2019): 51–57. http://dx.doi.org/10.5604/01.3001.0013.0742.

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The paper discusses the results of research concerning the formation of electroconductive transmission lines on textile substrates using the magnetron sputtering technique. The transmission lines developed can potentially be applied in clothing for emergency and security services to affect electrical connections between electronic elements incorporated in the garments. The time of metallic layer deposition and the type of substrate used was optimised in the study. The surface resistivity, resistance to bending and abrasion of the transmission lines obtained were tested. The tests demonstrated that it is possible to obtain electroconductive copper layers with a surface resistivity approximating 0.2 Ω by direct deposition on spun-bonded type polypropylene nonwoven.

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30

Maeda, Masakatsu, Naoto Inoue, Takaaki Sato, and Yasuo Takahashi. "Early Stage of Solid State Interfacial Reaction between Copper and Tin." Defect and Diffusion Forum 283-286 (March 2009): 323–28. http://dx.doi.org/10.4028/www.scientific.net/ddf.283-286.323.

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High-purity plates of Cu and Sn were diffusion bonded to clarify the early stage of the solid state interfacial reaction between Cu and Sn, focusing on the incubation time for the formation of intermetallic compounds. A clear incubation time for the formation of intermetallic compounds is observed at every temperature between 423 and 493 K. The incubation time changes depending on the annealing temperature. The interface annealed at 423 K for 3.60 ks maintains the direct interconnection between Cu and Sn being free of intermetallic compounds. The exposure of Cu surface to air affects the interfacial reaction. Annealing of the Cu/Sn interface at 493 K for 3600 s starts to form voids by using the Cu plates exposed for 8.64×104 s or longer to air. Furthermore, the reaction product layer formed by the same annealing condition becomes thinner when the Cu plates exposed for 8.64×105 s or longer to air are used.

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31

Nishimoto, Akio, Katsuya Akamatsu, and Kenji Ikeuchi. "Microstructure of SiC/Cu Interface by Pulsed Electric-Current Bonding." Materials Science Forum 539-543 (March 2007): 3883–87. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.3883.

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Pulsed electric-current sintering (PECS) was applied to the bonding of SiC (pressureless-sintered silicon carbide) to Cu (oxygen-free copper) using a mixture of Cu and Ti powders as an intermediate layer. The influences of the intermediate powders on the bond strength of the joint were investigated by observation of the microstructure. The bonding was carried out at carbon-die temperatures from 973 to 1173 K at a bonding pressure of 10 MPa for 3.6 ks. The application of intermediate layers of 100% Ti, 95% Ti + 5% Cu, and 5% Ti + 95% Cu remarkably improved the bond strength as compared with direct bonding without an intermediate powder. SEM observations of the joint with the intermediate powders revealed that a Cu solid-solution layer, a TiC layer, and a Ti5Si3 layer had covered most of the interface, similar to those observed in the friction-bonded and pulsed-electric current bonded joints of SiC to Cu in which the application of a Ti foil as an intermediate layer remarkably improved the bond strength.

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32

Yoon, Sang Won, Michael D. Glover, H. Alan Mantooth, and Koji Shiozaki. "Highly Reliable Double-sided Bonding used in Double-sided Cooling for High Temperature Power Electronics." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, HITEC (January 1, 2012): 000045–50. http://dx.doi.org/10.4071/hitec-2012-ta23.

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This paper demonstrates the feasibility of double-sided die attachment bonding, a key technology for double-sided cooling structures, using copper-tin transient liquid phase (Cu-Sn TLP) bonding. Recently, double-sided cooling has drawn particular interest by providing a notable improvement in thermal management and increasing allowable power density for automotive power electronics. The use of TLP bonding for double-sided attachment avoids a number of complications in the assembly process, enables multiple attachments, and provides a high bonding quality and reliability at high temperature operation (because of its high re-melting temperature). In addition, Cu-Sn TLP facilitates high thermal and electrical conductivities, which exactly correspond to the aim of double-sided cooling. Cu-Sn TLP bonding is developed using silicon dummy dies and DBC (direct bonded copper) substrates. The feasibility of double-sided Cu-Sn TLP bonding is demonstrated by (1) proof-of-concept fabrication, (2) optical analysis using optical microscopy and SAM, and (3) material identification using SEM and EDX analysis.

