Deformation Analysis of Thin Films in PCB Process
First of all, the reasons for the deformation of the film and its solution:
(1) Poor temperature and humidity control
(2) The exposure machine temperature rises too high
(1) Generally, the temperature is controlled at 22 ± 2 ° C and the humidity is controlled at 55% ± 5% RH.
(2) Use a cold light source or an aerator with a cooling device and keep replacing the spare film
Second, the process of film deformation correction:
1. Under the conditions of mastering the operation technology of the digital programming device, first compare the negative film with the drilled test plate and measure the length and width of the deformation. On digital programming devices, the length of the deformation is lengthened or shortened depending on the amount of deformation. The test plate drilled after lengthening or shortening the hole position is used to remove the deformed negative film, thereby eliminating the troublesome work of cutting the negative film and ensuring the integrity and accuracy of the graphic. Call this method "Change Hole Position Method."
2. For the physical phenomenon that the negative film changes with the change of ambient temperature and humidity, put the negative film into the sealed bag before copying the negative film, and hang it under working environment for 4-8 hours, so that the negative film is deformed before copying, thereby Make the negative film after copying very small, which is called "drying method".
3. For the pattern with simple lines, wide lines, large spacing and irregular deformation, the deformed part of the negative piece can be cut and re-spliced after controlling the hole position of the punching test board, and then copied, which is called “stitching method”. . .
4. Use the holes on the test board to enlarge the pads to deform the tube to ensure minimum loop width technical requirements. This method is called "pad overlap method".
5. Zoom in on the graphic on the deformed film and reposition the plate to make it a "texture method."
6. Use the camera to zoom in or out of the distorted graphics, which is called the “shooting method”.