How to deal with PCB deformation? Can it be restored?
PCB manufacturers, PCB designers and PCBA manufacturers explain how to deal with PCB deformation? Can it be restored?
For pcb board copying, a little carelessness may lead to deformation of the bottom plate. If it is not improved, it will affect the quality and performance of pcb board copying. If it is discarded directly, it will cause cost loss. Here are some methods to correct the deformation of the floor.
01 - splICing method
For graphics with SIMple lines, large line width and spacing, and irregular deformation, cut the deformed part of the negative film, and then re splice it against the hole position of the drilling test plate, and then copy it. Of course, this is for graphics with simple deformation lines, large line width and spacing, and irregular deformation; It is not applicable to films with high conductor density, line width and spacing less than 0.2mm. During splicing, pay attention to minimize the damage to the wire and the bonding pad. When splicing copies for revision, pay attention to the correctness of the connection relationship. This method is applicable to the films with less dense lines and inconsistent deformation of each layer of negative film, especially for the correction of resistance welding negative film and multilayer power supply layer negative film.
02 - Method of changing hole position for PCB copy
Under the condition of mastering the operation technology of the digital programming instrument, first compare the negative film with the drilling test plate, measure and record the length and width of the drilling test plate, then adjust the hole position on the digital programming instrument according to the two deformations of the length and width, and adjust the drilling test plate to meet the deformed negative film. The advantage of this method is that it avoids the tedious work of splicing negative films, and can ensure the integrity and accuracy of graphics. The disadvantage is that the correction of the film with very serious local deformation and uneven deformation is not effective. To use this method, first of all, you should master the operation of the digital programmer. After using the programmer to lengthen or shorten the hole position, you should reset the out of tolerance hole position to ensure accuracy. This method is applicable to the correction of the film with dense lines or the film with consistent deformation of each layer.
03 - Overlapping pad method
Enlarge the hole on the test board into a pad to overlap the deformed circuit piece, so as to ensure the minimum ring width technical requirements. Because after overlapping copy, the pad is elliptical. After overlapping copy, the halo and deformation of the line and disk edge. If the user has very strict requirements on the appearance of PCB, please use it with caution. This method is applicable to films with line width and spacing greater than 0.30mm and less dense graphic lines.
04 - Photographic method
Just use the CAMera to enlarge or reduce the deformed figure. Generally, the negative film has a lot of loss, and it requires multiple debugging to obtain a satisfactory circuit diagram. Focus accurately when taking pictures to prevent line deformation. This method is only applicable to silver salt films. It can be used when it is inconvenient to drill the test plate again and the deformation ratio of the film in the length and width directions is consistent.
05 - Hanging method
In view of the physical phenomenon that the negative film changes with the change of ambient temperature and humidity, take it out of the seaLED bag before copying the negative film, and hang it in the working environment for 4-8 hours, so that the negative film has been deformed before copying, then the probability of deformation is very SMAll after copying.
For the deformed film, other methods shall be adopted. Because the negative film will change with the change of ambient temperature and humidity, when hanging the negative film, it is necessary to ensure that the humidity and temperature of the hanging place are consistent with that of the operation place, and it is necessary to be in a ventilated and dark environment to prevent the negative film from being polluted. PCB manufacturers, PCB designers and PCBA manufacturers explain how to deal with PCB deformation? Can it be restored?