Mechanical Design and Optimization of Electronic Systems - Assignment Example

Mechanical Design and Optimization of Electronic System The major difference between the inner layer process of the PCB and the outer layer process of the PHT is thatPHT provides conductive connections between layers and mechanical support and also there is activation, DE smear, the hole conditioning, micro etch while in PCB there is cutting, beveling, pre-treatment, roller coating, exposure DES Line, I/L holes formation. 2. The photosensitive metal would have a reliability problem due to the charging up effect which results to the fundamental problem associated with single photoelectron detection. 3. The interconnect types in:- 1): Gold ball bearing bonding 2): Aluminum wedge bonding. 3). Gold wire is bonded using ultra sound bonding between the IC bond pad and the matching package pad 4).its manufacturing technology is much higher. 5).tape automated bonding (TAP) is an interconnect technology between the substrate and with copper leads adapted to the IC pads instead of single wires. 4. Statement True/false The most widely used printed wiring board material is an epoxy-glass composite known as FR4 F The most common technique for interconnecting die to lea frames in standard commercial plastic encapsulated microcircuits is wire bonding T At low normal forces, the contact resistance can be reduced by increasing the normal force T Copper interconnects and polyimide interval dielectrics are replacing aluminum and silicon dioxide respectively because their higher resistance and higher dielectric constant increase signal speed in chips T Qualification test is performed before manufacturing and quality assurance test is performed after manufacturing F An acceleration test can be used for a quality assurance test T Product A will have a longer life than product B regardless of the operating conditions if product A is known to be more reliable the product B under a typical operating condition F Only wear out mechanization can be accelerated by an accelerated test T Smart cards are smart because they replace passive magnetic strip memory with active microprocessor based memory and logic F In the questions with calculations, The logic operations are either written in uppercase (OR, AND, NOT) or represented by their logical symbol (V for OR, ^ for AND, ~ or the variable name over lined for NOT). The parenthesis are used to order the operations and also the force For example, to represent the AND operation, using A and B as input variables and Z as output, you just write     Z = A AND B this can also be represented as     Z = A ^ B 8. Growth of narrow copper fibers from a negatively charged plated through hole of metallization trace to a positively charged plated through hole or metalized trace- via fatigue Electrochemical attack of a plated through hole or metallization trace in the presence of moisture, ionic contamination and voltage potential- corrosion Iterdiffusion and chemical reaction of a bond pad on a chip and an interconnection wire leading to the growth of a new compound containing elements from both structure- intermetallic formations Thermo mechanicaldegradation of the interconnection between the silicon chip and substrate or lead frame resulting from repeated thermal or power cycling- Die attach fatigue Thermo mechanicaldegradation of the interconnection between metallization traces different layers of a multilayer printed wiring board resulting from repeated thermal power cycling –conductive filament formation Wire bonding is the method of making interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication therefore this process can lead to contact migration Metallization can lead to an Electromigration which is a process that results from the momentum transfer from the electrons which move in the applied electric field, to ions which make up the lattice of the interconnect material 9. Bond pad refers to the process used to connect the circuit on the die pin on a packaged chip that can results into Electrostatic discharge/ electrical overstress due to the process of the bonding pad creations In Field oxide, the oxidation process in the manufacture of integrated circuits, field oxide is normally used to isolate the devices from one another leading to the excessive intermetallic formation The gate oxide refers to the dielectric layer that separates the gate terminal of a MOSFET from the underlying source and it also drains and which makes it very critical to every transistor – hot carrier injection 13. The major flip-chip bonding technology includes multiple interconnections and low parasitic resistance and inductance. Ground bumps andmany powerscan also be placed in an area-array configuration in the die center. The several characteristics of FC-BGA package to accommodate the bumped die include:- the fine design rules, low resistance and the dielectric losses,the impedance matching, ground inductance and the low power, the low-inductance decoupling capacitance,low thermal resistance, and the excellent package and second-level-packaging reliability. 14. The advantages and disadvantages of different fan placement positions in an enclosure, these include: SeriesFilter Fans: These fans are a cost-effective solution for a variety of applications this therefore contributes majorly to their advantage. Filter Fans: These fans (filter fans) arevery durable, attractive plastic grilles which contribute to a clean, linear design. They also have extremely flat profile, which blends well with modern enclosures and keeps the unit from protruding from the cabinet wall. Sentry Series Indoor/Outdoor Filter Fans: The fans offer the same convenience; versatility and reliability as the Advantage Series FilterFansthey also have an added protection of a NEMA 3R rating, which makes them an excellent choice for the telecommunications and the food service industry. The Kool-Jet High Performance Fan: These fans are designed specifically to overcome severe space limitations in electronics and instrumentation cooling. The excellent pressure characteristics of such fans result from the adaptation of tube-axial fan principals. They have either push or pull airflow in one unit. Its main advantage also is the only shock-mounted fan of its type eliminating transfer of vibration or AC hum into equipment. Filter Box Fans: The fans operates under very low noise high air flow which makes them more advantageous and very popular in a wide range of applications, especially with their minimal internal cabinet depth requirement Twin and Triple Fans: These fans provide a very high airflow in a very thin package In low static pressure applications, their design also provides exceptionally quiet operation in both intake and exhaust applications which adds to their advantage. The fans also provide very minimum vibrations whether they are mounted horizontally or vertically hence require little internal cabinet space, leaving virtually the entire cabinet free for power supplies hence adding to their advantage. Disadvantages: Their small sizes, slim etc. making them more difficult to use especially where the enclosure is of a fixed size or measurement Most of the fans are powered by bus power, meaning it does not require an external power adapter. Since the bus power is not always guaranteed, there is a need for an enclosure which provides a DC jack for an optional power adapter to be used. 15. Complex systems are the ones that cannot be broken down into groups of series and parallel components and their reliability equation is given by: Where0 Read More