The following stage of development is the technology of superficial installation of crystals. The technology of superficial installation of crystals provides miniaturization of the radio-electronic equipment with a growth of its functional complexity. Hinged components it is much less, than mounted in openings that provides higher density of installation and reduces mass-dimensional indicators. Along with it apply microassemblies and hybrid integrated schemes to bigger miniaturization.
Printed-circuit boards from an epoxy steklotekstolit are characterized by smaller deformation, than printed-circuit boards from a phenolic and epoxy getinaks; the last have extent of deformation ten times bigger, than steklotekstolit.
It is also necessary to stipulate what radioelements directly on a payment handles of management of loudness and a timbre are not installed, for example, push-button switches, light-emitting diodes are taken out on the forward panel, safety locks - on a back wall. For the socket installed on the printed-circuit board combination or with an opening in a back wall, or with rigidly fixed instrument reciprocal nested block can be demanded.
These materials in the form of tough sheets are formed of several layers of paper or fiber glass fabric fastened among themselves with binding substance by hot pressing. Binding substance usually are phenolic pitch for paper or epoxy for fiber glass fabric. In some cases polyester, silicone pitches or can be also applied. Layered plasticity becomes covered from one or both parties by a copper foil of standard thickness.
The crack in the metallized layer on walls of openings sharply reduces reliability of connection. In case of application of an epoxy steklotekstolit the relation of temperature coefficients of expansion approximately equally we rub, and the risk of formation of cracks in openings is rather small.
Considering all above-mentioned moments, we draw a conclusion that production of the set device on GIS is not possible therefore we make the decision to make this device on the printed-circuit board.
Now amplifiers gained very wide circulation practically in all spheres of human activity: in the industry, in equipment, in medicine, in music, on transport and in many others. Amplifiers are a necessary element of any communication systems, broadcastings, acoustics, automatic equipment, measurements and management. But before the amplifier became such extended to him it was necessary to go very long way.
Printing conductors have to be carried out a rectangular shape parallel to the parties of a payment and coordinate grid or at an angle 450 to them. Width of the conductor has to be identical on all length. Distance between uninsulated cases of electroradioelements, between cases and conclusions, between conclusions of the next electroradioelements or between a conclusion and any conducting detail it is necessary to choose taking into account an admissible potential difference between them and the provided heat sink, but not less than 1 mm (for the isolated details not less than 0,5 mm). Distance between the case an electroradioelement and edge of the printed-circuit board not less than 1 mm, between a conclusion and edge of the printed-circuit board not less than 2 mm, between the conductor and edge of the printed-circuit board not less than 1 mm.
The copper foil is issued various thickness. Standard thickness of a foil of the broadest application - 17,5; 35; 50; 70; 105 microns. During etching of copper on thickness the travitel influences also a copper foil from lateral edges under photoresist, causing a so-called podtravlivaniye. That to reduce it usually apply thinner copper foil 35 and 17,5 microns thick. Therefore we choose a copper foil 35 microns thick.
As a rule, layered plasticity on a phenolic, and also epoxy getinaks is not used in payments with the metallized openings. In such payments on walls of openings a thin film of copper is applied. As the temperature coefficient of expansion of copper is 6-12 times less, than at a phenolic getinaks, there is a certain risk of formation of cracks in the metallized layer on walls of openings at thermal shock to which the printed-circuit board in the car for the group soldering is exposed.
The electron tube was an active element of the first amplifiers. Such amplifiers were bulky, consumed a lot of energy and quickly failed. Only in the middle of our century after long persistent searches and works at last it was succeeded to create for the first time the intensifying semiconductor device replacing the electron tube. This important opening made large revolution in radio electronics. Dimensions of transistor amplifiers became several times less lamp, and power consumption - is tens times less. Besides considerably reliability increased.