Causes and solutions of erection and displacement of products after SMT placement

2022-08-13 109

Causes and countermeasures

(1)PCB design-the size of two pads is asymmetric, and the pad spacing is too large or too small, which means that one end of the component cannot touch the pad U. Design according to the pad design principle of CHIP components, and pay attention to the symmetry and pad spacing of the pads.

(2) Patch quality-position deviation; The component thickness setting is incorrect; The Z-axis height of the mounting head is too high (the mounting pressure is low), and when mounting, the components are dropped from a height, which causes U to improve the mounting accuracy and accurately adjust the mounting accuracy of the first piece; U Correct mounting coordinates in time when position deviation is found during continuous production;

U Set the correct component thickness and mounting height.

(3) Component quality-the welding end is oxidized or polluted or the adhesion of the terminal electrode is poor. When the end of the welding element is not wet or the end electrode falls off, U strict incoming inspection system U strict first piece welding inspection.

U Check the components after each replacement, and replace the components in time if any problems are found.

(4)PCB quality-the pads are contaminated (there are silk screens, characters, solder mask or oxidation, etc.) u Strict incoming inspection system, and the silk screens and characters on the processed PCB pads can be gently scraped off with a knife.

(5) Printing process-the amount of solder paste in the two pads is inconsistent. U Clean the solder paste in the template leakage hole, and wipe the bottom of the template frequently during printing; If the U opening is too small, the opening size should be enlarged.

(6) Whether the conveyor belt vibrates and causes the components to move, u If the conveyor belt is too loose, remove 1 ~ 2 chains, u check whether the connecting height and distance of the guide rails at the entrance and exit of PCB board match;

U Manually place PCB with care.

(7) whether the air volume is too large u adjust the air volume