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Engineering Materials

Subject : engineering
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. 1. Yield = ratio of functional chips to total # of chips - Most yield loss during wafer processing - b/c of complex 2. Reliability - No device has infinite lifetime. Statistical methods to predict expected lifetime - Failure mechanisms: Diffusion reg






2. No appreciable plastic deformation. The crack propagates very fast; nearly perpendicular to applied stress. Cracks often propagate along specific crystal planes or boundaries.






3. Specific heat = energy input/(mass*temperature change)






4. 1. Imperfections increase resistivity - grain boundaries - dislocations - impurity atoms - vacancies 2. Resistivity - increases with temperature - wt% impurity - and %CW






5. Measures Hardness - No major sample damage - Each scales runs to 130 but only useful in range 20-100 - Minor load is 10 kg - Major load: 60 kg (diamond) - 100 kg (1/16 in. ball) - 150 kg (diamond)






6. Another optical property - Depends on the wavelength of the visible spectrum.






7. Materials change size when temperature is changed






8. These are liquid crystal polymers- not your normal "crystal" -Rigid - rod shaped molecules are aligned even in liquid form.

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9. (sigma)=F/Ai (rho)=(rho)'(1+(epsilon))






10. Is analogous to toughness.






11. Flaws and Defects - They concentrate stress locally to levels high enough to rupture bonds.






12. A measure of the ease with which a B field can be induced inside a material.






13. They are used to assess properties of ceramics & glasses.






14. Transmitted light distorts electron clouds - The velocity of light in a material is lower than in a vacuum - Adding large ions to glass decreases the speed of light in the glass - Light can be "bent" (or refracted) as it passes through a transparent






15. Without passing a current a continually varying magnetic field will cause a current to flow






16. These materials are relatively unaffected by magnetic fields.






17. Emitted light is in phase






18. 1. Tensile (opening) 2. Sliding 3. Tearing






19. Becomes harder (more strain) to stretch (elongate)






20. Growth of an oxide layer by the reaction of oxygen with the substrate - Provides dopant masking and device isolation - IC technology uses 1. Thermal grown oxidation (dry) 2. Wet Oxidation 3. Selective Oxidation






21. Metals are good conductors since their _______is only partially filled.






22. # of thermally generated electrons = # of holes (broken bonds)






23. Superconductors expel magnetic fields - This is why a superconductor will float above a magnet.






24. With Increasing temperature - the saturation magnetization diminishes gradually and then abruptly drops to zero at Curie Temperature - Tc.






25. Digitalized data in the form of electrical signals are transferred to and recorded digitally on a magnetic medium (tape or disk) - This transference is accomplished by a recording system that consists of a read/write head - "write" or record data by






26. Not ALL the light is refracted - SOME is reflected. Materials with a high index of refraction also have high reflectance - High R is bad for lens applications - since this leads to undesirable light losses or interference.






27. Dramatic change in impact energy is associated with a change in fracture mode from brittle to ductile.






28. Degree of opacity depends on size and number of particles - Opacity of metals is the result of conduction electrons absorbing photons in the visible range.






29. Measures Hardness 1. psia = 500 x HB 2. MPa = 3.45 x HB






30. Because of ionic & covalent-type bonding.






31. These materials are "attracted" to magnetic fields.






32. Cp: Heat capacity at constant pressure Cv: Heat capacity at constant volume.






33. Defines the ability of a material to resist fracture even when a flaw exists - Directly depends on size of flaw and material properties - K(ic) is a materials constant






34. A three terminal device that acts like a simple "on-off" switch. (the basis of Integrated Circuits (IC) technology - used in computers - cell phones - automotive control - etc) - If voltage (potential) applied to the "gate" - current flows between th






35. Created by current through a coil N= total number of turns L= length of turns (m) I= current (ampere) H= applied magnetic field (ampere-turns/m) Bo= magnetic flux density in a vacuum (tesla)






36. - The emission of light from a substance due to the absorption of energy. (Could be radiation - mechanical - or chemical energy. Could also be energetic particles.) - Traps and activator levels are produced by impurity additions to the material - Whe






37. Ohms Law: voltage drop = current * resistance






38. Growing interconnections to connect devices -Low electrical resistance - good adhesion to dielectric insulators.






39. The size of the material changes with a change in temperature - polymers have the largest values






40. If a material has ________ - then the field generated by those moments must be added to the induced field.






41. Increase temperature - no increase in interatomic separation - no thermal expansion






42. Width of smallest feature obtainable on Si surface






43. Light Amplification by Stimulated Emission of Radiation






44. heat flux = -(thermal conductivity)(temperature gradient) - Defines heat transfer by CONDUCTION

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45. 1. Data for Pure Silicon - electrical conductivity increases with T - opposite to metals






46. Transformer cores require soft magnetic materials - which are easily magnetized and de-magnetized - and have high electrical resistivity - Energy losses in transformers could be minimized if their cores were fabricated such that the easy magnetizatio






47. 1. Diamagnetic (Xm ~ 10^-5) - small and negative magnetic susceptibilities 2. Paramagnetic (Xm ~ 10^-4) - small and positive magnetic susceptibilities 3. Ferromagnetic - large magnetic susceptibilities 4. Ferrimagnetic (Xm as large as 10^6) - large m






48. 1. Insulators: Higher energy states NOT ACCESSIBLE due to gap 2. Semiconductors: Higher energy states separated by a smaller gap.






49. Second phase particles with n > glass.






50. The ability of a material to transport heat - Atomic Perspective: Atomic vibrations and free electrons in hotter regions transport energy to cooler regions - Metals have the largest values