Name ____________________________

EE 4143/5143 Design of Digital Circuits

Quiz #2

Please answer the following questions:

1. In SILICON RUN II we saw individual chips placed into packages followed by the assembly of packaged chips onto printed circuit boards and finally the assembly of complete systems from a set of printed circuit boards, power supplies, and other components. We also saw that testing occurred at several stages of this process. Why is testing done throughout the manufacturing process rather than simply after final system assembly?

2. Some of the electrical testing was performed at higher-than-normal temperatures or at higher-than-normal voltages. Why would this testing be performed under such stressful conditions even before the chips, boards, or systems have left the manufacturing area?

3. Virtually all of the automated pieces of manufacturing equipment shown in SILICON RUN II are controlled by computers. For example, the die attach machine uses a computer-controlled camera to "look at" the individual dice that are mounted on the sticky tape and then uses a computer-controlled arm to pick up the selected die and mount it on the adhesive of the lead frame. Describe a number of the decisions and actions that the computer must control to successfully complete this process.

4. Printed circuit boards were assembled using both surface mount and through-hole processes. Describe the differences between these two mounting approaches.

5. The four basic elements of a computer are input devices, output devices, the memory, and the central processing unit. Which of these units is generally thought of a being the "brain" of the computer? Which of these units is sued to store the data and program instructions?

6. List several examples of "input devices" that send signals to the computers that control the automated manufacturing equipment shown in SILICON RUN II. What are examples of "output devices" on these same pieces of equipment?

7. Application software programs control the computer so that it performs tasks that are of interest or used to the person using the computer. List a variety of tasks performed by application programs.

8. With their large number of solder bonding pads and high density signal carrier substrates, multichip units (MCUs) allow chips to be packaged closer to one another when compared to conventional printed circuits boards. Why is that an advantage in high speed computer systems?

9. We saw two processes used for electrically connecting signals on the chip to the interconnection wires closest to the chip: wire bonding and tape automated bonding (TAB). What are some advantages of tape automated bonding compared to conventional wire bonding?

10. Electrical signals can travel no faster than the speed of light and often travel slower than this due to resistance, capacitance, and inductance encountered in real systems. The speed of light is 3 x 10⁸ meters/second. What is the maximum distance that an electrical signal can travel in 100 picoseconds?