Keyword: PCB light painting process, PCB process, PCB design
PCB light painting process in transfer line is PCB process of an important link of any discrepancies in this link, all subsequent process, could potentially bring serious problem, so the inside of every step should be strictly controlled.
(a) check the user's file
User files, the first thing to routine inspection:
1, check that the file is in good condition;
2, check the file with poisonous and toxic to antivirus;
3, if the Gerber file, then check the presence of D clock or containing D yards.
(b) check the PCB design is in line with the technological level of our factory
1, check the customer file in PCB design is in line with the spacing of the various process: our factory ` line between line and line spacing between the solder and the spacing of ` spacing between welding plate and welding plate. Above various spacing 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.
(c) determine the process requirement
According to user requirements to determine various process parameters.
Technical requirements:
1, Order process of different requirements, after determine whether PCB light painting film (film) is commonly known as the image. Negative image principle: release.it surface (surface) release.it surface, to reduce the error. Determinants of mirror: film process. 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 PCB light painting film, rather than on the PCB light painting film puzzle, you have a mirror.
2, to determine the parameters of the resistance welding expand.
Determine the principle:
1) not show solder wires.
2) small can't cover the solder.
As a result of the operation error, figure for resistance welding line deviation may be produced. If the resistance welding is too small, the result of the deviation may make the edge of the pad cover. So have thrown some for resistance welding. But if the resistance welding to expand too much, because of the influence of the deviation may reveal next to the wire.
Required by above knowable, determinants of resistance welding expand as follows:
1) resistance welding position deviation, the deviation of resistance welding graphics.
Due to various process caused by the deviation, so the corresponding resistance welding expand the technology value Different. Large deviation of resistance welding expanding value should choose something big.
2) the board wire density, small spacing between welding plate and wire, choose the smaller resistance welding expand value; plate
Conductor density is small, resistance welding expand larger value is optional.
3, according to the board on whether to have printed plug (commonly known as the gold finger) to determine whether to add process line.
4, according to the requirement of electroplating process whether to add 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.
8, according to the board shape 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.
(d) CAD file conversion for the Gerber file
For unified management in CAM process, should be all light painting machine standard format CAD file conversion for PCB Gerber and considerable D spec.
Should be paid attention to in the process of transformation, the required process parameters, because some of the requirement is to finish in the transformation.
Now general all kinds of CAD software, in addition to Smart Work and Tango software, can be converted into Gerber, the above two kinds of software can also use tools to Protel format first, then the Gerber.
(e) CAM processing
According to the prescribed process for all kinds of process.
Special note: the user file where is there a spacing is too small, must make the corresponding processing
(f) PCB with light output
After processed by the CAM files, can output PCB light painting.
Puzzle of the work can be done in CAM, also can be in the output.
Good PCB light painting system has certain function of CAM, some process is a must in the PCB light painting machine, such as line width is.
(g) darkroom processing
The film, PCB light painting through developing, fixing treatment shall be used for subsequent working procedure. Darkroom processing, we will strictly control the following link:
Development time: effect in the production of blank optical density (commonly known as black degrees) and contrast. Time is short, the optical density and contrast is not enough; Time is too long, fog.
Fixing time: fixing didn't have enough time, the production of blank background transparent enough.
Don't wash: water washing time is not enough, production blank easy to turn yellow.
Special note: don't scratch release.it film.
Source: //www.seekic.com
