Keyword: PCB image processing, PCB board technology, PCB manufacturers, PCB cad software
The previous we have talked about PCB board technology, system includes computer-aided manufacturing processing technology, also known as CAD/CAM, and light painting technology. Plate-making technology (1) this paper introduces the CAD/CAM computer-aided manufacturing processing, they will be introduced this plate-making technology of 2, light painting technology. General process of the light painting process is: check the file a to determine the process parameters a CAD file transfer Gerber file a CAM processing and output.
1. Check the file
(1) check the user's file user files, first check for the following.
Check whether the disk file is intact.
Check if the file with a virus, a virus must first antivirus.
Check the user data format.
If the Gerber file, check the presence of D clock or containing D code (RS274 - X format).
So to correctly analyze a data format. Especially the RS274D in Gerber format to deeply understand, to analyze and understand correctly, the standard Aperture, a detailed analysis of the relationship between them. One thing very important is to carefully read Apeture file, because sometimes there will be some special cases, such as, sometimes the user will change an Aperture from circular to rectangular, from a rectangle with the cooling plate, etc. If open the original Gerber file, will find its data only D yards and coordinate, because the graphics file consists of three parts: coordinates, size, shape, and only coordinates in Gerber file, so I need two other conditions, if the file has received Apertuer file, then open it, will find it contains the data you need, if we can combine the good, so will be able to read the user's original data.
(2). check whether the design is in line with the technological level of our factory
1) check whether the customer file design various spacing conforms to the factory process, line spacing, and the question of line and line spacing between the solder, welding plate and welding plate spacing, between various spacing above should be greater than our factory production technology can achieve the minimum spacing.
2) check the width of the wire to wire should be greater than the width of the factory production process can achieve the minimum line width.
3). Check the guide hole size, the minimum aperture in place to ensure that the factory production process.
4) check the pad size and its internal diameter, to ensure that the borehole after welding plate edge has a certain width.
2. Determine the process parameters
According to user requirements to determine various process parameters. The process parameters may have the following several ways.
(1) according to the requirement of the order after the process, to determine whether light painting film images
1) the principle of negative image in order to reduce the error, surface (i.e., emulsion side) must be directly attached to the sensitive glue release.it surface.
2) the negative image of the deciding factor if it is screen printing process or dry film, with film release.it copper substrate surface stick shall prevail. If it is to use diazo field exposure, due to the diazo copy image, so the mirror shall be the negatives release.it noodles don't stick a copper substrate surface. If as a unit when the light painting film, rather than on the light painting film puzzle, you have a mirror.
(2) to determine the resistance welding graphics expansion parameters
1) to determine the principle of resistance welding graphics increase the solder wire beside light shall prevail; Narrowing of the resistance welding graphics with not cover bonding pad for the principle. As a result of the operation error, resistance welding graphics on line deviation may be produced. If resistance welding graphics is too small, the result of the deviation is likely to make the edge of the pad cover, therefore requires resistance welding graphics increase some; But if the resistance welding graphics to expand too much, because of the influence of the deviation may reveal next to the wire.
2) the determinants of resistance welding graphics to expand our resistance welding position deviation, the deviation of resistance welding graphics. Due to various process caused by the deviation is different, so the corresponding resistance welding graphics to expand the technology value are also different. Big deviation of resistance welding graphics expanded value should choose something big. Density board wires between welding plate and wire asked from small, choose the smaller resistance welding graphics expanded value; Bat wire density is small, resistance welding graphics expand larger value is optional.
(3) according to whether the board need to plug the gilded (commonly known as the gold finger) to determine whether to increase the wire process.
(4) according to the requirement of electroplating process is to increase the plating with conductive frame.
(5) according to the hot air leveling (commonly known as spray tin) process requirements to determine whether to add conductive process line.
(6) according to the drilling process to determine whether to add solder center hole.
(7) according to the order process to determine whether to add positioning hole.
According to the board
(8) appearance to determine whether to add horn line shape.
(9) when the user high precision boards require line width precision is high, according to the factory production level, determine whether to carry on the line width correction, to adjust the effect of lateral erosion.
3. The light of the blank drawing output
Because many PCB manufacturers don't draw light painting machine film directly used in production, but use it to remake work film, here we call light painting film negatives. At the beginning of the new light painting before, first of all to adjust the parameters of the light painting machine, make it in proper working condition.
(1) light painting machine parameter Settings
1) the light source intensity Settings in light painting process, if the light source intensity, high drawing graphics will appear halo; If the intensity of the light source is too low, is drawn graphics will be underexposed, therefore both vector light painting machine and laser light painting machine there is a light section stress problem. In a high-grade light painting machine set has a light intensity detection circuit, when insufficient light intensity, light painting machine will refuse to work or don't open the shutter, and the error message on the screen. Sometimes laser light painting machine drawing of the film didn't exposure, is due to inadequate Yu Guangjiang. Can usually be by adjusting the light emitting device of voltage to control the intensity of light source, when replacing a light-emitting device or replace a developer, using light painting test piece to check whether the light intensity is appropriate.
2) light painting speed regulating light painting machine, especially in the vector light painting machine, the speed of the drawing is also important factor affecting the quality of painting pieces. In the vector light painting machine line, if the drawing speed too fast, the beam on the negatives stay time is too short, will produce underexposed phenomenon; If the drawing speed is too slow, the beam on the film for a long time, will be overexposed to appear the phenomenon of the halo.
Light painting speed will affect not only painting effect, and acceleration at the light painting and exposure when the shutter opens and closes delay time will have an impact on the result, also need to seriously to adjust these parameters.
