Academic literature on the topic 'Fabrication and finishing- Aluminium and copper'

Electroless metal/alloy deposition can be an efficient process in certain areas of microelectronic fabrication. In fact, it is often easier to obtain coatings of uniform thickness and composition using electroless deposition than with electrodeposition, since one does not have the current density uniformity problem of the latter. For example, we were able to develop a Ni(P) process as a replacement for the final aluminum interconnect level, significantly decreasing wafer processing cycle time, by selectively depositing a Ni(P) capping layer on the Cu bitline wiring level. In STTM MRAM, we successfully employed this Ni(P) capping process to enable the evaluation of memory state retention via functional testing in an air atmosphere at elevated temperatures (1). However, there is a need to explore materials + deposition methods for rapidly developing fields, such as Quantum computing, e.g., materials with superconducting properties. Conventional electroless metal deposition, utilizing a separate reducing agent, can deposit materials with unique and useful properties, such as phosphorus-containing alloys in the case of hypophosphite reducing agents. This talk discusses work we have carried out on electroless tin deposition, including aspects of electroless solution preparation and stability, copper substrate surface preparation and catalyzation, and the mechanisms of electroless deposition and solution decomposition. Electroless processes can deposit a limited number of materials, especially pure metals. This is in part due to conventional electroless processes requiring catalytically active surfaces both to initiate the deposition reaction and to sustain it, the heterogeneous oxidation of the reducing agent being a kinetically hindered process, often with multiple reaction pathways (2). Though not possessing good catalytic activity due to its Periodic Table related, p -block element status, pure Sn, an environmentally robust, superconducting metal, can be electrolessly deposited through a disproportionation reaction involving stannous ions (3) in an alkaline aqueous medium. We achieved electroless Sn deposition rates of up to 8 – 9 μm/hr for tartrate-citrate complexed electroless Sn solutions in the temperature range 80 – 85 ⁰C with sodium and potassium hydroxides to adjust alkalinity. We found that either in-house formulated, or commercially available, immersion Sn solutions deposited a uniform Sn catalyst layer (≤ 0.5 μm) to initiate the electroless Sn deposition reaction on copper; however, improperly formulated immersion Sn solutions rapidly developed precipitates due to tin ion hydrolysis. The biggest technical challenge was minimizing unwanted electroless deposition of tin in bulk solution, i.e., deposition not associated with the catalytically active substrate surface. Tin oxide (SnO) is known to be metastable at ambient conditions and to decompose at temperatures above 300 ⁰C with “noticeable rate” into Sn and SnO2 (4). Thus, removal of filterable hydrolysis products of Sn(II) following solution preparation was important, but not always sufficient, for obtaining solutions that were viable for several days of use. The reasons for, and mechanisms of, electroless Sn solution decomposition do not appear to have been adequately addressed in the literature. We will show SIMS analysis of both immersion and electroless Sn layers along with synchrotron X-Ray analysis results of immersion Sn catalyst films on Cu to determine the extent of Sn-Cu intermetallic formation following their formation. We will discuss the current understanding of the mechanism of electroless Sn deposition including that of concomitant H2 gas evolution. We will conclude with contrasting the Ni(P) and Sn electroless processes in terms of ease of operation and reliability for routine processing. † Present address: Solvay, 1937 West Main Street, Stamford 06902, CT. ‡ Quantum intern at the IBM TJ Watson Research Center, Summer 2019, 2020 and 2021. [1]. E. J. O'Sullivan, C. Camagong et al., 2019 Meet. Abstr. MA2019-02 916; https://doi.org/10.1149/MA2019-02/15/916. [2]. E. J. O'Sullivan, Ch 5, Advances in Electrochemical Science and Engineering, Volume 7, https://doi.org/10.1002/3527600264.ch5. [3]. A. Molenaar and J. W. G. de Bakker, 1989, J. Electrochem. Soc. 136, 378 and refs therein; H. Koyano, M. Kato, and M. Uchida, 1991, Plating and Surface Finishing, 78, 68-74 and refs therein. [4]. H. Giefers et al, 2005, Solid State Ionics, 176, 199-207; https://doi.org/10.1016/j.ssi.2004.06.006. Acknowledgements The authors gratefully acknowledge the efforts of the staff of the Microelectronics Research Laboratory (MRL) at the IBM T. J. Watson Research Center, where some of the fabrication work described in this talk was carried out.