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Unger, Andreas, Matthias Hunstig, Michael Brökelmann, Dirk Siepe, and Hans J. Hesse. "Cell Interconnections in Battery Packs Using Laser-assisted Ultrasonic Wire Bonding." International Symposium on Microelectronics 2020, no. 1 (September 1, 2020): 000217–21. http://dx.doi.org/10.4071/2380-4505-2020.1.000217.

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Abstract This paper presents the results of a series of bonding tests using a laser-assisted ultrasonic wire bonding process. Aluminium and copper wire, both 500 μm (20 mil) thick, were bonded to nickel-coated steel caps of type 21700 battery cells. Mechanical bond strength tests prove that laser-assisted wire bonding has significant advantages over room temperature wire bonding. For example, it can be used to reduce the process time with aluminium wire or to increase the bondability of copper wire on nickel-coated steel. The results show a direct relation between tool tip temperature and measured bond strength. The quality of the joints was effectively improved by heating the tool tip up to 430 °C. These advantages are the same as in classic thermosonic wire bonding, but without the major disadvantage of having to heat to whole package. The cell temperature was shown to remain safely below the critical 60 °C in any application.

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Lee, Chung Hyo, Young Sup Lee, Dong Choul Cho, and Chang Hee Lee. "Microstructure and Mechanical Properties of DBC on Sputter Deposited Copper on Alumina Substrate." Materials Science Forum 449-452 (March 2004): 677–80. http://dx.doi.org/10.4028/www.scientific.net/msf.449-452.677.

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The process of Direct Bonding Copper (DBC) is performed by a spinel reaction between CuO and Al2O3. In order to develop DBC on alumina substrate with high bonding strength, alumina substrate was preformed as follows: Cu was sputter-deposited on alumina substrate. Sputter-Deposited Cu (SDC) on alumina substrate was oxidized at 673K for 30min in air atmosphere and then stabilized at 1273K for 30min in N2 gas atmosphere to improve bonding strtrength between preformed alumina substrate and SDC layer. Subsequently, the Cu-foil (300µm) was bonded on preformed-alumina substrate in N2 gas atmosphere at 1342~1345K. It was found that optimum condition of DBC on preformed-alumina substrate could be successfully obtained at 1345K for 30min. Consequently, bonding strength of DBC on alumina substrate was the high value of 80N/cm. Observation and analysis of microstructure for Cu sputtered DBC showed that reaction compounds such as CuAlO2 and CuAl2O4 approved to be formed in the vicinity of interface between Cu and alumina substrate.

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Castillo, H. A., E. Restrepo-Parra, W. De La Cruz, B. Bixbi, and A. Hernandez. "CuO thin films produced for improving the adhesion between Cu and Al2O3 foils in a direct bonded copper (DBC) process." Journal of Adhesion 94, no. 8 (July 24, 2017): 615–26. http://dx.doi.org/10.1080/00218464.2017.1320222.

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Kulkarni, Srikanth, Shams Arifeen, Brian Patterson, Gabriel Potirniche, Aicha Elshabini, and Fred Barlow. "Evaluation of Ceramic Substrates for High Power and High Temperature Applications." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2011, CICMT (September 1, 2011): 000199–206. http://dx.doi.org/10.4071/cicmt-2011-wp11.

