(1) Manual manufacturing process of printed circuit boardA basic process of manual manufacturing of PCB is the transfer of the designed PCB to the copper clad plate. The simple and effective method, etching, uses a protective anti-corrosion material to form a pattern on the copper-covered plate. Unwanted copper foil is removed with chemical corrosion. At the end of the corrosion, the resist layer is washed away so that the pattern can be seen.
(2) Factory production process of printed circuit boards Factory production of printed circuit boards need to go through complicated processes. In the production process, each technology has a clear operation method, in addition to the production of negatives, hole metallization and graphic plating etching is the key to production. Printed circuit original base map production method: for printed circuit board, what method is the best to meet the quality requirements of 1: There are two sources of original negatives: one is to make a photographic base and get the original negatives after taking photos; the other is to draw the original negatives directly by using computer system and optical drawing machine. PCB printing and etching and process: There are two general methods for making the mask graphics of corrosion resistance or electroplating: Screen leakage and photosensitive dry film method. Screen leakage method is generally used for single or double sided PCB production with large batch and low single precision, which is convenient for automation. The photosensitive dry film method is mainly to improve the production efficiency, simplify the process and improve the quality of the plate.
(2) green color is welding resistance ink, the main components are resin, talc and pigment, the current market is more popular mainly Japan Sun taiyo, Taiwan South Asia resin, Taiwan Changxing Chemical industry, Taiwan Yongshengtai ink, the price is generally 60~120 yuan/kg; Of course there are other colors, such as red, black and so on. Green is widely used.
On this question (why is the circuit board mostly green?) There are several ways to say:
Point of view 1, Generally speaking, the whole electronic board level products have to go through the process of board making and Posting. In the process of board making, there are several processes to go through the yellow light room. The visual effect of green in the yellow light room is better, but this is not the main.
During SMT welding, it is necessary to go through tinning, Posting and AOI verification. These processes should be calibrated by optical positioning. Green background color has better recognition effect on the instrument.
Opinion 2, the common red, yellow, green, blue and black, due to the problem of the process, a lot of line inspection or rely on workers to see with the eyes (of course, most of the flying needle test now). Keep looking at the board with bright eyes, which is a very tiring job oh, green relatively does not hurt the eyes, so most use green.
Blue and black, because they are mixed with cobalt and carbon respectively, have certain electrical conductivity, so there is a risk of short circuit. Green PCB is more environmentally friendly, will not release toxic gas when used in high temperature environment.
Around 2007, people began to pay attention to the color of PCB board, mainly because the board type of Asus, Microstar, these big factories have adopted black PCB board color design, so people gradually believe that the PCB color is black. Since then, more and more manufacturers have begun to use black PCB coating - can be said to be an inexplicable reason for such an inexplicable phenomenon. No one has ever said that if PCB color is black, the quality of the motherboard must be good. This is the product misdirection caused by using black to identify product positioning. Indeed, black PCB is able to show its own technical strength, because black PCB is not easy to see the line, so whether the design or after-sales will suffer from the cost pressure, and the technical strength of the board card manufacturers using black PCB tone is not because black can improve the performance of the motherboard, From the point of view of rational analysis also know that color alone can not improve the performance of the board.
Welding principle and welding tools
First, welding principle
At present, the soldering technology of electronic components is mainly used. Tin welding technology uses tin alloy material mainly as solder, solder melts at a certain temperature, mutual attraction, diffusion and combination between metal welds and tin atoms, forming a combination layer of infiltration. It seems that the copper platinum of the printing board and the leads of the components are very smooth, but in fact, there are many small convex and convex gaps on the surface of them. The molten solder diffuses along the surface of the welds with the help of capillary suction, forming the infiltration of solder and welds, firmly bonding the components and the printing board, and has good electrical conductivity.
The conditions of tin welding are: the surface of the solder should be clean, oil dirt, rust will affect the welding; Metals that can be moistened by tin solder can be weldable. For materials that are easy to generate oxide film on the surface of brass and other materials, you can use flux to solder the surface of the welding parts before soldering; To have appropriate heating temperature, so that the solder material has a certain fluidity, can achieve the purpose of welding, but the temperature can not be too high, too high is easy to form oxide film and affect the welding quality.