What are the adverse phenomena in PCBA processing?
In the process of PCBA processing and production, some errors in operation may lead to poor patch phenomenon. So, what are the undesirable phenomena in PCBA processing?
1, stand upright
Causes: uneven tension on both sides of copper and platinum; too fast preheating heating rate; machine placement offset; uneven thickness of solder paste printing; uneven temperature distribution in the reflow oven; solder paste printing offset; The machine track splint is not tight, resulting in placement offset, etc.
2, short circuit
Causes: Too large distance between stencil and PCB board leads to too thick solder paste printing and short circuit; component mounting height is set too low to squeeze solder paste and cause short circuit; reflow oven heats up too fast, resulting in short circuit; component placement offset Lead to short circuit; poor stencil opening (too thick thickness, too long pin opening, too large opening) lead to short circuit, etc.
3, offset
Causes of : The positioning reference point on the circuit board is not clear; the positioning reference point on the circuit board is not aligned with the reference point of the stencil; the fixed clamp of the circuit board in the printing machine is loose, and the positioning thimble is not in place, etc.
4, missing parts
Causes of : The vacuum pump is not good enough, the vacuum is not enough to cause missing parts; the suction nozzle is blocked or the suction nozzle is bad; the thickness of the component is not detected properly or the detector is bad; the mounting height is not set properly, etc.
5, empty welding
Causes: weak solder paste activity; poor stencil opening; too large copper-platinum spacing or large copper paste small components; too much scraper pressure; poor flatness of component feet (upset, deformation) The hot zone heats up too fast, etc.
1, stand upright
Causes: uneven tension on both sides of copper and platinum; too fast preheating heating rate; machine placement offset; uneven thickness of solder paste printing; uneven temperature distribution in the reflow oven; solder paste printing offset; The machine track splint is not tight, resulting in placement offset, etc.
2, short circuit
Causes: Too large distance between stencil and PCB board leads to too thick solder paste printing and short circuit; component mounting height is set too low to squeeze solder paste and cause short circuit; reflow oven heats up too fast, resulting in short circuit; component placement offset Lead to short circuit; poor stencil opening (too thick thickness, too long pin opening, too large opening) lead to short circuit, etc.
3, offset
Causes of : The positioning reference point on the circuit board is not clear; the positioning reference point on the circuit board is not aligned with the reference point of the stencil; the fixed clamp of the circuit board in the printing machine is loose, and the positioning thimble is not in place, etc.
4, missing parts
Causes of : The vacuum pump is not good enough, the vacuum is not enough to cause missing parts; the suction nozzle is blocked or the suction nozzle is bad; the thickness of the component is not detected properly or the detector is bad; the mounting height is not set properly, etc.
5, empty welding
Causes: weak solder paste activity; poor stencil opening; too large copper-platinum spacing or large copper paste small components; too much scraper pressure; poor flatness of component feet (upset, deformation) The hot zone heats up too fast, etc.