3) when the light painting film placement due to the changes of various external factors, light painted film small scale deformation will happen, in general it for printed circuit board processing will not have much impact, but sometimes also can make the film doesn't work. Therefore, in addition to try to eliminate the influence of external environment factors, also should pay attention when light painting operation. When placed in the film, should try to draw the same printed circuit diagram of different layers (such as element surface and welding surface) of X, y direction and a film of X, y direction is consistent, so that change the shape to somewhat identity. For some precision is not very high light painting machine, painted a little as far as possible from the origin of the drawing mesa, draw the same circuit different levels of graphics, as far as possible on the mesa of the same coordinate range, placed the film also corresponding to attention. In addition, put the film should be keep film release.it face up to the light source, to reduce the negative dielectric optical diffraction effect.
4) the negatives of mesa maintain drawing (mesa) or surface cleaning level is an important guarantee of quality of drawing, (surface) on the table on the negatives in addition to the need to draw the film should not have other items, also don't scratch your face, the vacuum absorption holes should be kept clear of film, so as to draw the negatives of the high precision.
(2) drawings of the blank when the normal work of the light painting it through disk, RS232 port or tape (the current tape has rarely used) light painting input data, then draw the data on the film described in the graph. In fact, in the light painting machine in addition to simple operation, do not need to do more work, light painting graphics is the large amount of work in production and processing of light painting file.
1) of line drawing typically require to evaluate the design of graphics data directly to generate light painting, the light painting data input light painting machine. Line should be 1:1, usually for some ratio
Should be paid attention to more complex circuit, light painting figure yuan size on the film and the design value of error will affect to the production, if there is influence, should modify the design of the primitive size to make up for the light painting value deviation.
2) the resistance welding pieces of drawing and to low resistance welding requirements than line pills, but according to different technical requirements, resistance welding lines of bonding pad should be than pills amplification, in generating resistance welding light painting data should be attention.
3) characters draw the characters of pills slightly lower, but because the characters are often the layout of the device as the device out of the library, the size of the characters, the structure character of line width is often uneven. Some characters is too small, ink printed when blurred; Some lines are too thin, printing effect is not good, which requires the character light painting was generated in the file before carefully check the character, character light painting was generated in the file, try to put the line width of characters incorporated into one or several, to make it conform to the requirements of the process.
4) drilling piece drawing normally does not need to draw hole film, but sometimes in order to better check borehole or clear distinction between aperture, also can draw a borehole. For vector light painting machine, when drawn to distinguish the aperture drilling, consideration should be given to save the time of light painting, namely the generated light painting data should be paid attention to when using simple symbols to identify the aperture.
5) the power of the large area of copper clad, formation of drawing for the power of the standard design, formation, according to the design drawings of the film and the printed circuit board on the graphics are opposite, that is to say, not exposure on the part of the film is the copper foil, while part of the graphics on the PCB are on the plate is isolation part, there is no copper layer. Because of the process, when drawing power, formation, isolation plate should drive some welding than line layer, connected to a power source and formation of hole, it is best not to what all don't paint, but should draw special welding plate, it is not only guarantee the solderability problem, more important is to check of film, where there are holes, where no hole, hole which connect power or ground, be clear at a glance.
6) painted mirror slice in printed circuit board in the imaging process needs to be release.it of film surface (graphics surface) on the printed circuit board copper foil adhesion of dry film. So in painting for a little while to graphic phase should be considered the positive and negative) (that is, the graphics surface, it is not advocated by put release.it of film surface reverse phase method to realize the graphic, and when a few small graphics drawing on a big plate, with this method also can't make them in different phase, shall, in the light painting is generated when the data file is attention. Typically, given the need before with film, a film, so the singular layer of printed circuit boards (1, 3, 5,...), layer graphics, generate light painting as the positive phase, data should be facing the dual layer graphics, generate light painting data the graphics should be described as the mirror graphics. If direct light painted film for PCB image processing, then said in front of the phase should in turn.
7) All landowners graphics hierarchy logo identifies film graphics for PCB level is quite important, for example, one of the most simple single panel, if you don't identify graphics in the surface layer, may make weld surface into a component surface, in the end will lead to bad device installation, double and multilayer panels
Plate. Some PCB cad software can generate light painting files automatically add graphics in the hierarchy, it bring a lot of convenience. But in two points should be paid attention to when using, the first is whether the level of the printed circuit wiring is what processing arrangement level; Second, when the design graphics zero tend to stay away from the origin of coordinates, and the level of the automatic add tag is near the origin of coordinates, so that at level will have a lot of space between tag and shape not only affects the effect of logo, and will cause the waste of film.
8) End aperture matching vector light painting machine and laser light painting machine, aperture matching problems. If the design of graphics is 40 mil solder, and light painting with 50 mil aperture, clearly draw graphics will have differences, but because in designing graphics primitives (line, welding plate) size can literally set, so if you want the aperture of the light painting machine, in full compliance with the for vector light painting machine is made, is also a trouble for laser light painting machine, and from all the necessary processing point of view, is to do the aperture are a perfect match, due to the focus and development, the influence of such factors as the primitives on the paint film size will there is a little difference with the design value. Therefore, as long as the process in the actual process allows, can use existing aperture (the vector light painting machine) or has been set good aperture (of laser light painting machine). In many times with 50 mil aperture to corresponding to the design value of 46 55 mil mil or even with 60 40 mil mil aperture to the corresponding design values are allowed.
Source: //www.seekic.com
