Chapter 22 Materials Selection and Design Considerations
Chapter 22 Materials Selection and Design Considerations
Chapter 22 Materials Selection and Design Considerations
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W130 • <strong>Chapter</strong> <strong>22</strong> / <strong>Materials</strong> <strong>Selection</strong> <strong>and</strong> <strong>Design</strong> <strong>Considerations</strong><br />
REFERENCES<br />
General<br />
<strong>and</strong> exposure rate. Equations were provided that allow computation of these<br />
parameters, <strong>and</strong> values were determined for seven common protective glove materials.<br />
Only two materials {multilayered [poly(vinyl alcohol)/polyethylene] <strong>and</strong> Viton<br />
rubber} were deemed satisfactory for this application.<br />
<strong>Materials</strong> for Integrated Circuit Packages<br />
<strong>Materials</strong> utilized for the integrated circuit package incorporating the leadframe<br />
design were the topics of the final case study. An IC chip is bonded to the leadframe<br />
plate using either a eutectic solder or an epoxy resin. The leadframe material<br />
must be both electrically <strong>and</strong> thermally conductive, <strong>and</strong>, ideally, have a<br />
coefficient of thermal expansion that matches the IC chip material (i.e., silicon<br />
or gallium arsenide); copper alloys are commonly used leadframe materials. Very<br />
thin wires (preferably of gold, but often of copper or aluminum) are used to make<br />
electrical connections from the microscopic IC chip contact pads to the leadframe.<br />
Ultrasonic microjoining welding/brazing techniques are used where each<br />
connection joint may be in the form of either a ball or wedge. The final step is<br />
package encapsulation, wherein this leadframe–wire–chip assembly is encased in<br />
a protective enclosure. Ceramic glasses <strong>and</strong> polymeric resins are the most common<br />
encapsulation materials. Resins are less expensive than glasses <strong>and</strong> require<br />
lower encapsulation temperatures; however, glasses normally offer a higher level<br />
of protection.<br />
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<strong>and</strong> Applications, 3rd edition, Butterworth-<br />
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of Machine Component <strong>Design</strong>, 4th edition,<br />
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Shigley, J., C. Mischke, <strong>and</strong> R. Budynas, Mechanical<br />
Engineering <strong>Design</strong>, 7th edition, <strong>Chapter</strong> 10,<br />
McGraw-Hill Companies, New York, 2004.<br />
Artificial Total Hip Replacement<br />
Black, J. <strong>and</strong> G. Hastings (Editors), H<strong>and</strong>book<br />
of Biomaterial Properties, Chapman & Hall,<br />
London, 1998.<br />
Davis, J. R., H<strong>and</strong>book of <strong>Materials</strong> for Medical<br />
Devices, ASM International, <strong>Materials</strong> Park,<br />
OH, 2003.<br />
Chemical Protective Clothing<br />
Forsberg, K. <strong>and</strong> S. Z. Mansdorf, Quick <strong>Selection</strong><br />
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edition, John Wiley & Sons, Hoboken, NJ,<br />
2003.<br />
<strong>Materials</strong> for Integrated Circuit Packages<br />
Electronic <strong>Materials</strong> H<strong>and</strong>book, Vol. I, Packaging,<br />
ASM International, <strong>Materials</strong> Park, OH, 1989.<br />
Grovenor, C. R. M., Microelectronic <strong>Materials</strong>, Institute<br />
of Physics Publishing, Bristol, 1989.<br />
Reprinted by Adam Hilger, Ltd., Bristol, UK.