The main reasons and countermeasures for PCBA missing parts

It is normal for the SMT machine to have PCBA missing parts, but if the PCBA missing parts rate is high, it will seriously affect the production efficiency and production cost, and must be solved.

Reason 1: Nozzle problem, such as deformation, blockage, and damage of the nozzle, resulting in insufficient air pressure and air leakage, resulting in the inability to suck the material, incorrect material picking, and PCBA component missing due to failure in identification.

Countermeasures: Clean and replace the nozzle;

Reason 2: Feeder problem, incorrect feeder setting, position deformation, and poor feeding mechanism cause the material to be unable to be picked up or the material is not picked up properly, resulting in PCBA material throwing.

Countermeasures: Reset the feeder, clean the equipment, calibrate or replace the feeder.

Reason 3: Identification system problem, poor vision, unclean vision or laser lens, foreign matter interfering with identification, improper selection of identification light source or insufficient intensity and grayscale, and it is also possible that the identification system is broken.

Countermeasures: Clean and wipe the surface of the recognition system, keep it clean without foreign matter, oil interference, etc., adjust the light source intensity and grayscale, and replace the recognition system components;

Reason 4: Position problem, position offset, the nozzle is not in the center of the material when picking up the material, the material picking height is incorrect (generally based on pressing down 0.05mm after touching the part), causing deviation, incorrect material picking, offset, and inconsistent with the corresponding data parameters during identification, and the recognition system treats it as invalid material and discards it.

Countermeasures: Adjust the material picking position, height and other parameters;

Reason 5: Vacuum problem, insufficient air pressure, the vacuum air pipe channel is not smooth, foreign matter blocks the vacuum pipe, or there is a vacuum leak causing insufficient air pressure and the material cannot be picked up or it falls on the way to paste after picking up.

Countermeasures: Adjust the air pressure steep slope to the required air pressure value of the equipment (generally the requirement of the SMT machine is 0.5~~0.6Mpa), clean and clear the air pressure pipeline, and repair the leaking air path;

Reason 6: SMT program problem, the component parameters in the edited program are incorrectly set, and the parameters such as the actual size and brightness of the incoming material are inconsistent, resulting in the recognition failure and being discarded.

Countermeasures: Modify the component parameters and search for the best parameter values of the components;

Reason 7: Incoming material problem, non-standard incoming materials, or unqualified products such as oxidation of incoming material pins.

Countermeasures: IQC should do a good job of incoming material inspection and contact the component supplier;

Reason 8: Feeder problem, feeder deformation, poor feeder feeding (feeder ratchet gear is damaged, the material belt hole is not stuck on the ratchet gear of the feeder, there is a foreign object under the feeder, the spring is aging, the force is insufficient, or the electrical is poor), resulting in the failure to pick up the component or the poor component picking and PCBA missing, and the feeder is damaged.

Countermeasures: calibrate the feeder, clean the feeder platform, replace the damaged parts or feeder; According to relevant research, static electricity is also a cause of PCBA parts missing, so the placement machine must be well grounded and anti-static work must be done at the production site.

It is normal for the placement machine to have PCBA missing parts, but if the missing parts rate is high, it will seriously affect the production efficiency and production cost, and must be solved. When there is a serious PCBA missing parts phenomenon, you can first ask the on-site personnel, through the description, and then observe and analyze according to the above seven reasons to find the problem directly, so that it can more effectively find the cause and solve it, while improving production efficiency and not occupying too much machine production time.