Field of electronics engineering that deals with the design and fabrication of small electronic devices such as microprocessors, using techniques such as photolithography.
The small electronic devices are typically fabricated using microelectromechanical systems (MEMS) or microelectronicmechanicalsystems (MEMS).
Microelectromechanical systems (MEMS)
These are small structures that can be integrated into electronic circuits.
Semiconductormaterials
These are the building blocks of microelectronics.
One key aspect of microelectronics is the use of semiconductormaterials, such as silicon, to create the small structures and devices that are needed.
Benefits of Microelectronics
Miniaturization
PowerEfficiency
Advancementsincomputing
Innovationacrossindustries
Economicimpact
Vacuum Tubes
Controls flow of electric current; used in transistors for amplifiers
1 integrated circuit = m/billions of transistors
Transistors
Three terminal device; usually for amplifiers.
SemiconductorDiode
Two terminal device
Vacuum tubes uses metal chassis which weighs 40 to 50 pounds.
Vacuum tubes required a warm-up time from 1 to 2 minutes, it generated a lot of heat.
Vacuum tubes required hefty power supply voltages of 300 volts dc and more.
A circuit could be designed either as a complete system or as a functionalpart of a larger system.
In complexsystems, such as radar, many separatecircuits were needed to accomplish the desired tasks.
Multiple function tubes, such as dualdiodes, dualtriodes, tetrodes, and others helped considerably to reduce the size of circuits.
Weight, heat, and power consumption continued to be problems that plagued designers.
Point-to-point wiring
A method of wiring components which is another major problem with vacuum-tube circuits.
Point-to-point wiring
This wiring looks like a rat's nest and it often caused unwanted interactions between components.
Point-to-point wiring
Usually repaired with general purpose test equipment and common hand tools.
EINAC
A completely electronic computer built in 1945 which contained 18,000 tubes. It often required a full day just to locate and replace faulty tubes.
Cathode-raytubes
Used in radar, television, and oscilloscopes do not, as yet, have solid-state counterparts.
MODULAR PACKAGING
One concept that eased the technician's job because instead of building a system on one large chassis, it was built of modules or blocks.
Vacuum tubes
Basis for electronic technology for many years and some are still with us.
The emphasis of technology is in the field of microelectronics.
Applications of Microelectronics
Integrated Circuits
Microprocessors
Memory Devices
Microsensors and Actuators
Microcontrollers
Solid-State Devices
Device which electrically flows through solid semiconductor crystals rather than vacuum tubes
Solid-state chassis
Considerably smaller and lighter than the older tube chassis.
Printed Circuit Board (PCB)
One of the most significant developments in circuit packaging.
Printed Circuit Board (PCB)
Usually an epoxy board on which the circuit leads have been added by the photoetching process.
Photoetching process
This process is similar to photography in that copper-cladboards are exposed to controlled light in the desired circuit pattern and then etched to remove the unwanted copper.
Photoetching process leaves copperstrips (LANDS) that are used to connect the components.
Printed Circuit Boards eliminate both the heavy, metal chassis, and the point-to-point wiring.
Vacuum tubes are easily removed for testing or replacements while PCB components are soldered into place and are not as easily removed.
Normally, each PCB circuit contains a single circuit or a subassembly of a system.
Cabling Harnesses
Groups of wiring or ribbons of wiring.
All printed circuit boards within the system are routinely interconnected through cabling harnesses.
Cordwood Module
Another mounting form that has been used to increase the number of components in a given space.
In cordwood module, components are placed perpendicular to the end plates.
The components in a cordwood module are closely packed, appearing to be stacked like a cordwood for a fireplace.