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Analysis of Surface Mount Defects in PCBA
During the PCBA SMT production process, operational errors can easily lead to various defects such as poor solder joints, short circuits, warping, missing components, solder balls, bent pins, high floating, incorrect placement, cold solder joints, reversed placement, reversed sides, offsetting, component damage, insufficient solder, excessive solder, poor solder joints on gold fingers, and excess glue. These defects require analysis and improvement to enhance product quality.
During PCBA SMT production, operational errors can easily lead to PCBA technical assembly defects such as cold solder joints, short circuits, warping, missing components, solder balls, bent pins, high floating, misalignment, cold soldering, reversed placement, reversed sides, offset, component damage, insufficient solder, excessive solder, gold finger cold solder joints, and excess glue. These defects require analysis and improvement to enhance product quality.
PCBA design solder voids
Weak red glue specificity; poor stencil aperture; excessive distance between copper foils or large solder paste sticking to small components; excessive squeegee pressure; poor component flatness (bent or deformed pins); too rapid heating in the reflow oven preheating zone; excessively dirty or oxidized copper foil in the PCB; PCB board contains moisture; SMT machine mounting shift; red glue printing offset; loose machine clamp track causing component mounting shift; misalignment of alignment points causing component offset, resulting in solder voids.
PCBA design solder short circuit
Excessive distance between the stencil and the PCB design board, excessively thick red glue printing, causing short circuits; excessively low component mounting height, squeezing the red glue causing short circuits; too rapid reflow oven heating; component mounting offset; poor stencil aperture (excessive thickness, excessively long pin aperture, excessively large aperture); red glue unable to withstand component weight; stencil or squeegee deformation causing excessively thick red glue printing; strong red glue specificity; empty sticky glue paper roll-up, causing excessively thick red glue printing around the components; large vibration or unlevelness during reflow soldering.
PCBA design solder warping
Uneven tension caused by different sizes of copper pads on both sides; too rapid heating, uneven red glue printing thickness; component mounting offset; uneven temperature distribution in the reflow oven; red glue printing offset; loose machine track fixture causing mounting offset; machine head shaking; excessively strong red glue specificity; improper furnace temperature setting; excessive distance between copper pads; misalignment of alignment points causing component mounting offset.
PCBA design missing components
Poor vacuum pump carbon film or insufficient vacuum causing component leakage; nozzle blockage or nozzle malfunction; improper or faulty component thickness detection; improper component mounting height; excessive or no nozzle air blowing; improper nozzle vacuum setting (applicable to MPA); excessively fast mounting speed for irregular components; broken machine head air tube; worn air valve sealing ring; foreign objects on the reflow oven guide rail wiping off components from the board.
PCBA design solder solder balls
Insufficient reflow soldering preheating, too rapid heating; incomplete reheating of red glue after cooling; red glue moisture causing splashing (excessive indoor humidity); excessive moisture in the PCB design board; excessive thinner addition; poor stencil aperture design; uneven solder powder particles.
PCBA design solder offset
Unclear positioning reference points on the circuit board; misalignment of positioning reference points on the circuit board and reference points on the stencil; loose circuit board fixing fixture in the printing machine, positioning die locating pin not in place; malfunction of the printing machine optical positioning system; solder paste leakage does not meet the stencil opening and circuit board design document requirements. Improving defects in PCBA technical mounting requires strict inspection at each stage to prevent problems from flowing from one process to the next as much as possible.
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