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Ceramic substrates with thin film and thick film conductor traces are widely used in microelectronic packages for high temperature operation. In high power applications where the maximum current in the package may be hundreds of amperes, much thicker conductive traces are normally required. For such applications, Direct Bonded Copper (DBC), Direct Bonded Aluminum (DBA) or Active Metal Bonded (AMB) substrates are good candidates. These substrates provide low electrical resistance and high ampacity, thereby enable the design of high power circuits for high temperature operation. The most commonly observed failure mode in these substrates is the delamination of metal layer from the ceramic. The lifetime of a ceramic substrate can be significantly reduced by the processing conditions such as maximum process temperature, and the process gases that the substrates are exposed to. It has also been shown that the propagation of cracks in the ceramic can be abated by dimpling the metal layers along edges and corners. In order to evaluate the effectiveness of these types of substrates for power applications, substrates with various combinations of metal thicknesses and ceramic composition (Al2O3 and AlN) were evaluated for delamination as a function of thermal shock cycles. These samples included both dimpled and non-dimpled metallization. The samples were thermally cycled between −40 °C and 200 °C. A few of these substrates were exposed to forming gas at 340 °C prior to thermal cycling to imitate process conditions. Sample randomization was performed to provide statistically significant data. After a certain number of thermal cycles, delamination cracks were observed to nucleate and propagate in the substrates. Data regarding the reliability of these substrates as a function of thermal shock cycles is presented in this paper, along with failure mechanisms that are commonly observed. Computer simulations were performed to understand the conditions that lead to delamination cracks, and to estimate the crack growth rates in these substrates.

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Martina, Katia, Federica Calsolaro, Alessio Zuliani, Gloria Berlier, Fernando Chávez-Rivas, Maria Jesus Moran, Rafael Luque, and Giancarlo Cravotto. "Sonochemically-Promoted Preparation of Silica-Anchored Cyclodextrin Derivatives for Efficient Copper Catalysis." Molecules 24, no. 13 (July 7, 2019): 2490. http://dx.doi.org/10.3390/molecules24132490.

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Silica-supported metallic species have emerged as valuable green-chemistry catalysts because their high efficiency enables a wide range of applications, even at industrial scales. As a consequence, the preparation of these systems needs to be finely controlled in order to achieve the desired activity. The present work presents a detailed investigation of an ultrasound-promoted synthetic protocol for the grafting of β-cyclodextrin (β-CD) onto silica. Truly, ultrasound irradiation has emerged as a fast technique for promoting efficient derivatization of a silica surface with organic moieties at low temperature. Three different β-CD silica-grafted derivatives have been obtained, and the ability of β-CD to direct and bind Cu when CD is bonded to silica has been studied. A detailed characterization has been performed using TGA, phenolphthalein titration, FT-IR, diffuse reflectance (DR), DR UV-Vis, as well as the inductively-coupled plasma (ICP) of the β-CD silica-grafted systems and the relative Cu-supported catalysts. Spectroscopic characterization monitored the different steps of the reaction, highlighting qualitative differences in the properties of amino-derivatized precursors and final products. In order to ensure that the Cu-β-CD silica catalyst is efficient and robust, its applicability in Cu(II)-catalyzed alkyne azide reactions in the absence of a reducing agent has been explored. The presence of β-CD and an amino spacer has been shown to be crucial for the reactivity of Cu(II), when supported.

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Cheng, Tzu-Hsuan, Kenji Nishiguchi, Yoshi Fukawa, B. Jayant Baliga, Subhashish Bhattacharya, and Douglas C. Hopkins. "Characterization of Highly Thermally Conductive Organic Substrates for a Double-Sided Cooled Power Module." International Symposium on Microelectronics 2020, no. 1 (September 1, 2020): 000277–81. http://dx.doi.org/10.4071/2380-4505-2020.1.000277.

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Abstract Silicon-Carbide (SiC) power devices have become a promising option for traditional Silicon (Si) due to the superior material properties. To fully take advantage of the SiC devices, a high-performance power device packaging solution is necessary. This study proposes a cost-effective double-sided cooled (DSC) 1.2 kV SiC half-bridge power module using organic epoxy-resin composite dielectric (ERCD) substrates. The high mechanical and thermal performance of the power module is achieved by the low-modulus, moderate thermal conductivity, and relatively thin (120 μm) layer of ERCD material compared with traditional metal-clad ceramic approaches. This novel organic dielectric can withstand high voltage (5 kV @ 120 μm) and operate up to 250°C continuously, which is indispensable for high power applications. The thermal modeling results show that the equivalent thermal resistance junction-to-case (Rjc_eq) of the DSC power module using dual direct bonded copper (DBC) is 17% higher than the dual ERCD configuration. Furthermore, a non-insulated DSC power module concept is proposed for maximizing thermal performance by considering thermal vias in the ERCD substrate and direct-soldered heat sink. A thought process for optimization of thermal via design is demonstrated and it shows up to 24% of improvement on thermal performance compared with the insulated DSC power module.

