An integrated circuit board is a carrier for carrying integrated circuits. But it is often said that the integrated circuit board should also be brought with it. The integrated circuit board is mainly composed of silica gel, so it is generally green.
Integrated circuit board (IC) adopts semiconductor manufacturing technology. Many transistors, resistors, capacitors and other components are made on a small single-crystal silicon wafer, and the components are combined into a complete electronic circuit by multilayer wiring or tunnel wiring. It is represented by the letter “IC” in the circuit (there are also useful characters “N”, etc.).
classify
According to functional structure
According to their different functions and structures, integrated circuit boards can be divided into analog integrated circuit boards and digital ones.
Analog is used to generate, amplify and process all kinds of analog signals (signals whose amplitude varies with time. For example, audio signals of transistor radio, tape signals of video recorders, etc.), while digital signals are used to generate, amplify and process various digital signals (referring to signals with discrete values in time and amplitude). E.g., audio signals and video signals of VCD and DVD playback).
According to the manufacturing process
According to the manufacturing process, it can be divided into semiconductor and thin film.
Films are classified into thick film and thin film.
According to the level of integration
According to the level of integration, it can be divided into small scale, medium scale, large scale and super scale.
According to the conductivity type
According to the conductivity type, it can be divided into bipolar type and unipolar type.
Bipolar has complex manufacturing process and high power consumption, and it is represented by TTL, ECL, HTL, LST-TL, STTL and other types. Monopole is simple in manufacturing process, low in power consumption, and easy to be made into large scale, which is represented by CMOS, NMOS, PMOS and other types.
By purpose
According to the use, it can be divided into TV sets. Audio, DVD player, video recorder, computer (microcomputer), electronic organ, communication, camera, remote control, language, alarm and other special purposes.
Television sets include line scanning, field scanning, intermediate amplifier, accompanying sound, color decoding, AV/TV conversion, switching power supply, remote control, Liyin decoding, picture-in-picture processing, microprocessor (CPU), memory, etc.
Audio system includes AM/FM high intermediate frequency circuit, stereo decoding circuit, audio preamplifier circuit, audio operational amplifier, audio power amplifier, surround sound processing, level drive, electronic volume control, delayed reverberation, electronic switch, etc.
DVD player is used for system control, video coding, MPEG decoding, audio signal processing, sound effects, RF signal processing, digital signal processing, servo, motor driving, etc.
The video recorder has system control, servo, drive, audio processing and video processing.
Production process
1. Printed circuit board. Print the drawn circuit board with transfer paper, and pay attention to the slippery side facing yourself. Generally, two circuit boards are printed, that is, two circuit boards are printed on a piece of paper. Among them, the printed circuit board with the best printing effect is selected.
2. Cut the copper clad laminate and use the photosensitive plate to make the circuit board. Copper clad laminate (CCL), that is, the circuit board covered with copper film on both sides, should be cut into the size of the circuit board, not too large, so as to save materials.
3. Pretreatment of copper clad laminate. Grind the oxide layer on the surface of the copper clad laminate with fine sandpaper to ensure that the carbon powder on the heat transfer paper can be firmly printed on the copper clad laminate when transferring the circuit board. The polished standard is that the board surface is bright and there is no obvious stain.
4. Transfer printing circuit board. Cut the printed circuit board into a suitable size, stick the printed side of the circuit board on the copper clad laminate, put the copper clad laminate into the thermal transfer printer after alignment, and make sure that there is no dislocation of the transfer paper. Generally speaking, after 2-3 times of transfer printing, the circuit board can be firmly transferred to the copper clad laminate. The heat transfer machine has been preheated in advance, and the temperature is set at 160-200 degrees Celsius. Because of the high temperature, pay attention to safety during operation!
5. Corrosion of circuit board reflow oven. First, check whether the printed circuit board is completely transferred. If there are a few places that are not transferred properly, you can repair them with a black oily pen. Then it can be corroded. When the exposed copper film on the circuit board is completely corroded, take the circuit board out of the corrosive liquid and clean it, so that a circuit board is corroded. The composition of the corrosive liquid is concentrated hydrochloric acid, concentrated hydrogen peroxide and water at a ratio of 1: 2: 3. When preparing the corrosive liquid, water should be drained first, and then concentrated hydrochloric acid and concentrated hydrogen peroxide should be added. If the concentrated hydrochloric acid, concentrated hydrogen peroxide or corrosive liquid accidentally splashes on the skin or clothes during operation, it should be cleaned with clean water in time. Because of the strong corrosive solution, you must pay attention to safety during operation!
6. Drilling the circuit board. Electronic components are to be inserted into the circuit board, so it is necessary to drill the circuit board. Choose different drill pins according to the thickness of electronic components. When using the drill to drill holes, the circuit board must be held steady, and the speed of the drill cannot be too slow. It is relatively simple to operate the drill, and it can be done well as long as you are careful. Please watch the operation carefully.
7. Pretreatment of circuit board. After drilling, polish off the toner coated on the circuit board with fine sandpaper, and clean the circuit board with clean water. After drying, apply rosin water to the side with wiring, only a thin layer is needed, which not only prevents the wiring from being oxidized, but also makes rosin a good flux. Generally speaking, rosin on the surface of the circuit board will solidify within 24 hours. To speed up the solidification of rosin, we use a hot air blower to heat the circuit board, and it only takes 2-3 minutes for rosin to solidify. The temperature of the hot fan is as high as 300 degrees. When using it, the air outlet should not be directed towards combustible materials, people and small animals. Safety is still the first requirement!
8. Welding electronic components. After welding the electronic components on the board, electrify them, realize their functions, and make them.