An Experimental investigation on the thermal performance of copper with aluminium based finned heat sinks for electronics cooling system was studied. The heat sinks have different material proportions containing major constituent of aluminium and minor constituent of copper. Considered with straight finned heat sink for the experiments for its easiness in fabrication and efficient heat transfer properties. The observational results for aluminium with copper alloy are compared with pure aluminium heat sink. Heat sink geometry, fin pitch and its height were taken from the commercially available heat sinks. In this research work best heat sink geometry is chosen and cooked up with different volume of copper added with aluminium. Selected four different spots of heat sinks and the temperature raising characteristics were measured for natural convection. also the temperature is raised to a fixed temperature and the temperature lowering characteristics were measured in forced convection as the air circulation takes more heat to keep the heat sink temperature within the desired level.

Demand of powerful & fast computing requires the packaging configured with finer lines. The current requirement for Line and Space (L/S) is around 10μm/10μm, it will go down to less than that and 5 μm/5 μm is industry's target in our site. To achieve this miniaturization, a number of improvements are ongoing in equipment, material and chemical for surface finishing process. It seems there is a threshold which requires non-contiguous improvement for the miniaturization. The improvement in surface finishing process requires finer surface roughening for Dielectric material, selective dissolution of metals, or same metal made by different method such as Electroless copper and Electroplated copper, which never exist in the industry. In this paper, advanced chemical processes for semi-additive process (SAP) to fabricate PWB with fine line formation targeting L/S =5μm/5μm are reported. The series of improvements of chemical process enables confidence to manufacture fine lines which L/S=5μm/5μm using finer surface roughening of Electroless copper seed for better Dry Film Resist (DFR) formation, better stripping of the DFR, selective dissolution of Electroless copper seed, finer surface roughening for Solder Mask application, etc.

The influence of alloying elements, deliberate or otherwise, and material processing on the performance of aluminium during surface treatment and finishing are considered. Thus, with a significant focus on copper, but with consideration of other elemental additions, the behaviour of aluminium during growth of oxide at ambient temperature, etching or pickling, conversion coating and anodizing, essential processes for generation of fit-for-purpose products, is highlighted. Further, such processes generate, modify or transform the initially present air-formed alumina film. Consequently, with knowledge of the phenomena proceeding at the alloy/film and film/environment interfaces and those within anodic or other films, the possibility of controlling features of nanoscale dimensions for improved performance arises. For example, deliberate selection of alloying elements enables control of nanotextures formed at treated surfaces, and formation of compositionally and morphologically modified films as well as generation of nanoparticles with various functional properties.

In this study, intelligent eco-diapers are made by combining antibacterial yarns coated with quaternary ammonium salts with conductive yarns to improve caretaking for urinary incontinence. The combination of conductive yarns and sensors can detect the moisture content in eco-diapers, and an alarm is sent when moisture is significant. A wireless module is used to send detected signals to a smartphone or tablet PC via the Internet. This concept is used for a scenario in which nurses do not randomly check on patients in a long-term care institution. When used offline, eco-diapers can send caregivers an alarm for the need to change diapers via cell phones. The diameters of the copper and silver-plated copper fibers are 0.08 and 0.10 mm, respectively. Cotton yarns are twisted with copper and silver-plated copper fibers to form the conductive yarns, which are 0.12 mm in diameter. Moreover, 30-count cotton and 150 D nylon yarns are coated with quaternary ammonium salt via dyeing and finishing processes to form antibacterial yarns. In the current study, intelligent eco-diapers are tested for their electrical and antibacterial properties as specified by AATC and JISL test standards.