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Chen, Zheng, Yiying Yao, Wenli Zhang, Dushan Boroyevich, Khai Ngo, Paolo Mattavelli, and Rolando Burgos. "Development of an SiC Multichip Phase-Leg Module for High-Temperature and High-Frequency Applications." Journal of Microelectronics and Electronic Packaging 13, no. 2 (April 1, 2016): 39–50. http://dx.doi.org/10.4071/imaps.503.

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This article presents a 1,200-V, 120-A silicon carbide metal-oxide-semiconductor field-effect transistor (SiC MOSFET) phase-leg module capable of operating at 200°C ambient temperature. Paralleling six 20-A MOSFET bare dice for each switch, this module outperforms the commercial SiC modules in higher operating temperature and lower package parasitics at a comparable power rating. The module's high-temperature capability is validated through the extensive characterizations of the SiC MOSFET, as well as the careful selections of suitable packaging materials. Particularly, the sealed-step-edge technology is implemented on the direct-bonded-copper substrates to improve the module's thermal cycling lifetime. Though still based on the regular wire-bond structure, the module is able to achieve over 40% reduction in the switching loop inductance compared with a commercial SiC module by optimizing its internal layout. By further embedding decoupling capacitors directly on the substrates, the module also allows SiC MOSFETs to be switched twice faster with only one-third turn-off overvoltages compared with the commercial module.

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Kim, Dongjin, Yasuyuki Yamamoto, Shijo Nagao, Naoki Wakasugi, Chuantong Chen, and Katsuaki Suganuma. "Measurement of Heat Dissipation and Thermal-Stability of Power Modules on DBC Substrates with Various Ceramics by SiC Micro-Heater Chip System and Ag Sinter Joining." Micromachines 10, no. 11 (October 31, 2019): 745. http://dx.doi.org/10.3390/mi10110745.

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This study introduced the SiC micro-heater chip as a novel thermal evaluation device for next-generation power modules and to evaluate the heat resistant performance of direct bonded copper (DBC) substrate with aluminum nitride (AlN-DBC), aluminum oxide (DBC-Al2O3) and silicon nitride (Si3N4-DBC) ceramics middle layer. The SiC micro-heater chips were structurally sound bonded on the two types of DBC substrates by Ag sinter paste and Au wire was used to interconnect the SiC and DBC substrate. The SiC micro-heater chip power modules were fixed on a water-cooling plate by a thermal interface material (TIM), a steady-state thermal resistance measurement and a power cycling test were successfully conducted. As a result, the thermal resistance of the SiC micro-heater chip power modules on the DBC-Al2O3 substrate at power over 200 W was about twice higher than DBC-Si3N4 and also higher than DBC-AlN. In addition, during the power cycle test, DBC-Al2O3 was stopped after 1000 cycles due to Pt heater pattern line was partially broken induced by the excessive rise in thermal resistance, but DBC-Si3N4 and DBC-AlN specimens were subjected to more than 20,000 cycles and not noticeable physical failure was found in both of the SiC chip and DBC substrates by a x-ray observation. The results indicated that AlN-DBC can be as an optimization substrate for the best heat dissipation/durability in wide band-gap (WBG) power devices. Our results provide an important index for industries demanding higher power and temperature power electronics.

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Cheng, Tzu-Hsuan, Kenji Nishiguchi, Yoshi Fukawa, B. Jayant Baliga, Subhashish Bhattacharya, and Douglas C. Hopkins. "Thermal and Reliability Characterization of an Epoxy Resin-Based Double-Side Cooled Power Module." Journal of Microelectronics and Electronic Packaging 18, no. 3 (July 1, 2021): 123–36. http://dx.doi.org/10.4071/imaps.1427774.

