It is not known who first came up with the idea to make two or more transistors on a single semiconductor chip. The idea may have originated just after the start of semiconductor element production. It is known that the theoretical foundations of this approach were published in the early 50's of the last century. It took less than 10 years to overcome technological problems, and already in the early 60's the first device containing several electronic components in one package was produced - a microchip (chip). Since then mankind has embarked on a path of improvement, which has yet to see the end.
Purpose of ICs
At present, a wide variety of electronic assemblies with varying degrees of integration are made in integrated designs. From them, as of bricks, you can assemble various electronic devices. Thus, the circuit of a radio receiver can be implemented in different ways. The starting point is to use chips and sets of transistors. By connecting their pins, you can make a receiver device. The next step is to use individual assemblies in an integrated design (each in its own enclosure):
- radiofrequency amplifier;
- heterodyne;
- mixer;
- audio frequency amplifier.
Finally, the most modern variant - the entire receiver in a single chip, you only need to add a few external passive elements. Obviously, as the degree of integration increases, the construction of circuits becomes simpler. Even a full computer nowadays can be realized on one chip. Its performance will still be lower than that of conventional computing devices, but with the development of technology, perhaps even this point can be defeated.
Types of chips
There are a huge number of chip types nowadays. Virtually any complete electronic assembly, standard or specialized, comes in a micro design. It is not possible to list and disassemble all types in one review. But in general, chips can be divided into three global categories according to their functionality.
- Digital. They work with discrete signals. Digital levels are fed to the input and signals in digital form are also taken from the output. This class of devices covers the field from simple logic elements to the most advanced microprocessors. It also includes programmable logic matrices, memory devices, etc.
- Analog. They work with signals that change according to a continuous law. A typical example of such a chip is an audio frequency amplifier. This class also includes integrated line stabilizers, signal generators, measurement sensors, and more. The analog category also includes sets of passive elements (Resistors, RC circuits, etc.).
- Analog-to-digital (digital-to-analog). These chips not only convert discrete data into continuous data or vice versa. Source or received signals in the same case can be amplified, converted, modulated, decoded, etc. Analog-to-digital sensors are widely used to communicate measurement circuits of various technological processes with computing devices.
Also microcircuits are divided according to the type of production:
- Semiconductor - made on a single semiconductor crystal;
- Film - passive elements are created on the basis of thick or thin films;
- Hybrid: active semiconductor devices are "planted" to passive film elements (transistors etc.).
But for the application of microcircuits this classification in most cases does not give much practical information.
Chipshells
To protect the internal contents and to simplify installation, microcircuits are placed in a package. Initially, most microcircuits were produced in a metal shell (circular or rectangular) with flexible pins arranged along the perimeter.
This design did not allow to use all the advantages of miniaturization, because the dimensions of the device were very large compared to the size of the crystal. In addition, the degree of integration was low, which only exacerbated the problem. In the mid sixties, the DIP (dual in-line package), a rectangular box with rigid pins on both sides. The problem of bulky size was not solved, but nevertheless, this solution allowed to achieve a higher packing density, as well as to simplify automated assembly of electronic circuits. The number of chip pins in a DIP package ranges from 4 to 64, although packages with more than 40 "legs" are still rare.
Important! DIP microcircuits of domestic production have pin spacing of 2.5 mm, while imported - 2.54 mm (1 line = 0.1 inch). Because of this, problems arise when mutually replacing complete, seemingly analogues of Russian and imported production. A small discrepancy makes it difficult to install the same functionality and pin assignment devices in the boards and panels.
With the development of electronic technology, the disadvantages of DIP packages became apparent. Microprocessors did not have enough pins, and increasing numbers of pins required increasing the size of packages. The second problem that brought the era of DIP domination to a close was the proliferation of surface mounting. These chips were no longer mounted in holes on boards, but soldered directly onto pads. This way of mounting turned out to be very rational, that's why there was a need for chips in packages which were adapted to surface soldering. And the process of displacement of devices for "hole" mounting (true hole) elements named as SMD (surface mounted detail).
The first step to surface mounted was the introduction of SOIC packages and their modifications (SOP, HSOP and other variants). Like the DIP, they have two rows of dowel pins on the long sides but they are parallel to the bottom plane of the enclosure.
A further development is the QFP housing. This case has square-shaped pins on each side. It was similar to the PLLC case but it was still closer to the DIP case although the pins were also all around the circumference.
For some time DIP chips held their own in the programmable device sector (ROM, controller, PLM), but the proliferation of on-chip programming pushed the true hole double-row packages out of that area as well. Nowadays, even parts that seemed to have no alternative to hole mounting - such as integrated voltage regulators, etc. - are SMD-formatted.
The development of housings for microprocessors has taken a different path. Since the number of pins does not fit into the perimeter of any reasonable size square, the legs of a large chip are arranged in the form of a matrix (PGA, LGA, etc.).
Advantages of using chips
The advent of the microchip revolutionized the world of electronics (especially in microprocessor technology). Light bulb computers, which took up one or more rooms, are remembered as a historical curiosity. But a modern processor contains about 20 billion transistors. If we assume a discrete transistor area of at least 0.1 square centimeters, the area occupied by the processor as a whole would have to be at least 200000 square meters - about 2000 three-room medium-sized apartments.
It is also necessary to provide space for memory, sound card, audio card, network adapter and other peripherals. The cost of mounting so many discrete elements would be enormous, and the reliability would be unacceptably low. Troubleshooting and repair would have taken an incredibly long time. It is clear that the era of personal computers would have never happened without highly integrated chips. Also, without today's technology, computing-intensive devices, from consumer to industrial or scientific
The direction of electronics development is predetermined for many years to come. This is, first of all, an increase in the degree of integration of microchip elements, which is associated with the continuous development of technology. There is a qualitative leap ahead when microelectronics capabilities reach their limits, but this is a matter of the rather distant future.
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