PCBA board copying decryption production PCBA clone replication

Analysis of Film Deformation in PCB Process

1、 Reasons and solutions for film deformation: Reasons:

(1) Temperature and humidity control malfunction

(2) Exposure machine temperature rise too high

Solution:

(1) Normally, the temperature is controlled at 22 ± 2 ℃ and the humidity is 55% ± 5% RH.

(2) Using cold light sources or exposure machines with cooling devices and constantly replacing backup films

2、 The process method for correcting film deformation:

1. After mastering the operation technology of the digital programming instrument, first install the film and compare it with the drilling test board to measure its length and width deformation. On the digital programming instrument, lengthen or shorten the hole position according to the size of the deformation, and use the drilling test board after lengthening or shortening the hole position to match the deformed film, eliminating the tedious work of splicing the film and ensuring the integrity and accuracy of the graphics. This method is called "changing the hole position method".

2. In response to the physical phenomenon that the film changes with the temperature and humidity of the environment, the film is taken out of the sealed bag before copying, and hung for 4-8 hours under working environment conditions to deform the film before copying. This will cause minimal deformation of the copied film, known as the "hanging method".

3. For graphics with simple lines, large line widths and spacing, and irregular deformation, the method of "splicing" can be used by cutting the deformed part of the film and reconnecting the hole positions of the reference drilling test board before copying.

4. The method of using the holes on the test board to enlarge the circuit board and remove the heavy deformation of the solder pads to ensure the minimum ring width technical requirements is called the "solder pad overlap method".

5. The method of enlarging the graphics on the deformed film proportionally and then remapping and making a plate is called the "mapping method".

6. The method of using a camera to enlarge or shrink deformed graphics is called "imaging method".

3、 Notes on relevant methods:

1. Splicing method: applicable to films with less dense lines and inconsistent deformation of each layer of film; It is particularly suitable for the deformation of solder mask film and multi-layer board power supply layer film; Not applicable: negative films with high wire density, line width and spacing less than 0.2mm; Attention: During splicing, it is advisable to minimize damage to the wires and avoid damaging the solder pads. When editing after splicing and copying, attention should be paid to the correctness of the connection relationship.

2. Change hole position method: Applicable: The deformation of each layer of film is consistent. This method is also applicable to films with dense lines; Not applicable: The film deformation is uneven, and local deformation is particularly severe. Attention: After using a programmer to lengthen or shorten the hole position, the hole position that exceeds the tolerance should be reset.

3. Hanging method: applicable; The film that has not yet been deformed and prevents deformation after copying; Not applicable: Deformed film. Attention: Hang the film in a well ventilated and dark environment (if safe) to avoid contamination. Ensure that the temperature and humidity of the hanging area are consistent with that of the work area.

4. Pad overlap method: applicable: the graphic lines are not too dense, and the line width and spacing are greater than 0.30mm; Not applicable: Especially when users have strict requirements for the appearance of printed circuit boards; Note: Due to overlapping copies, the solder pads will appear elliptical. The halo and deformation at the edges of the line and disk after overlapping copies. 5. Photography method: Applicable: When the deformation ratio in the length and width directions of the film is consistent, and it is inconvenient to drill the test plate again, only silver salt film is suitable. Not applicable: Inconsistent deformation in the length and width directions of the film. Attention: During photography, the focus should be accurate to prevent line deformation. There is a significant amount of film loss, and in general, multiple adjustments are required to obtain satisfactory circuit graphics.