Ce travail de thèse vise à démontrer la faisabilité de la réparation de pièces de fonderie à haute performance et haute valeur ajoutée faites d’un alliage aluminiumcuivre en utilisant un procédé de fabrication additive métallique par projection de poudre avec fusion laser dénommé Laser Metal Deposition. Ces alliages présentent notamment une faible soudabilité et ne peuvent donc être réparés de façon fiable par des procédés traditionnels de soudage à l’arc. Afin de permettre l’utilisation de ce procédé innovant pour la réparation de pièces en alliage Al-Cu, des difficultés majeures ont dû être levées en ce qui concerne notamment la coulabilité des poudres Al-Cu et leur comportement en fusion et en solidification, ainsi que la méthodologie de réparation pour effectuer l’opération de façon fiable et efficace. Des travaux expérimentaux, théoriques et numériques ont permis d’élucider ces aspects et in fine de permettre l’utilisation de ce matériau avec ce procédé de fabrication additive. Une méthode de réparation comprenant un algorithme de segmentation robuste a également été développée et mise en oeuvre afin d’automatiser le processus de réparation en permettant la génération de trajectoire sur la base de mesures 3D in-situ. Des réparations de pièces de fonderie en aluminium-cuivre ont ainsi pu être effectuées avec le procédé Laser Metal Deposition, et les analyses métallographiques montrent que les rechargements effectués avec ce procédé offrent une microstructure très fine avec un taux de ségrégation chimique limité et peu de fissuration à chaud
The present thesis aims at demonstrating the feasibility of repairing high performance castings made of an aluminiumcopper alloy using the Laser Metal Deposition metal additive manufacturing process. These alloys present a low weldability and thus cannot be reliably repaired with manual arc-welding processes. To instead use this innovative additive manufacturing process for repair applications and thereby improve upon current methods, major challenges had to be overcome regarding the flowability and solidification behavior of this aluminium alloy powder as well as the overall methodology to reliably and efficiently perform the repair operation. Experimental, theoretical and numerical studies allowed to elucidate some of these aspects and eventually enabled the use of a 224.0 casting aluminium alloy with the Laser Metal Deposition metal additive manufacturing process. A repair methodology including a robust segmentation algorithm was also developped to automate the repair process and permit the generation of toolpaths based on raw in-situ 3D scanning measurements. Repairs of high performance aluminium-copper castings were carried out successfully as no major lack of fusion, bonding or cracking defects were observed. A metallographic analysis showed that the aluminium deposits obtained by Laser Metal Deposition generally offer a refined microstructure with limited solute segregation and hot cracking

Ce travail est consacre a l'elaboration, la caracterisation structurale et microstructurale, ainsi qu'a l'etude de la conductivite electrique de couches minces de l'alliage quasicristallin alcufe. Les echantillons ont ete fabriques par evaporation sequentielle des elements constitutifs de l'alliage, puis traitement thermique. Nous avons etudie les chemins reactionnels conduisant a la phase quasicristalline par diffraction des rayons x lors du traitement thermique de tricouches metalliques. La phase quasicristalline peut etre obtenue quelle que soit la sequence d'empilement du tricouche. Nous montrons que la premiere phase qui cristallise est al#2cu y compris lorsque la couche de fer est placee entre celles de al et cu. Dans ce cas on observe la formation d'alliages binaires al, cu de part et d'autre de la couche de fe, indiquant une diffusion croisee des deux elements al et cu a travers celle-ci. A plus haute temperature le fer participe aux reactions, s'alliant d'abord avec l'aluminium, avant que des phases ternaires n'apparaissent, qui conduisent ensuite au quasicristal. Nous nous sommes ensuite concentre sur l'elaboration de couches tres minces (jusqu'a 125 angstroms). Nous avons pu fabriquer des couches quasicristallines tres minces compactes et d'epaisseur homogene. Ainsi nous avons pu etudier la conductivite electrique des echantillons en fonction de leur epaisseur. A basse temperature, les dependances en temperature et en champ magnetique de la conductivite font apparaitre une transition vers un regime bidimensionnel, qui est une signature de la presence d'effets d'interferences quantiques. Cette etude confirme leur importance dans la conductivite des quasicristaux, et permet de preciser les valeurs des parametres microscopiques qui la regissent.