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Abstract Wide-Band Gap (WBG) power devices have become a promising option for high-power applications due to the superior material properties over traditional Silicon. To not limit WBG devices’ mother nature, a rugged and high-performance power device packaging solution is necessary. This study proposes a Double-Side Cooled (DSC) 1.2 kV half-bridge power module having dual epoxy resin insulated metal substrate (eIMS) for solving convectional power module challenges and providing a cost-effective solution. The thermal performance outperforms traditional Alumina (Al2O3) Direct Bonded Copper (DBC) DSC power module due to moderate thermal conductivity (10 W/mK) and thin (120 mm) epoxy resin composite dielectric working as the IMS insulation layer. This novel organic dielectric can withstand high voltage (5 kVAC @ 120 μm) and has a Glass Transition Temperature (Tg) of 300°C, which is suitable for high-power applications. In the thermal-mechanical modeling, the organic DSC power module can pass the thermal cycling test over 1,000 cycles by optimizing the mechanical properties of the encapsulant material. In conclusion, this article not only proposes a competitive organic-based power module but also a methodology of evaluation for thermal and mechanical performance.

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Wentlent, Luke A., James Wilcox, and Mohammed Genanu. "Applicability of Selective Laser Reflow for Thin Die Stacking." International Symposium on Microelectronics 2018, no. 1 (October 1, 2018): 000741–47. http://dx.doi.org/10.4071/2380-4505-2018.1.000741.

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Abstract A 3-D packaging approach such as die stacking is an attractive way to package greater functionality and performance into a smaller footprint, often at a reduced overall product cost. Achieving such 3-D integration can however place significant demands on the manufacturing process, often requiring substantial production expense to bond multiple die in a sequential manner. One alternative, potentially offering significant throughput, is the use of selective laser reflow to bond stacked die. This process produces a localized heating of the stacked die sufficient to produce soldered interconnects at the bonding interface but with very short exposure times that minimize the heating of other parts of the assembly and decrease the overall duration of the bonding process. The use of a commercial infrared (IR) laser reflow instrument for the sequential attachment of thin die into a 3-D stack was considered. The bonding technology under study consists of an infrared laser coupled with a custom optics system that allows the laser beam to be shaped into a range of rectangular shapes and sizes. This allows for a single device or target area to be selectively heated and reflowed while other regions in the near vicinity are not. The target reflow area is exposed to a shaped laser beam for a combination of laser powers and exposure times according to the desired thermal profile. The top most materials absorb the IR energy of the incident laser and conduct that thermal energy down to the solder joints and into rest of the assembly. The rates of heat transfer realized depend significantly upon the sample geometry and material composition. Since this produces a highly accelerated reflow, typically 2–8 seconds, the entire process is highly transient in nature. This paper reports on the investigation into the utility of a selective area laser reflow process to sequentially bond thin die into a multi-chip stack. Thin silicon die (~60μm thick) were bonded to a 150μm thick laminate substrate using a selected area laser reflow process. The die interconnects were formed through the soldering of SnAg capped copper pedestals under the local laser heat. First level die were placed onto copper pads on the laminate and then bonded using the laser process. Subsequent die (2nd level) were placed on and bonded to gold plated nickel pad sites on the top of the first level die. At each step of the process the quality of the solder interconnects was examined using optical and electron microscopy. A range of laser profiles were utilized with several different thermal parameters: peak temperatures ranging from 235–255°C, time above liquidus between 1–3 seconds, and a fixed cooling rate of 40°C/s. Control samples of stacked die were assembled using conventional manufacturing techniques to enable direct comparisons of the interconnects and die bonding characteristics.

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Zhao, Xin, K. Jagannadham, Wuttichai Reainthippayasakul, Michael T. Lanagan, and Douglas C. Hopkins. "Characterization of Ultra-Thin Epoxy-Resin Based Dielectric Substrate for Flexible Power Electronics Applications." International Symposium on Microelectronics 2017, no. 1 (October 1, 2017): 000151–56. http://dx.doi.org/10.4071/isom-2017-tp55_094.

