Black copy fault solution in PCB making and exposure process

1. Problem: the width of all wires of the black and white film after turning becomes thin and uneven

Reasons:

(1) Improper selection of exposure process parameters

(2) The quality of the original film is poor

(3) There is a problem with silicon control in the turning process

Solution:

(1) First check whether the positive or negative positive is overexposed and should be corrected according to the actual situation.

(2) Check the optical density of the original film, especially whether the "shading density" is too low.

(3) Check the developer concentration and device.

2. Problem: the width of the wire on the outer edge of the film after turning becomes thin or irregular

Reasons:

(1) The verification of the exposure device is expired

(2) The light source is too close to the larger film

(3) The distance and Angle of the reflector of the light source are misaligned

Solution:

(1) Check again according to the process requirements to check whether the energy of the light source is within the technical requirements

(2) readjust the distance of the light source or use a large exposure machine

(3) readjust the distance and Angle of the "reflection mask"

3. Problems: the resolution of the turned film is not ideal, and the edge of the wire is not sharp

Reasons:

(1) The quality of the original film is not good

(2) The function of the vacuum system of the exposure machine is poor

Solution:

(1) Check the wire edge status of the original film

(2)A: It is especially necessary to check whether the sealing part and the sealing part of the film are sealed

B: In case of insufficient pumping, check whether the pumping hose is damaged

4, the problem: the local resolution of the film after turning is poor

Reasons:

(1) The quality of the original film is not good

(2) The function of the vacuum system of the exposure machine is poor

(3) There are bubbles between the negatives during exposure

Solution:

(1) Check the bad condition of the wire edge of the original film

(2)A: Check the sealing part of the vacuum system and the sealing part of the negatives

B: Check whether there are damaged parts in the air hose

(3) There are ash particles on the surface of the exposure machine, so the pumping system must be strengthened.

5. Problem: insufficient optical density of the film after turning (mainly refers to the insufficient shading degree of the dark area)

Reasons:

(1) The development process of the turned negative is incorrect

(2) Poor storage conditions of original negatives

(3) The function of developing equipment deteriorates

Solution:

(1) Check the developing process conditions and developer concentration

(2) need to be stored in the room that meets the process requirements, especially to avoid the light.

(3) Inspection and repair, especially the temperature and time control system

6. Problem: pinholes or holes appear on the graphic surface of the film after turning

Reasons:

(1) There is dust or particles on the surface of the exposure machine

(2) Poor quality of original film

(3) The substrate quality of the original film is poor

Solution:

(1) The original film and exposure table should be carefully cleaned.

(2) Check the graphic surface state of the original negative. If necessary, you can try to turn over the second negative for comparative inspection

(3) Experimental inspection is carried out to observe whether there are pinholes or holes in the black surface of the dark area after the whole piece is exposed and developed.

7, the problem: after turning the negative circuit graphic deformation

Reasons:

(1) The temperature and humidity of the working environment are incorrect

(2) Incorrect drying process

(3) The pre-processing of the negatives to be turned is not appropriate

Solution:

(1) Operation of ambient temperature and humidity control: temperature 20-27℃, humidity 40-70%RH, high precision film, its operating humidity should be controlled at 55-60%RH.

(2) Place the film horizontally and blow dry, and dry the film with thickness (100um) for 1-2 hours; Dry the 175-micron substrate for 6-8 hours.

(3) It should be placed in the environment of the film room for at least 24 hours for stability treatment

8. Problem: insufficient transparent area of negative or cloudy substrate

Reasons:

(1) There are inclusions in the original negative substrate

(2) The original substrate surface is poor

(3) The quality of the original film is poor

(4) There are problems in the exposure and development process

Solution:

(1) The original film with high resolution and high quality is selected

(2) Ensure that the temperature and humidity of the storage environment are controlled

(3) First of all, the performance and quality of the original film should be tested

(4) Check and adjust the equipment condition, developer solution, fixer solution and process conditions.

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