Analysis Of The Deformation Of The Bottom Plate In PCB Process

- Jan 26, 2018-

1. The cause and solution of the deformation of the film:


Reason:


(1) malfunction of temperature and humidity control


(2) the temperature rise of the exposure machine is too high


Resolvent:


(1) under normal conditions, the temperature control is 22 + 2 C, and the humidity is 55% + 5%RH.


(2) use the cold light source or the aerator with the cooling device and replace the backup film continuously.


Two. The process method of the deformation correction of the bottom film:


In 1, operation technology to master the situation of digital programming instrument, first put film and drilling test board control, measure the length and width of the two deformation in the digital programming instrument according to the deformation amount of lengthen or shorten the hole position should be shortened to drilling hole deformation test plate after long use or the film from the film, splicing the troublesome work, ensure the integrity and accuracy of graphics. This method is called "change the hole position method".


2, according to the physical phenomenon of negative change with the environmental temperature and humidity changes, take the film before the seal bag will copy the film out of work, under the condition of hanging 4-8 hours, the film in the copy before deformation, which will make a copy of the film deformation is small, the method of "hanging method".


3, for the simple line, line width and spacing of larger deformation, irregular graphics, can be used to cut part of film deformation control drilling test plate hole re connecting to copy, "said the splicing method".


4. Use the hole on the test plate to lay heavy welded plate to deform the wire to ensure the minimum ring width technical requirement, which is called the "welding disk overlap method".


5. After enlarging the shape of the deformed negatives in proportion, we re map the plate to make the plate, which is called "the mapping method".


6, the camera will deformation graphics zoom in or out, which is called the "photographic method".


Three, related methods of attention:


1. The splicing method:


Application: the negative line is not too dense and the deformation of the bottom film of each layer is not consistent; it is especially suitable for the deformation of the resistance welding plate and the layer plate of the multi-layer plate power supply.


Not applicable: the film with high conductor density, line width and less than 0.2mm;


Note: cut the wire as little as possible when cutting, and do not hurt the weld plate.  The correctness of the connection should be paid attention to when the copy is repaired.


2. Change the hole position method:


Application: the deformation of the bottom film of each layer is consistent. This method is also suitable for line - intensive negatives.


It is not applicable: the deformation of the film is not uniform, and the local deformation is particularly serious.


Note: after using the programming instrument to lengthen or shorten the hole position, the hole position of the super difference should be rearranged.


3. Air hanging method:


Applicable; a negative film that has not been deformed and deformed after a copy;


Not applicable: deformed negatives.


Note: air and dark (safe and easy) environment to hang the film, to avoid and pollution. Ensure that the air and air is in accordance with the temperature and humidity of the working place.


4. The overlap method of pads:


Application: the graph line is not too dense, the line width and the distance are more than 0.30mm;


Not applicable: in particular, users have strict requirements on the appearance of printed circuit boards;


Note: the plate is elliptical because of duplication. After duplication, the halo and deformation of the edge of the line and disc.


5. The image method:


For the negative direction of length and width ratio of deformation, inconvenient redrilled test plate, only for silver halide film.


Not applicable: the deformation of the film is not consistent in the direction of length and width.


Note: the focus should be accurate when the image is taken to prevent the lines from deforming. The loss of the film is more. In general, it is necessary to get the satisfactory circuit graphics after many debugging.


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