In the process of PCBA processing and production, some operational errors may lead to bad phenomena in the patch. So, what adverse phenomena will occur in PCBA processing?
1. Stand up
Causes: Uneven tensile force caused by different sizes on both sides of copper and platinum; too fast preheating rate; machine mounting offset; uneven tin printing thickness; uneven temperature distribution in the reflow furnace; tin printing offset; The lack of tightness of the machine track splint leads to mounting deviation, etc.
2. Short circuit
Causes: The distance between the steel mesh and the PCB board is too large, resulting in too thick solder paste printing, resulting in a short circuit; the component mounting height is set too low and the solder paste is squeezed, resulting in a short circuit; the reflow oven temperature rises too fast, resulting in a short circuit; component placement offset Cause short circuit; poor steel mesh opening (thickness is too thick, pin opening is too long, opening is too large) lead to short circuit, etc.
3. Offset
Causes: 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 on the screen; the fixed clamping of the circuit board in the printing machine is loose, and the positioning thimble is not in place, etc.
4. Missing parts
Causes: The carbon sheet of the vacuum pump is poor and 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 properly detected or the detector is not good;
5. Empty welding
Causes: Weak activity of solder paste; poor stencil opening; too large copper-platinum spacing or large copper paste small components; too much scraper pressure; Hot zone heats up too quickly etc.