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Abstract Available substrate materials for power module applications has been investigated for a long time. Though Direct Bonded Copper (DBC) substrates, nowadays, have been widely applied in power electronics applications, especially power modules, due to its superior performance in mechanical ruggedness, thermal conductivity, and isolation capability. Its cost and complicated requirements during fabrication processes are always concerns in industries. At the same time, flexible electronics has become a rapidly expanding area with commercial applications including displays, medical, automotive, sensors arrays, wearable electronics, etc. This paper will initiate an investigation on a dielectric material that has potential in high power wearable electronics applications. A recently developed ultra-thin Epoxy-Resin Based Dielectric (ERBD) substrate material which is suitable for power electronic applications, is introduced. The ERBD can be fabricated with thickness as low as 80μm, with more than 5kV DC isolation capability. Its thermal conductivity is 8W/mK, higher than similar product currently available in the market. ERBD is also able to be bonded with Cu plates on both sides. In this paper, the properties of ERBD are investigated. Scanning Electron Microscope (SEM) is applied to analyze the microstructure of ERBD, and its bonding interface with Cu plates. 3-omega and Transient Thermal Reflectance methods are employed to precisely measure the thermal conductivity. Dielectric constant and loss are measured at different frequency. Simulations are applied to correct the error from the fringing effect during the measurement. The leakage current of ERBD is also measured under different voltage and temperature with DC and AC condition. Reliability tests are conducted to examine the electrical isolation and shearing strength of ERBD. The suitability of ERBD for potential flexible power electronics application is discussed based on the results from investigation of properties of the dielectric.

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Bach, Hoang Linh, Daniel Dirksen, Christoph Blechinger, Tobias Maximilian Endres, Christoph Friedrich Bayer, Andreas Schletz, and Martin März. "Stackable SiC-Embedded Ceramic Packages for High-Voltage and High-Temperature Power Electronic Applications." Journal of Microelectronics and Electronic Packaging 16, no. 4 (October 1, 2019): 176–81. http://dx.doi.org/10.4071/imaps.952440.

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Abstract This study encompasses the development of a high-voltage and high-temperature–capable package for power electronic applications based on the embedding of silicon carbide (SiC) semiconductor devices in the ceramic circuit carrier such as the direct bonded copper (DBC) substrate. By sealing semiconductor devices into DBC substrates, high temperature, high voltage, and high current capability as well as high corrosion resistance can be achieved compared with the state-of-the-art printed circuit board (PCB) embedding technology. The power devices are attached with high-temperature stable solder and sinter material and are surrounded by thermal conductive ceramic and high-temperature–capable potting materials that enable the complete package to operate at 250°C or above. Furthermore, the single embedded packages can be stacked together to multilevel DBC topologies with increased voltage blocking characteristics. Thus, current limits of the PCB and low-temperature cofired ceramic–based multilayer solutions are exceeded and will be confirmed in the course of this study. This package is designed to carry out the maximal performance of SiC and future wide bandgap devices. It is a promising solution not only for applications in harsh ambient environments such as aerospace and turbine, geothermal well logging, and downhole oil and gas wells but also for hybrid electric/electric vehicle and energy conversion.

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De Villiers, Johan PR, Delphin Mulange, and Andrie Mariana Garbers-Craig. "The Effect of Titanium Oxide Additions on the Phase Chemistry and Properties of Chromite-Magnesia Refractories." Ceramics 3, no. 1 (March 20, 2020): 127–43. http://dx.doi.org/10.3390/ceramics3010013.

