What adverse phenomena will occur in PCBA processing?

In the process of processing and production of PCBA, there may be some errors in operation, leading to the adverse phenomenon of the patch. So, what adverse phenomena will occur in PCBA processing?

1. Tilt up

Causes: the size of both sides of the copper platinum produced uneven tension; The preheating rate is too fast; Machine mounting offset; Uneven solder paste printing thickness; Uneven temperature distribution in the back welding furnace; Solder paste printing offset; Machine track splint is not tight resulting in mounting deviation.

2. Short circuit

Causes: the spacing between steel mesh and PCB board is too large, resulting in thick solder paste printing, resulting in short circuit; Too low component mounting height will squeeze the solder paste resulting in short circuit; High temperature of backwelding furnace leads to short circuit; Component mounting offset resulting in short circuit; The opening of steel mesh is not good (too thick, too long pin opening, too large opening), resulting in short circuit, etc.

3. Offset

Cause: the positioning reference point on the circuit board is not clear; The positioning datum point on the circuit board and the datum point of the grid board are not aligned; Circuit board in the printing press fixed clamping loose, positioning thimble is not in place.

4. Missing parts

Causes: vacuum pump carbon sheet poor vacuum is not enough to cause the lack of parts; Plug or bad suction nozzle; Improper component thickness detection or bad detector; Mounting height is set improperly, etc.

5, air welding

Causes: the activity of tin paste is weak; Steel mesh opening is not good; Copper platinum spacing is too large or large copper paste small components; Scraper pressure is too large; Element foot flatness is not good (foot warping, deformation) back welding furnace preheating area too fast.