Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement
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University of Akron / OhioLINK
2009
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=akron1248114951 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-akron12481149512021-08-03T05:25:56Z Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement Drews, Aaron M. Chemical Engineering Mechanical Engineering solder composite coefficient of thermal expansion nanofiber titania Solder is used in nearly all electronic packages to provide mechanical, electrical and thermal contact between various components. The mismatch between the components‟ coefficient of thermal expansion results in thermal stresses which can damage components or connections and render the circuit board useless. In order to reduce this mismatch, a novel fabrication method was developed to produce composites of solder and ceramic reinforcement are presented. Composites were prepared by uniaxial compression of 63Sn/37Pb solder powder and various morphologies of titania reinforcement. A solution of poly(vinyl pyrrolidone), ethanol and tetraisopropyl titanate was used to produce beaded nanofibers; acetic acid was added to the solution in order to lower the dielectric constant of the solution and produce smooth nanofibers. Ultrasonication was used to cut the calcined, electrospun nanofibers to consistent lengths of about 6μm. Optical microscopy, electron microscopy and x-ray diffraction were used to characterize the size, shape and crystalline phase of the filler. Analysis of the different fillers revealed three distinct categories of shape and size, including spherical titania powder (6.5μm diameter), smooth cylindrical titania nanofibers (150nm diameter) and a mixture of 80wt% spherical beaded titania (3.5μm diameter) with 20wt% cylindrical nanofibers (400nm diameter). A 25% reduction in the coefficient of thermal expansion of the composite was achieved regardless of the shape, size or quantity of reinforcement. The melting and freezing points of the composite samples were not statistically different from that of pure solder but the specific gravity was lowered by about 1.5%. During reflow it was observed that the majority of the filler was expelled from the molten solder core. The differences in density between the filler and solder provide a buoyant force that tends to expel the less dense titania from the more dense molten solder. A force balance on a rigid cylinder floating at a liquid-gas interface revealed that the filler is dominated by surface tension forces; once the filler reaches the surface of the molten solder its equilibrium position is located primarily in the surrounding gas. Therefore a novel recommendation is presented to investigate neutrally buoyant filler in order to prevent filler expulsion during reflow. 2009-10-05 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1248114951 http://rave.ohiolink.edu/etdc/view?acc_num=akron1248114951 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Chemical Engineering Mechanical Engineering solder composite coefficient of thermal expansion nanofiber titania |
| spellingShingle |
Chemical Engineering Mechanical Engineering solder composite coefficient of thermal expansion nanofiber titania Drews, Aaron M. Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement |
| author |
Drews, Aaron M. |
| author_facet |
Drews, Aaron M. |
| author_sort |
Drews, Aaron M. |
| title |
Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement |
| title_short |
Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement |
| title_full |
Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement |
| title_fullStr |
Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement |
| title_full_unstemmed |
Control of Thermal Expansion Coefficient of a Metal Powder Composite via Ceramic Nanofiber Reinforcement |
| title_sort |
control of thermal expansion coefficient of a metal powder composite via ceramic nanofiber reinforcement |
| publisher |
University of Akron / OhioLINK |
| publishDate |
2009 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=akron1248114951 |
| work_keys_str_mv |
AT drewsaaronm controlofthermalexpansioncoefficientofametalpowdercompositeviaceramicnanofiberreinforcement |
| _version_ |
1719420028745416704 |