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The microstructure of a direct-bonded chromite-magnesia refractory brick, typically used in copper and platinum converters, was modified by adding different amounts of nano-size TiO2 to the raw material mixture. Bricks with 0, 1, 3, 5, and 7 mass% TiO2 were produced and compared in terms of spinel formation; the role of the tetravalent cation Ti4+ in the bonding phase; as well as changes in density, porosity, thermal expansion, and internal stress. This was done through a comprehensive XRD and SEM-EDS study. It was found that Ti is accommodated in the secondary spinel that has formed, where Mg in excess of unity in the tetrahedral site combines with an equal amount of Ti in the octahedral sites to maintain charge balance. The 1 mass% TiO2 brick had the lowest bulk density (but not significantly different from the original chromite-magnesia brick), the smallest difference in unit cell volumes between the primary and secondary spinels, and the lowest stress arising from the smallest difference in linear thermal expansion coefficients of the phases present. The calculated porosities correspond well with experimentally determined apparent porosity values, whereas the linear thermal expansion coefficients calculated at 1392K are similar to the values measured from 293 to 1273 K.

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Colacio, Enrique, José Suárez-Varela, José M. Dominguez-Vera, Juan C. Avila-Rosón, Miguel A. Hidalgo, and Daniel Martín-Ramos. "A novel example of a direct interaction between the carbonyl oxygen, O(6), of a N(7)-bonded 6-oxopurine and copper(II). Preparation, spectroscopic study and crystal structure of bis(8-methylthiotheophyllinato)bis(pyridine)copper(II)." Inorganica Chimica Acta 202, no. 2 (December 1992): 219–24. http://dx.doi.org/10.1016/s0020-1693(00)86837-1.

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Noh, Seungjun, Hao Zhang, and Katsuaki Suganuma. "Heat-Resistant Microporous Ag Die-Attach Structure for Wide Band-Gap Power Semiconductors." Materials 11, no. 12 (December 12, 2018): 2531. http://dx.doi.org/10.3390/ma11122531.

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In this work, efforts were made to prepare a thermostable die-attach structure which includes stable sintered microporous Ag and multi-layer surface metallization. Silicon carbide particles (SiCp) were added into the Ag sinter joining paste to improve the high-temperature reliability of the sintered Ag joints. The use of SiCp in the bonding structures prevented the morphological evolution of the microporous structure and maintained a stable structure after high temperature storage (HTS) tests, which reduces the risk of void formation and metallization dewetting. In addition to the Ag paste, on the side of direct bonded copper (DBC) substrates, the thermal reliability of various surface metallizations such as Ni, Ti, and Pt were also evaluated by cross-section morphology and on-resistance tests. The results indicated that Ti and Pt diffusion barrier layers played a key role in preventing interfacial degradations between sintered Ag and Cu at high temperatures. At the same time, a Ni barrier layer showed a relatively weak barrier effect due to the generation of a thin Ni oxide layer at the interface with a Ag plating layer. The changes of on-resistance indicated that Pt metallization has relatively better electrical properties compared to that of Ti and Ni. Ag metallization, which lacks barrier capability, showed severe growth in an oxide layer between Ag and Cu, however, the on-resistance showed fewer changes.

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Bach, Hoang Linh, Daniel Dirksen, Christoph Blechinger, Tobias Maximilian Endres, Christoph Friedrich Bayer, Andreas Schletz, and Martin März. "Stackable SiC Embedded Ceramic Packages for High Voltage and High Temperature Power Electronics Applications." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2019, HiTen (July 1, 2019): 000028–33. http://dx.doi.org/10.4071/2380-4491.2019.hiten.000028.

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Abstract This paper encompasses the development of a high voltage and high temperature capable package for power electronic applications based on the embedding of SiC (silicon carbide) semiconductor devices in ceramic circuit carrier such as direct bonded copper (DBC) substrate. By sealing the semiconductor devices into DBC substrates, high temperature, high voltage and high current capability as well as high corrosion resistance can be achieved compared to state-of-the-art PCB (printed circuit board) embedding technology. The power devices are attached with high temperature stable solder and sinter material, and are surrounded by thermal conductive ceramic and high temperature capable potting materials that enable the complete package to operate at 250 °C or above. Furthermore, the single embedded packages can be stacked together to multilevel DBC topologies with increased voltage blocking characteristics. Thus, current limits of PCB and LTCC (low-temperature co-fired ceramic) based multilayer solutions are exceeded and will be confirmed in the course of this study. This package is designed to carry out the maximal performance of SiC and future WBG (wide band-gap) devices. It is a promising solution for applications in harsh ambient environment such as aerospace and turbine, geothermal well logging, down hole-well oil & gas, but also applicable for HEV/EV (hybrid electric/electric vehicle) and energy conversion.

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Yahyaee, Ali, Amir Bahman, and Frede Blaabjerg. "A Modification of Offset Strip Fin Heatsink with High-Performance Cooling for IGBT Modules." Applied Sciences 10, no. 3 (February 7, 2020): 1112. http://dx.doi.org/10.3390/app10031112.

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For reliability and thermal management of power devices, the most frequently used technique is to employ heatsinks. In this work, a new configuration of offset strip fin heatsink based on using the concept of curvy fins and U-turn is proposed with the aim of improving the heat transfer performance. With this aim, a three-dimensional model of heatsink with Silicon Insulated-Gate Bipolar Transistors (IGBTs) and diodes, solder, Direct Bonded Copper (DBC) substrate, baseplate and thermal grease is developed. Richardson’s extrapolation is used for increasing the accuracy of the numerical simulations and to validate the simulations. To study the effectiveness of the new offset design, results are compared with conventional offset strip fin heatsink. Results show that in aspects of design of heatsinks (including heat transfer coefficient, maximum chip temperature and thermal resistance), the new introduced model has advantages compared to the conventional offset strip fin design. These enhancements are caused by the combination of the longer coolant passage in the heatsink associated with generation of disturbance and recirculation areas along the curvy fins, creation of centrifugal forces in the U-turn, and periodic breaking up boundary layers. Also, it is shown that due to narrower passage and back-and-forth route, the new introduced design can handle the hot spots better than conventional design.

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Dhillon, Jaidev, Sachin Passi, and Ajay Chhabra. "Effect of Reinforcement on the Fracture Resistance of Endodontically Treated Molars by Various Bonded Restorations-An In Vitro Study." Dental Journal of Advance Studies 03, no. 02 (August 2015): 103–11. http://dx.doi.org/10.1055/s-0038-1672023.

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Abstract Objective: To compare and evaluate the fracture resistance of endodontically treated molars reinforced with various bonded restorations and to study the type of fractures in various restorations. Methods: Forty extracted mandibular molars were endodontically treated. MOD (Mesio-Occluso-Distal) cavities were prepared and Mesio-Buccal cusp was reduced in all to provide cuspal coverage. All the teeth were then divided into 4 groups. The cavities in group 1(control) were filled with high copper amalgam. Group 2 was restored with direct resin composite. In group 3 after the priming and bonding procedures as in group 2, cavity surfaces were coated with flowable resin composite. Before curing a piece of polyethylene ribbon fiber was cut and coated with adhesive resin and was embedded inside the flowable composite. The resin composite was cured with visible light cure (VLC) gun. For group 4, restorations were done according to the recommendations provided by the manufacturers of SR Adoro (Ivoclar-Vivadent, Schaan, Liechtenstein) composite material. Compressive fracture strength test was performed after at least 24 hours of the fabrication of the specimens, by application of compressive loading in a Universal testing machine, applied on the occlusal aspect of each specimen with a steel bar. The mean loads necessary to fracture were recorded in Newton and the results were statistically analyzed. Results: Group 4 (indirect composite inlay) had the greater fracture resistance and group 1(Amalgam) had the poorest. Difference between group 1 and 3, group 1 and 4, group 2 and 4 were statistically significant. No statistically significant difference was found between group 1 and 2, group 2 and 3, group 3 and 4. Predominant type of fracture in group 1 and 3 was fracture of tooth below cemento enamel junction at tooth restoration interface without mesio buccal cusp involvement. In group 2 and 4, predominant fractures were of tooth below cemento enamel junction through center of restoration without mesio–buccal cusp involvement.

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Journal articles on the topic 'Direct bonded copper'

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